The Good and the Bad: Monocytes' and Macrophages' Diverse Functions in Inflammation

Costic acid, a sesquiterpene from Nectandra barbellata (Lauraceae), attenuates sponge implant-induced inflammation, angiogenesis and collagen deposition in vivo

Sesquiterpenes are a class of metabolites derived from plant species with immunomodulatory activity. In this study, we evaluated the effects of treatment with costic acid on inflammation, angiogenesis, and fibrosis induced by subcutaneous sponge implants in mice. One sponge disc per animal was aseptically implanted in the dorsal region of the mice and treated daily with costic acid (at concentrations of 0.1, 1, and 10 μg diluted in 10 μL of 0.5% DMSO) or 0.5% DMSO (control group). After 9 days of treatment, the animals were euthanized, and the implants collected for further analysis. Treatment with costic acid resulted in the reduction of the inflammatory parameters evaluated compared to the control group, with a decrease in the levels of inflammatory cytokines and chemokines (TNF, CXCL-1, and CCL2) and in the activity of MPO and NAG enzymes. Costic acid administration altered the process of mast cell degranulation. We also observed a reduction in angiogenic parameters, such as a decrease in the number of blood vessels, the hemoglobin content, and the levels of VEGF and FGF cytokines. Finally, when assessing implant-induced fibrogenesis, we observed a reduction in the levels of the pro-fibrogenic cytokine TGF-β1, and lower collagen deposition. The results of this study demonstrate, for the first time, the anti-inflammatory, anti-angiogenic, and anti-fibrotic effects of costic acid in an in vivo model of chronic inflammation and reinforce the therapeutic potential of costic acid.

Independent and joint associations of monocyte to high-density lipoprotein-cholesterol ratio and body mass index with cardiorenal syndrome: insights from NHANES 2003-2020

BACKGROUND

With the development of pathophysiology, cardiorenal syndrome (CRS), a complex and severe disease, has received increasing attention. Monocyte to high-density lipoprotein-cholesterol ratio (MHR) and body mass index (BMI) are independent risk factors for cardiovascular diseases, but their association with CRS remains unexplored. This study aims to explore the independent and joint effects of MHR and BMI on CRS.

METHODS

We included 42,178 NHANES participants. The determination of CRS referred to the simultaneous presence of cardiovascular disease (identified through self-report) and chronic kidney disease (eGFR < 60 mL/min per 1.73 m²). We employed multivariate weighted logistic regression to evaluate the odds ratio (OR) and 95% confidence interval (CI) for the independent and joint associations of MHR and BMI with CRS. We also conducted restricted cubic spines to explore nonlinear associations.

RESULTS

The prevalence of CRS was 3.45% among all participants. An increase in both MHR and BMI is associated with a higher risk of CRS (MHR: OR = 1.799, 95% CI = 1.520-2.129, P < 0.001, P-trend < 0.001; BMI: OR = 1.037, 95% CI = 1.023-1.051, P < 0.001). Individuals who simultaneously fall into the highest quartile of MHR and have a BMI of 30 or more face the highest risk of CRS compared to those in the lowest MHR quartile with a BMI of less than 25 (OR = 3.45, 95% CI = 2.40-4.98, P < 0.001). However, there is no interactive association between MHR and BMI with CRS.

CONCLUSIONS

Higher MHR and BMI are associated with higher odds of CRS. MHR and BMI can serve as tools for early prevention and intervention of CRS, respectively.

Inhaled Macrophage Apoptotic Bodies-Engineered Microparticle Enabling Construction of Pro-Regenerative Microenvironment to Fight Hypoxic Lung Injury in Mice

Oxygen therapy cannot rescue local lung hypoxia in patients with severe respiratory failure. Here, an inhalable platform is reported for overcoming the aberrant hypoxia-induced immune changes and alveolar damage using camouflaged poly(lactic-co-glycolic) acid (PLGA) microparticles with macrophage apoptotic body membrane (cMAB). cMABs are preloaded with mitochondria-targeting superoxide dismutase/catalase nanocomplexes (NCs) and modified with pathology-responsive macrophage growth factor colony-stimulating factor (CSF) chains, which form a core-shell platform called C-cMAB/NC with efficient deposition in deeper alveoli and high affinity to alveolar epithelial cells (AECs) after CSF chains are cleaved by matrix metalloproteinase 9. Therefore, NCs can be effectively transported into mitochondria to inhibit inflammasome-mediated AECs damage in mouse models of hypoxic acute lung injury. Additionally, the at-site CSF release is sufficient to rescue circulating monocytes and macrophages and alter their phenotypes, maximizing synergetic effects of NCs on creating a pro-regenerative microenvironment that enables resolution of lung injury and inflammation. This inhalable platform may have applications to numerous inflammatory lung diseases.

Bidirectional two-sample Mendelian randomization study of differential white blood cell counts and schizophrenia

BACKGROUND

Schizophrenia and white blood cell counts (WBC) are both complex and polygenic traits. Previous evidence suggests that increased WBC are associated with higher all-cause mortality, and other studies have found elevated WBC in first-episode psychosis and chronic schizophrenia. However, these observational findings may be confounded by antipsychotic exposures and their effects on WBC. Mendelian randomization (MR) is a useful method for examining the directions of genetically-predicted relationships between schizophrenia and WBC.

METHODS

We performed a two-sample MR using summary statistics from genome-wide association studies (GWAS) conducted by the Psychiatric Genomics Consortium Schizophrenia Workgroup (N = 130,644) and the Blood Cell Consortium (N = 563,946). The MR methods included inverse variance weighted (IVW), MR Egger, weighted median, MR-PRESSO, contamination mixture, and a novel approach called mixture model reciprocal causal inference (MRCI). False discovery rate was employed to correct for multiple testing.

RESULTS

Multiple MR methods supported bidirectional genetically-predicted relationships between lymphocyte count and schizophrenia: IVW (b = 0.026; FDR p-value = 0.008), MR Egger (b = 0.026; FDR p-value = 0.008), weighted median (b = 0.013; FDR p-value = 0.049), and MR-PRESSO (b = 0.014; FDR p-value = 0.010) in the forward direction, and IVW (OR = 1.100; FDR p-value = 0.021), MR Egger (OR = 1.231; FDR p-value < 0.001), weighted median (OR = 1.136; FDR p-value = 0.006) and MRCI (OR = 1.260; FDR p-value = 0.026) in the reverse direction. MR Egger (OR = 1.171; FDR p-value < 0.001) and MRCI (OR = 1.154; FDR p-value = 0.026) both suggested genetically-predicted eosinophil count is associated with schizophrenia, but MR Egger (b = 0.060; FDR p-value = 0.010) and contamination mixture (b = -0.013; FDR p-value = 0.045) gave ambiguous results on whether genetically predicted liability to schizophrenia would be associated with eosinophil count. MR Egger (b = 0.044; FDR p-value = 0.010) and MR-PRESSO (b = 0.009; FDR p-value = 0.045) supported genetically predicted liability to schizophrenia is associated with elevated monocyte count, and the opposite direction was also indicated by MR Egger (OR = 1.231; FDR p-value = 0.045). Lastly, unidirectional genetic liability from schizophrenia to neutrophil count were proposed by MR-PRESSO (b = 0.011; FDR p-value = 0.028) and contamination mixture (b = 0.011; FDR p-value = 0.045) method.

CONCLUSION

This MR study utilised multiple MR methods to obtain results suggesting bidirectional genetic genetically-predicted relationships for elevated lymphocyte counts and schizophrenia risk. In addition, moderate evidence also showed bidirectional genetically-predicted relationships between schizophrenia and monocyte counts, and unidirectional effect from genetic liability for eosinophil count to schizophrenia and from genetic liability for schizophrenia to neutrophil count. The influence of schizophrenia to eosinophil count is less certain. Our findings support the role of WBC in schizophrenia and concur with the hypothesis of neuroinflammation in schizophrenia.

Early Identification of Sepsis-Induced Acute Kidney Injury by Using Monocyte Distribution Width, Red-Blood-Cell Distribution, and Neutrophil-to-Lymphocyte Ratio

Sepsis-induced acute kidney injury (AKI) is a common complication in patients with severe illness and leads to increased risks of mortality and chronic kidney disease. We investigated the association between monocyte distribution width (MDW), red-blood-cell volume distribution width (RDW), neutrophil-to-lymphocyte ratio (NLR), sepsis-related organ-failure assessment (SOFA) score, mean arterial pressure (MAP), and other risk factors and sepsis-induced AKI in patients presenting to the emergency department (ED). This retrospective study, spanning 1 January 2020, to 30 November 2020, was conducted at a university-affiliated teaching hospital. Patients meeting the Sepsis-2 consensus criteria upon presentation to our ED were categorized into sepsis-induced AKI and non-AKI groups. Clinical parameters (i.e., initial SOFA score and MAP) and laboratory markers (i.e., MDW, RDW, and NLR) were measured upon ED admission. A logistic regression model was developed, with sepsis-induced AKI as the dependent variable and laboratory parameters as independent variables. Three multivariable logistic regression models were constructed. In Model 1, MDW, initial SOFA score, and MAP exhibited significant associations with sepsis-induced AKI (area under the curve [AUC]: 0.728, 95% confidence interval [CI]: 0.668-0.789). In Model 2, RDW, initial SOFA score, and MAP were significantly correlated with sepsis-induced AKI (AUC: 0.712, 95% CI: 0.651-0.774). In Model 3, NLR, initial SOFA score, and MAP were significantly correlated with sepsis-induced AKI (AUC: 0.719, 95% CI: 0.658-0.780). Our novel models, integrating MDW, RDW, and NLR with initial SOFA score and MAP, can assist with the identification of sepsis-induced AKI among patients with sepsis presenting to the ED.

Mesenchymal Stem Cell-Derived Exosomes Attenuate Murine Cytomegalovirus-Infected Pneumonia via NF-κB/NLRP3 Signaling Pathway

Reactivation and infection with cytomegalovirus (CMV) are frequently observed in recipients of solid organ transplants, bone marrow transplants, and individuals with HIV infection. This presents an increasing risk of allograft rejection, opportunistic infection, graft failure, and patient mortality. Among immunocompromised hosts, interstitial pneumonia is the most critical clinical manifestation of CMV infection. Recent studies have demonstrated the potential therapeutic benefits of exosomes derived from mesenchymal stem cells (MSC-exos) in preclinical models of acute lung injury, including pneumonia, ARDS, and sepsis. However, the role of MSC-exos in the pathogenesis of infectious viral diseases, such as CMV pneumonia, remains unclear. In a mouse model of murine CMV-induced pneumonia, we observed that intravenous administration of mouse MSC (mMSC)-exos reduced lung damage, decreased the hyperinflammatory response, and shifted macrophage polarization from the M1 to the M2 phenotype. Treatment with mMSC-exos also significantly reduced the infiltration of inflammatory cells and pulmonary fibrosis. Furthermore, in vitro studies revealed that mMSC-exos reversed the hyperinflammatory phenotype of bone marrow-derived macrophages infected with murine CMV. Mechanistically, mMSC-exos treatment decreased activation of the NF-κB/NLRP3 signaling pathway both in vivo and in vitro. In summary, our findings indicate that mMSC-exo treatment is effective in severe CMV pneumonia by reducing lung inflammation and fibrosis through the NF-κB/NLRP3 signaling pathway, thus providing promising therapeutic potential for clinical CMV infection.

Empowering Naringin's Anti-Inflammatory Effects through Nanoencapsulation

Abundant in citrus fruits, naringin (NAR) is a flavonoid that has a wide spectrum of beneficial health effects, including its anti-inflammatory activity. However, its use in the clinic is limited due to extensive phase I and II first-pass metabolism, which limits its bioavailability. Thus, lipid nanoparticles (LNPs) were used to protect and concentrate NAR in inflamed issues, to enhance its anti-inflammatory effects. To target LNPs to the CD44 receptor, overexpressed in activated macrophages, functionalization with hyaluronic acid (HA) was performed. The formulation with NAR and HA on the surface (NAR@NPsHA) has a size below 200 nm, a polydispersity around 0.245, a loading capacity of nearly 10%, and a zeta potential of about 10 mV. In vitro studies show the controlled release of NAR along the gastrointestinal tract, high cytocompatibility (L929 and THP-1 cell lines), and low hemolytic activity. It was also shown that the developed LNPs can regulate inflammatory mediators. In fact, NAR@NPsHA were able to decrease TNF-α and CCL-3 markers expression by 80 and 90% and manage to inhibit the effects of LPS by around 66% for IL-1β and around 45% for IL-6. Overall, the developed LNPs may represent an efficient drug delivery system with an enhanced anti-inflammatory effect.

Identification of memory mechanism in tissue-resident stem cells via ANGPTL4 beyond immune cells upon viral antigen exposure

Although memory functions of immune cells characterized by increased resistance to subsequent infections after initial pathogen exposure are well-established, it remains unclear whether non-immune cells, especially tissue-resident stem cells, exhibit similar memory mechanisms. The present study revealed that detrimental effects of initial viral antigen exposure (human papillomavirus [HPV]) on diverse stem cell functions were significantly exacerbated upon subsequent secondary exposure both in vitro and in vivo. Importantly, endometrial stem cells exhibited robust memory functions following consecutive HPV antigen exposures, whereas fully differentiated cells such as fibroblasts and vesicular cells did not show corresponding changes in response to the same antigen exposures. Deficiency of angiopoietin-like 4 (ANGPTL4) achieved through small hairpin RNA knockdown in vitro and knockout (KO) mice in vivo highlighted the critical role of ANGPTL4 in governing memory functions associated with various stem cell processes. This regulation occurred through histone H3 methylation alterations and PI3K/Akt signaling pathways in response to successive HPV antigen exposures. Furthermore, memory functions associated with various stem cell functions that were evident in wild-type mice following consecutive exposures to HPV antigen were not observed in ANGPTL4 KO mice. In summary, our findings strongly support the presence of memory mechanism in non-immune cells, particularly tissue-resident stem cells.

Studies Related to the Involvement of EsA in Improving Intestinal Inflammation in Acute Pancreatitis via the NF-κB Pathway

Background

Acute pancreatitis (AP) is a clinically frequent acute abdominal condition, which refers to an inflammatory response syndrome of edema, bleeding, and even necrosis caused by abnormal activation of the pancreas's own digestive enzymes. Intestinal damage can occur early in the course of AP and is manifested by impaired intestinal mucosal barrier function, and inflammatory reactions of the intestinal mucosa, among other factors. It can cause translocation of intestinal bacteria and endotoxins, further aggravating the condition of AP. Therefore, actively protecting the intestinal mucosal barrier, controlling the progression of intestinal inflammation, and improving intestinal dynamics in the early stages of AP play an important role in enhancing the prognosis of AP.

Methods

The viability and apoptosis of RAW264.7 cells treated with Esculentoside A (EsA) and/or lipopolysaccharide were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry, respectively. The expression of apoptosis-related proteins and NF-κB signaling pathway-related proteins were detected by western blot (WB). An enzyme-linked immunosorbent assay was used to measure TNF-α and IL-6 secretion.

Results

In vitro experiments demonstrated that EsA not only promoted the apoptosis of inflammatory cells but also reduced the secretion of TNF-α and IL-6 in a dose-dependent manner. Additionally, it inhibited the activation of the NF-κB signaling pathway by decreasing the expression of phosphorylated-p65(p-p65) and elevating the expression of IκBα. Similarly, in vivo experiments using a rat AP model showed that EsA inhibited the expression of p-p65 elevating the expression of IκBα in the intestinal tissues of the rat AP model and promoting the apoptosis of inflammatory cells in the intestinal mucosa in vivo experiments, while improving the pathological outcome of the pancreatic and intestinal tissues.

Conclusion

Our results suggest that EsA can reduce intestinal inflammation in the rat AP model and that EsA may be a candidate for treating intestinal inflammation in AP and further arresting AP progression.

CLEC-1 Restrains Acute Inflammatory Response and Recruitment of Neutrophils following Tissue Injury

The inflammatory response is a key mechanism for the elimination of injurious agents but must be tightly controlled to prevent additional tissue damage and progression to persistent inflammation. C-type lectin receptors expressed mostly by myeloid cells play a crucial role in the regulation of inflammation by recognizing molecular patterns released by injured tissues. We recently showed that the C-type lectin receptor CLEC-1 is able to recognize necrotic cells. However, its role in the acute inflammatory response following tissue damage had not yet been investigated. We show in this study, in a mouse model of liver injury induced by acetaminophen intoxication, that Clec1a deficiency enhances the acute immune response with increased expression of Il1b, Tnfa, and Cxcl2 and higher infiltration of activated neutrophils into the injured organ. Furthermore, we demonstrate that Clec1a deficiency exacerbates tissue damage via CXCL2-dependent neutrophil infiltration. In contrast, we observed that the lack of CLEC-1 limits CCL2 expression and the accumulation, beyond the peak of injury, of monocyte-derived macrophages. Mechanistically, we found that Clec1a-deficient dendritic cells increase the expression of Il1b, Tnfa, and Cxcl2 in response to necrotic cells, but decrease the expression of Ccl2. Interestingly, treatment with an anti-human CLEC-1 antagonist mAb recapitulates the exacerbation of acute immunopathology observed by genetic loss of Clec1a in a preclinical humanized mouse model. To conclude, our results demonstrate that CLEC-1 is a death receptor limiting the acute inflammatory response following injury and represents a therapeutic target to modulate immunity.

Immunological factors linked to geographical variation in vaccine responses

Vaccination is one of medicine's greatest achievements; however, its full potential is hampered by considerable variation in efficacy across populations and geographical regions. For example, attenuated malaria vaccines in high-income countries confer almost 100% protection, whereas in low-income regions these same vaccines achieve only 20-50% protection. This trend is also observed for other vaccines, such as bacillus Calmette-Guérin (BCG), rotavirus and yellow fever vaccines, in terms of either immunogenicity or efficacy. Multiple environmental factors affect vaccine responses, including pathogen exposure, microbiota composition and dietary nutrients. However, there has been variable success with interventions that target these individual factors, highlighting the need for a better understanding of their downstream immunological mechanisms to develop new ways of modulating vaccine responses. Here, we review the immunological factors that underlie geographical variation in vaccine responses. Through the identification of causal pathways that link environmental influences to vaccine responsiveness, it might become possible to devise modulatory compounds that can complement vaccines for better outcomes in regions where they are needed most.

Immunologic basis for development of keratoconjunctivitis sicca in systemic autoimmune diseases: Role of innate immune sensors

The literature is filled with citations reporting an increased incidence of chronic dry eye disease, also known as keratoconjunctivitis sicca, in patients with systemic autoimmune diseases such as rheumatoid arthritis, Sjögren's Syndrome, systemic sclerosis and lupus. As the most environmentally exposed mucosal surface of the body, the conjunctiva constantly responds to environmental challenges which are typically self limited, but when persistent and unresolved may provoke pathogenic innate and adaptive immune reactions. Our understanding of the pathophysiological mechanisms by which systemic autoimmune diseases cause dry eye inducing ocular surface inflammation continues to evolve. Conjunctival immune tone responds to self or foreign danger signals (including desiccating stress) on the ocular surface with an initial non-specific innate inflammatory response. If unchecked, this can lead to activation of dendritic cells that present antigen and prime T and B cells resulting in an adaptive immune reaction. These reactions generally resolve, but dysfunctional, hyper-responsive immune cells found in systemic autoimmune diseases that are recruited to the ocular surface can amplify inflammatory stress responses in the ocular surface and glandular tissues and result in autoimmune reactions that disrupt tear stability and lead to chronic dry eye disease. We here propose that unique features of the ocular surface immune system and the impact of systemic immune dysregulation in autoimmune diseases, can predispose to development of dry eye disease, and exacerbate severity of existing dry eye.

Distinct developmental reprogramming footprint of macrophages during acute kidney injury across species

Acute kidney injury (AKI) is a common finding in hospitalized patients, particularly those who are critically ill. The development of AKI is associated with several adverse outcomes including mortality, morbidity, progression to chronic kidney disease, and an increase in healthcare expenditure. Despite the well-established negative impact of AKI and rigorous efforts to better define, identify, and implement targeted therapies, the overall approach to the treatment of AKI continues to principally encompass supportive measures. This enduring challenge is primarily due to the heterogeneous nature of insults that activate many independent and overlapping molecular pathways. Consequently, it is evident that the identification of common mechanisms that mediate the pathogenesis of AKI, independent of etiology and engaged pathophysiological pathways, is of paramount importance and could lead to the identification of novel therapeutic targets. To better distinguish the commonly modulated mechanisms of AKI, we explored the transcriptional characteristics of human kidney biopsies from patients with acute tubular necrosis (ATN), and acute interstitial nephritis (AIN) using a NanoString inflammation panel. Subsequently, we used publicly available single-cell transcriptional resources to better interpret the generated transcriptional findings. Our findings identify robust acute kidney injury (AKI-induced) developmental reprogramming of macrophages (MΦ) with the expansion of C1Q+, CD163+ MΦ that is independent of the etiology of AKI and conserved across mouse and human species. These results would expand the current understanding of the pathophysiology of AKI and potentially offer novel targets for additional studies to enhance the translational transition of AKI research.NEW & NOTEWORTHY Our findings identify robust acute kidney injury (AKI)-induced developmental reprogramming of macrophages (MΦ) with the expansion of C1Q+, CD163+ MΦ that is independent of the etiology of AKI and conserved across mouse and human species.

A novel selective leukocyte depletion human whole blood model reveals the specific roles of monocytes and granulocytes in the cytokine response to Escherichia coli

The lepirudin-based human whole blood model is a well-established ex vivo system to characterize inflammatory responses. However, the contribution of individual cell populations to cytokine release has not been investigated. Thus, we modified the model by selectively removing leukocyte subpopulations to elucidate their contribution to the inflammatory response. Lepirudin-anticoagulated whole blood was depleted from monocytes or granulocytes using StraightFrom Whole Blood MicroBeads. Reconstituted blood was incubated with Escherichia coli (108/mL) for 2 hours at 37 °C. CD11b, CD62P, and CD63 were detected by flow cytometry. Complement (C3bc, sC5b-9) and platelet activation (platelet factor 4, NAP-2) were measured by enzyme-linked immunosorbent assay. Cytokines were quantified by multiplex assay. A significant (P < 0.05) specific depletion of the monocyte (mean = 86%; 95% confidence interval = 71%-92%) and granulocyte (mean = 97%; 95% confidence interval = 96%-98%) population was obtained. Background activation induced by the depletion protocol was negligible for complement (C3bc and sC5b-9), leukocytes (CD11b), and platelets (NAP-2). Upon Escherichia coli incubation, release of 10 of the 24 cytokines was solely dependent on monocytes (interleukin [IL]-1β, IL-2, IL-4, IL-5, IL-17A, interferon-γ, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, macrophage inflammatory protein-1α, and fibroblast growth factor-basic), whereas 8 were dependent on both monocytes and granulocytes (IL-1ra, IL-6, IL-8, IL-9, IL-10, macrophage inflammatory protein-1β, tumor necrosis factor, and eotaxin). Six cytokines were not monocyte or granulocyte dependent, of which platelet-derived growth factor and RANTES were mainly platelet dependent. We document an effective model for selective depletion of leukocyte subpopulations from whole blood, without causing background activation, allowing in-depth cellular characterization. The results are in accordance with monocytes playing a major role in cytokine release and expand our knowledge of the significant role of granulocytes in the response to E. coli.

Complete Rescue of HTLV-1p12KO Infectivity by Depletion of Monocytes Together with NK and CD8+ T Cells

The transient depletion of monocytes alone prior to exposure of macaques to HTLV-1 enhances both HTLV-1WT (wild type) and HTLV-1p12KO (Orf-1 knockout) infectivity, but seroconversion to either virus is not sustained over time, suggesting a progressive decrease in virus expression. These results raise the hypotheses that either HTLV-1 persistence depends on a monocyte reservoir or monocyte depletion provides a transient immune evasion benefit. To test these hypotheses, we simultaneously depleted NK cells, CD8+ T cells, and monocytes (triple depletion) prior to exposure to HTLV-1WT or HTLV-1p12KO. Remarkably, triple depletion resulted in exacerbation of infection by both viruses and complete rescue of HTLV-1p12KO infectivity. Following triple depletion, we observed rapid and sustained seroconversion, high titers of antibodies against HTLV-1 p24Gag, and frequent detection of viral DNA in the blood and tissues of all animals when compared with depletion of only CD8+ and NK cells, or monocytes alone. The infection of macaques with HTLV-1WT or HTLV-1p12KO was associated with higher plasma levels of IL-10 after 21 weeks, while IL-6, IFN-γ, IL-18, and IL-1β were only elevated in animals infected with HTLV-1WT. The repeat depletion of monocytes, NK, and CD8+ cells seven months following the first exposure to HTLV-1 did not further exacerbate viral replication. These results underscore the contribution of monocytes in orchestrating anti-viral immunity. Indeed, the absence of orf-1 expression was fully compensated by the simultaneous depletion of CD8+ T cells, NK cells, and monocytes, underlining the primary role of orf-1 in hijacking host immunity.

miR-345-3p Modulates M1/M2 Macrophage Polarization to Inhibit Inflammation in Bone Infection via Targeting MAP3K1 and NF-κB Pathway

Infection after fracture fixation (IAFF), a complex infectious disease, causes inflammatory destruction of bone tissue and poses a significant clinical challenge. miR-345-3p is a biomarker for tibial infected nonunion; however, the comprehensive mechanistic role of miR-345-3p in IAFF is elusive. In this study, we investigated the role of miR-345-3p in IAFF pathogenesis through in vivo and in vitro experiments. In vivo, in a rat model of IAFF, miR-345-3p expression was downregulated, accompanied by increased M1 macrophage infiltration and secretion of proinflammatory factors. In vitro, LPS induced differentiation of primary rat bone marrow-derived macrophages into M1 macrophages, which was attenuated by miR-345-3p mimics. miR-345-3p promoted M1 to M2 macrophage transition-it reduced the expression of cluster of differentiation (CD) 86, inducible NO synthase, IL-1β, and TNF-α but elevated those of CD163, arginase-1, IL-4, and IL-10. MAPK kinase kinase 1 (MAP3K1), a target mRNA of miR-345-3p, was overexpressed in the bone tissue of IAFF rats compared with that in those of the control rats. The M1 to M2 polarization inhibited MAP3K1 signaling pathways in vitro. Conversely, MAP3K1 overexpression promoted the transition from M2 to M1. miR-345-3p significantly inhibited NF-κB translocation from the cytosol to the nucleus in a MAP3K1-dependent manner. In conclusion, miR-345-3p promotes the polarization of M1 macrophages to the M2 phenotype by inhibiting the MAP3K1 and NF-κB pathways. These findings provide insight into the pathogenesis and immunotherapeutic strategies for IAFF and offer potential new targets for subsequent research.

Anti-Inflammatory and Immunomodulatory Properties of a Crude Polysaccharide Derived from Green Seaweed Halimeda tuna: Computational and Experimental Evidences

In this study, we investigated for the first time the anti-inflammatory and immunomodulatory properties of crude polysaccharide (PSHT) extracted from green marine algae Halimeda tuna. PSHT exhibited anti-oxidant activity in vitro through scavenging 1, 1-diphenyl-2-picryl hydroxyl free radical, reducing Fe3+/ferricyanide complex, and inhibiting nitric oxide. PSHT maintained the erythrocyte membrane integrity and prevented hemolysis. Our results also showed that PSHT exerted a significant anti-edematic effect in vivo by decreasing advanced oxidation protein products and malondialdehyde levels and increasing the superoxide dismutase and glutathione peroxidase activities in rat's paw model and erythrocytes. Interestingly, PSHT increased the viability of murine RAW264.7 macrophages and exerted an anti-inflammatory effect on lipopolysaccharide-stimulated cells by decreasing pro-inflammatory molecule levels, including nitric oxide, granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF-α). Our findings indicate that PSHT could be used as a potential immunomodulatory, anti-inflammatory, anti-hemolytic, and anti-oxidant agent. These results could be explained by the computational findings showing that polysaccharide building blocks bound both cyclooxygenase-2 (COX-2) and TNF-α with acceptable affinities.

Parasite-induced IFN-γ regulates host defense via CD115 and mTOR-dependent mechanism of tissue-resident macrophage death

Host resistance to a common protozoan parasite Toxoplasma gondii relies on a coordinated immune response involving multiple cell types, including macrophages. Embryonically seeded tissue-resident macrophages (TRMs) play a critical role in maintaining tissue homeostasis, but their role in parasite clearance is poorly understood. In this study, we uncovered a crucial aspect of host defense against T. gondii mediated by TRMs. Through the use of neutralizing antibodies and conditional IFN-γ receptor-deficient mice, we demonstrated that IFN-γ directly mediated the elimination of TRMs. Mechanistically, IFN-γ stimulation in vivo rendered macrophages unresponsive to macrophage colony-stimulating factor (M-CSF) and inactivated mTOR signaling by causing the shedding of CD115 (CSFR1), the receptor for M-CSF. Further experiments revealed the essential role of macrophage IFN-γ responsiveness in host resistance to T. gondii. The elimination of peritoneal TRMs emerged as an additional host defense mechanism aimed at limiting the parasite's reservoir. The identified mechanism, involving IFN-γ-induced suppression of CD115-dependent mTOR signaling in macrophages, provides insights into the adaptation of macrophage subsets during infection and highlights a crucial aspect of host defense against intracellular pathogens.

Silymarin and Inflammation: Food for Thoughts

Inflammation is a vital defense mechanism, creating hostile conditions for pathogens, preventing the spread of tissue infection and repairing damaged tissues in humans and animals. However, when inflammation resolution is delayed or compromised as a result of its misregulation, the process proceeds from the acute phase to chronic inflammation, leading to the development of various chronic illnesses. It is proven that redox balance disturbances and oxidative stress are among major factors inducing NF-κB and leading to over-inflammation. Therefore, the anti-inflammatory properties of various natural antioxidants have been widely tested in various in vitro and in vivo systems. Accumulating evidence indicates that silymarin (SM) and its main constituent silibinin/silybin (SB) have great potential as an anti-inflammation agent. The main anti-inflammatory mechanism of SM/SB action is attributed to the inhibition of TLR4/NF-κB-mediated signaling pathways and the downregulated expression of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, IL-12, IL-23, CCL4, CXCL10, etc. Of note, in the same model systems, SM/SB was able to upregulate anti-inflammatory cytokines (IL-4, IL-10, IL-13, TGF-β, etc.) and lipid mediators involved in the resolution of inflammation. The inflammatory properties of SM/SB were clearly demonstrated in model systems based on immune (macrophages and monocytes) and non-immune (epithelial, skin, bone, connective tissue and cancer) cells. At the same time, the anti-inflammatory action of SM/SB was confirmed in a number of in vivo models, including toxicity models, nonalcoholic fatty liver disease, ischemia/reperfusion models, stress-induced injuries, ageing and exercising models, wound healing and many other relevant model systems. It seems likely that the anti-inflammatory activities of SM/SB are key elements on the health-promoting properties of these phytochemicals.

Current status and development direction of immunomodulatory therapy for intervertebral disk degeneration

Intervertebral disk (IVD) degeneration (IVDD) is a main factor in lower back pain, and immunomodulation plays a vital role in disease progression. The IVD is an immune privileged organ, and immunosuppressive molecules in tissues reduce immune cell (mainly monocytes/macrophages and mast cells) infiltration, and these cells can release proinflammatory cytokines and chemokines, disrupting the IVD microenvironment and leading to disease progression. Improving the inflammatory microenvironment in the IVD through immunomodulation during IVDD may be a promising therapeutic strategy. This article reviews the normal physiology of the IVD and its degenerative mechanisms, focusing on IVDD-related immunomodulation, including innate immune responses involving Toll-like receptors, NOD-like receptors and the complement system and adaptive immune responses that regulate cellular and humoral immunity, as well as IVDD-associated immunomodulatory therapies, which mainly include mesenchymal stem cell therapies, small molecule therapies, growth factor therapies, scaffolds, and gene therapy, to provide new strategies for the treatment of IVDD.

Dynamical changes in the expression of GABAergic and purinergic components occur during the polarization of THP-1 monocytes to proinflammatory macrophages

The monocytes are key components of innate immunity, as they can differentiate into phagocytic cells or macrophages with proinflammatory or anti-inflammatory phenotypes. The gamma-aminobutyric acid (GABA) and adenosine triphosphate (ATP), two known neurotransmitters, are two environmental signals that contribute to the differentiation of monocytes into macrophages and their subsequent polarization into proinflammatory M1 and anti-inflammatory M2 macrophages. Although monocytes and macrophages express proteins related to GABA and ATP-mediated response (GABAergic and purinergic systems, respectively), it is unknown whether changes in their expression occur during monocyte activation or their differentiation and polarization into macrophages. Therefore, we evaluated the expression levels of GABAergic and purinergic signaling components in the THP-1 monocyte cell line and their changes during monocyte activation, differentiation, and polarization to M1 proinflammatory macrophages. Our results showed that activated monocytes are characterized by increased expression of two GABAergic components, the GABA transporter 2 (GAT-2) and the glutamic acid decarboxylase (GAD)-67, an enzyme involved in GABA synthesis. Also, monocytes showed a pronounced expression of the purinergic receptors P2X4 and P2X7. Interestingly, during differentiation, monocytes increased the expression of the β2 subunit of GABA A-type receptor (GABA-AR), while the purinergic receptors P2X1 and P2X1del were reduced. In contrast, proinflammatory M1 macrophages showed a reduced expression in the α4 subunit of GABA-AR and GAD67, while P2X4 and P2X7 were overexpressed. These results indicate that dynamical changes in the GABAergic and purinergic components occur during the transition from monocytes to macrophages. Since GABA and ATP are two neurotransmitters, our results suggest that monocytes and macrophages respond to neurotransmitter-induced stimulation and may represent a path of interaction between the nervous and immune systems during peripheral inflammation and neuroinflammation development.

Single-Cell Transcriptomics Reveals Crucial Cell Subsets and Functional Heterogeneity Associated With Carotid Atherosclerosis and Cerebrovascular Events

BACKGROUND

Carotid atherosclerosis is a chronic inflammatory disorder and is responsible for the vast majority of ischemic strokes. Inappropriate innate and adaptive immune responses synergize with malfunctional vascular wall cells to cause atherosclerotic lesions. Yet, functional characteristics of specific immune and endothelial cell subsets associated with atherosclerosis and cerebrovascular events are poorly understood.

METHODS

Here, using single-cell RNA sequencing, the unprecedentedly largest data set from 20 patients' carotid artery plaques and paired peripheral blood mononuclear cells was generated, with which an ultra-high-precision cellular landscape of the atherosclerotic microenvironment involving 372 070 cells was depicted.

RESULTS

Compared with peripheral blood mononuclear cells, 3 plaque-specific T-cell subsets exhibiting proatherogenic features of both activation and exhaustion were identified. Strikingly, usually antiatherogenic, CD4+FOXP3+ regulatory T cells from plaques of patients with symptomatic disease acquired proinflammatory properties by probably converting to T helper 17 and T helper 9 cells, while CD4+NR4A1+/C0 and CD8+SLC4A10+ T cells related to cerebrovascular events possessed atherogenic attributes including proinflammation, polarization, and exhaustion. In addition, monocyte-macrophage dynamics dominated innate immune response. Two plaque-specific monocyte subsets performed diametrically opposed functions, EREG+ monocytes promoted cerebrovascular events while C3+ monocytes are anti-inflammatory. Similarly, IGF1+ and HS3ST2+ macrophages with classical proinflammatory M1 macrophage features were annotated and contributed to cerebrovascular events. Moreover, SULF1+ (sulfatase-1) endothelial cells were also found to participate in cerebrovascular events through affecting plaque vulnerability.

CONCLUSIONS

This compendium of single-cell transcriptome data provides valuable insights into the cellular heterogeneity of the atherosclerotic microenvironment and the development of more precise cardiovascular immunotherapies.

Anti-inflammatory Effect of Polyunsaturated Fatty Acid N-Acylethanolamines Mediated by Macrophage Activity In Vitro and In Vivo

In recent years, there has been increasing interest in studying the anti-inflammatory activity of polyunsaturated fatty acid ethanolamides (N-acylethanolamines, NAE), which are highly active lipid mediators. The results of this study demonstrate that a dietary supplement (DS) of fatty acid-derived NAEs reduces LPS-induced inflammation. The processes of cell proliferation, as well as the dynamics of Iba-1-, CD68-, and CD163-positive macrophage activity within the thymus and spleen were studied. The production of pro-inflammatory cytokines (TNF, IL1β, IL6, and INFγ), ROS, NO, and nitrites was evaluated in the blood serum, thymus, and LPS-stimulated RAW264.7 mouse macrophages. In vitro and in vivo experiments have shown that DS (1) prevents LPS-induced changes in the morphological structure of the thymus and spleen; (2) levels out changes in cell proliferation; (3) inhibits the activity of Iba-1 and CD68-positive cells; (4) reduces the production of pro-inflammatory cytokines (TNF, IL1β, IL6, and INFγ), ROS, and CD68; and (5) enhances the activity of CD-163-positive cells. In general, the results of this study demonstrate the complex effect of DS on inflammatory processes in the central and peripheral immune systems.

Peritoneal and Systemic Interleukin-10 as Early Biomarkers for Colorectal Anastomotic Leakage Following Surgery in Colorectal Cancer Patients: A Systematic Review and Meta-Analysis

<b><br>Introduction:</b> Despite advancements in diagnostic methods, the early detection of colorectal anastomotic leakage (CAL) continues to pose challenges. The identification of reliable markers is crucial to reduce patient morbidity and mortality. Cytokines present in drain fluid and systemic cytokine levels have shown promise as predictive markers for CAL; however, additional high-quality evidence is warranted to enhance the reliability and validity of the findings in this field.</br> <b><br>Aim:</b> This systematic review and meta-analysis aimed to assess the significance of peritoneal and serum/plasma interleukin-10 (IL-10) levels in the early detection of CAL in patients undergoing colorectal surgery for colorectal cancer.</br> <b><br>Methods:</b> A comprehensive literature search was conducted in PubMed, Scopus, and Web of Science databases, covering studies published until July 2023. The search aimed to identify relevant studies investigating the levels of plasma/serum and peritoneal IL-10 (or both) in colorectal cancer patients undergoing colorectal surgery, specifically focusing on the presence of CAL. Data on the mean and standard deviation of IL-10 levels in both CAL and non-CAL patients were extracted from the selected studies. Mean differences in IL-10 levels were analyzed for each postoperative day (POD) using the OpenMeta [analyst] software.</br> <b><br>Results:</b> 11 articles were selected for inclusion in this systematic review. Among them, nine articles reported data on peritoneal IL-10 levels, while four articles focused on circulating IL-10 levels. The statistical analysis included four eligible articles that assessed peritoneal IL-10 levels, and the results indicated no significant increase in CAL patients compared to non-CAL patients on any postoperative day (POD). Meta-analysis for circulating IL-10 levels was not feasible.</br> <b><br>Conclusions:</b> Up to now, peritoneal and systemic IL-10 levels cannot be considered as early markers for CAL after colorectal surgery in colorectal cancer patients. More high-quality studies are needed to establish the potential of IL-10 as a reliable marker for detecting anastomotic leakage after colorectal surgery.</br>.

Williams-Beuren syndrome shapes the gut microbiota metaproteome

Williams-Beuren syndrome (WBS) is a rare genetic neurodevelopmental disorder with multi-systemic manifestations. The evidence that most subjects with WBS face gastrointestinal (GI) comorbidities, have prompted us to carry out a metaproteomic investigation of their gut microbiota (GM) profile compared to age-matched healthy subjects (CTRLs). Metaproteomic analysis was carried out on fecal samples collected from 41 individuals with WBS, and compared with samples from 45 CTRLs. Stool were extracted for high yield in bacterial protein group (PG) content, trypsin-digested and analysed by nanoLiquid Chromatography-Mass Spectrometry. Label free quantification, taxonomic assignment by the lowest common ancestor (LCA) algorithm and functional annotations by COG and KEGG databases were performed. Data were statistically interpreted by multivariate and univariate analyses. A WBS GM functional dissimilarity respect to CTRLs, regardless age distribution, was reported. The alterations in function of WBSs GM was primarily based on bacterial pathways linked to carbohydrate transport and metabolism and energy production. Influence of diet, obesity, and GI symptoms was assessed, highlighting changes in GM biochemical patterns, according to WBS subsets' stratification. The LCA-derived ecology unveiled WBS-related functionally active bacterial signatures: Bacteroidetes related to over-expressed PGs, and Firmicutes, specifically the specie Faecalibacterium prausnitzii, linked to under-expressed PGs, suggesting a depletion of beneficial bacteria. These new evidences on WBS gut dysbiosis may offer novel targets for tailored interventions.

TNFα counteracts interleukin-10 anti-inflammatory pathway through the NOX2-Lyn-SHP-1 axis in human monocytes

TNFα-mediated signaling pathways play a pivotal role in the pathogenesis of inflammatory diseases such as rheumatoid arthritis (RA) and inflammatory bowel disease (IBD) by promoting phagocyte inflammatory functions, notably cytokine release and reactive oxygen species (ROS) production by NOX2. In contrast, interleukin-10 (IL-10), a powerful anti-inflammatory cytokine, potently shuts down phagocyte activation, making IL-10 an attractive therapeutic candidate. However, IL-10 therapy has shown limited efficacy in patients with inflammatory diseases. Here, we report that TNFα blocks IL-10 anti-inflammatory pathways in human monocytes, thereby prolonging inflammation. TNFα decreased IL-10-induced phosphorylation of STAT3 and consequently IL-10-induced expression of the major anti-inflammatory factor, SOCS3. Decreased STAT3 phosphorylation was due to a SHP1/2 phosphatase, as NSC-87877, a SHP1/2 inhibitor, restored STAT3 phosphorylation and prevented the TNFα-induced inhibition of IL-10 signaling. TNFα activated only SHP1 in human monocytes and this activation was NOX2-dependent, as diphenyleneiodonium, a NOX2 inhibitor, suppressed SHP1 activation and STAT3 dephosphorylation triggered by TNFα. ROS-induced activation of SHP1 was mediated by the redox-sensitive kinase, Lyn, as its inhibition impeded TNFα-induced SHP1 activation and STAT3 dephosphorylation. Furthermore, H2O2 recapitulated TNFα-inhibitory activity on IL-10 signaling. Finally, NSC-87877 dampened collagen antibody-induced arthritis (CAIA) in mice. These results reveal that TNFα disrupts IL-10 signaling by inducing STAT3 dephosphorylation through a NOX2-ROS-Lyn-SHP1 axis in human monocytes and that inhibition of SHP1/2 in vivo protects against CAIA. These new findings might explain the poor efficacy of IL-10 therapy in patients with inflammatory diseases and suggest that anti-TNFα agents and SHP1/2 inhibitors could improve the therapeutic use of IL-10.

Maladaptive lymphangiogenesis is associated with synovial iron accumulation and delayed clearance in factor VIII-deficient mice after induced hemarthrosis

BACKGROUND

Mechanisms of iron clearance from hemophilic joints are unknown.

OBJECTIVES

To better understand mechanisms of iron clearance following joint bleeding in a mouse model of hemophilia.

METHODS

Hemarthrosis was induced by subpatellar puncture in factor VIII (FVIII)-deficient (FVII-/-) mice, +/- periprocedural recombinant human FVIII, and hypocoagulable (HypoBALB/c) mice. HypoBALB/c mice experienced transient FVIII deficiency (anti-FVIII antibody) at the time of injury combined with warfarin-induced hypocoagulability. Synovial tissue was harvested weekly up to 6 weeks after injury for histological analysis, ferric iron and macrophage accumulation (CD68), blood and lymphatic vessel remodeling (αSMA; LYVE1). Synovial RNA sequencing was performed for FVIII-/- mice at days 0, 3, and 14 after injury to quantify expression changes of iron regulators and lymphatic markers.

RESULTS

Bleed volumes were similar in FVIII-/- and HypoBALB/c mice. However, pronounced and prolonged synovial iron accumulation colocalizing with macrophages and impaired lymphangiogenesis were detected only in FVIII-/- mice and were prevented by periprocedural FVIII. Gene expression changes involved in iron handling (some genes with dual roles in inflammation) and lymphatic markers supported proinflammatory milieu with iron retention and disturbed lymphangiogenesis.

CONCLUSION

Accumulation and delayed clearance of iron-laden macrophages were associated with defective lymphangiogenesis after hemarthrosis in FVIII-/- mice. The absence of such findings in HypoBALB/c mice suggests that intact lymphatics are required for removal of iron-laden macrophages and that these processes depend on FVIII availability. Studies to elucidate the biological mechanisms of disturbed lymphangiogenesis in hemophilia appear critical to develop new therapeutic targets.

Systematic Analysis of Long Non-Coding RNAs in Inflammasome Activation in Monocytes/Macrophages

The NLRP3 inflammasome plays a pivotal role in regulating inflammation and immune responses. Its activation can lead to an inflammatory response and pyroptotic cell death. This is beneficial in the case of infections, but excessive activation can lead to chronic inflammation and tissue damage. Moreover, while most of the mammalian genome is transcribed as RNAs, only a small fraction codes for proteins. Among non-protein-coding RNAs, long non-coding RNAs (lncRNAs) have been shown to play key roles in regulating gene expression and cellular processes. They interact with DNA, RNAs, and proteins, and their dysregulation can provide insights into disease mechanisms, including NLRP3 inflammasome activation. Here, we systematically analyzed previously published RNA sequencing (RNA-seq) data of NLRP3 inflammasome activation in monocytes/macrophages to uncover inflammasome-regulated lncRNA genes. To uncover the functional importance of inflammasome-regulated lncRNA genes, one inflammasome-regulated lncRNA, ENSG00000273124, was knocked down in an in vitro model of macrophage polarization. The results indicate that silencing of ENSG00000273124 resulted in the up-regulation tumor necrosis factor (TNF), suggesting that this lncRNA might be involved in pro-inflammatory response in macrophages. To make our analyzed data more accessible, we developed the web database InflammasomeDB.

Monocyte distribution width (MDW) in sepsis

Sepsis is a life-threatening syndrome due to a dysregulated host response to infection, which can be caused by bacterial, viral, or fungal infection. Thus, it is crucial to know how the different microorganisms influence the levels of a biomarker. In the last decade, monocyte distribution width (MDW) has emerged as a promising sepsis biomarker, especially in acute settings, such as the Emergency Department and Intensive Care Unit. In this article, we explore the relationship between MDW and the different pathogens causing infection. Noteworthy, MDW is not a biological molecule, but it is calculated by a mathematical formula based on monocyte characteristics. Monocytes represent the first line defence against microorganisms and undergo activation upon infection, independently from the invading pathogen. According to the knowledge on the biomarker biology and the few literatures evidence, MDW may be considered a biomarker of sepsis, independent of the causative pathogen. However, further investigations are warranted before drawing definite conclusion.

Spatial transcriptomics reveals asymmetric cellular responses to injury in the regenerating spiny mouse (Acomys) ear

In contrast to other mammals, the spiny mouse (Acomys) regenerates skin and ear tissue, which includes hair follicles, glands, and cartilage, in a scar-free manner. Ear punch regeneration is asymmetric with only the proximal wound side participating in regeneration. Here, we show that cues originating from the proximal side are required for normal regeneration and use spatially resolved transcriptomics (tomo-seq) to understand the molecular and cellular events underlying this process. Analyzing gene expression across the ear and comparing expression modules between proximal and distal wound sides, we identify asymmetric gene expression patterns and pinpoint regenerative processes in space and time. Moreover, using a comparative approach with nonregenerative rodents (Mus, Meriones), we strengthen a hypothesis in which particularities in the injury-induced immune response may be one of the crucial determinants for why spiny mice regenerate whereas their relatives do not. Our data are available in SpinyMine, an easy-to-use and expandable web-based tool for exploring Acomys regeneration-associated gene expression.

Multi-transcriptomics reveals brain cellular responses to peripheral infection in Alzheimer's disease model mice

Peripheral inflammation has been linked to various neurodegenerative disorders, including Alzheimer's disease (AD). Here we perform bulk, single-cell, and spatial transcriptomics in APP/PS1 mice intranasally exposed to Staphylococcus aureus to determine how low-grade peripheral infection affects brain transcriptomics and AD-like pathology. Chronic exposure led to increased amyloid plaque burden and plaque-associated microglia, significantly affecting the transcription of brain barrier-associated cells, which resulted in barrier leakage. We reveal cell-type- and spatial-specific transcriptional changes related to brain barrier function and neuroinflammation during the acute infection. Both acute and chronic exposure led to brain macrophage-associated responses and detrimental effects in neuronal transcriptomics. Finally, we identify unique transcriptional responses at the amyloid plaque niches following acute infection characterized by higher disease-associated microglia gene expression and a larger effect on astrocytic or macrophage-associated genes, which could facilitate amyloid and related pathologies. Our findings provide important insights into the mechanisms linking peripheral inflammation to AD pathology.

Central IRF4/5 Signaling Are Critical for Microglial Activation and Impact on Stroke Outcomes

Microglia and monocytes play a critical role in immune responses to cerebral ischemia. Previous studies have demonstrated that interferon regulatory factor 4 (IRF4) and IRF5 direct microglial polarization after stroke and impact outcomes. However, IRF4/5 are expressed by both microglia and monocytes, and it is not clear if it is the microglial (central) or monocytic (peripheral) IRF4-IRF5 regulatory axis that functions in stroke. In this work, young (8-12 weeks) male pep boy (PB), IRF4 or IRF5 flox, and IRF4 or IRF5 conditional knockout (CKO) mice were used to generate 8 types of bone marrow chimeras, to differentiate the role of central (PB-to-IRF CKO) vs. peripheral (IRF CKO-to-PB) phagocytic IRF4-IRF5 axis in stroke. Chimeras generated from PB and flox mice were used as controls. All chimeras were subjected to 60-min middle cerebral artery occlusion (MCAO) model. Three days after the stroke, outcomes and inflammatory responses were analyzed. We found that PB-to-IRF4 CKO chimeras had more robust microglial pro-inflammatory responses than IRF4 CKO-to-PB chimeras, while ameliorated microglial response was seen in PB-to-IRF5 CKO vs. IRF5 CKO-to-PB chimeras. PB-to-IRF4 or IRF5 CKO chimeras had worse or better stroke outcomes respectively than their controls, whereas IRF4 or 5 CKO-to-PB chimeras had similar outcomes compared to controls. We conclude that the central IRF4/5 signaling is responsible for microglial activation and mediates stroke outcomes.

Damage-mediated macrophage polarization in sterile inflammation

Most of the leading causes of death, such as cardiovascular diseases, cancer, dementia, neurodegenerative diseases, and many more, are associated with sterile inflammation, either as a cause or a consequence of these conditions. The ability to control the progression of inflammation toward tissue resolution before it becomes chronic holds significant clinical potential. During sterile inflammation, the initiation of inflammation occurs through damage-associated molecular patterns (DAMPs) in the absence of pathogen-associated molecules. Macrophages, which are primarily localized in the tissue, play a pivotal role in sensing DAMPs. Furthermore, macrophages can also detect and respond to resolution-associated molecular patterns (RAMPs) and specific pro-resolving mediators (SPMs) during sterile inflammation. Macrophages, being highly adaptable cells, are particularly influenced by changes in the microenvironment. In response to the tissue environment, monocytes, pro-inflammatory macrophages, and pro-resolution macrophages can modulate their differentiation state. Ultimately, DAMP and RAMP-primed macrophages, depending on the predominant subpopulation, regulate the balance between inflammatory and resolving processes. While sterile injury and pathogen-induced reactions may have distinct effects on macrophages, most studies have focused on macrophage responses induced by pathogens. In this review, which emphasizes available human data, we illustrate how macrophages sense these mediators by examining the expression of receptors for DAMPs, RAMPs, and SPMs. We also delve into the signaling pathways induced by DAMPs, RAMPs, and SPMs, which primarily contribute to the regulation of macrophage differentiation from a pro-inflammatory to a pro-resolution phenotype. Understanding the regulatory mechanisms behind the transition between macrophage subtypes can offer insights into manipulating the transition from inflammation to resolution in sterile inflammatory diseases.

Free heme exacerbates colonic injury induced by anti-cancer therapy

Gastrointestinal inflammation and bleeding are commonly induced by cancer radiotherapy and chemotherapy but mechanisms are unclear. We demonstrated an increased number of infiltrating heme oxygenase-1 positive (HO-1+) macrophages (Mø, CD68+) and the levels of hemopexin (Hx) in human colonic biopsies from patients treated with radiation or chemoradiation versus non-irradiated controls or in the ischemic intestine compared to matched normal tissues. The presence of rectal bleeding in these patients was also correlated with higher HO-1+ cell infiltration. To functionally assess the role of free heme released in the gut, we employed myeloid-specific HO-1 knockout (LysM-Cre : Hmox1flfl), hemopexin knockout (Hx-/-) and control mice. Using LysM-Cre : Hmox1flfl conditional knockout (KO) mice, we showed that a deficiency of HO-1 in myeloid cells led to high levels of DNA damage and proliferation in colonic epithelial cells in response to phenylhydrazine (PHZ)-induced hemolysis. We found higher levels of free heme in plasma, epithelial DNA damage, inflammation, and low epithelial cell proliferation in Hx-/- mice after PHZ treatment compared to wild-type mice. Colonic damage was partially attenuated by recombinant Hx administration. Deficiency in Hx or Hmox1 did not alter the response to doxorubicin. Interestingly, the lack of Hx augmented abdominal radiation-mediated hemolysis and DNA damage in the colon. Mechanistically, we found an altered growth of human colonic epithelial cells (HCoEpiC) treated with heme, corresponding to an increase in Hmox1 mRNA levels and heme:G-quadruplex complexes-regulated genes such as c-MYC, CCNF, and HDAC6. Heme-treated HCoEpiC cells exhibited growth advantage in the absence or presence of doxorubicin, in contrast to poor survival of heme-stimulated RAW247.6 Mø. In summary, our data indicate that accumulation of heme in the colon following hemolysis and/or exposure to genotoxic stress amplifies DNA damage, abnormal proliferation of epithelial cells, and inflammation as a potential etiology for gastrointestinal syndrome (GIS).

Optimizing THP-1 Macrophage Culture for an Immune-Responsive Human Intestinal Model

Previously established immune-responsive co-culture models with macrophages have limitations due to the dedifferentiation of macrophages in long-term cultures. This study is the first report of a long-term (21-day) triple co-culture of THP-1 macrophages (THP-1m) with Caco-2 intestinal epithelial cells and HT-29-methotrexate (MTX) goblet cells. We demonstrated that high-density seeded THP-1 cells treated with 100 ng/mL phorbol 12-myristate 13-acetate for 48 h differentiated stably and could be cultured for up to 21 days. THP-1m were identified by their adherent morphology and lysosome expansion. In the triple co-culture immune-responsive model, cytokine secretions during lipopolysaccharide-induced inflammation were confirmed. Tumor necrosis factor-alpha and interleukin 6 levels were elevated in the inflamed state, reaching 824.7 ± 130.0 pg/mL and 609.7 ± 139.5 pg/mL, respectively. Intestinal membrane integrity was maintained with a transepithelial electrical resistance value of 336.4 ± 18.0 Ω·cm². Overall, our findings suggest that THP-1m can be effectively employed in models of long-term immune responses in both normal and chronic inflammatory states of the intestinal epithelium, making them a valuable tool for future research on the association between the immune system and gut health.

Protective effect of soloxolone derivatives in carrageenan- and LPS-driven acute inflammation: Pharmacological profiling and their effects on key inflammation-related processes

The anti-inflammatory potential of three cyanoenone-containing triterpenoids, including soloxolone methyl (SM), soloxolone (S) and its novel derivative bearing at the C-30 amidoxime moiety (SAO), was studied in murine models of acute inflammation. It was found that the compounds effectively suppressed the development of carrageenan-induced paw edema and peritonitis as well as lipopolysaccharide (LPS)-driven acute lung injury (ALI) with therapeutic outcomes comparable with that of the reference drugs indomethacin and dexamethasone. Non-immunogenic carrageenan-stimulated inflammation was more sensitive to the transformation of C-30 of SM compared with immunogenic LPS-induced inflammation: the anti-inflammatory properties of the studied compounds against carrageenan-induced paw edema and peritonitis decreased in the order of SAO > S > > SM, whereas the efficiency of these triterpenoids against LPS-driven ALI was similar (SAO ≈ S ≈ SM). Further studies demonstrated that soloxolone derivatives significantly inhibited a range of immune-related processes, including granulocyte influx and the expression of key pro-inflammatory cytokines and chemokines in the inflamed sites as well as the functional activity of macrophages. Moreover, SM was found to prevent inflammation-associated apoptosis of A549 pneumocytes and effectively inhibited the protease activity of thrombin (IC₅₀ = 10.3 µM) tightly associated with rodent inflammatome. Taken together, our findings demonstrate that soloxolone derivatives can be considered as novel promising anti-inflammatory drug candidates with multi-targeted mechanism of action.

Exosomal RBP4 potentiated hepatic lipid accumulation and inflammation in high-fat-diet-fed mice by promoting M1 polarization of Kupffer cells

Exosomes containing various biological cargoes have potential to be novel diagnostic biomarkers for metabolic diseases. In this study, retinol-binding protein 4 (RBP4) was found to be enriched in serum exosomes, and its increased levels could be considered as an independent risk factor for the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Exosomal RBP4 (exo-RBP4), primarily derived from hepatocytes, significantly enhanced the M1-like polarization of Kupffer cells (KCs) via promoting the activation of NOX2 and NF-κB and reactive oxygen species (ROS) accumulation, resulting in the over-production of inflammatory cytokines including TNF-α. Subsequently, those excess cytokines remarkably increased the levels of intracellular free fatty acid uptake and lipogenesis-related genes (FAS and SREBP-1c) but decreased fatty acid degradation-related genes (CPT-1 and PPARα) in palmitic acid-treated LO2 cells. More notably, TNF-α significantly elevated RBP4 transcription by activating STAT3 in hepatocytes, playing a positive role in NAFLD development. Intravenous injection with RBP4 (50 μg/kg) potentiated hepatic lipid accumulation, M1-type KC proportion, and serum pro-inflammatory cytokine levels in the hepatic tissues of high-fat-diet-fed mice. Collectively, these data indicated that exo-RBP4 converted KCs to M1 subtype by mediating the NOX2/ROS/NF-κB pathway, subsequently promoting de novo lipogenesis in hepatocytes by TNF-α secretion to activate the JAK2/STAT3 signaling pathway. Therefore, this study uncovered a novel intercellular communication between the inflammatory microenvironment and lipid metabolism for fostering NAFLD progression and found the potential of exo-RBP4 as a novel diagnostic biomarker and therapeutic target for NAFLD.

Alterations in Serum Concentration of Soluble CD163 within Five Study Days from ICU Admission Are Associated with In-Hospital Mortality of Septic Patients-A Preliminary Study

BACKGROUND

CD163, a cell membrane surface molecule specifically expressed by macrophages with an anti-inflammatory phenotype, participates in innate immunity. The purpose of the study was to evaluate the clinical utility of sCD163 in septic patients in comparison to other parameters associated with infections, mainly PCT, CRP and IL-18.

METHODS

Serum samples were obtained from 40 septic patients on the ICU admission day, 3rd and 5th study days. The control group consisted of 30 healthy volunteers from whom the specimen was collected once. An enzyme-linked immunosorbent assay (ELISA) was used to determine the concentrations of sCD163 and IL-18. CRP and PCT records, among others, were provided by the hospital.

RESULTS

Septic shock was associated with the highest concentrations of sCD163 and IL-18. Admission values of sCD163 significantly contributed to mortality prediction in septic patients.

CONCLUSIONS

The concentration of sCD163 determined on the ICU admission day may potentially be utilized in estimation of the odds of death among septic patients.

A transcriptional program associated with cell cycle regulation predominates in the anti-inflammatory effects of CX-5461 in macrophage

CX-5461, a novel selective RNA polymerase I inhibitor, shows potential anti-inflammatory and immunosuppressive activities. However, the molecular mechanisms underlying the inhibitory effects of CX-5461 on macrophage-mediated inflammation remain to be clarified. In the present study, we attempted to identify the systemic biological processes which were modulated by CX-5461 in inflammatory macrophages. Primary peritoneal macrophages were isolated from normal Sprague Dawley rats, and primed with lipopolysaccharide or interferon-γ. Genome-wide RNA sequencing was performed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases were used for gene functional annotations. Enrichment analysis was conducted using the ClusterProfiler package of R software. We found that CX-5461 principally induced a molecular signature related to cell cycle inhibition in primed macrophages, featuring downregulation of genes encoding cell cycle mediators and concomitant upregulation of cell cycle inhibitors. At the same concentration, however, CX-5461 did not induce a systemic anti-inflammatory transcriptional program, although some inflammatory genes such as IL-1β and gp91phox NADPH oxidase were downregulated by CX-5461. Our data further highlighted a central role of p53 in orchestrating the molecular networks that were responsive to CX-5461 treatment. In conclusion, our study suggested that limiting cell proliferation predominated in the inhibitory effects of CX-5461 on macrophage-mediated inflammation.

Early monocyte response following local ablation in hepatocellular carcinoma

Local ablative therapies are established treatment modalities in the treatment of early- and intermediate-stage hepatocellular carcinoma (HCC). Systemic effects of local ablation on circulating immune cells may contribute to patients' response. Depending on their activation, myeloid cells are able to trigger HCC progression as well as to support anti-tumor immunity. Certain priming of monocytes may already occur while still in the circulation. By using flow cytometry, we analyzed peripheral blood monocyte cell populations from a prospective clinical trial cohort of 21 HCC patients following interstitial brachytherapy (IBT) or radiofrequency ablation (RFA) and investigated alterations in the composition of monocyte subpopulations and monocytic myeloid-derived suppressor cells (mMDSCs) as well as receptors involved in orchestrating monocyte function. We discovered that mMDSC levels increased following both IBT and RFA in virtually all patients. Furthermore, we identified varying alterations in the level of monocyte subpopulations following radiation compared to RFA. (A) Liquid biopsy liquid biopsy of circulating monocytes in the future may provide information on the inflammatory response towards local ablation as part of an orchestrated immune response.

Cationic Polyethyleneimine (PEI)–Gold Nanocomposites Modulate Macrophage Activation and Reprogram Mouse Breast Triple-Negative MET-1 Tumor Immunological Microenvironment

Nanomedicines based on inorganic nanoparticles have grown in the last decades due to the nanosystems’ versatility in the coating, tuneability, and physical and chemical properties. Nonetheless, concerns have been raised regarding the immunotropic profile of nanoparticles and how metallic nanoparticles affect the immune system. Cationic polymer nanoparticles are widely used for cell transfection and proved to exert an adjuvant immunomodulatory effect that improves the efficiency of conventional vaccines against infection or cancer. Likewise, gold nanoparticles (AuNPs) also exhibit diverse effects on immune response depending on size or coatings. Photothermal or photodynamic therapy, radiosensitization, and drug or gene delivery systems take advantage of the unique properties of AuNPs to deeply modify the tumoral ecosystem. However, the collective effects that AuNPs combined with cationic polymers might exert on their own in the tumor immunological microenvironment remain elusive. The purpose of this study was to analyze the triple-negative breast tumor immunological microenvironment upon intratumoral injection of polyethyleneimine (PEI)–AuNP nanocomposites (named AuPEI) and elucidate how it might affect future immunotherapeutic approaches based on this nanosystem. AuPEI nanocomposites were synthesized through a one-pot synthesis method with PEI as both a reducing and capping agent, resulting in fractal assemblies of about 10 nm AuNPs. AuPEI induced an inflammatory profile in vitro in the mouse macrophage-like cells RAW264.7 as determined by the secretion of TNF-α and CCL5 while the immunosuppressor IL-10 was not increased. However, in vivo in the mouse breast MET-1 tumor model, AuPEI nanocomposites shifted the immunological tumor microenvironment toward an M2 phenotype with an immunosuppressive profile as determined by the infiltration of PD-1-positive lymphocytes. This dichotomy in AuPEI nanocomposites in vitro and in vivo might be attributed to the highly complex tumor microenvironment and highlights the importance of testing the immunogenicity of nanomaterials in vitro and more importantly in vivo in relevant immunocompetent mouse tumor models to better elucidate any adverse or unexpected effect.