The choice of phorbol 12-myristate 13-acetate differentiation protocol influences the response of THP-1 macrophages to a pro-inflammatory stimulus

Human PTGR2 Inactivation Alters Eicosanoid Metabolism and Cytokine Response of Inflammatory Macrophages

Prostaglandin reductase 2 (PTGR2) regulates inflammatory lipid signaling through the metabolism of the PGE2 metabolite 15-keto-PGE2. PTGR2 inhibitors have been reported but whether small molecule inactivation can recapitulate the anti-inflammatory phenotype observed in PTGR2 knockout systems has not been explored. Here, we disclose an optimized sulfonyl triazole (SuTEx) inhibitor of human PTGR2 that blocks biochemical activity by liganding the noncatalytic tyrosines Y100 and Y265 in the active site. Quantitative and multiplexed chemoproteomics verified covalent engagement of endogenous PTGR2 in THP1 macrophages with moderate proteome-wide selectivity. PTGR2 inactivation with the SuTEx inhibitor resulted in suppression of secreted inflammatory lipids and TNF-α in lipopolysaccharide (LPS)-stimulated macrophages. Collectively, our findings identify a potent covalent inhibitor of human PTGR2 that can serve as a tool compound for exploring lipid metabolism and signaling in macrophages.

N-terminomics and proteomics analysis of Calpain-2 reveal key proteolytic processing of metabolic and cell adhesion proteins

Aberrant levels of the cysteine protease Calpain-2 have been linked to neurodegeneration, inflammation, and cancer, yet our understanding of this protease and its substrates remains limited. Systematic studies to identify Calpain-2 substrates have been largely confined to peptide libraries or in vitro studies, which fail to represent physiological cellular conditions and physiologically relevant substrates. To identify existing and novel Calpain-2 substrates, we used a genetic approach to knockout Calpain-2 in the THP-1 human monocyte-like cells, followed by proteomic and N-terminomic/TAILS mass spectrometry approaches to identify Calpain-2 substrates. We identified 51 substrates that may be cleaved directly by Calpain-2 or indirectly by downstream proteases. The direct cleavage of selected substrates by Calpain-2 was confirmed using in vitro assays. Finally, metabolomics analysis identified a role for Calpain-2 in the regulation of pyrimidine and glutathione metabolism. Our unbiased and quantitative mass spectrometry analytical pipeline provides new evidence on the physiological functions of Calpain-2 and its newly identified substrates in THP-1 cells.

Macrophage-to-Myofibroblast Transition Contributes to Cutaneous Scarring Formation Through the TGF-β/Smad3 Signaling Pathways

Cutaneous scarring typically arises after surgery, trauma, and infection, occurring when normal skin tissue is replaced by fibrous tissue during the healing process. Myofibroblasts have been identified as a significant contributor to this scarring. While the differentiation of fibroblasts into myofibroblasts is well-recognized as essential for wound healing and tissue repair, the mechanisms underlying the macrophage-myofibroblast transition (MMT) remain largely unexplored. This study aimed to investigate the role and potential mechanisms of MMT in cutaneous scarring. In specimens of hypertrophic scars, keloid and scleroderma, we confirmed the coexistence of MMT markers CD68 and α-smooth muscle actin (α-SMA) in areas of skin fibrosis. Additionally, most MMT cells in human cutaneous scar co-expressed the M2-type macrophage marker CD206. Fate-mapping in Lyz2-Cre/Rosa26-tdTomato mice further demonstrated that the majority of myofibroblasts in cutaneous scars were derived from bone marrow macrophages. Furthermore, higher levels of TGF-β were released from scar fibroblasts, which contributed to MMT through the Smad3 pathways. In vivo studies inhibiting Smad3 reduced MMT and scarring. Macrophage depletion with clodronate liposomes also reduced cutaneous scar formation. Our findings indicate that MMT plays a pivotal role in cutaneous scarring through the TGF-β/Smad3 pathways. Consequently, inhibiting MMT may be a novel strategy for the treatment of cutaneous scarring.

TREM-1-Linked Inflammatory Cargo in SARS-CoV-2-Stimulated Macrophage Extracellular Vesicles Drives Cellular Senescence and Impairs Antibacterial Defense

The COVID-19 pandemic, caused by SARS-CoV-2, has significantly affected global health, with severe inflammatory responses leading to tissue damage and persistent symptoms. Macrophage-derived extracellular vesicles (EVs) are involved in the modulation of immune responses, but their involvement in SARS-CoV-2-induced inflammation and senescence remains unclear. Triggering receptors expressed on myeloid cell-1 (TREM-1) are myeloid cell receptors that amplify inflammation, described as a biomarker of the severity and mortality of COVID-19. This study investigated the composition and effects of macrophage-derived EVs stimulated by SARS-CoV-2 (MφV-EVs) on the recipient cell response. Our results, for the first time, show that SARS-CoV-2 stimulation modifies the cargo profile of MφV-EVs, enriching them with TREM-1 and miRNA-155 association, along with MMP-9 and IL-8/CXCL8. These EVs carry senescence-associated secretory phenotype (SASP) components, promote cellular senescence, and compromise antibacterial defenses upon internalization. Our findings provide evidence that MφV-EVs are key drivers of inflammation and immune dysfunction, underscoring their potential as therapeutic targets in COVID-19.

Identification of Tie2 as a sensor for reactive oxygen species and its therapeutic implication

Psoriasis is a chronic inflammatory disease characterized by hyperproliferation of keratinocytes and abnormal blood vessels. As hyperproliferation is driven by pro-inflammatory cytokines produced by activated immune cells, therapeutic strategies often target these cytokines to manage the disease. However, the role of abnormally developed blood vessels has often been overlooked in treatment approaches. In this study, we focused on blood vessels in psoriatic lesions and investigated the potential interplay between immune and endothelial cells by adopting imiquimod treated mice as in vivo model, together with various cell biological, biochemical, and structural analyses. We found that activated immune cells can generate reactive oxygen species, subsequently inducing oxidative stress in endothelial cells. Oxidative stress impairs endothelial cell layer integrity, thereby facilitating transendothelial migration of immune cells. Mechanistically, oxidative conditions inhibit Tie2 activation, potentially by modifying its cysteine residues, leading to deactivation of its vessel-stabilizing functions. Additionally, we demonstrated that reactivating Tie2 under such conditions could restore endothelial barrier function and alleviate the disease. These results suggest that Tie2 serves as a receptor that is directly responsive to oxidative environments, thereby modulating its kinase activity. Furthermore, we suggest that Tie2 reactivation is a promising alternative therapeutic approach for psoriasis.

Human dermal fibroblast senescence in response to single and recurring oxidative stress

Introduction: Aging results in an accumulation of damaged cells, which reduces the health of tissues and their regenerative capabilities. In the skin, there are both internal and external drivers of oxidative stress that result in aging phenotypes. Oxidative stress has been used to model senescence in vitro; however, there has been a lack of research determining whether the severity of oxidative stress correlates with senescent phenotypes. Methods: In this work, we compare cellular and secretory responses to a single (500 μM hydrogen peroxide, 2 hours) or recurring dose of hydrogen peroxide (500 μM hydrogen peroxide, 2 hours + 4 × 300 μM hydrogen peroxide each 48 hours). Senescence induction was studied using markers including cell morphology, senescence-associated-beta-galactosidase, absence of apoptosis, and cell cycle inhibition genes. Next, functional studies of the effects of the signaling of these cells were completed, such as vascular potential, keratinocyte proliferation, and macrophage polarization. Results: Fibroblasts exposed to both single and recurring oxidative stress had increased total cell and nucleic area, increased senescence-associated-beta-galactosidase (SABGAL) expression, and they were able to escape apoptosis - all characteristics of senescent cells. Additionally, cells exposed to recurring oxidative stress expressed increased levels of cell cycle inhibitor genes and decreased expression of collagen-I, -III, and -IV. Cytokine profiling showed that the single stressed cells had a more inflammatory secretory profile. However, in functional assays, the recurring stressed cells had reduced vascular potential, reduced keratinocyte proliferation, and increased IL-1β gene expression in unpolarized and polarized macrophages. Discussion: The described protocol allows for the investigation of the direct effects of single and recurring oxidative stress in fibroblasts and their secretory effects on surrounding healthy cells. These results show that recurringly stressed fibroblasts represent a more intense senescent phenotype, which can be used in in vitro aging studies to understand the severity of senescent responses.

Combining in vitro, in vivo, and in silico approaches to evaluate the effect of serotonergic-based topical therapies on mild to moderate psoriasis

Psoriasis, a chronic inflammatory skin disease, poses a significant burden on patients' quality of life and healthcare systems. While mild-to-moderate cases are treated topically, usually combined with phototherapy, severe cases require systemic treatment with immunosuppressants, retinoids or biologics. However, all available treatments have drawbacks in terms of efficiency and side effects. Drawing from studies linking depression treatment to psoriasis improvement, we investigated whether topical formulations of selective serotonin reuptake inhibitors (SSRIs) could offer a viable therapy for psoriasis. Five SSRIs (sertraline, fluoxetine, paroxetine, escitalopram, fluvoxamine) were evaluated for their in vitro cytotoxicity, in human keratinocytes and THP-1 monocytes. Their anti-inflammatory action was tested using cell differentiation assays and immunoassays of pro-inflammatory cytokines in THP-1 monocytes. The results obtained with sertraline, escitalopram, and fluvoxamine suggested further evaluation in vivo. Anti-inflammatory effects were evaluated by skin parameter monitoring and histopathology, in an imiquimod-induced psoriasis-like inflammation mice model, and the best results were obtained for fluvoxamine. These findings were further supported by in silico molecular docking studies of the structural interaction between the serotonergic receptors and the drugs. Future research will focus on developing and characterizing of topical fluvoxamine formulations, like emulsions and penetration-enhancer vesicles, which offer advantages over the gels used herein.

High-resolution targeted mass spectrometry for comprehensive quantification of sphingolipids: clinical applications and characterization of extracellular vesicles

Sphingolipids (SL), a class of membrane lipids, play important roles in numerous biological processes. Their significant structural diversity poses challenges for accurate quantification. To address this, liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) has emerged as a powerful tool for sphingolipidomics, capable of profiling these lipids comprehensively. In this study, we utilized LC-MS/MS with high-resolution mass spectrometry (MRMHR) to develop a targeted method for the identification and quantification of various SL species. This method, based on validated parameters such as precursor/fragment ions (m/z) and retention time, demonstrated high sensitivity and accuracy, successfully identifying SL species across 12 distinct classes. Its open-panel design also facilitates the analysis of new SL-species targets. Notably, using this approach, we identified 40 SL species in plasma samples from COVID-19 patients, and we determined the influence of matrix metalloproteinase-3 (MMP-3) expression on the positive downstream of SL metabolism. Beyond plasma analysis, this method has potential applications in other biomedical contexts, such as extracellular vesicles (EVs), describing the cargo of sphingosine-1-phosphate (S1P) on macrophage-derived EVs. The establishment of this targeted workflow enabling precise quantification of a wide range of SL species, holds promise for identifying novel biomarkers and therapeutic targets.

Identification of amino acid metabolism‑related genes as diagnostic and prognostic biomarkers in sepsis through machine learning

Previous research has highlighted the critical role of amino acid metabolism (AAM) in the pathophysiology of sepsis. The present study aimed to explore the potential diagnostic and prognostic value of AAM-related genes (AAMGs) in sepsis, as well as their underlying molecular mechanisms. Gene expression profiles from the Gene Expression Omnibus (GSE65682, GSE185263 and GSE154918 datasets) were analyzed. Based on weighted gene co-expression network analysis and machine learning algorithms, hub AAMGs were identified in the GSE65682 database. Subsequently, hub AAMGs were evaluated for their expression levels and diagnostic and prognostic significance in sepsis, as well as their interactions with regulatory pathways and role in immune cell infiltration. Additionally, trends in AAMG expression were validated using clinical samples, and their functions in sepsis were confirmed through an in vitro model. In total, four AAMGs were identified, two of which, methionine synthase (MTR) and methionine-R-isomerase 1 (MRI1), demonstrated significant differential expression in the GSE65682, GSE185263 and GSE154918 datasets, which was further validated using clinical samples. A diagnostic nomogram based on MTR and MRI1 expression demonstrated strong diagnostic effectiveness across the three aforementioned databases. Moreover, the expression of both genes were negatively correlated with sepsis prognosis and showed stratified prognostic capabilities. Newly identified pathways included KRAS and IL-2/STAT5 signaling. MTR and MRI1 negatively correlated with the infiltration of inflammatory cells, such as M1 macrophages and neutrophils, and positively correlated with anti-inflammatory cells, such as CD8+ T and dendritic cells. In vitro experiments further demonstrated that overexpression of MTR could mitigate the inhibition of cloning and proliferation induced by LPS and ATP in RAW 264.7 cells. These findings highlighted the potential of MTR and MRI1 as biomarkers for diagnosing and prognosticating sepsis, potentially acting through the regulation of methionine in the pathophysiology of this disease. The present study provided new insights into the role of AAM in the mechanisms underlying sepsis and in the potential development of future targeted therapies.

Screening and identification of host signaling pathways for alleviating influenza-induced production of pro-inflammatory cytokines, IP-10, IL-8, and MCP-1, using a U937 cell-based influenza model

Influenza virus infection initiates an exaggerated inflammatory response, which may culminate in a fatal cytokine storm characterized by the excessive production of pro-inflammatory cytokines. Prior research indicates that IP-10, IL-8, and MCP-1, primarily produced by monocytes and macrophages, play a crucial role in influenza-induced inflammation. The lung injury from influenza virus infection can be mitigated by suppressing or inhibiting these cytokines through knockout, knockdown, or targeted intervention approaches. To identify the key host signaling pathways responsible for producing pro-inflammatory cytokines, we utilized a U937 cell model that secretes IP-10, IL-8, and MCP-1 in response to influenza infection. This model has been previously validated in our laboratory as an appropriate system for screening anti-inflammatory agents and potential drug targets. We conducted a screening assay employing an inhibitor library consisting of 2,138 compounds that target various known pathways and host factors. Our findings indicated that inhibitors targeting protein tyrosine kinases and mitogen-activated protein kinases demonstrated superior efficacy in suppressing cytokine production induced by influenza A virus infection compared to inhibitors aimed at other host factors. Notably, a substantial proportion of the identified hits capable of inhibiting the expression of all three cytokines in the secondary screening were classified as tyrosine kinase inhibitors. Validation experiments further established that Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathways, along with p38 MAPK and Raf-MEK-ERK pathways, are the principal regulators of pro-inflammatory cytokine expression in monocytes and macrophages. Moreover, our results suggest that TKIs present promising opportunities as novel therapeutic agents against influenza-induced pneumonia.

Serotonin receptor 5-HT7 modulates inflammatory-associated functions of macrophages

The hormone and neurotransmitter serotonin regulates numerous physiological functions within the central nervous system and in the periphery upon binding to specific receptors. In the periphery, the serotonin receptor 7 (5-HT7R) is expressed on different immune cells including monocytes and macrophages. To investigate the impact of 5-HT7R-mediated signaling on macrophage properties, we used human THP-1 cells and differentiated them into pro-inflammatory M1- and anti-inflammatory M2-like macrophages. Pharmacological 5-HT7R activation with the specific agonist LP-211 especially modulates morphology of M1-like macrophages by increasing the number of rounded cells. Furthermore, 5-HT7R stimulation results in significantly reduced phagocytic and migratory ability of M1-like macrophages. Noteworthy, LP-211 treatment leads to changes in secretory properties of all macrophage types with the highest effects obtained for M0- and M2c-like macrophages. Finally, the importance of 5-HT7R for regulation of phagocytosis was confirmed in human primary CD14+ cells. These results indicate that 5-HT7R activation selectively impairs basic functions of macrophages and might thus be a new access point for the modulation of macrophage responses in the future treatment of inflammatory diseases.

Influence of physico-chemical properties of two lipoxin emulsion-loaded hydrogels on pre-polarized macrophages: a comparative analysis

Inflammation, a crucial defense mechanism, must be rigorously regulated to prevent the onset of chronic inflammation and subsequent tissue damage. Specialized pro resolving mediators (SPMs) such as lipoxin A4 (LXA4) have demonstrated their ability to facilitate the resolution of inflammation by orchestrating a transition of M1 pro-inflammatory macrophages towards an anti-inflammatory M2 phenotype. However, the hydrophobic and chemically labile nature of LXA4 necessitates the development of a delivery system capable of preserving its integrity for clinical applications. In this study, two types of emulsion were formulated using different homogenization processes:mechanical overhead stirrer (MEB for blank Emulsion and MELX for LXA4 loaded-Emulsion) or Luer-lock syringes (SEB for blank Emulsion and SELX for LXA4 loaded-Emulsion)). Following characterization, including size and droplet morphology assessment by microscopy, the encapsulation efficiency (EE) was determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS). To exert control over LXA4 release, these emulsions were embedded within silanized hyaluronic acid hydrogels. A comprehensive evaluation, encompassing gel time, swelling, and degradation profiles under acidic, basic, and neutral conditions, preceded the assessment of LXA4 cumulative release using LC-MS/MS. Physicochemical results indicate that H-MELX (Mechanical overhead stirrer LXA4 Emulsion loaded-Hydrogel) exhibits superior efficiency over H-SELX (Luer-lock syringes LXA4 Emulsion loaded-Hydrogel). While both formulations stimulated pro-inflammatory cytokine secretion and promoted a pro-inflammatory macrophage phenotype, LXA4 emulsion-loaded hydrogels displayed a diminished pro-inflammatory activity compared to blank emulsion-loaded hydrogels. These findings highlight the biological efficacy of LXA4 within both systems, with H-SELX outperforming H-MELX in terms of efficiency. To the best of our knowledge, this is the first successful demonstration of the biological efficacy of LXA4 emulsion-loaded hydrogel systems on macrophage polarization. These versatile H-MELX and H-SELX formulations can be customized to enhance their biological activity making them promising tools to promote the resolution of inflammation in diverse clinical applications.

Matairesinol repolarizes M2 macrophages to M1 phenotype to induce apoptosis in triple-negative breast cancer cells

OBJECTIVE

Triple-Negative Breast Cancer (TNBC), the most challenging subtype of Breast Cancer (BC), currently lacks targeted therapy, presenting a significant therapeutic gap in its management. Tumor Associated Macrophages (TAMs) play a significant role in TNBC progression and could be targeted by repolarizing them from M2 to M1 phenotype. Matairesinol (MAT), a plant lignan, has been shown to exhibit anticancer, anti-inflammatory and immunomodulatory activities. In this study, we explored how MAT-induced repolarization of THP-1-derived M2 macrophages towards the M1 phenotype, which could effectively target the TNBC cell line, MDA-MB-231.

METHODS

The differential expression of genes in THP-1-derived macrophages at mRNA levels was evaluated by RNAseq assay. An inverted microscope equipped with a CMOS camera was utilized to capture the morphological variations in THP-1 cells and THP-1-derived macrophages. Relative mRNA expression of M1 and M2 specific marker genes was quantified by qRT-PCR. Cell viability and induction of apoptosis were evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1 dye) assays, respectively.

RESULTS

MAT reduced the viability of M2a and M2d macrophages and repolarized them to M1 phenotype. Conditioned medium (CM) from MAT-treated M2a and M2d macrophages significantly reduced the viability of TNBC cells by apoptosis.

CONCLUSION

Targeting M2 macrophages is an important strategy to regulate cancer progression. Our study provides evidence that MAT may be a promising drug candidate for developing novel anti-TNBC therapy. However, further studies are warranted to thoroughly elucidate the molecular mechanism of action of MAT and evaluate its therapeutic potential in TNBC in vitro and in vivo models.

Soluble factors released by peripheral blood-derived CAR-NK cells cause bystander myeloid cell activation

Introduction

CAR-T cell therapy is associated with life-threatening inflammatory toxicities, partly due to the activation and secretion of inflammatory cytokines by bystander myeloid cells (BMCs). However, due to limited clinical data, it is unclear whether CAR-NK cells cause similar toxicities.

Methods

We characterized the soluble factors (SFs) released by activated human CAR-T and CAR-NK cells and assessed their role in BMC activation (BMCA).

Results

We found that SFs from both activated, peripheral blood-derived CAR-T (PB-CAR-T) and CAR-NK (PB-CAR-NK) cells induced BMCA; however, PB-CAR-NK cells caused significantly lower BMCA compared to PB-CAR-T cells. Interestingly, SFs from cord-blood-derived (CB) NK cells caused little to no BMCA, consistent with previous clinical studies showing minimal inflammatory toxicity with CB-CAR-NK cells. Comparative analysis of SFs released by PB-NK and PB-CAR-NK cells following CAR-dependent and CAR-independent activation revealed several candidate factors with the potential to cause BMCA. Antibody-mediated neutralization studies identified a combination of four factors that contribute to PB-CAR-NK cell-mediated BMCA. siRNA-mediated knockdown studies confirmed that inactivating these four factors in PB-CAR-NK cells significantly reduces BMCA. Importantly, neutralization or knockdown of these four factors did not affect CAR-NK cell potency.

Discussion

These data suggest that specific SFs released by PB-CAR-NK cells activate BMCs and have the potential to contribute to inflammatory toxicities. Furthermore, inactivation of these four factors in PB-CAR-NK cells could reduce inflammatory toxicities and improve safety of PB-CAR-NK cell therapy without compromising potency.

Szabo B, Kothalawala RC, Szekelyhidi V, Nagy P, Varga Z, Panyi G, Zakany F. Inhibition of the HV1 voltage-gated proton channel compromises the viability of human polarized macrophages in a polarization- and ceramide-dependent manner

The human voltage-gated proton channel (HV1) provides an efficient proton extrusion pathway from the cytoplasm contributing to the intracellular pH regulation and the oxidative burst. Although its pharmacological inhibition was previously shown to induce cell death in various cell types, no such effects have been examined in polarized macrophages albeit HV1 was suggested to play important roles in these cells. This study highlights that 5-chloro-2-guanidinobenzimidazole (ClGBI), the most widely applied HV1 inhibitor, reduces the viability of human THP-1-derived polarized macrophages at biologically relevant doses with M1 macrophages being the most, and M2 cells the least sensitive to this compound. ClGBI may exert this effect principally by blocking HV1 since the sensitivity of polarized macrophages correlates well with their HV1 expression levels; inhibitors of other macrophage ion channels that may be susceptible for off-target ClGBI effects cause no viability reductions; and Zn2+, another non-specific HV1 blocker, exerts similar effects. As a potential mechanism behind the ClGBI-induced cell death, we identify a complex pH dysregulation involving acidification of the cytoplasm and alkalinization of the lysosomes, which eventually result in membrane ceramide accumulation. Furthermore, ClGBI effects are alleviated by ARC39, a selective acid sphingomyelinase inhibitor supporting the unequivocal significance of ceramide accumulation in the process. Altogether, our results suggest that HV1 inhibition leads to cellular toxicity in polarized macrophages in a polarization-dependent manner, which occurs due to a pH dysregulation and concomitant ceramide overproduction mainly depending on the activity of acid sphingomyelinase. The reduced macrophage viability and plausible concomitant changes in homeostatic M1-M2 balance could contribute to both the therapeutic and potential side effects of HV1 inhibitors that show great promise in the treatment of neuroinflammation and malignant diseases.

Anti-inflammatory effects of 1,7-dihydroxy-3,4-dimethoxyxanthone through inhibition of M1-phenotype macrophages via arginine/mitochondrial axis

It is known that 1,7-dihydroxy-3,4-dimethoxyxanthone (XAN), derived from Securidaca inappendiculata Hassk., exhibits anti-inflammatory and analgesic activities and inhibits M1 polarization of macrophages. However, its ability to alleviate inflammation induced by pro-inflammatory cytokines in THP-1 cells and its anti-inflammatory mechanisms remain unclear. THP-1 cells were treated with phorbol 12-myristate-13-acetate to differentiate and divided into three groups. They were stimulated with lipopolysaccharide (LPS) and interferon-γ (IFN-γ). The toxicity of XAN was assessed using Cell Counting Kit-8, and the expression of various genes and proteins was analyzed using real-time quantitative polymerase chain reaction, flow cytometry, and western blotting. Transmission electron microscopy was used to observe changes in mitochondrial structure. XAN at concentrations ≤ 10 µg/mL did not affect THP-1 cell viability and reduced the mRNA expression of pro-inflammatory factors, including interleukin (IL)-1β, inducible nitric oxide synthase (iNOS), NOD-like receptor thermal protein domain protein 3 (NLRP3), and tumor necrosis factor-α (TNF-α). XAN also increased the levels of anti-inflammatory factors, including chemokine ligand 22, mannose receptor (CD206), IL-10, peroxisome proliferator-activated receptor-γ, and transglutaminase 2. Additionally, XAN downregulated the expression of inflammation-related proteins iNOS, NLRP3, and IL-1β; significantly increased the expression of arginase 1, ornithine decarboxylase, and arginine metabolism-related proteins and genes; inhibited mitochondrial damage; and reduced reactive oxygen species (ROS) generation. XAN enhanced the arginine metabolism pathway, prevented mitochondrial damage, reduced ROS levels, and provided an effective defensive response against LPS/IFN-γ-induced inflammation.

HIV-1 N-myristoylation-dependent hijacking of late endosomes/lysosomes to drive Gag assembly in macrophages

Macrophages represent an important viral reservoir in HIV-1-infected individuals. Different from T cells, HIV-1 assembly in macrophages occurs at intracellular compartments termed virus-containing compartments (VCCs). Our previous research in HeLa cells - in which assembly resembles that found in infected T cells - suggested that late endosomes/lysosomes (LELs) play a role in HIV-1 trafficking towards its assembly sites. However, the role of LELs during assembly at VCCs is not fully understood. Herein, we used the HIV-1-inducible cell line THP-1 GagZip as a model to study HIV-1 Gag intracellular trafficking and assembly in macrophages. We demonstrated LEL involvement at VCCs using various microscopy techniques and biochemical approaches. Live-cell imaging revealed that HIV-1 repositions LELs towards the plasma membrane and modulates their motility. We showed that Arl8b-mediated LEL repositioning is not responsible for Gag trafficking to VCCs. Additionally, the inhibition of myristoylation by PCLX-001 decreased the presence of Gag on endosomes and inhibited VCC formation in both the THP-1 cell line and primary macrophages. In conclusion, we present evidence supporting the idea that HIV-1 manipulates the LEL trajectory to guide Gag to VCCs in an N-myristoylation-dependent manner.

Functional interleukin-4 releasing microparticles impact THP-1 differentiated macrophage phenotype

Introduction

Macrophage cell therapies offer potential treatment in inflammatory diseases due to their ability to mobilize and stimulate their environment. However, successful treatment requires a pro-regenerative macrophage phenotype to be retained in vivo. Polymeric microparticles may provide a potential route to direct and sustain macrophage phenotype. Interleukin-4 (IL-4) is the most commonly used cytokine for in vitro modulation towards M2a macrophage phenotype. We designed IL-4 encapsulated microparticles to investigate the impact of drug release kinetics and developed a robust human peripheral blood monocyte cell (THP-1) in vitro assay to assess functional IL-4 release upon macrophage phenotype.

Methods

IL-4 was encapsulated with human serum albumin (HSA) in microparticles fabricated from a blend of PLGA and a PLGA-PEG-PLGA triblock copolymer. Functional release of IL-4 and HSA over different time periods was measured using ELISAs. THP-1 differentiated macrophages were cultured either in direct contact with microparticles or indirectly through transwells. The immunomodulatory impact of microparticles on THP-1 cells were measured using ELISA and qPCR.

Results and Discussion

IL-4 release kinetics fit with the first-order release kinetics model, indicating concentration dependent release. IL-4/HSA encapsulated microparticles modulated THP-1 differentiated macrophages towards pro-immunoregulatory subgroups. This strategy provides a novel approach in drug carrier development for in vitro assessments of macrophage phenotype to inform development of targeted therapies for inflammation and immune modulation.

Expression of Toll-like Receptor Genes and Antiviral Cytokines in Macrophage-like Cells in Response to Indole-3-carboxylic Acid Derivative

Ongoing outbreaks and often rapid spread of infections caused by coronaviruses, influenza, Nipah, Dengue, Marburg, monkeypox, and other viruses are a concern for health authorities in most countries. Therefore, the search for and study of new antiviral compounds are in great demand today. Since almost all viruses with pandemic potential have immunotoxic properties of various origins, particular attention is paid to the search and development of immunomodulatory drugs. We have synthesised a new compound related to indole-3-carboxylic acid derivatives (hereinafter referred to as the XXV) that has antiviral and interferon-inducing activity. The purpose of this work is to study the effect of the XXV on the stimulation of the expression of toll-like receptor genes, interferons, and immunoregulatory cytokines in a macrophage-like cell model. In this study, real-time PCR methods were used to obtain data on the transcriptional activity of genes in macrophage-like cells. Stimulation of the genes of toll-like receptors TLR2, TLR3, TLR4, TLR7, TLR8, and TLR9 was detected. A high-fold increase in stimulation (from 6.5 to 16,000) of the expression of the TLR3 and TLR4 genes was detected after 4 h of exposure to the XXV. Increased activity of interferon (IFNA1, IFNA2, IFNB1, IFNK, and IFNλ1) genes with simultaneous stimulation of the expression of interferon receptor (IFNAR1 and IFNAR2) genes and signalling molecule (JAK1 and ISG15) genes was detected. Increased fold stimulation of the expression of the cytokine genes IL6, TNFA, IL12A, and IL12B was also observed. Thus, it is shown that the XXV is an activator of TLR genes of innate immunity, which trigger signalling mechanisms of pathogen "recognition" and lead to stimulation of the expression of genes of proinflammatory cytokines and interferons.

Association between baseline lipid profile and risk of worsening in patients with myasthenia gravis: A retrospective cohort study

Background

Dyslipidemia has been implicated in autoimmunity; however, its association with myasthenia gravis (MG) prognosis is unclear. We aimed to investigate the correlation between baseline lipid profiles and risk of MG worsening.

Methods

This 7-year retrospective cohort study conducted at a Chinese hospital included 264 adult patients with MG. Data on baseline lipids, 1-year worsening, and covariates, including demographics, MG characteristics, comorbidities, and treatments were extracted.

Results

Univariate and multivariate logistic regression analyses failed to show a significant association between the risk of 1-year MG worsening and any of the seven blood lipid-related indicators. However, the subsequent non-linear analysis revealed an inflection point in the risk curve of ln[lipoprotein(a)], at 4.06 (58 nmol/L). The lipoprotein(a) levels on the left side of the inflection point presented a positive significant correlation with the risk of MG worsening (relative risk [RR]: 6.06, 95 % confidence interval [CI]: 1.00-38.57), whereas those on the right side of the inflection point demonstrated no significant correlation (RR: 0.86, 95 % CI: 0.55-1.34).

Conclusions

Except for lipoprotein(a) levels being associated with worsening of myasthenia gravis, most lipid parameters were not associated with changes in the clinical course and severity of myasthenia gravis.we observed that lower levels of lipoprotein(a) were associated with a better prognosis in the interval 7-58 nml/L, whereas beyond this interval this was not observed, suggesting dyslipidemia may impact MG prognosis. Further studies are required to validate these findings.

MCP-1 exerts the inflammatory response via ILK activation during endometriosis pathogenesis

AIMS

MCP-1 has been shown to be elevated in endometriosis. ILK functions in several cellular events and interacts with MCP-1-signaling. In the current study, we evaluated the role of MCP-1-ILK signaling in human endometriotic cell's (Hs832(C).TCs) potential for colonization, invasion, adhesion, etc. and differentiation of macrophage along with inflammation in an endometriosis mouse model.

MATERIALS AND METHODS

A mouse model of endometriosis with elevated levels of MCP-1 was developed by injecting MCP-1. We examined the migration, adhesion, colonization and invasion of Hs832(C).TCs in response to MCP-1-ILK signaling. We also examined the differentiation of THP-1 cells to macrophage in response to MCP-1-ILK signaling.

KEY FINDINGS

We observed that MCP-1 increased Ser246 phosphorylation of ILK in Hs832(C).TCs and enhanced the migration, adhesion, colonization, and invasion of Hs832(C).TCs. In the mouse model of endometriosis, we found elevated chemokines (CCL-11, CCL-22 and CXCL13) levels. An increased level of MCP-1 mediated ILK activation, leading to increased inflammatory reaction and infiltration of residential and circulatory macrophages, and monocyte differentiation, but suppressed the anti-inflammatory reaction. The inhibitor (CPD22) of ILK reversed the MCP-1-mediated action by restoring Hs832(C).TCs and THP-1 phenotype. ILK inhibition in a mouse model of endometriosis reduced the effects of MCP-1 mediated pro-inflammatory cytokines, but increased anti-inflammatory response along with T-regulatory and T-helper cell restoration.

SIGNIFICANCE

Targeting ILK restores MCP-1 milieu in the peritoneal cavity and endometrial tissues, reduces the inflammatory response, improves the T-regulatory and T-helper cells in the endometriosis mouse model and decreases the migration, adhesion, colonization and invasion of endometriotic cells.

Activated THP-1 Macrophage-Derived Factors Increase the Cytokine, Fractalkine, and EGF Secretions, the Invasion-Related MMP Production, and Antioxidant Activity of HEC-1A Endometrium Cells

Endometrium receptivity is a multifactor-regulated process involving progesterone receptor-regulated signaling, cytokines and chemokines, and additional growth regulatory factors. In the female reproductive system, macrophages have distinct roles in the regulation of receptivity, embryo implantation, immune tolerance, and angiogenesis or oxidative stress. In the present study, we investigated the effects of PMA-activated THP-1 macrophages on the receptivity-related genes, cytokines and chemokines, growth regulators, and oxidative stress-related molecules of HEC-1A endometrium cells. We established a non-contact co-culture in which the culture medium of the PMA-activated macrophages exhibiting the pro-inflammatory phenotype was used for the treatment of the endometrial cells. In the endometrium cells, the expression of the growth-related factors activin and bone morphogenetic protein 2, the growth hormone EGF, and the activation of the downstream signaling molecules pERK1/2 and pAkt were analyzed by ELISA and Western blot. The secretions of cytokines and chemokines, which are involved in the establishment of endometrial receptivity, and the expression of matrix metalloproteinases implicated in invasion were also determined. Based on the results, the PMA-activated THP-1 macrophages exhibiting a pro-inflammatory phenotype may play a role in the regulation of HEC-1A endometrium cells. They alter the secretion of cytokines and chemokines, as well as the protein level of MMPs of HEC-1A cells. Moreover, activated THP-1 macrophages may elevate oxidative stress protection of HEC-1A endometrium cells. All these suggest that pro-inflammatory macrophages have a special role in the regulation of receptivity-related and implantation-related factors of HEC-1A cells.

1,25-dihydroxyvitamin D3 augments low-dose PMA-based monocyte-to-macrophage differentiation in THP-1 cells

The human monocytic THP-1 cell line is the most routinely employed in vitro model for studying monocyte-to-macrophage differentiation. Despite the wide use of this model, differentiation protocols using phorbol 12-myristate-13-acetate (PMA) or 1,25-dihydroxyvitamin D3 (1,25D3) vary drastically between studies. Given that differences in differentiation protocols have the potential to impact the characteristics of the macrophages produced, we aimed to assess the efficacy of three different THP-1 differentiation protocols by assessing changes in morphology and gene- and cell surface macrophage marker expression. THP-1 cells were differentiated with either 5 nM PMA, 10 nM 1,25D3, or a combination thereof, followed by a rest period. The results indicated that all three protocols significantly increased the expression of the macrophage markers, CD11b (p < 0.001) and CD14 (p < 0.010). Despite this, THP-1 cells exposed to 1,25D3 alone did not adopt the morphological and expression characteristics associated with macrophages. PMA was required to produce these characteristics, which were found to be more pronounced in the presence of 1,25D3. Both PMA- and PMA with 1,25D3-differentiated THP-1 cells were capable of M1 and M2 macrophage polarization, though the gene expression of polarization-associated markers was most pronounced in PMA with 1,25D3-differentiated THP-1 cells. Moreover, the combination of PMA with 1,25D3 appeared to support the process of commitment to a particular polarization state.

Nitric oxide water-driven immunogenic cell death: Unfolding mitochondrial dysfunction's role in sensitizing lung adenocarcinoma to ferroptosis and autophagic cell death

Non-small cell lung cancer (NSCLC), particularly lung adenocarcinoma (LUAD), significantly influences cancer-related mortality and is frequently considered by poor therapeutic responses due to genetic alterations. Cancer cells possess an inclination to develop resistance to individual treatment modalities, thus it is necessary to investigate several pathways simultaneously to obtain insights that will aid in the establishment of improved therapeutic approaches. Exploring regulated cell death (RCD) mechanisms offers promising avenues to augment immunotherapy by reshaping the tumor microenvironment (TME). Here, we investigated the prospective of microwave plasma-infused nitric oxide water (NOW) to initiate immunogenic cell death (ICD) while concurrently modulating autophagy and ferroptosis signaling in LUAD-associated A549 cells. Plasma treatment results in stable NO species nitrite/nitrate (NO2-/NO3-) in the water, altering its physicochemical properties. Analysis of ICD markers reveals increased expression of damage-associated molecular patterns (DAMPs) at both protein and mRNA levels post-NOW exposure. Intracellular reactive oxygen and nitrogen species (RONS) accumulation suggests NO-mediated mitochondrial dysfunction, triggering autophagy induction. Flow cytometry and western blotting confirm alterations in autophagy regulators Beclin 1 and SQSTM1. Furthermore, NOW treatment induces lipid peroxidation and upregulates ferroptosis-associated genes, as determined by qRT-PCR. Transmission electron microscopy (TEM) imaging reveals autophagosome formation and loss of cristae structures, corroborating the occurrence of autophagy and ferroptosis. Our findings propose that NOW may considered as inducer of ICD and the stimulation of other RCD-related proteins may enhance the anti-tumor immunogenicity.

Growth differentiation factor 15 alleviates diastolic dysfunction in mice with experimental diabetic cardiomyopathy

Growth differentiation factor 15 (GDF15) is a peptide with utility in obesity, as it decreases appetite and promotes weight loss. Because obesity increases the risk for type 2 diabetes (T2D) and cardiovascular disease, it is imperative to understand the cardiovascular actions of GDF15, especially since elevated GDF15 levels are an established biomarker for heart failure. As weight loss should be encouraged in the early stages of obesity-related prediabetes/T2D, where diabetic cardiomyopathy is often present, we assessed whether treatment with GDF15 influences its pathology. We observed that GDF15 treatment alleviates diastolic dysfunction in mice with T2D independent of weight loss. This cardioprotection was associated with a reduction in cardiac inflammation, which was likely mediated via indirect actions, as direct treatment of adult mouse cardiomyocytes and differentiated THP-1 human macrophages with GDF15 failed to alleviate lipopolysaccharide-induced inflammation. Therapeutic manipulation of GDF15 action may thus have utility for both obesity and diabetic cardiomyopathy.

THP-1 Monocytic Cells Are Polarized to More Antitumorigenic Macrophages by Serial Treatment with Phorbol-12-Myristate-13-Acetate and PD98059

Background and Objectives: As modulators of the tumor microenvironment, macrophages have been extensively studied for their potential in developing anticancer strategies, particularly in regulating macrophage polarization towards an antitumorigenic (M1) phenotype rather than a protumorigenic (M2) one in various experimental models. Here, we evaluated the effect of PD98059, a mitogen-activated protein kinase kinase MAPKK MEK1-linked pathway inhibitor, on the differentiation and polarization of THP-1 monocytes in response to phorbol-12-myristate-13-acetate (PMA) under various culture conditions for tumor microenvironmental application. Materials and Methods: Differentiation and polarization of THP-1 were analyzed by flow cytometry and RT-PCR. Polarized THP-1 subsets with different treatment were compared by motility, phagocytosis, and so on. Results: Clearly, PMA induced THP-1 differentiation occurs in adherent culture conditions more than nonadherent culture conditions by increasing CD11b expression up to 90%, which was not affected by PD98059 when cells were exposed to PMA first (post-PD) but inhibited when PD98059 was treated prior to PMA treatment (pre-PD). CD11bhigh THP-1 cells treated with PMA and PMA-post-PD were categorized into M0 (HLA-DRlow and CD206low), M1 (HLA-DRhigh and CD206low), and M2 (HLA-DRlow and CD206high), resulting in an increased population of M1 macrophages. The transcription levels of markers of macrophage differentiation and polarization confirmed the increased M1 polarization of THP-1 cells with post-PD treatment rather than with PMA-only treatment. The motility and cytotoxicity of THP-1 cells with post-PD treatment were higher than THP-1 cells with PMA, suggesting that post-PD treatment enhanced the anti-tumorigenicity of THP-1 cells. Confocal microscopy and flow cytometry showed the effect of post-PD treatment on phagocytosis by THP-1 cells. Conclusions: We have developed an experimental model of macrophage polarization with THP-1 cells which will be useful for further studies related to the tumor microenvironment.

A 3D spheroid model of quadruple cell co-culture with improved liver functions for hepatotoxicity prediction

Drug-induced liver injury (DILI) is one of the major concerns during drug development. Wide acceptance of the 3 R principles and the innovation of in-vitro techniques have introduced various novel model options, among which the three-dimensional (3D) cell spheroid cultures have shown a promising prospect in DILI prediction. The present study developed a 3D quadruple cell co-culture liver spheroid model for DILI prediction via self-assembly. Induction by phorbol 12-myristate 13-acetate at the concentration of 15.42 ng/mL for 48 hours with a following 24-hour rest period was used for THP-1 cell differentiation, resulting in credible macrophagic phenotypes. HepG2 cells, PUMC-HUVEC-T1 cells, THP-1-originated macrophages, and human hepatic stellate cells were selected as the components, which exhibited adaptability in the designated spheroid culture conditions. Following establishment, the characterization demonstrated the competence of the model in long-term stability reflected by the maintenance of morphology, viability, cellular integration, and cell-cell junctions for at least six days, as well as the reliable liver-specific functions including superior albumin and urea secretion, improved drug metabolic enzyme expression and CYP3A4 activity, and the expression of MRP2, BSEP, and P-GP accompanied by the bile acid efflux transport function. In the comparative testing using 22 DILI-positive and 5 DILI-negative compounds among the novel 3D co-culture model, 3D HepG2 spheroids, and 2D HepG2 monolayers, the 3D culture method significantly enhanced the model sensitivity to compound cytotoxicity compared to the 2D form. The novel co-culture liver spheroid model exhibited higher overall predictive power with margin of safety as the classifying tool. In addition, the non-parenchymal cell components could amplify the toxicity of isoniazid in the 3D model, suggesting their potential mediating role in immune-mediated toxicity. The proof-of-concept experiments demonstrated the capability of the model in replicating drug-induced lipid dysregulation, bile acid efflux inhibition, and α-SMA upregulation, which are the key features of liver steatosis and phospholipidosis, cholestasis, and fibrosis, respectively. Overall, the novel 3D quadruple cell co-culture spheroid model is a reliable and readily available option for DILI prediction.

The effects of fine particulate matter (SRM 2786) on three different 3D lung models exposed at the air-liquid interface - A comparative study

3D cell culture models exposed at the air-liquid interface (ALI) represent a potential alternative to animal experiments for hazard and risk assessment of inhaled compounds. This study compares cocultures composed of either Calu-3, A549 or HBEC3-KT lung epithelial cells, cultured together with THP-1-derived macrophages and EA.hy926 endothelial cells, in terms of barrier capacity and responses to a standard reference sample of fine particulate matter (SRM 2786). High-content imaging analysis revealed a similar cellular composition between the different cell models. The 3D cell cultures with Calu-3 cells showed the greatest barrier capacity, as measured by transepithelial electrical resistance and permeability to Na-fluorescein. Mucus production was detected in 3D cell cultures based on Calu-3 and A549 cells. Exposure to SRM 2786 at ALI increased cytokine release and expression of genes associated with inflammation and xenobiotic metabolism. Moreover, the presence of THP-1-derived macrophages was central to the cytokine responses in all cell models. While the different 3D cell culture models produced qualitatively similar responses, more pronounced pro-inflammatory responses were observed in the basolateral compartment of the A549 and HBEC3-KT models compared to the Calu-3 model, likely due to their reduced barrier capacity and lower retention of secreted mediators in the apical compartment.

Bacterial metallothionein, PmtA, a novel stress protein found on the bacterial surface of Pseudomonas aeruginosa and involved in management of oxidative stress and phagocytosis

Metallothioneins (MTs) are small cysteine-rich proteins that play important roles in homeostasis and protection against heavy metal toxicity and oxidative stress. The opportunistic pathogen, Pseudomonas aeruginosa, expresses a bacterial MT known as PmtA. Utilizing genetically modified P. aeruginosa PAO1 strains (a human clinical wound isolate), we show that inducing pmtA increases levels of pyocyanin and biofilm compared to other PAO1 isogenic strains, supporting previous results that pmtA is important for pyocyanin and biofilm production. We also show that overexpression of pmtA in vitro provides protection for cells exposed to oxidants, which is a characteristic of inflammation, indicating a role for PmtA as an antioxidant in inflammation. We found that a pmtA clean deletion mutant is phagocytized faster than other PAO1 isogenic strains in THP-1 human macrophage cells, indicating that PmtA provides protection from the phagocytic attack. Interestingly, we observed that monoclonal anti-PmtA antibody binds to PmtA, which is accessible on the surface of PAO1 strains using both flow cytometry and enzyme-linked immunosorbent assay techniques. Finally, we investigated intracellular persistence of these PAO1 strains within THP-1 macrophages cells and found that the phagocytic endurance of PAO1 strains is affected by pmtA expression. These data show for the first time that a bacterial MT (pmtA) can play a role in the phagocytic process and can be found on the outer surface of PAO1. Our results suggest that PmtA plays a role both in protection from oxidative stress and in the resistance to the host's innate immune response, identifying PmtA as a potential therapeutic target in P. aeruginosa infection.

IMPORTANCE

The pathogen Pseudomonas aeruginosa is a highly problematic multidrug-resistant (MDR) pathogen with complex virulence networks. MDR P. aeruginosa infections have been associated with increased clinical visits, very poor healthcare outcomes, and these infections are ranked as critical on priority lists of both the Centers for Disease Control and Prevention and the World Health Organization. Known P. aeruginosa virulence factors have been extensively studied and are implicated in counteracting host defenses, causing direct damage to the host tissues, and increased microbial competitiveness. Targeting virulence factors has emerged as a new line of defense in the battle against MDR P. aeruginosa strains. Bacterial metallothionein is a newly recognized virulence factor that enables evasion of the host immune response. The studies described here identify mechanisms in which bacterial metallothionein (PmtA) plays a part in P. aeruginosa pathogenicity and identifies PmtA as a potential therapeutic target.

Cholesterol nanoarchaeosomes for alendronate targeted delivery as an anti-endothelial dysfunction agent

Sodium alendronate (ALN) is a very hydrosoluble and poorly permeable molecule used as an antiresorptive agent and with vascular anticalcifying capacity. Loaded into targeted nanovesicles, its anti-inflammatory activity may be amplified towards extra-osseous and noncalcified target cells, such as severely irritated vascular endothelium. Here cytotoxicity, mitochondrial membrane potential, ATP content, and membrane fluidity of human endothelial venous cells (HUVECs) were determined after endocytosis of ALN-loaded nanoarchaeosomes (nanoARC-Chol(ALN), made of polar lipids from Halorubrum tebenquichense: cholesterol 7:3 w/w, 166 ± 5 nm, 0.16 ± 0.02 PDI, -40.8 ± 5.4 mV potential, 84.7 ± 21 µg/mg ALN/total lipids, TL). The effect of nanoARC-Chol(ALN) was further assessed on severely inflamed HUVECs. To that aim, HUVECs were grown on a porous barrier on top of a basal compartment seeded either with macrophages or human foam cells. One lighter and one more pronounced inflammatory context was modelled by adding lipopolysaccharide (LPS) to the apical or the apical and basal compartments. The endocytosis of nanoARC-Chol(ALN), was observed to partly reduce the endothelial-mesenchymal transition of HUVECs. Besides, while 10 mg/mL dexamethasone, 7.6 mM free ALN and ALN-loaded liposomes failed, 50 μg/mL TL + 2.5 μg/mL ALN (i.e., nanoARC-Chol(ALN)) reduced the IL-6 and IL-8 levels by, respectively, 75% and 65% in the mild and by, respectively, 60% and 40% in the pronounced inflammation model. This is the first report showing that the endocytosis of nanoARC-Chol(ALN) by HUVECs magnifies the anti-inflammatory activity of ALN even under conditions of intense irritation, not only surpassing that of free ALN but also that of dexamethasone.

β-Glucan fragmentation by microfluidization and TNF-α-immunostimulating activity of fragmented β-glucans

Fragmentation of β-glucans secreted by the fungus Ophiocordyceps dipterigena BCC 2073 achieved by microfluidization was investigated. The degree of β-glucan fragmentation was evaluated based on the average number of chain scissions (α). The effects on the α value of experimental variables like solid concentration of the β-glucan suspension, interaction chamber pressure, and number of passes through the microfluidizer were examined. Kinetic studies were conducted using the relationships of the α and suspension viscosity values with the number of passes. Evidence indicated that α increases with the interaction chamber pressure and the number of passes, whereas the solid concentration shows the inverted effect. Kinetic data indicated that the fragmentation rate increases with β-glucan solid concentration and interaction chamber pressure. Furthermore, since β-glucan molecular weight is a key factor determining its biological activity, the effect of β-glucans of different molecular weights produced by fragmentation on tumor necrosis factor (TNF)-α-stimulating activity in THP-1 human macrophage cells was investigated. Evidence suggested that β-glucans have an immunostimulating effect on macrophage function, in the absence of cytotoxic effects. Indeed, β-glucans characterized by a range of molecular weights produced via microfluidization exhibited promise as immunostimulatory agents.

Gasdermin D promotes influenza virus-induced mortality through neutrophil amplification of inflammation

Influenza virus activates cellular inflammasome pathways, which can be both beneficial and detrimental to infection outcomes. Here, we investigate the function of the inflammasome-activated, pore-forming protein gasdermin D (GSDMD) during infection. Ablation of GSDMD in knockout (KO) mice (Gsdmd-/-) significantly attenuates influenza virus-induced weight loss, lung dysfunction, lung histopathology, and mortality compared with wild type (WT) mice, despite similar viral loads. Infected Gsdmd-/- mice exhibit decreased inflammatory gene signatures shown by lung transcriptomics. Among these, diminished neutrophil gene activation signatures are corroborated by decreased detection of neutrophil elastase and myeloperoxidase in KO mouse lungs. Indeed, directly infected neutrophils are observed in vivo and infection of neutrophils in vitro induces release of DNA and tissue-damaging enzymes that is largely dependent on GSDMD. Neutrophil depletion in infected WT mice recapitulates the reductions in mortality, lung inflammation, and lung dysfunction observed in Gsdmd-/- animals, while depletion does not have additive protective effects in Gsdmd-/- mice. These findings implicate a function for GSDMD in promoting lung neutrophil responses that amplify influenza virus-induced inflammation and pathogenesis. Targeting the GSDMD/neutrophil axis may provide a therapeutic avenue for treating severe influenza.

Dexmedetomidine activates the PKA/CREB pathway and inhibits proinflammatory factor expression through β2 adrenergic receptors

INTRODUCTION

Dexmedetomidine (DEX) is primarily utilized for sedation in the context of general anesthesia or intensive care. However, the exact regulatory mechanism by which DEX affects cytokines remains unclear. This study aims to investigate the underlying mechanism by which DEX inhibits proinflammatory factors through activation of the β2 adrenergic receptor (β2 AR).

METHODS

The inflammatory cell model of human mononuclear macrophage (THP-1) cells induced by lipopolysaccharide (LPS) was established to study the effect of DEX on the expression of cell-related inflammatory factors. ADRA2A gene knockout THP-1 cells (THP-1KO ) were constructed by CRISPR technology, and the effect of DEX on the expression of inflammatory factors of THP-1KO cells was detected. The target sites of DEX on β2 AR were screened by molecular docking. Reversion experiments were performed using ADRB2-siRNA. Western blot was used to detect the activation of β2 AR/PKA/CREB pathway and NF-κB, and ELISA was used to detect the release level of inflammatory factors.

RESULTS

The results demonstrated a significant reduction in the expression levels of MCP-1, interleukin-06, and IL-8 in both THP-1 and THP-1KO cells when induced by LPS following treatment with DEX. Additionally, DEX treatment led to an increase in IL-10 expression. Immunofluorescence analysis revealed an upregulation of β2 AR expression after DEX treatment. Western blot results indicated that DEX notably enhanced the activation of the β2 AR and PKA/CREB pathways, while concurrently suppressing the activation of NF-κB. Notably, the use of ADRB2 siRNA reversed the effects of DEX treatment and promoted the release of inflammatory cytokines.

CONCLUSION

DEX initiates the activation of the PKA/CREB pathway through the activation of β2 AR. Simultaneously, it exerts an inhibitory effect on the activation of NF-κB, consequently reducing the transcription of proinflammatory factors while increasing the transcription of anti-inflammatory factors.

YB-1-based oncolytic virotherapy in combination with CD47 blockade enhances phagocytosis of pediatric sarcoma cells

Oncolytic viruses (OVs) selectively replicate in tumor cells resulting in lysis, spreading of new infectious units and induction of antitumor immune responses through abrogating an immunosuppressive tumor microenvironment (TME). Due to their mode of action, OVs are ideal combination partners with targeted immunotherapies. One highly attractive combination is the inhibition of the 'don't-eat-me'-signal CD47, which is known to increase the phagocytic potential of tumor-associated macrophages. In this work, we analyzed the combination approach consisting of the YB-1-based oncolytic adenovirus XVir-N-31 (XVir) and the CD47 inhibitor (CD47i) B6.H12.2 concerning its phagocytic potential. We investigate phagocytosis of XVir-, adenovirus wildtype (AdWT)-, and non-infected established pediatric sarcoma cell lines by different monocytic cells. Phagocytes (immature dendritic cells and macrophages) were derived from THP-1 cells and healthy human donors. Phagocytosis of tumor cells was assessed via FACS analysis in the presence and absence of CD47i. Additional characterization of T cell-stimulatory surface receptors as well as chemo-/cytokine analyses were performed. Furthermore, tumor cells were infected and studied for the surface expression of the 'eat-me'-signal calreticulin (CALR) and the 'don't-eat-me'-signal CD47. We herein demonstrate that (1) XVir-infected tumor cells upregulate both CALR and CD47. XVir induces higher upregulation of CD47 than AdWT. (2) XVir-infection enhances phagocytosis in general and (3) the combination of XVir and CD47i compared to controls showed by far superior enhancement of phagocytosis, tumor cell killing and innate immune activation. In conclusion, the combination of CD47i and XVir causes a significant increase in phagocytosis exceeding the monotherapies considerably accompanied by upregulation of T cell-stimulatory receptor expression and inflammatory chemo/-cytokine secretion.

Discovery of a novel pyroptosis inhibitor acting though modulating glutathionylation to suppress NLRP3-related signal pathway

Pyroptosis is a proinflammatory type of regulated cell death and has been involved in many pathological processes. Inhibition of pyroptosis is thought to be a promising strategy for the treatment of related diseases. Here, we performed a phenotypic screening against NLRP3-dependent pyroptosis and obtained the novel compound N77 after structure optimization. N77 showed a half-maximal effective concentration (EC50) of 0.070 ± 0.008 μM against cell pyroptosis induced by nigericin, and exhibited a remarkable ability to prevent NLRP3-dependent inflammasome activation and the release of IL-1β. Chemical proteomics revealed the biological target of N77 to be glutathione-S-transferase Mu 1 (GSTM1); our mechanism of action studies indicated that GSTM1 might act as a negative regulator of NLRP3 inflammasome activation by modulating the glutathionylation of caspase-1. In vivo, N77 substantially alleviated the inflammatory reaction in a pyroptosis-related acute keratitis model. Overall, we identified a novel pyroptosis inhibitor and revealed a new regulatory mechanism of pyroptosis. Our findings suggest an alternative potential therapeutic strategy for pyroptosis-related diseases.

Embedded macrophages induce intravascular coagulation in 3D blood vessel-on-chip

Macrophages are innate immune cells that prevent infections and help in wound healing and vascular inflammation. While these cells are natural helper cells, they also contribute to chronic diseases, e.g., by infiltrating the endothelial layer in early atherosclerosis and by promoting vascular inflammation. There is a crosstalk between inflammatory pathways and key players in thrombosis, such as platelets and endothelial cells - a phenomenon known as 'thromboinflammation'. The role of the embedded macrophages in thromboinflammation in the context of vascular disease is incompletely understood. Blood vessels-on-chips, which are microfluidic vascular cell culture models, have been used extensively to study aspects of vascular disease, like permeability, immune cell adhesion and thrombosis. Blood perfusion assays in blood vessel-on-chip models benefit from multiple unique aspects of the models, such as control of microvessel structure and well-defined flow patterns, as well as the ability to perform live imaging. However, due to their simplified nature, blood vessels-on-chip models have not yet been used to capture the complex cellular crosstalk that is important in thromboinflammation. Using induced pluripotent stem cell-derived endothelial cells and polarized THP-1 monocytes, we have developed and systematically set up a 3D blood vessel-on-chip with embedded (lipid-laden) macrophages, which is created using sequential cell seeding in viscous finger patterned collagen hydrogels. We have set up a human whole blood perfusion assay for these 3D blood vessels-on-chip. An increased deposition of fibrin in the blood vessel-on-chip models containing lipid-laden macrophages was observed. We anticipate the future use of this advanced vascular in vitro model in drug development for early atherosclerosis or aspects of other vascular diseases.

Anti-inflammatory mechanisms in cancer research: Characterization of a distinct M2-like macrophage model derived from the THP-1 cell line

AIMS

Macrophages play an essential role in cancer development. Tumor-associated macrophages (TAMs) have predominantly M2-like attributes that are associated with tumor progression and poor patient survival. Numerous methods have been reported for differentiating and polarizing macrophages in vitro, but there is no standardized and validated model for creating TAMs. Primary cells show varying cytokine responses depending on their origin and functional studies utilizing these cells may lack generalization and validity. A distinct cell line-derived TAM-like M2 subtype is required to investigate the mechanisms mediated by anti-inflammatory TAMs in vitro. Our previous work demonstrated a standardized protocol for creating an M2 subtype derived from a human THP-1 cell line. The cell expression profile, however, has not been validated. The aim of this study was to characterize and validate the TAM-like M2 subtype macrophage created based on our protocol to introduce them as a standardized model for cancer research.

METHODS AND RESULTS

Using qRT-PCR and ELISA, we demonstrated that proinflammatory, anti-inflammatory, and tumor-associated marker expression changed during THP-1-derived marcrophage development in vitro, mimicking a TAM-related profile (e.g., TNFα, IL-1β). The anti-inflammatory marker IL-8/CXCL8, however, is most highly expressed in young M0 macrophages. Flow cytometry showed increased expression of CD206 in the final TAM-like M2 macrophage. Single-cell RNA-sequencing analysis of primary human monocytes and colon cancer tissue macrophages demonstrated that cell line-derived M2 macrophages resembled a TAM-related gene profile.

CONCLUSIONS

The THP-1-derived M2 macrophage based on a standardized cell line model represents a distinct anti-inflammatory TAM-like phenotype with an M2a subtype profile. This model may provide a basis for in vitro investigation of functional mechanisms in a variety of anti-inflammatory settings, particularly colon cancer development.

In vitro immunomodulatory effect of solid versus porous phosphate-based glass microspheres using macrophages

This study aimed to investigate the immunomodulatory effect of two different forms of phosphate-based glass microspheres (solid and porous), on human macrophages. Human THP-1 monocytes were converted to M0 macrophages after being treated with 100 ng/mL phorbol 12-myristate 13-acetate for 48 h. The differentiated cells were analysed for the CD14 marker using flow cytometry. The adhesion, spreading, and viability of M0 macrophages grown directly or indirectly (extracts) at varying concentrations of solid and porous glass microspheres (GMs) were analysed via phase contrast microscopy, confocal microscopy, and XTT assay. The expression of IL-8, IL-1β, IL-6, IL-10, TNF-α, and IL-12p70 cytokines was investigated using flow cytometry. The conversion to M0 macrophages was confirmed by their adherent nature, increased granularity, and CD14 expression. The results showed that both solid and porous GMs or extracts favored the attachment, spreading, and proliferation of macrophages in a comparable manner to cells grown in a normal tissue culture medium. Only the higher concentration of porous GMs (10 mg/mL) changed the morphology of M0 macrophages and increased the expression of IL-1β and IL-8 pro-inflammatory cytokines; this could be related to the fast degradation nature of porous GMs. Of the six cytokines analysed, M0 macrophages grown directly or indirectly with GMs only expressed IL-1β, IL-10, and IL-8. Accordingly, solid microspheres may have advantages as regenerative agents due to their controlled degradation.

Polymeric Particle BAM15 Targeting Macrophages Attenuates the Severity of LPS-Induced Sepsis: A Proof of Concept for Specific Immune Cell-Targeted Therapy

Macrophage polarization requires different energy sources and metabolic processes. Therefore, cell energy interference to alter macrophage functions has been proposed as a treatment for severe inflammatory diseases, including sepsis. In this study, targeting cell energy using BAM15 (a mitochondrial uncoupling agent) in human THP-1 and mouse RAW264.7 macrophages prominently interfered with M1 but not M2 polarization. Free BAM15 (BAM15) and BAM15-loaded PLGA particles (BAM15 particles) reduced the inflammatory response of M1 macrophages and enhanced the expression of M2 signature genes with the restoration of mitochondrial activity (extracellular flux analysis) in RAW264.7 cells. Furthermore, BAM15 particles but not BAM15 showed specific effects on the inflammatory response of macrophages but not neutrophils, and the particles were actively captured by splenic and liver macrophages in vivo. Administration of BAM15 and BAM15 particles attenuated the severity of sepsis in LPS-induced sepsis mice. Interestingly, BAM15 particles but not BAM15 alleviated LPS-induced liver injury by reducing hepatic inflammation. Our findings substantiate the superior efficacy of macrophage-targeted therapy using a BAM15 particle-delivery system and provide further support for clinical development as a potential therapy for severe inflammatory diseases.

Proteomic analysis reveals changes in the proteome of human THP-1 macrophages infected with Paracoccidioides brasiliensis

Paracoccidioides spp. is the etiologic agent of Paracoccidioidomycosis (PCM), a systemic disease with wide distribution in Latin America. Macrophages are very important cells during the response to infection by P. brasiliensis. In this study, we performed a proteomic analysis to evaluate the consequences of P. brasiliensis yeast cells on the human THP-1 macrophage proteome. We have identified 443 and 2247 upregulated or downregulated proteins, respectively, in macrophages co-cultured with yeast cells of P. brasiliensis in comparison to control macrophages unexposed to the fungus. Proteomic analysis revealed that interaction with P. brasiliensis caused metabolic changes in macrophages that drastically affected energy production pathways. In addition, these macrophages presented regulated many factors related to epigenetic modifications and gene transcription as well as a decrease of many proteins associated to the immune system activity. This is the first human macrophage proteome derived from interactions with P. brasiliensis, which contributes to elucidating the changes that occur during the host response to this fungus. Furthermore, it highlights proteins that may be targets for the development of new therapeutic approaches to PCM.

The DNA-binding induced (de)AMPylation activity of a Coxiella burnetii Fic enzyme targets Histone H3

The intracellular bacterial pathogen Coxiella burnetii evades the host response by secreting effector proteins that aid in establishing a replication-friendly niche. Bacterial filamentation induced by cyclic AMP (Fic) enzymes can act as effectors by covalently modifying target proteins with the posttranslational AMPylation by transferring adenosine monophosphate (AMP) from adenosine triphosphate (ATP) to a hydroxyl-containing side chain. Here we identify the gene product of C. burnetii CBU_0822, termed C. burnetii Fic 2 (CbFic2), to AMPylate host cell histone H3 at serine 10 and serine 28. We show that CbFic2 acts as a bifunctional enzyme, both capable of AMPylation as well as deAMPylation, and is regulated by the binding of DNA via a C-terminal helix-turn-helix domain. We propose that CbFic2 performs AMPylation in its monomeric state, switching to a deAMPylating dimer upon DNA binding. This study unveils reversible histone modification by a specific enzyme of a pathogenic bacterium.

Study of tissue transglutaminase spliced variants expressed in THP-1 derived macrophages exhibiting distinct functional phenotypes

Tissue transglutaminase (TG2) expressed in monocytes and macrophage is known to participate in processes during either early and resolution stages of inflammation. The alternative splicing of tissue transglutaminase gene is a mechanism that increases its functional diversity. Four spliced variants are known with truncated C-terminal domains (TGM2_v2, TGM2_v3, TGM2_v4a, TGM2_v4b) but scarce information is available about its expression in human monocyte and macrophages. We studied the expression of canonical TG2 (TGM2_v1) and its short spliced variants by RT-PCR during differentiation of TPH-1 derived macrophages (dTHP-1) using two protocols (condition I and II) that differ in Phorbol-12-myristate-13-acetate dose and time schedule. The production of TNF-α and IL-1β in supernatant of dTHP-1, measured by ELISA in supernatants showed higher proinflammatory milieu in condition I. We found that the expression of all mRNA TG2 spliced variants were up-regulated during macrophage differentiation and after IFN-γ treatment of dTHP-1 cells in both conditions. Nevertheless, the relative fold increase or TGM2_v3 in relation with TGM2_v1 was higher only with the condition I. M1/M2-like THP-1 macrophages obtained with IFN-γ/IL-4 treatments showed that the up-regulation of TGM2_v1 induced by IL-4 was higher in relation with any short spliced variants. The qualitative profile of relative contribution of spliced variants in M1/M2-like THP-1 cells showed a trend to higher expression of TGM2_v3 in the inflammatory functional phenotype. Our results contribute to the knowledge about TG2 spliced variants in the biology of monocyte/macrophage cells and show how the differentiation conditions can alter their expression and cell function.

Native low-density lipoproteins are priming signals of the NLRP3 inflammasome/interleukin-1β pathway in human adipose tissue and macrophages

Elevated plasma numbers of atherogenic apoB-lipoproteins (apoB), mostly as low-density lipoproteins (LDL), predict diabetes risk by unclear mechanisms. Upregulation of the NLRP3 inflammasome/interleukin-1 beta (IL-1β) system in white adipose tissue (WAT) is implicated in type 2 diabetes (T2D); however, metabolic signals that stimulate it remain unexplored. We hypothesized that (1) subjects with high-apoB have higher WAT IL-1β-secretion than subjects with low-apoB, (2) WAT IL-1β-secretion is associated with T2D risk factors, and (3) LDL prime and/or activate the WAT NLRP3 inflammasome. Forty non-diabetic subjects were assessed for T2D risk factors related to systemic and WAT glucose and fat metabolism. Regulation of the NLRP3 inflammasome was explored using LDL without/with the inflammasome's priming and activation controls (LPS and ATP). LDL induced IL1B-expression and IL-1β-secretion in the presence of ATP in WAT and macrophages. Subjects with high-apoB had higher WAT IL-1β-secretion independently of covariates. The direction of association of LDL-induced WAT IL-1β-secretion to T2D risk factors was consistently pathological in high-apoB subjects only. Adjustment for IL-1β-secretion eliminated the association of plasma apoB with T2D risk factors. In conclusion, subjects with high-apoB have higher WAT IL-1β-secretion that may explain their risk for T2D and may be related to LDL-induced priming of the NLRP3 inflammasome.ClinicalTrials.gov (NCT04496154): Omega-3 to Reduce Diabetes Risk in Subjects With High Number of Particles That Carry "Bad Cholesterol" in the Blood-Full Text View-ClinicalTrials.gov.

Interleukin-11 Suppresses Ocular Surface Inflammation and Accelerates Wound Healing

Purpose

Regulation of inflammation is critical for achieving favorable outcomes in wound healing. In this study, we determine the functional role and mechanism of action of IL-11, an immunomodulatory cytokine, in regulating inflammatory response at the ocular surface.

Methods

Corneal injury was induced by mechanical removal of the epithelium and anterior stroma using an AlgerBrush II. Transcript and protein levels of IL-11 in injured cornea were quantified using real-time PCR and ELISA analysis. Corneal inflammation was assessed by measuring frequencies of total CD45+ inflammatory cells, CD11b+Ly6G+ polymorphonuclear cells (neutrophils), and CD11b+Ly6G- mononuclear cells (macrophages, monocytes) at the ocular surface using flow cytometry. To assess the effect of IL-11 on innate immune cell function, cell activation marker and inflammatory cytokines including major histocompatibility complex (MHC) class II, myeloperoxidase (MPO), TNFα, and inducible nitric oxide synthase (iNOS) were measured following recombinant IL-11 treatment (1 µg/mL). Injured corneas were topically treated with IL-11 (1 µg/mL), and wound healing was evaluated using corneal fluorescein staining.

Results

Corneal injury resulted in increased levels of IL-11 in the cornea, particularly in the stroma. Neutrophils and CD11b+ mononuclear cells (macrophages, monocytes) substantially expressed IL-11 receptor. Interestingly, IL-11 significantly downregulated the activation of immune cells, as evidenced by the lower expression of MHC II and TNFα by CD11b+ mononuclear cells and lower levels of MPO by neutrophils. Topical administration of IL-11 to injured corneas led to faster wound healing and better retention of tissue architecture.

Conclusions

Our findings demonstrate IL-11 is a key modulator of ocular surface inflammation and provide novel evidence of IL-11 as a potential therapeutic to control inflammatory damage and accelerate wound repair following injury.

Host cell-type and pathogen-specific immunomodulatory functions of macrophage migration inhibitory factor (MIF) in infectious keratitis

Therapeutic management of inflammation in infectious keratitis (IK) requires new strategy and targets for selective immunomodulation. Targeting host cell-type specific inflammatory responses might be a viable strategy to curtail unnecessary inflammation and reduce tissue damage without affecting pathogen clearance. This study explores the possibility of pathogen and host cell-type dependent differences in the inflammatory pathways relevant in the pathogenesis of IK. Human corneal epithelial cell line (HCEC) and phorbol 12-myristate-13 acetate (PMA) differentiated THP-1 macrophage line were infected with either Aspergillus flavus conidia or Acanthamoeba castellanii trophozoites and the elicited inflammatory responses were studied in terms of gene expression and secretion of proinflammatory factors interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) and an upstream inflammatory regulator and mediator protein-the Macrophage Migration Inhibitory Factor (MIF). Given the pleotropic mode of MIF function in diverse cell types relevant in many human diseases, we tested if MIF driven responses to infection is different in HCECs and THP-1 macrophages by studying its expression, secretion and involvement in inflammation by siRNA mediated knockdown. We also examined IK patient tear samples for MIF levels. Infection with A. flavus or A. castellanii induced IL-8 and TNF-α responses in HCECs and THP-1 macrophages but to different levels. Our preliminary human data showed that the level of secreted MIF protein was elevated in IK patient tear, however, MIF secretion by the two cell types were strikingly different in-vitro, under both normal and infected conditions. We found that HCECs released MIF constitutively, which was significantly inhibited with infection, whereas THP-1 macrophages were stimulated to release MIF during infection. MIF gene expression remained largely unaffected by infection in both the cell lines. Although MIF in HCECs appeared to be intracellularly captured during infection, MIF knockdown in HCECs associated with a partial reduction of the IL-8 and TNF-α expression produced by either of the pathogens, suggesting a pro-inflammatory role for MIF in HCECs, independent of its canonical cytokine like function. In contrast, MIF knockdown in THP-1 macrophages accompanied a dramatic increase in IL-8 and TNF-α expression during A. castellanii infection, while the responses to A. flavus infection remained unchanged. These data imply a host cell-type and pathogen specific distinction in the MIF- related inflammatory signaling and MIF as a potential selective immunomodulatory target in infectious keratitis.

Deoxynivalenol increases pro-inflammatory cytokine secretion and reduces primary bile acid transport in an inflamed intestinal in vitro co-culture model

The fungal secondary metabolite deoxynivalenol (DON) that can contaminate cereal-based food products not only induces inflammation but also reduces bile acid absorption by a healthy human intestine. Bile acid malabsorption is commonly observed in individuals with an inflamed intestine. Here we studied the effects of DON on inflammation and primary bile acid transport using an in vitro model for an inflamed intestine. An inflamed intestinal in vitro model was established by co-culturing a Caco-2 cell-layer and LPS-pre-stimulated THP-1 macrophages in Transwells. We observed a decreased transport of 5 primary bile acids across inflamed co-cultures compared to healthy co-cultures but not of chenodeoxycholic acid. DON exposure further reduced the transport of the affected primary bile acids across the inflamed co-cultures. DON exposure also enhanced the secretion of pro-inflammatory cytokines in the inflamed co-cultures, while it did not increase the pro-inflammatory cytokines secretion from LPS-pre-stimulated THP-1 monocultures. Exposure of Caco-2 cell-layers to pro-inflammatory cytokines or THP-1 conditioned media partly mimicked the DON-induced effects of the co-culture model. Local activation of intestinal immune cells reinforces the direct pro-inflammatory effects of DON on intestinal epithelial cells. This affects the bile acid intestinal kinetics in an inflamed intestine.

Development and characterization of a prototypic pan-amyloid clearing agent - a novel murine peptide-immunoglobulin fusion

Introduction

Systemic amyloidosis is a progressive disorder characterized by the extracellular deposition of amyloid fibrils and accessory proteins in visceral organs and tissues. Amyloid accumulation causes organ dysfunction and is not generally cleared by the immune system. Current treatment focuses on reducing amyloid precursor protein synthesis and slowing amyloid deposition. However, curative interventions will likely also require removal of preexisting amyloid deposits to restore organ function. Here we describe a prototypic pan-amyloid binding peptide-antibody fusion molecule (mIgp5) that enhances macrophage uptake of amyloid.

Methods

The murine IgG1-IgG2a hybrid immunoglobulin with a pan amyloid-reactive peptide, p5, fused genetically to the N-terminal of the immunoglobulin light chain was synthesized in HEK293T/17 cells. The binding of the p5 peptide moiety was assayed using synthetic amyloid-like fibrils, human amyloid extracts and amyloid-laden tissues as substrates. Binding of radioiodinated mIgp5 with amyloid deposits in vivo was evaluated in a murine model of AA amyloidosis using small animal imaging and microautoradiography. The bioactivity of mIgp5 was assessed in complement fixation and in vitro phagocytosis assays in the presence of patient-derived amyloid extracts and synthetic amyloid fibrils as substrates and in the presence or absence of human serum.

Results

Murine Igp5 exhibited highly potent binding to AL and ATTR amyloid extracts and diverse types of amyloid in formalin-fixed tissue sections. In the murine model of systemic AA amyloidosis, 125I-mIgp5 bound rapidly and specifically to amyloid deposits in all organs, including the heart, with no evidence of non-specific uptake in healthy tissues. The bioactivity of the immunoglobulin Fc domain was uncompromised in the context of mIgp5 and served as an effective opsonin. Macrophage-mediated uptake of amyloid extract and purified amyloid fibrils was enhanced by the addition of mIgp5. This effect was exaggerated in the presence of human serum coincident with deposition of complement C5b9.

Conclusion

Immunostimulatory, amyloid-clearing therapeutics can be developed by incorporating pan-amyloid-reactive peptides, such as p5, as a targeting moiety. The immunologic functionality of the IgG remains intact in the context of the fusion protein. These data highlight the potential use of peptide-antibody fusions as therapeutics for all types of systemic amyloidosis.

Inflammatory macrophages exploited by oral streptococcus increase IL-1B release via NLRP6 inflammasome

Chronic inflammatory periodontal disease develops in part from the infiltration of a large number of classically activated inflammatory macrophages that release inflammatory cytokines important for disease progression, including inflammasome-dependent interleukin (IL)-1β. Streptococcus gordonii is a normally commensal oral microorganism; while not causative, recent evidence indicates that commensal oral microbes are required for the full development of periodontal disease. We have recently reported that inflammatory macrophages counterintuitively allow for the increased survival of phagocytosed S. gordonii over nonactivated or alternatively activated macrophages. This survival is dependent on increased reactive oxygen species production within the phagosome of the inflammatory macrophages, and resistance by the bacterium and can result in S. gordonii damaging the phagolysosomes. Here, we show that activated macrophages infected with live S. gordonii release more IL-1β than non-activated macrophages infected with either live or dead S. gordonii, and that the survival of oral Streptococci are more dependent on macrophage activation than other Gram positive microbes, both classical pathogens and commensals. We also find that S. gordonii-dependent inflammatory macrophage inflammasome activation requires the cytoplasmic NLRP6. Overall, our results suggest S. gordonii is capable of evading immune destruction, increasing inflammatory mediators, and increasing inflammatory macrophage response, and that this ability is increased under conditions of inflammation. This work reveals additional mechanisms by which normally commensal oral streptococci-macrophage interactions can change, resulting in increased release of mature IL-1β, potentially contributing to an environment that perpetuates inflammation.

Interferon-independent processes constrain measles virus cell-to-cell spread in primary human airway epithelial cells

Amplification of measles virus (MeV) in human airway epithelia may contribute to its extremely high contagious nature. We use well-differentiated primary cultures of human airway epithelial cells (HAE) to model ex vivo how MeV spreads in human airways. In HAE, MeV spreads cell-to-cell for 3-5 days, but then, infectious center growth is arrested. What stops MeV spread in HAE is not understood, but interferon (IFN) is known to slow MeV spread in other in vitro and in vivo models. Here, we assessed the role of type I and type III IFN in arresting MeV spread in HAE. The addition of IFN-β or IFN-λ1 to the medium of infected HAE slowed MeV infectious center growth, but when IFN receptor signaling was blocked, infectious center size was not affected. In contrast, blocking type-I IFN receptor signaling enhanced respiratory syncytial virus spread. HAE were also infected with MeV mutants defective for the V protein. The V protein has been demonstrated to interact with both MDA5 and STAT2 to inhibit activation of innate immunity; however, innate immune reactions were unexpectedly muted against the V-defective MeV in HAE. Minimal innate immunity activation was confirmed by deep sequencing, quantitative RT-PCR, and single-cell RNA-seq analyses of the transcription of IFN and IFN-stimulated genes. We conclude that in HAE, IFN-signaling can contribute to slowing infectious center growth; however, IFN-independent processes are most important for limiting cell-to-cell spread. IMPORTANCE Fundamental biological questions remain about the highly contagious measles virus (MeV). MeV amplifies within airway epithelial cells before spreading to the next host. This final step likely contributes to the ability of MeV to spread host-to-host. Over the course of 3-5 days post-infection of airway epithelial cells, MeV spreads directly cell-to-cell and forms infectious centers. Infectious center formation is unique to MeV. In this study, we show that interferon (IFN) signaling does not explain why MeV cell-to-cell spread is ultimately impeded within the cell layer. The ability of MeV to spread cell-to-cell in airway cells without appreciable IFN induction may contribute to its highly contagious nature. This study contributes to the understanding of a significant global health concern by demonstrating that infectious center formation occurs independent of the simplest explanation for limiting viral transmission within a host.