Chemokine CXCL1 mediated neutrophil recruitment: Role of glycosaminoglycan interactions

Case report: Regression of in-transit metastases of cutaneous squamous cell carcinoma with combination pembrolizumab and topical diphencyprone

While typically low-risk, cutaneous squamous cell carcinoma (cSCC) can infrequently progress to metastatic disease with in-transit lesions, localized to the dermis or subcutaneous tissue between the primary tumor and draining regional lymph nodes. These lesions are associated with poor prognostic values, including decreased survival rates and increased risk of recurrence. We present the case of a 75-year-old male with cSCC and in-transit metastases on his scalp treated with the immune checkpoint inhibitor (ICI) pembrolizumab in conjunction with diphencyprone (DPCP), a topical hapten that induces a delayed-type hypersensitivity reaction in the skin. The patient was enrolled in a clinical trial (NCT05481658) that involved the twice-weekly application of DPCP 0.04% ointment to four of the in-transit metastases on his frontal scalp, concurrent with pembrolizumab 300 mg administered every three weeks. Following effective sensitization and a twelve-week treatment course, complete clearance of all lesions, DPCP-treated and non-DPCP treated, was achieved, with no adverse events. The immunologic profiles of the post-treatment biopsies were analyzed by TaqMan Low Density Array quantitative real-time polymerase chain reaction to measure immune marker gene expression. Relative to the non-DPCP-treated lesion, the DPCP-treated lesion demonstrated increased pro-inflammatory genetic markers and T-cell activation. This case represents the first reported instance of in-transit metastases of cSCC successfully treated with DPCP and an ICI. It highlights the potential safety and efficacy of DPCP with systemic immunotherapy for the management of in-transit metastases of cSCC in patients for whom surgery and radiation may be contraindicated.

Cell type-dependent modulation of senescence features using Weo electrolyzed water

Electrolyzed-reduced water has powerful antioxidant properties with constituents that scavenge reactive oxygen species (ROS), which are known to be produced by several intrinsic and extrinsic processes. When there is an imbalance between ROS production and antioxidant defenses, oxidative stress occurs. Persistent oxidative stress leads to cellular senescence, an important hallmark of aging, and is involved in several age-related conditions and illnesses. This study aims to investigate whether Weo electrolyzed water (WEW) could modulate the phenotype of senescent cells. We compared normal human lung fibroblasts (BJ) and breast cancer cells (T47D) treated with hydrogen peroxide (H2O2) to induce senescence. We assessed the molecular impact of WEW on markers of cellular senescence, senescence-associated secretory phenotype (SASP) factors, and stress response genes. Treatment with WEW modulated markers of cellular senescence, such as the senescence-associated β-galactosidase (SA-β-gal) activity, EdU incorporation and p21 expression, similarly in both cell types. However, WEW modulated the expression of SASP factors and stress response genes in a cell type-dependent and opposite fashion, significantly decreasing them in BJ cells, while stimulating their expression in T47D cells. Reduction in the expression of SASP factors and stress-related genes in BJ cells suggests that WEW acts as a protective factor, thereby reducing oxidative stress in normal cells, while making cancer cells more sensitive to the effects of cellular stress, thus increasing their elimination and consequently reducing their deleterious effects. These findings suggest that, due to its differential effects as a senomorphic factor, WEW could have a positive impact on longevity and age-related diseases.

Neutrophil-mediated innate immune resistance to bacterial pneumonia is dependent on Tet2 function

Individuals with clonal hematopoiesis of indeterminate potential (CHIP) are at increased risk of aging related health conditions and all-cause mortality, but whether CHIP affects risk of infection is much less clear. Using UK Biobank data, we revealed a positive association between CHIP and incident pneumonia in 438,421 individuals. We show that inflammation enhanced pneumonia risk, as CHIP carriers with a hypomorphic IL6 receptor polymorphism were protected. To better characterize the pathways of susceptibility, we challenged hematopoietic Tet Methylcytosine Dioxygenase 2-knockout (Tet2-/-) and floxed control mice (Tet2fl/fl) with Streptococcus pneumoniae. As with human CHIP carriers, Tet2-/- mice had hematopoietic abnormalities resulting in the expansion of inflammatory monocytes and neutrophils in peripheral blood. Yet, these cells were insufficient in defending against S. pneumoniae and resulted in increased pathology, impaired bacterial clearance, and higher mortality in Tet2-/- mice. We delineated the transcriptional landscape of Tet2-/- neutrophils and found that, while inflammation-related pathways were upregulated in Tet2-/- neutrophils, migration and motility pathways were compromised. Using live-imaging techniques, we demonstrated impairments in motility, pathogen uptake, and neutrophil extracellular trap (NET) formation by Tet2-/- neutrophils. Collectively, we show that CHIP is a risk factor for bacterial pneumonia related to innate immune impairments.

IL-33 supplementation improves uterine artery resistance and maternal hypertension in response to placental ischemia

Preeclampsia (PE), a leading cause of maternal/fetal morbidity and mortality, is a hypertensive pregnancy disorder with end-organ damage that manifests after 20 wk of gestation. PE is characterized by chronic immune activation and endothelial dysfunction. Clinical studies report reduced IL-33 signaling in PE. We use the Reduced Uterine Perfusion Pressure (RUPP) rat model, which mimics many PE characteristics including reduced IL-33, to identify mechanisms mediating PE pathophysiology. We hypothesized that IL-33 supplementation would improve blood pressure (BP), inflammation, and oxidative stress (ROS) during placental ischemia. We implanted intraperitoneal mini-osmotic pumps infusing recombinant rat IL-33 (1 µg/kg/day) into normal pregnant (NP) and RUPP rats from gestation day 14 to 19. We found that IL-33 supplementation in RUPP rats reduces maternal blood pressure and improves the uterine artery resistance index (UARI). In addition to physiological improvements, we found decreased circulating and placental cytolytic Natural Killer cells (cNKs) and decreased circulating, placental, and renal TH17s in IL-33-treated RUPP rats. cNK cell cytotoxic activity also decreased in IL-33-supplemented RUPP rats. Furthermore, renal ROS and placental preproendothelin-1 (PPET-1) decreased in RUPP rats treated with IL-33. These findings demonstrate a role for IL-33 in controlling vascular function and maternal BP during pregnancy by decreasing inflammation, renal ROS, and PPET-1 expression. These data suggest that IL-33 may have therapeutic potential in managing PE.NEW & NOTEWORTHY Though decreased IL-33 signaling has been clinically associated with PE, the mechanisms linking this signaling pathway to overall disease pathophysiology are not well understood. This study provides compelling evidence that mechanistically links reduced IL-33 with the inflammatory response and vascular dysfunction observed in response to placental ischemia, such as in PE. Data presented in this study submit the IL-33 signaling pathway as a possible therapeutic target for the treatment of PE.

SARS-CoV-2 spike protein induces endothelial dysfunction in 3D engineered vascular networks

With new daily discoveries about the long-term impacts of COVID-19, there is a clear need to develop in vitro models that can be used to better understand the pathogenicity and impact of COVID-19. Here, we demonstrate the utility of developing a model of endothelial dysfunction that utilizes human induced pluripotent stem cell-derived endothelial progenitors encapsulated in collagen hydrogels to study the effects of COVID-19 on the endothelium. These cells form capillary-like vasculature within 1 week after encapsulation and treating these cell-laden hydrogels with SARS-CoV-2 spike protein resulted in a significant decrease in the number of vessel-forming cells as well as vessel network connectivity quantified by our computational pipeline. This vascular dysfunction is a unique phenomenon observed upon treatment with SARS-CoV-2 SP and is not seen upon treatment with other coronaviruses, indicating that these effects were specific to SARS-CoV-2. We show that this vascular dysfunction is caused by an increase in inflammatory cytokines, associated with the COVID-19 cytokine storm, released from SARS-CoV-2 spike protein treated endothelial cells. Following treatment with the corticosteroid dexamethasone, we were able to prevent SARS-CoV-2 spike protein-induced endothelial dysfunction. Our results highlight the importance of understanding the interactions between SARS-CoV-2 spike protein and the endothelium and show that even in the absence of immune cells, the proposed 3D in vitro model for angiogenesis can reproduce COVID-19-induced endothelial dysfunction seen in clinical settings. This model represents a significant step in creating physiologically relevant disease models to further study the impact of long COVID and potentially identify mitigating therapeutics.

Testosterone Inhibits Secretion of the Pro-Inflammatory Chemokine CXCL1 from Astrocytes

Astrocytes play an important role in the regulation of the inflammatory response in the CNS, e.g., in demyelinating diseases. Since the chemokine CXCL1 is known to be secreted by astrocytes and to have a pro-inflammatory effect on immune cells in the CNS, we verified the effect of testosterone on its secretion in vitro (in the astrocytic cell line DI TNC1). Testosterone reduced the increase in CXCL1 production caused by the pro-inflammatory agent lysophosphatidylcholine and restored the basal production level of CXCL1. The androgen receptor (present and functional in the studied cell line) was strongly suggested to mediate this effect-its non-steroid ligand flutamide exerted an agonist-like effect, mimicking the activity of testosterone itself on CXCL1 secretion. This novel mechanism has important implications for the known immunomodulatory effect of testosterone and potentially other androgenic hormones. It provides a potential explanation on the molecular level and shows that astrocytes are important players in inflammatory homeostasis in the CNS and its hormonal regulation. Therefore, it suggests new directions for the development of the therapeutic intervention.

Neutrophils at the Crossroads: Unraveling the Multifaceted Role in the Tumor Microenvironment

Over the past decade, research has prominently established neutrophils as key contributors to the intricate landscape of tumor immune biology. As polymorphonuclear granulocytes within the innate immune system, neutrophils play a pivotal and abundant role, constituting approximately ∼70% of all peripheral leukocytes in humans and ∼10-20% in mice. This substantial presence positions them as the frontline defense against potential threats. Equipped with a diverse array of mechanisms, including reactive oxygen species (ROS) generation, degranulation, phagocytosis, and the formation of neutrophil extracellular traps (NETs), neutrophils undeniably serve as indispensable components of the innate immune system. While these innate functions enable neutrophils to interact with adaptive immune cells such as T, B, and NK cells, influencing their functions, they also engage in dynamic interactions with rapidly dividing tumor cells. Consequently, neutrophils are emerging as crucial regulators in both pro- and anti-tumor immunity. This comprehensive review delves into recent research to illuminate the multifaceted roles of neutrophils. It explores their diverse functions within the tumor microenvironment, shedding light on their heterogeneity and their impact on tumor recruitment, progression, and modulation. Additionally, the review underscores their potential anti-tumoral capabilities. Finally, it provides valuable insights into clinical therapies targeting neutrophils, presenting a promising approach to leveraging innate immunity for enhanced cancer treatment.

Human Macrophages Activate Bystander Neutrophils' Metabolism and Effector Functions When Challenged with Mycobacterium tuberculosis

Neutrophils are dynamic cells, playing a critical role in pathogen clearance; however, neutrophil infiltration into the tissue can act as a double-edged sword. They are one of the primary sources of excessive inflammation during infection, which has been observed in many infectious diseases including pneumonia and active tuberculosis (TB). Neutrophil function is influenced by interactions with other immune cells within the inflammatory lung milieu; however, how these interactions affect neutrophil function is unclear. Our study examined the macrophage-neutrophil axis by assessing the effects of conditioned medium (MΦ-CM) from primary human monocyte-derived macrophages (hMDMs) stimulated with LPS or a whole bacterium (Mycobacterium tuberculosis) on neutrophil function. Stimulated hMDM-derived MΦ-CM boosts neutrophil activation, heightening oxidative and glycolytic metabolism, but diminishes migratory potential. These neutrophils exhibit increased ROS production, elevated NET formation, and heightened CXCL8, IL-13, and IL-6 compared to untreated or unstimulated hMDM-treated neutrophils. Collectively, these data show that MΦ-CM from stimulated hMDMs activates neutrophils, bolsters their energetic profile, increase effector and inflammatory functions, and sequester them at sites of infection by decreasing their migratory capacity. These data may aid in the design of novel immunotherapies for severe pneumonia, active tuberculosis and other diseases driven by pathological inflammation mediated by the macrophage-neutrophil axis.

Cxcl1 monomer-dimer equilibrium controls neutrophil extravasation

The chemokine Cxcl1 plays a crucial role in recruiting neutrophils in response to infection. The early events in chemokine-mediated neutrophil extravasation involve a sequence of highly orchestrated steps including rolling, adhesion, arrest, and diapedesis. Cxcl1 function is determined by its properties of reversible monomer-dimer equilibrium and binding to Cxcr2 and glycosaminoglycans. Here, we characterized how these properties orchestrate extravasation using intravital microscopy of the cremaster. Compared to WT Cxcl1, which exists as both a monomer and a dimer, the trapped dimer caused faster rolling, less adhesion, and less extravasation. Whole-mount immunofluorescence of the cremaster and arrest assays confirmed these data. Moreover, the Cxcl1 dimer showed impaired LFA-1-mediated neutrophil arrest that could be attributed to impaired Cxcr2-mediated ERK signaling. We conclude that Cxcl1 monomer-dimer equilibrium and potent Cxcr2 activity of the monomer together coordinate the early events in neutrophil recruitment.

NOD1 deficiency ameliorates the progression of diabetic retinopathy by modulating bone marrow-retina crosstalk

BACKGROUND

Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) plays a pivotal role in inducing metabolic inflammation in diabetes. Additionally, the NOD1 ligand disrupts the equilibrium of bone marrow-derived hematopoietic stem/progenitor cells, a process that has immense significance in the development of diabetic retinopathy (DR). We hypothesized that NOD1 depletion impedes the advancement of DR by resolving bone marrow dysfunction.

METHODS

We generated NOD1-/--Akita double-mutant mice and chimeric mice with hematopoietic-specific NOD1 depletion to study the role of NOD1 in the bone marrow-retina axis.

RESULTS

Elevated circulating NOD1 activators were observed in Akita mice after 6 months of diabetes. NOD1 depletion partially restored diabetes-induced structural changes and retinal electrical responses in NOD1-/--Akita mice. Loss of NOD1 significantly ameliorated the progression of diabetic retinal vascular degeneration, as determined by acellular capillary quantification. The preventive effect of NOD1 depletion on DR is linked to bone marrow phenotype alterations, including a restored HSC pool and a shift in hematopoiesis toward myelopoiesis. We also generated chimeric mice with hematopoietic-specific NOD1 ablation, and the results further indicated that NOD1 had a protective effect against DR. Mechanistically, loss of hematopoietic NOD1 resulted in reduced bone marrow-derived macrophage infiltration and decreased CXCL1 and CXCL2 secretion within the retina, subsequently leading to diminished neutrophil chemoattraction and NETosis.

CONCLUSIONS

The results of our study unveil, for the first time, the critical role of NOD1 as a trigger for a hematopoietic imbalance toward myelopoiesis and local retinal inflammation, culminating in DR progression. Targeting NOD1 in bone marrow may be a potential strategy for the prevention and treatment of DR.

Construction of a diagnostic model for osteoarthritis based on transcriptomic immune-related genes

Background

Osteoarthritis (OA) is a leading cause of disability globally, affecting over 500 million individuals worldwide. However, accurate and early diagnosis of OA is challenging to achieve. Immune-related genes play an essential role in OA development. Therefore, the objective of this study was to develop a diagnostic model for OA based on immune-related genes identified in synovial membrane.

Methods

The gene expression profile of OA were downloaded based on four datasets. The significantly differentially expressed genes (DEGs) between OA and control groups were selected. The differential immune cells were analyzed, followed by immune-related DEGs screening. WGCNA was used to screen module genes and these genes were further selected through optimization algorithm. Then, nomogram model was constructed. Chemical drug small molecule related to OA was predicted. Finally, expression levels of several key genes were validated by qRT-PCR through construction of OA rat models.

Results

The total 656 DEGs were obtained. Eight immune cells were significantly differential between two groups, and 317 immune-related DEGs were obtained. WGCNA identified three modules. The genes in modules were significantly involved in 15 pathways, involving in 65 genes. Then 12 DEGs were screened as the final optimal combination of DEGs, such as CEBPB, CXCL1, JUND, GABARAPL2 and PDGFC. The Nomogram model was also constructed. Furthermore, the chemical small molecules, such as acetaminophen, aspirin, and caffeine were predicted. The expression levels of CEBPB, CXCL1, GABARAPL2 and PDGFC were validated in OA rat models.

Conclusion

A diagnostic model based on twelve immune related genes was constructed. These model genes, such as CEBPB, CXCL1, GABARAPL2, and PDGFC, may serve as diagnostic biomarkers and immunotherapeutic targets.

Multimodal nanoparticle-containing modified suberoylanilide hydroxamic acid polymer conjugates to mitigate immune dysfunction in severe inflammation

Excessive immune activation and immunosuppression are opposing factors that contribute to the dysregulated innate and adaptive immune responses seen in severe inflammation and sepsis. Here, a novel analog of the histone deacetylase inhibitor (HDACi), suberoylanilide hydroxamic acid (SAHA-OH), was incorporated into immunomodulatory poly(lactic acid)-based nanoparticles (iNP-SAHA) by employing a prodrug approach through the covalent modification of poly(lactic-co-glycolic acid) (PLGA) with SAHA-OH. iNP-SAHA formulation allowed for controlled incorporation and delivery of SAHA-OH from iNP-SAHA and treatment led to multimodal biological responses including significant reductions in proinflammatory cytokine secretions and gene expression, while increasing the survival of primary macrophages under lipopolysaccharide (LPS) challenge. Using a lethal LPS-induced endotoxemia mouse model of sepsis, iNP-SAHA administration improved the survival of mice in a dose-dependent manner and tended to improve survival at the lowest doses compared to iNP control. Further, iNP-SAHA reduced the levels of plasma proinflammatory cytokines and chemokines associated with sepsis more significantly than iNP and similarly improved inflammation-induced spleen and liver toxicity as iNP, supporting its potential polypharmacological activity. Collectively, iNP-SAHA offers a potential drug delivery approach to modulate the multifaceted inflammatory responses observed in diseases such as sepsis.

GLIS1, Correlated with Immune Infiltrates, Is a Potential Prognostic Biomarker in Prostate Cancer

Prostate cancer (PCa) is a prevalent malignant disease and the primary reason for cancer-related mortality among men globally. GLIS1 (GLIS family zinc finger 1) is a key regulator in various pathologies. However, the expression pattern, clinical relevance, and immunomodulatory function of GLIS1 in PCa remain unclear. In this study, GLIS1 was discovered to serve as a key gene in PCa by integrating mRNA and miRNA expression profiles from GEO database. We systematically explored the expression and prognostic values of GLIS1 in cancers using multiple databases. Additionally, we examined the functions of GLIS1 and the relationship between GLIS1 expression levels and immune infiltration in PCa. Results showed that GLIS1 was differentially expressed between normal and tumor tissues in various cancer types and was significantly low-expressed in PCa. Low GLIS1 expression was associated with poor PCa prognosis. GLIS1 was also involved in the activation, proliferation, differentiation, and migration of immune cells, and its expression showed a positive correlation with the infiltration of various immune cells. Moreover, GLIS1 expression was positively associated with various chemokines/chemokine receptors, indicating the involvement in regulating immune cell migration. In summary, GLIS1 is a potential prognostic biomarker and a therapeutic target to modulate anti-tumor immune response in PCa.

miR-146a inhibits ovarian tumor growth in vivo via targeting immunosuppressive neutrophils and enhancing CD8+ T cell infiltration

Immunotherapies have emerged as promising strategies for cancer treatment. However, existing immunotherapies have poor activity in high-grade serous ovarian cancer (HGSC) due to the immunosuppressive tumor microenvironment and the associated low tumoral CD8+ T cell (CTL) infiltration. Through multiple lines of evidence, including integrative analyses of human HGSC tumors, we have identified miR-146a as a master regulator of CTL infiltration in HGSC. Tumoral miR-146a expression is positively correlated with anti-cancer immune signatures in human HGSC tumors, and delivery of miR-146a to tumors resulted in significant reduction in tumor growth in both ID8-p53-/- and IG10 murine HGSC models. Increasing miR-146a expression in tumors improved anti-tumor immune responses by decreasing immune suppressive neutrophils and increasing CTL infiltration. Mechanistically, miR-146a targets IL-1 receptor-associated kinase 1 and tumor necrosis factor receptor-associated factor 6 adaptor molecules of the transcription factor nuclear factor κB signaling pathway in ID8-p53-/- cells and decreases production of the downstream neutrophil chemoattractant, C-X-C motif chemokine ligand 1. In addition to HGSC, tumoral miR-146a expression also correlates strongly with CTL infiltration in other cancer types including thyroid, prostate, breast, and adrenocortical cancers. Altogether, our findings highlight the ability of miR-146a to overcome immune suppression and improve CTL infiltration in tumors.

Vancomycin modestly attenuates symptom severity during onset of and recovery from exertional heat stroke in mice

Increased intestinal permeability during exertion and subsequent leakage of bacteria into circulation is hypothesized to accelerate exertional heat stroke (EHS) onset and/or exacerbate EHS severity. To provide proof of concept for this theory, we targeted intestinal microbiota via antibiotic prophylaxis and determined whether vancomycin would delay EHS onset and/or mitigate EHS severity and mortality rates using a mouse model of EHS. Mice were 1) designated as EHS or Exercise Control (ExC) and 2) given 7 days of vancomycin (VEHS, VExC) or untreated water (EHS, ExC) before EHS/Exercise. Following EHS/ExC, mice were euthanized immediately (0 h) or returned to their home cage (25°C) and euthanized after 3 h or 24 h. VEHS mice exhibited reduced abundance and altered composition of fecal bacteria (with notable decreases in genera within orders Clostridiales and Bacteroidales); increased water consumption, lower core temperature (TC) before and during heating (TCMax), lower circulating markers of organ damage and inflammation at 24 h; and reduced hepatic activation of stress pathways at 0 and 3 h compared with EHS mice. Vancomycin-induced alterations to the intestinal microbiota likely influenced EHS outcomes, but it is unconfirmed whether this is due to attenuated bacterial leakage into circulation or other (in)direct effects on physiology and behavior (e.g., decreased TC, increased water consumption). To our knowledge, this is the first study quantitating antibiotic effects in conscious/unanesthetized, exertional HS animals.NEW & NOTEWORTHY Vancomycin prophylaxis lowered core temperature before and during EHS, mitigated EHS-associated rise of hepatic biomarkers and cytokines/chemokines in circulation (particularly at 24 h), and corresponded to inhibited phosphorylation of hepatic c-Jun NH2-terminal kinase on Threonine 183/Tyrosine 185 at 0 and 3 h in conscious, unanesthetized mice. However, vancomycin also induced cecal enlargement suggesting its off-target effects could limit its utility against EHS.

Chemokine Cxcl1-Cxcl2 heterodimer is a potent neutrophil chemoattractant

Microbial infection is characterized by release of multiple proinflammatory chemokines that direct neutrophils to the insult site. How collective function of these chemokines orchestrates neutrophil recruitment is not known. Here, we characterized the role for heterodimer and show that the Cxcl1-Cxcl2 heterodimer is a potent neutrophil chemoattractant in mice and can recruit more neutrophils than the individual chemokines. Chemokine-mediated neutrophil recruitment is determined by Cxcr2 receptor signaling, Cxcr2 endocytosis, and binding to glycosaminoglycans. We have now determined heterodimer's Cxcr2 activity using cellular assays and Cxcr2 density in blood and recruited neutrophils in heterodimer-treated mice. We have shown that the heterodimer binds glycosaminoglycans with higher affinity and more efficiently than Cxcl1 or Cxcl2. These data collectively indicate that optimal glycosaminoglycan interactions and dampened receptor activity acting in concert in a dynamic fashion promote heterodimer-mediated robust neutrophil recruitment. We propose that this could play a critical role in combating infection.

Neutrophil peptidylarginine deiminase 4 is essential for detrimental age-related cardiac remodelling and dysfunction in mice

Mice fully deficient in peptidylarginine deiminase 4 (PAD4) enzyme have preserved cardiac function and reduced collagen deposition during ageing. The cellular source of PAD4 is hypothesized to be neutrophils, likely due to PAD4's involvement in neutrophil extracellular trap release. We investigated haematopoietic PAD4 impact on myocardial remodelling and systemic inflammation in cardiac ageing by generating mice with Padi4 deletion in circulating neutrophils under the MRP8 promoter (Ne-PAD4-/-), and ageing them for 2 years together with littermate controls (PAD4fl/fl). Ne-PAD4-/- mice showed protection against age-induced fibrosis, seen by reduced cardiac collagen deposition. Echocardiography analysis of structural and functional parameters also demonstrated preservation of both systolic and diastolic function with MRP8-driven PAD4 deletion. Furthermore, cardiac gene expression and plasma cytokine levels were evaluated. Cardiac genes and plasma cytokines involved in neutrophil recruitment were downregulated in aged Ne-PAD4-/- animals compared to PAD4fl/fl controls, including decreased levels of C-X-C ligand 1 (CXCL1). Our data confirm PAD4 involvement from circulating neutrophils in detrimental cardiac remodelling, leading to cardiac dysfunction with old age. Deletion of PAD4 in MRP8-expressing cells impacts the CXCL1-CXCR2 axis, known to be involved in heart failure development. This supports the future use of PAD4 inhibitors in cardiovascular disease. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.

The critical role of interleukin-6 in protection against neurotropic flavivirus infection

West Nile virus (WNV) and Japanese encephalitis virus (JEV) are emerging mosquito-borne flaviviruses causing encephalitis globally. No specific drug or therapy exists to treat flavivirus-induced neurological diseases. The lack of specific therapeutics underscores an urgent need to determine the function of important host factors involved in flavivirus replication and disease progression. Interleukin-6 (IL-6) upregulation has been observed during viral infections in both mice and humans, implying that it may influence the disease outcome significantly. Herein, we investigated the function of IL-6 in the pathogenesis of neurotropic flavivirus infections. First, we examined the role of IL-6 in flavivirus-infected human neuroblastoma cells, SK-N-SH, and found that IL-6 neutralization increased the WNV or JEV replication and inhibited the expression of key cytokines. We further evaluated the role of IL-6 by infecting primary mouse cells derived from IL-6 knockout (IL-6-/-) mice and wild-type (WT) mice with WNV or JEV. The results exhibited increased virus yields in the cells lacking the IL-6 gene. Next, our in vivo approach revealed that IL-6-/- mice had significantly higher morbidity and mortality after subcutaneous infection with the pathogenic WNV NY99 or JEV Nakayama strain compared to WT mice. The non-pathogenic WNV Eg101 strain did not cause mortality in WT mice but resulted in 60% mortality in IL-6-/- mice, indicating that IL-6 is required for the survival of mice after the peripheral inoculation of WNV or JEV. We also observed significantly higher viremia and brain viral load in IL-6-/- mice than in WT mice. Subsequently, we explored innate immune responses in WT and IL-6-/- mice after WNV NY99 infection. Our data demonstrated that the IL-6-/- mice had reduced levels of key cytokines in the serum during early infection but elevated levels of proinflammatory cytokines in the brain later, along with suppressed anti-inflammatory cytokines. In addition, mRNA expression of IFN-α and IFN-β was significantly lower in the infected IL-6-/- mice. In conclusion, these data suggest that the lack of IL-6 exacerbates WNV or JEV infection in vitro and in vivo by causing an increase in virus replication and dysregulating host immune response.

Donor IL-17 receptor A regulates LPS-potentiated acute and chronic murine lung allograft rejection

Chronic lung allograft dysfunction (CLAD) is a major complication after lung transplantation that results from a complex interplay of innate inflammatory and alloimmune factors, culminating in parenchymal and/or obliterative airway fibrosis. Excessive IL-17A signaling and chronic inflammation have been recognized as key factors in these pathological processes. Herein, we developed a model of repeated airway inflammation in mouse minor alloantigen-mismatched single-lung transplantation. Repeated intratracheal LPS instillations augmented pulmonary IL-17A expression. LPS also increased acute rejection, airway epithelial damage, and obliterative airway fibrosis, similar to human explanted lung allografts with antecedent episodes of airway infection. We then investigated the role of donor and recipient IL-17 receptor A (IL-17RA) in this context. Donor IL-17RA deficiency significantly attenuated acute rejection and CLAD features, whereas recipient IL-17RA deficiency only slightly reduced airway obliteration in LPS allografts. IL-17RA immunofluorescence positive staining was greater in human CLAD lungs compared with control human lung specimens, with localization to fibroblasts and myofibroblasts, which was also seen in mouse LPS allografts. Taken together, repeated airway inflammation after lung transplantation caused local airway epithelial damage, with persistent elevation of IL-17A and IL-17RA expression and particular involvement of IL-17RA on donor structural cells in development of fibrosis.

CXCL1 enhances COX-II expression in rheumatoid arthritis synovial fibroblasts by CXCR2, PLC, PKC, and NF-κB signal pathway

Rheumatoid arthritis (RA) is the most common autoimmune disease, affecting the joints of the hands and feet. Several chemokines and their receptors are crucial in RA pathogenesis through immune cell recruitment. C-X-C Motif Chemokine Ligand 1 (CXCL1), a chemokine for the recruitment of various immune cells, can be upregulated in patients with RA. However, the discussion on the role of CXCL1 in RA pathogenesis is insufficient. Here, we found that CXCL1 promoted cyclooxygenase-2 (COX-II) expression in a dose- and time-dependent manner in rheumatoid arthritis synovial fibroblasts (RASFs). CXCL1 overexpression in RASFs led to a significant increase in COX-II expression, while the transfection of RASFs with the shRNA plasmid resulted in a noticeable decrease in COX-II expression. Next, we delineated the molecular mechanism underlying CXCL1-promoted COX-II expression and noted that CXC chemokine receptor 2 (CXCR2), phospholipase C (PLC), and protein kinase C (PKC) signal transduction were responsible for COX-II expression after CXCL1 incubation for RASFs. Finally, we confirmed the transcriptional activation of nuclear factor κB (NF-κB) in RASFs after incubation with CXCL1. In conclusion, the current study provided a novel insight into the role of CXCL1 in RA pathogenesis.

Chemokines, molecular drivers of thromboinflammation and immunothrombosis

Blood clotting is a finely regulated process that is essential for hemostasis. However, when dysregulated or spontaneous, it promotes thrombotic disorders. The fact that these are triggered, accompanied and amplified by inflammation is reflected in the term thromboinflammation that includes chemokines. The role of chemokines in thrombosis is therefore illuminated from a cellular perspective, where endothelial cells, platelets, red blood cells, and leukocytes may be both the source and target of chemokines. Chemokine-dependent prothrombotic processes may thereby occur independently of chemokine receptors or be mediated by chemokine receptors, although the binding and activation of classical G protein-coupled receptors and their signaling pathways differ from those of atypical chemokine receptors, which do not function via cell activation and recruitment. Regardless of binding to their receptors, chemokines can induce thrombosis by forming platelet-activating immune complexes with heparin or other polyanions that are pathognomonic for HIT and VITT. In addition, chemokines can bind to NETs and alter their structure. They also change the electrical charge of the cell surface of platelets and interact with coagulation factors, thereby modulating the balance of fibrinolysis and coagulation. Moreover, CXCL12 activates CXCR4 on platelets independently of classical migratory chemokine activity and causes aggregation and thrombosis via the PI3Kβ and Btk signaling pathways. In contrast, typical chemokine-chemokine receptor interactions are involved in the processes that contribute to the adhesiveness of the endothelium in the initial phase of venous thrombosis, where neutrophils and monocytes subsequently accumulate in massive numbers. Later, the reorganization and resolution of a thrombus require coordinated cell migration and invasion of the thrombus, and, as such, indeed, chemokines recruit leukocytes to existing thrombi. Therefore, chemokines contribute in many independent ways to thrombosis.

The effects of Phycocyanobilin on experimental arthritis involve the reduction in nociception and synovial neutrophil infiltration, inhibition of cytokine production, and modulation of the neuronal proteome

Introduction

The antinociceptive and pharmacological activities of C-Phycocyanin (C-PC) and Phycocyanobilin (PCB) in the context of inflammatory arthritis remain unexplored so far. In the present study, we aimed to assess the protective actions of these compounds in an experimental mice model that replicates key aspects of human rheumatoid arthritis.

Methods

Antigen-induced arthritis (AIA) was established by intradermal injection of methylated bovine serum albumin in C57BL/6 mice, and one hour before the antigen challenge, either C-PC (2, 4, or 8 mg/kg) or PCB (0.1 or 1 mg/kg) were administered intraperitoneally. Proteome profiling was also conducted on glutamate-exposed SH-SY5Y neuronal cells to evaluate the PCB impact on this key signaling pathway associated with nociceptive neuronal sensitization.

Results and discussion

C-PC and PCB notably ameliorated hypernociception, synovial neutrophil infiltration, myeloperoxidase activity, and the periarticular cytokine concentration of IFN-γ, TNF-α, IL-17A, and IL-4 dose-dependently in AIA mice. In addition, 1 mg/kg PCB downregulated the gene expression for T-bet, RORγ, and IFN-γ in the popliteal lymph nodes, accompanied by a significant reduction in the pathological arthritic index of AIA mice. Noteworthy, neuronal proteome analysis revealed that PCB modulated biological processes such as pain, inflammation, and glutamatergic transmission, all of which are involved in arthritic pathology.

Conclusions

These findings demonstrate the remarkable efficacy of PCB in alleviating the nociception and inflammation in the AIA mice model and shed new light on mechanisms underlying the PCB modulation of the neuronal proteome. This research work opens a new avenue to explore the translational potential of PCB in developing a therapeutic strategy for inflammation and pain in rheumatoid arthritis.

Unbiased gene expression analysis of the delayed fracture healing observed in Zucker diabetic fatty rats

Aims

Impaired fracture repair in patients with type 2 diabetes mellitus (T2DM) is not fully understood. In this study, we aimed to characterize the local changes in gene expression (GE) associated with diabetic fracture. We used an unbiased approach to compare GE in the fracture callus of Zucker diabetic fatty (ZDF) rats relative to wild-type (WT) littermates at three weeks following femoral osteotomy.

Methods

Zucker rats, WT and homozygous for leptin receptor mutation (ZDF), were fed a moderately high-fat diet to induce T2DM only in the ZDF animals. At ten weeks of age, open femoral fractures were simulated using a unilateral osteotomy stabilized with an external fixator. At three weeks post-surgery, the fractured femur from each animal was retrieved for analysis. Callus formation and the extent of healing were assessed by radiograph and histology. Bone tissue was processed for total RNA extraction and messenger RNA (mRNA) sequencing (mRNA-Seq).

Results

Radiographs and histology demonstrated impaired fracture healing in ZDF rats with incomplete bony bridge formation and an influx of intramedullary inflammatory tissue. In comparison, near-complete bridging between cortices was observed in Sham WT animals. Of 13,160 genes, mRNA-Seq analysis identified 13 that were differentially expressed in ZDF rat callus, using a false discovery rate (FDR) threshold of 10%. Seven genes were upregulated with high confidence (FDR = 0.05) in ZDF fracture callus, most with known roles in inflammation.

Conclusion

These findings suggest that elevated or prolonged inflammation contributes to delayed fracture healing in T2DM. The identified genes may be used as biomarkers to monitor and treat delayed fracture healing in diabetic patients.

Cytokine fluctuation during acute stress is correlated to life trauma

BACKGROUND

Multiple studies have demonstrated that human neurobiology and behavior are inextricably linked to the activity of our immune systems. Trauma is associated with a multitude of immune system changes; reflecting this, posttraumatic stress disorder (PTSD) is often comorbid with immune-related conditions such as autoimmune disorders. To further investigate this phenomenon, we tested our hypothesis that cytokine fluctuations during and after an acute stress response correlates with experienced life trauma.

METHODS

Using a prospective observational approach, this cohort study measured biomarker profiles in firefighter participants (n = 63), with 9 participants having prior PTSD diagnoses and 54 without prior PTSD diagnoses. In addition, life trauma scores were determined from all participants using the Life Events Checklist 5 (LEC-5) survey. Baseline salivary biomarker concentrations were determined, along with levels immediately before, immediately after, and 1 hour following a standardized stressful training event. Biomarkers measured using these salivary samples included 42 cytokines and 6 steroid and thyroid hormones. The concentrations of these markers were then correlated, using Pearson correlation coefficients, with the participants' LEC-5 scores. t Tests were also performed to compare cytokine values between the populations with and without prior PTSD diagnosis.

RESULTS

Included in the cytokine panel were interleukin (IL)-8, IL-10, IL-1B, GCSF, IL1-Ra, Groα, IFNa2, PDGFAA, and VEGF, all of which demonstrated positive correlation at various time points in individuals with increased severity of LEC-5 scores (and thus increased experienced life trauma). Concentrations of Groα, PDGFAA, IL1-Ra, IL-1a, Mip1a, IL-1a, IL-6, Mip1b, TNFα, and TGFα were also found to be significantly altered at various time points in participants with prior PTSD diagnoses, demonstrating some overlap with the LEC-5 Pearson correlations.

CONCLUSION

The results support our hypothesis and demonstrate that LEC-5 scores are indeed significantly correlated to cytokine concentrations and fluctuations surrounding a stress test.

LEVEL OF EVIDENCE

Diagnostic Tests or Criteria; Level IV.

Central regulation of stress-evoked peripheral immune responses

Stress-linked psychiatric disorders, including anxiety and major depressive disorder, are associated with systemic inflammation. Recent studies have reported stress-induced alterations in haematopoiesis that result in monocytosis, neutrophilia, lymphocytopenia and, consequently, in the upregulation of pro-inflammatory processes in immunologically relevant peripheral tissues. There is now evidence that this peripheral inflammation contributes to the development of psychiatric symptoms as well as to common co-morbidities of psychiatric disorders such as metabolic syndrome and immunosuppression. Here, we review the specific brain and spinal regions, and the neuronal populations within them, that respond to stress and transmit signals to peripheral tissues via the autonomic nervous system or neuroendocrine pathways to influence immunological function. We comprehensively summarize studies that have employed retrograde tracing to define neurocircuits linking the brain to the bone marrow, spleen, gut, adipose tissue and liver. Moreover, we highlight studies that have used chemogenetic or optogenetic manipulation or intracerebroventricular administration of peptide hormones to control somatic immune responses. Collectively, this growing body of literature illustrates potential mechanisms through which stress signals are conveyed from the CNS to immune cells to regulate stress-relevant behaviours and comorbid pathophysiology.

Neutrophil infiltration leads to fetal growth restriction by impairing the placental vasculature in DENV-infected pregnant mice

BACKGROUND

Dengue virus (DENV) infection during pregnancy increases the risk of adverse fetal outcomes, which has become a new clinical challenge. However, the underlying mechanism remains unknown.

METHODS

The effect of DENV-2 infection on fetuses was investigated using pregnant interferon α/β receptor-deficient (Ifnar1-/-) mice. The histopathological changes in the placentas were analyzed by morphological techniques. A mouse inflammation array was used to detect the cytokine and chemokine profiles in the serum and placenta. The infiltration characteristics of inflammatory cells in the placentas were evaluated by single-cell RNA sequencing.

FINDINGS

Fetal growth restriction observed in DENV-2 infection was mainly caused by the destruction of the placental vasculature rather than direct damage from the virus in our mouse model. After infection, neutrophil infiltration into the placenta disrupts the expression profile of matrix metalloproteinases, which leads to placental dysvascularization and insufficiency. Notably, similar histopathological changes were observed in the placentas from DENV-infected puerperae.

INTERPRETATION

Neutrophils play key roles in placental histopathological damage during DENV infection, which indicates that interfering with aberrant neutrophil infiltration into the placenta may be an important therapeutic target for adverse pregnancy outcomes in DENV infection.

FUNDING

The National Key Research and Development Plans of China (2021YFC2300200-02 to J.A., 2019YFC0121905 to Q.Z.C.), the National Natural Science Foundation of China (NSFC) (U1902210 and 81972979 to J. A., 81902048 to Z. Y. S., and 82172266 to P.G.W.), and the Support Project of High-level Teachers in Beijing Municipal Universities in the Period of 13th Five-year Plan, China (IDHT20190510 to J. A.).

γδ T cells control murine skin inflammation and subcutaneous adipose wasting during chronic Trypanosoma brucei infection

African trypanosomes colonise the skin to ensure parasite transmission. However, how the skin responds to trypanosome infection remains unresolved. Here, we investigate the local immune response of the skin in a murine model of infection using spatial and single cell transcriptomics. We detect expansion of dermal IL-17A-producing Vγ6+ cells during infection, which occurs in the subcutaneous adipose tissue. In silico cell-cell communication analysis suggests that subcutaneous interstitial preadipocytes trigger T cell activation via Cd40 and Tnfsf18 signalling, amongst others. In vivo, we observe that female mice deficient for IL-17A-producing Vγ6+ cells show extensive inflammation and limit subcutaneous adipose tissue wasting, independently of parasite burden. Based on these observations, we propose that subcutaneous adipocytes and Vγ6+ cells act in concert to limit skin inflammation and adipose tissue wasting. These studies provide new insights into the role of γδ T cell and subcutaneous adipocytes as homeostatic regulators of skin immunity during chronic infection.

Influenza breakthrough infection in vaccinated mice is characterized by non-pathological lung eosinophilia

Eosinophils are important mediators of mucosal tissue homeostasis, anti-helminth responses, and allergy. Lung eosinophilia has previously been linked to aberrant Type 2-skewed T cell responses to respiratory viral infection and may also be a consequence of vaccine-associated enhanced respiratory disease (VAERD), particularly in the case of respiratory syncytial virus (RSV) and the formalin-inactivated RSV vaccine. We previously reported a dose-dependent recruitment of eosinophils to the lungs of mice vaccinated with alum-adjuvanted trivalent inactivated influenza vaccine (TIV) following a sublethal, vaccine-matched H1N1 (A/New Caledonia/20/1999; NC99) influenza challenge. Given the differential role of eosinophil subset on immune function, we conducted the investigations herein to phenotype the lung eosinophils observed in our model of influenza breakthrough infection. Here, we demonstrate that eosinophil influx into the lungs of vaccinated mice is adjuvant- and sex-independent, and only present after vaccine-matched sublethal influenza challenge but not in mock-challenged mice. Furthermore, vaccinated and challenged mice had a compositional shift towards more inflammatory eosinophils (iEos) compared to resident eosinophils (rEos), resembling the shift observed in ovalbumin (OVA)-sensitized allergic control mice, however without any evidence of enhanced morbidity or aberrant inflammation in lung cytokine/chemokine signatures. Furthermore, we saw a lung eosinophil influx in the context of a vaccine-mismatched challenge. Additional layers of heterogeneity in the eosinophil compartment were observed via unsupervised clustering analysis of flow cytometry data. Our collective findings are a starting point for more in-depth phenotypic and functional characterization of lung eosinophil subsets in the context of vaccine- and infection-induced immunity.

Heterodimers Are an Integral Component of Chemokine Signaling Repertoire

Chemokines are a family of signaling proteins that play a crucial role in cell-cell communication, cell migration, and cell trafficking, particularly leukocytes, under both normal and pathological conditions. The oligomerization state of chemokines influences their biological activity. The heterooligomerization occurs when multiple chemokines spatially and temporally co-localize, and it can significantly affect cellular responses. Recently, obligate heterodimers have emerged as tools to investigate the activities and molecular mechanisms of chemokine heterodimers, providing valuable insights into their functional roles. This review focuses on the latest progress in understanding the roles of chemokine heterodimers and their contribution to the functioning of the chemokine network.

Lactobacillus rhamnosus KBL2290 Ameliorates Gut Inflammation in a Mouse Model of Dextran Sulfate Sodium-Induced Colitis

Ulcerative colitis, a major form of inflammatory bowel disease (IBD) associated with chronic colonic inflammation, may be induced via overreactive innate and adaptive immune responses. Restoration of gut microbiota abundance and diversity is important to control the pathogenesis. Lactobacillus spp., well-known probiotics, ameliorate IBD symptoms via various mechanisms, including modulation of cytokine production, restoration of gut tight junction activity and normal mucosal thickness, and alterations in the gut microbiota. Here, we studied the effects of oral administration of Lactobacillus rhamnosus (L. rhamnosus) KBL2290 from the feces of a healthy Korean individual to mice with DSS-induced colitis. Compared to the dextran sulfate sodium (DSS) + phosphate-buffered saline control group, the DSS + L. rhamnosus KBL2290 group evidenced significant improvements in colitis symptoms, including restoration of body weight and colon length, and decreases in the disease activity and histological scores, particularly reduced levels of pro-inflammatory cytokines and an elevated level of anti-inflammatory interleukin-10. Lactobacillus rhamnosus KBL2290 modulated the levels of mRNAs encoding chemokines and markers of inflammation; increased regulatory T cell numbers; and restored tight junction activity in the mouse colon. The relative abundances of genera Akkermansia, Lactococcus, Bilophila, and Prevotella increased significantly, as did the levels of butyrate and propionate (the major short-chain fatty acids). Therefore, oral L. rhamnosus KBL2290 may be a useful novel probiotic.

Macrophages Orchestrate Airway Inflammation, Remodeling, and Resolution in Asthma

Asthma is a heterogenous chronic inflammatory lung disease with endotypes that manifest different immune system profiles, severity, and responses to current therapies. Regardless of endotype, asthma features increased immune cell infiltration, inflammatory cytokine release, and airway remodeling. Lung macrophages are also heterogenous in that there are separate subsets and, depending on the environment, different effector functions. Lung macrophages are important in recruitment of immune cells such as eosinophils, neutrophils, and monocytes that enhance allergic inflammation and initiate T helper cell responses. Persistent lung remodeling including mucus hypersecretion, increased airway smooth muscle mass, and airway fibrosis contributes to progressive lung function decline that is insensitive to current asthma treatments. Macrophages secrete inflammatory mediators that induce airway inflammation and remodeling. Additionally, lung macrophages are instrumental in protecting against pathogens and play a critical role in resolution of inflammation and return to homeostasis. This review summarizes current literature detailing the roles and existing knowledge gaps for macrophages as key inflammatory orchestrators in asthma pathogenesis. We also raise the idea that modulating inflammatory responses in lung macrophages is important for alleviating asthma.

Shedding Light on the Cell Biology of Platelet-Derived Extracellular Vesicles and Their Biomedical Applications

EVs are membranous subcellular structures originating from various cells, including platelets which consist of biomolecules that can modify the target cell's pathophysiological functions including inflammation, cell communication, coagulation, and metastasis. EVs, which are known to allow the transmission of a wide range of molecules between cells, are gaining popularity in the fields of subcellular treatment, regenerative medicine, and drug delivery. PEVs are the most abundant EVs in circulation, being produced by platelet activation, and are considered to have a significant role in coagulation. PEV cargo is extremely diverse, containing lipids, proteins, nucleic acids, and organelles depending on the condition that induced their release and can regulate a wide range of biological activities. PEVs, unlike platelets, can overcome tissue barriers, allowing platelet-derived contents to be transferred to target cells and organs that platelets cannot reach. Their isolation, characterization, and therapeutic efficacy, on the other hand, are poorly understood. This review summarizes the technical elements of PEV isolation and characterization methods as well as the pathophysiological role of PEVs, including therapeutic potential and translational possibility in diverse disciplines.

Circulating extracellular vesicles promote recovery in a preclinical model of intracerebral hemorrhage

Circulating extracellular vesicles (EVs) are proposed to participate in enhancing pathways of recovery after stroke through paracrine signaling. To verify this hypothesis in a proof-of-concept study, blood-derived allogenic EVs from rats and xenogenic EVs from humans who experienced spontaneous good recovery after an intracerebral hemorrhage (ICH) were administered intravenously to rats at 24 h after a subcortical ICH. At 28 days, both treatments improved the motor function assessment scales score, showed greater fiber preservation in the perilesional zone (diffusion tensor-fractional anisotropy MRI), increased immunofluorescence markers of myelin (MOG), and decreased astrocyte markers (GFAP) compared with controls. Comparison of the protein cargo of circulating EVs at 28 days from animals with good vs. poor recovery showed down-expression of immune system activation pathways (CO4, KLKB1, PROC, FA9, and C1QA) and of restorative processes such as axon guidance (RAC1), myelination (MBP), and synaptic vesicle trafficking (SYN1), which is in line with better tissue preservation. Up-expression of PCSK9 (neuron differentiation) in xenogenic EVs-treated animals suggests enhancement of repair pathways. In conclusion, the administration of blood-derived EVs improved recovery after ICH. These findings open a new and promising opportunity for further development of restorative therapies to improve the outcomes after an ICH.

Neutrophil-derived catecholamines mediate negative stress effects on bone

Mental traumatization is associated with long-bone growth retardation, osteoporosis and increased fracture risk. We revealed earlier that mental trauma disturbs cartilage-to-bone transition during bone growth and repair in mice. Trauma increased tyrosine hydroxylase-expressing neutrophils in bone marrow and fracture callus. Here we show that tyrosine hydroxylase expression in the fracture hematoma of patients correlates positively with acknowledged stress, depression, and pain scores as well as individual ratings of healing-impairment and pain-perception post-fracture. Moreover, mice lacking tyrosine hydroxylase in myeloid cells are protected from chronic psychosocial stress-induced disturbance of bone growth and healing. Chondrocyte-specific β2-adrenoceptor-deficient mice are also protected from stress-induced bone growth retardation. In summary, our preclinical data identify locally secreted catecholamines in concert with β2-adrenoceptor signalling in chondrocytes as mediators of negative stress effects on bone growth and repair. Given our clinical data, these mechanistic insights seem to be of strong translational relevance.

Transcriptomic Profiling Reveals Chemokine CXCL1 as a Mediator for Neutrophil Recruitment Associated With Blood-Retinal Barrier Alteration in Diabetic Retinopathy

Inflammation plays an important role in the pathogenesis of diabetic retinopathy (DR). To precisely define the inflammatory mediators, we examined the transcriptomic profile of human retinal endothelial cells exposed to advanced glycation end products, which revealed the neutrophil chemoattractant chemokine CXCL1 as one of the top genes upregulated. The effect of neutrophils in the alteration of the blood-retinal barrier (BRB) was further assessed in wild-type C57BL/6J mice intravitreally injected with recombinant CXCL1 as well as in streptozotocin-induced diabetic mice. Both intravitreally CXCL1-injected and diabetic animals showed significantly increased retinal vascular permeability, with significant increase in infiltration of neutrophils and monocytes in retinas and increased expression of chemokines and their receptors, proteases, and adhesion molecules. Treatment with Ly6G antibody for neutrophil depletion in both diabetic mice as well as CXCL1-injected animals showed significantly decreased retinal vascular permeability accompanied by decreased infiltration of neutrophils and monocytes and decreased expression of cytokines and proteases. CXCL1 level was significantly increased in the serum samples of patients with DR compared with samples of those without diabetes. These data reveal a novel mechanism by which the chemokine CXCL1, through neutrophil recruitment, alters the BRB in DR and, thus, serves as a potential novel therapeutic target.

ARTICLE HIGHLIGHTS

Intravitreal CXCL1 injection and diabetes result in increased retinal vascular permeability with neutrophil and monocyte recruitment. Ly6G antibody treatment for neutrophil depletion in both animal models showed decreased retinal permeability and decreased cytokine expression. CXCL1 is produced by retinal endothelial cells, pericytes, and astrocytes. CXCL1 level is significantly increased in serum samples of patients with diabetic retinopathy. CXCL1, through neutrophil recruitment, alters the blood-retinal barrier in diabetic retinopathy and, thus, may be used as a therapeutic target.

Optogenetic stimulation of the brainstem dorsal motor nucleus ameliorates acute pancreatitis

Introduction

Inflammation is an inherently self-amplifying process, resulting in progressive tissue damage when unresolved. A brake on this positive feedback system is provided by the nervous system which has evolved to detect inflammatory signals and respond by activating anti-inflammatory processes, including the cholinergic anti-inflammatory pathway mediated by the vagus nerve. Acute pancreatitis, a common and serious condition without effective therapy, develops when acinar cell injury activates intrapancreatic inflammation. Prior study has shown that electrical stimulation of the carotid sheath, which contains the vagus nerve, boosts the endogenous anti-inflammatory response and ameliorates acute pancreatitis, but it remains unknown whether these anti-inflammatory signals originate in the brain.

Methods

Here, we used optogenetics to selectively activate efferent vagus nerve fibers originating in the brainstem dorsal motor nucleus of the vagus (DMN) and evaluated the effects on caerulein-induced pancreatitis.

Results

Stimulation of the cholinergic neurons in the DMN significantly attenuates the severity of pancreatitis as indicated by reduced serum amylase, pancreatic cytokines, tissue damage, and edema. Either vagotomy or silencing cholinergic nicotinic receptor signaling by pre-administration of the antagonist mecamylamine abolishes the beneficial effects.

Discussion

These results provide the first evidence that efferent vagus cholinergic neurons residing in the brainstem DMN can inhibit pancreatic inflammation and implicate the cholinergic anti-inflammatory pathway as a potential therapeutic target for acute pancreatitis.

Regulation of NOX/p38 MAPK/PPARα pathways and miR-155 expression by boswellic acids reduces hepatic injury in experimentally-induced alcoholic liver disease mouse model: novel mechanistic insight

Alcoholic liver disease (ALD) refers to hepatic ailments induced by excessive alcohol intake. The pathogenesis of ALD comprises a complex interplay between various mechanistic pathways, among which inflammation and oxidative stress are key players. Boswellic acids (BAs), found in Boswellia serrata, have shown hepatoprotective effects owing to their antioxidant and anti-inflammatory activities, nevertheless, their therapeutic potential against ALD has not been previously investigated. Hence, this study was performed to depict the possible protective effect of BAs and detect their underlying mechanism of action in an experimentally-induced ALD mouse model. Male BALB/c mice were equally categorized into six groups: control, BAs-treated, ALD, and ALD that received BAs at three-dose levels (125, 250, and 500 mg/kg) by oral gavage for 14 days. Results showed that the high dose of BAs had the most protective impact against ALD according to histopathology examination, blood alcohol concentration (BAC), and liver function enzymes. Mechanistic investigations revealed that BAs (500 mg/kg) caused a significant decrease in cytochrome P450 2E1(CYP2E1), nicotine adenine dinucleotide phosphate oxidase (NOX) 1/2/4, p38 mitogen-activated protein kinase (MAPK), and sterol regulatory element-binding protein-1c (SREBP-1c) levels, and the expression of miR-155, yet increased peroxisome proliferator-activated receptor alpha (PPARα) levels. This led to an improvement in lipid profile and reduced hepatic inflammation, oxidative stress, and apoptosis indices. In summary, our study concludes that BAs can protect against ethanol-induced hepatic injury, via modulating NOX/p38 MAPK/PPARα pathways and miR-155 expression.

Aging influence on pulmonary and systemic inflammation and neural metabolomics arising from pulmonary multi-walled carbon nanotube exposure in apolipoprotein E-deficient and C57BL/6 female mice

OBJECTIVE

Environmental exposures exacerbate age-related pathologies, such as cardiovascular and neurodegenerative diseases. Nanoparticulates, and specifically carbon nanomaterials, are a fast-growing contributor to the category of inhalable pollutants, whose risks to health are only now being unraveled. The current study assessed the exacerbating effect of age on multiwalled-carbon nanotube (MWCNT) exposure in young and old C57BL/6 and ApoE-/- mice.

MATERIALS AND METHODS

Female C57BL/6 and apolipoprotein E-deficient (ApoE-/-) mice, aged 8 weeks and 15 months, were exposed to 0 or 40 µg MWCNT via oropharyngeal aspiration. Pulmonary inflammation, inflammatory bioactivity of serum, and neurometabolic changes were assessed at 24 h post-exposure.

RESULTS

Pulmonary neutrophil infiltration was induced by MWCNT in bronchoalveolar lavage fluid in both C57BL/6 and ApoE-/-. Macrophage counts decreased with MWCNT exposure in ApoE-/- mice but were unaffected by exposure in C57BL/6 mice. Older mice appeared to have greater MWCNT-induced total protein in lavage fluid. BALF cytokines and chemokines were elevated with MWCNT exposure, but CCL2, CXCL1, and CXCL10 showed reduced responses to MWCNT in older mice. However, no significant serum inflammatory bioactivity was detected. Cerebellar metabolic changes in response to MWCNT were modest, but age and strain significantly influenced metabolite profiles assessed. ApoE-/- mice and older mice exhibited less robust metabolite changes in response to exposure, suggesting a reduced health reserve.

CONCLUSIONS

Age influences the pulmonary and neurological responses to short-term MWCNT exposure. However, with only the model of moderate aging (15 months) in this study, the responses appeared modest compared to inhaled toxicant impacts in more advanced aging models.

Fate of intravenously administered umbilical cord mesenchymal stromal cells and interactions with the host's immune system

Mesenchymal stromal cells (MSCs) are multipotent cells showing promise in pre-clinical studies and currently used in many clinical trials. The regenerative potential of MSCs is mediated, at least in part, by direct and indirect immunomodulatory processes. However, the mechanism of action is not fully understood yet, and there are still concerns about possible undesired negative effects associated with the administration of living cells. In this study, we (i) compare the long-term fate and safety of umbilical cord (UC-)MSCs administered to immunocompetent and immunocompromised (severe combined immunodeficient (SCID) and non-obese diabetic (NOD)/SCID) animals, and (ii) investigate the immunological response of the host to the administered cells. Intravenous administration of firefly luciferase expressing UC-MSCs revealed that the cells get trapped in the lungs of both immunocompetent and immunocompromised animals, with > 95% of the cells disappearing within 72 h after administration. In 27% of the SCID and 45% of the NOD/SCID, a small fraction of the cells lived up to day 14 but in most cases they all disappeared earlier. One NOD/SCID mouse showed a weak signal up to day 31. Immunocompetent mice displayed elevated percentages of neutrophils in the lungs, the blood, and the spleen 2 h after the administration of the cells. The concentration of neutrophil chemoattractants (MCP1, CCL7, Gro-α and IP-10) were also increased in the plasma of the animals 2 h after the administration of the MSCs. Our results suggest that although the UC-MSCs are short-lived in mice, they still result in an immunological response that might contribute to a therapeutic effect.

YAP-regulated type II alveolar epithelial cell differentiation mediated by human umbilical cord-derived mesenchymal stem cells in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) contributes to higher mortality worldwide. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) have immunomodulatory and regenerative potential. However, the effects of hUC-MSCs as an ARDS treatment remain unclear. We investigated the role of hUC-MSCs in the differentiation of type II alveolar epithelial cells (AECII) by regulating Yes-associated protein (YAP) in ARDS. Male C57BL/6JNarl mice were intratracheally (i.t.) administered lipopolysaccharide (LPS) to induce an ARDS model, followed by a single intravenous (i.v.) dose of hUC-MSCs. hUC-MSCs improved pulmonary function, decreased inflammation on day 3, and mitigated lung injury by reducing the lung injury score and increasing lung aeration (%) in mice on day 7 (p < 0.05). hUC-MSCs inactivated YAP on AECII and facilitated cell differentiation by decreasing Pro-surfactant protein C (Pro-SPC) and galectin 3 (LGALS3) while increasing podoplanin (T1α) in lungs of mice (p < 0.05). In AECII MLE-12 cells, both coculture with hUC-MSCs after LPS exposure and the YAP inhibitor, verteporfin, reduced Pro-SPC and LGALS3, whereas the YAP inhibitor increased T1α expression (p < 0.05). In conclusion, hUC-MSCs ameliorated lung injury of ARDS and regulated YAP to facilitate AECII differentiation.

Recovery of systemic hyperinflammation in patients with severe SARS-CoV-2 infection

INTRODUCTION

Patients with cardiovascular disease (CVD) and acute SARS-CoV-2 infection might show an altered immune response during COVID-19.

MATERIAL AND METHODS

Twenty-three patients with CVD and SARS-CoV-2 infection were prospectively enrolled and received a cardiological assessment at study entry and during follow-up visit. Inclusion criteria of our study were age older than 18 years, presence of CVD, and acute SARS-CoV-2 infection. The median age of the patient cohort was 69 (IQR 55-79) years. 12 (52.2%) patients were men. Peripheral monocytes and chemokine/cytokine profiles were analysed.

RESULTS

Numbers of classical and non-classical monocytes were significantly decreased during acute SARS-CoV-2 infection compared to 3-month recovery. While classical monocytes reached the expected level in peripheral blood after 3 months, the number of non-classical monocytes remained significantly reduced.

DISCUSSION

All three monocyte subsets exhibited changes of established adhesion and activation markers. Interestingly, they also expressed higher levels of pro-inflammatory cytokines like macrophage migration inhibitory factor (MIF) at the time of recovery, although MIF was only slightly increased during the acute phase.

CONCLUSION

Changes of monocyte phenotypes and increased MIF expression after 3-month recovery from acute SARS-CoV-2 infection may indicate persistent, possibly long-lasting, pro-inflammatory monocyte function in CVD patients.

Inhibition of sPLA2 enzyme activity by cell-permeable antioxidant EUK-8 and downregulation of p38, Akt, and p65 signals induced by sPLA2 in inflammatory mouse paw edema model

The arachidonic acid (AA) metabolic pathway, plays a vital role in the production of eicosanoids by the action of pro-inflammatory secretory phospholipase A₂ (PLA₂ ). Release of eicosanoids is known to be involved in many inflammatory diseases. Identification of the inhibitory molecules of this AA pathway enzyme along with the regulation of intracellular signaling cascades may be a finer choice to develop as a powerful anti-inflammatory drug. In this regard, we have screened few cell-permeable antioxidant molecules Tempo, Mito-TEMPO, N,N'-Bis(salicylideneamino)ethane-manganese(II) (EUK)-134, and EUK-8 against pro-inflammatory sPLA₂ s. Among these, we found EUK-8 is a potent inhibitor with its IC₅₀ value ranges 0.7-2.0 µM for sPLA₂ s isolated from different sources. Furthermore, docking studies confirm the strong binding of EUK-8 towards sPLA₂ . In vivo effect of EUK-8 was studied in HSF-sPLA₂ -induced edema in mouse paw model. In addition to neutralizing the edema, EUK-8 significantly reduces the phosphorylation level of inflammatory proteins such as p38 member of MAPK pathway, Akt, and p65 along with the suppression of pro-inflammatory cytokine (interleukin-6) and chemokine (CXCL1) in edematous tissue. This shows that EUK-8 not only inhibits the sPLA₂ activity, it also plays an important role in the regulation of sPLA₂ -induced cell signaling cascades. Apart from the sPLA₂ inhibition, we also examine the regulatory actions of EUK-8 with other downstream enzymes of AA pathway such as 5-LOX assay in human polymorphonuclear leukocytes (PMNs) and COX-2 expression in carrageenan-λ induced paw edema. Here EUK-8 significantly inhibits 5-LOX enzyme activity and downregulates COX-2 expression. These data indicate that EUK-8 found to be a promising multitargeted inhibitory molecule toward inflammatory pathway. In conclusion, mitochondrial targeted antioxidant EUK-8 is not only the powerful antioxidant, also a potent anti-inflammatory molecule and may be a choice of molecule for pharmacological applications.

Induction of toxicity in human colon cells and organoids by size- and composition-dependent road dust

Environmental pollution, including the annual resurgence of particulate matter derived from road dust, is a serious issue worldwide. Typically, the size of road dust is less than 10 μm; thus, road dust can penetrate into human organs, including the brain, through inhalation and intake by mouth. Therefore, the toxicity of road dust has been intensively studied in vitro and in vivo. However, in vitro systems, including 2D cell cultures, cannot mimic complex human organs, and there are several discrepancies between in vivo and human systems. Here, we used human colon cells and organoids to evaluate the cytotoxicity of particulate matter derived from road dust. The toxicity of road dust collected in industrialized and high traffic areas and NIST urban particulate matter reference samples were evaluated in 2D and 3D human colon cells as well as colon organoids and their characteristics were carefully examined. Data suggest that the size and elemental compositions of road dust can correlate with colon organoid toxicity, and thus, a more careful assessment of the size and elemental compositions of road dust should be conducted to predict its effect on human health.

TLR5 agonists enhance anti-tumor immunity and overcome resistance to immune checkpoint therapy

Primary and adaptive resistance to immune checkpoint therapies (ICT) represent a considerable obstacle to achieving enhanced overall survival. Innate immune activators have been actively pursued for their antitumor potential. Herein we report that a syngeneic 4T1 mammary carcinoma murine model for established highly-refractory triple negative breast cancer showed enhanced survival when treated intra-tumorally with either the TLR5 agonist flagellin or CBLB502, a flagellin derivative, in combination with antibodies targeting CTLA-4 and PD-1. Long-term survivor mice showed immunologic memory upon tumor re-challenge and a distinctive immune activating cytokine profile that engaged both innate and adaptive immunity. Low serum levels of G-CSF and CXCL5 (as well as high IL-15) were candidate predictive biomarkers correlating with enhanced survival. CBLB502-induced enhancement of ICT was also observed in poorly immunogenic B16-F10 melanoma tumors. Combination immune checkpoint therapy plus TLR5 agonists may offer a new therapeutic strategy to treat ICT-refractory solid tumors.

Tumor microenvironment and epithelial-mesenchymal transition in bladder cancer: Cytokines in the game?

Bladder cancer (BlCa) is a highly immunogenic cancer. Bacillus Calmette-Guérin (BCG) is the standard treatment for non-muscle invasive bladder cancer (NMIBC) patients and, recently, second-line immunotherapies have arisen to treat metastatic BlCa patients. Understanding the interactions between tumor cells, immune cells and soluble factors in bladder tumor microenvironment (TME) is crucial. Cytokines and chemokines released in the TME have a dual role, since they can exhibit both a pro-inflammatory and anti-inflammatory potential, driving infiltration and inflammation, and also promoting evasion of immune system and pro-tumoral effects. In BlCa disease, 70-80% are non-muscle invasive bladder cancer, while 20-30% are muscle-invasive bladder cancer (MIBC) at the time of diagnosis. However, during the follow up, about half of treated NMIBC patients recur once or more, with 5-25% progressing to muscle-invasive bladder cancer, which represents a significant concern to the clinic. Epithelial-mesenchymal transition (EMT) is one biological process associated with tumor progression. Specific cytokines present in bladder TME have been related with signaling pathways activation and EMT-related molecules regulation. In this review, we summarized the immune landscape in BlCa TME, along with the most relevant cytokines and their putative role in driving EMT processes, tumor progression, invasion, migration and metastasis formation.

Proteomic profiling of a patient with cutaneous melanoma metastasis regression following topical contact sensitizer diphencyprone and immune checkpoint inhibitor treatment

Immune checkpoint inhibitors (ICIs) such as pembrolizumab have revolutionized the treatment of advanced melanoma, but many patients do not respond to ICIs alone, and thus there is need for additional treatment options. Topical immunomodulators such as diphencyprone (DPCP) also have clinical use in advanced melanoma, particularly in the treatment of cutaneous metastases. In a previous report, we characterized the enhanced clinical response to dual agent immunotherapy with pembrolizumab and DPCP in a patient with cutaneous melanoma metastases. To improve mechanistic understanding of this response, we analyzed proteomic data using the Olink immuno-oncology panel of 96 biomarkers from tissue and serum samples of this patient throughout his treatment course. Particular attention was paid to programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), and lymphocyte-activation gene 3 (LAG-3) given they are all targeted by ICIs in clinical practice. These proteins were upregulated during the period of DPCP monotherapy, then downregulated during pembrolizumab monotherapy, and then robustly upregulated again during dual therapy. Although not exclusively, the induction of checkpoint inhibitor proteins in the presence of DPCP suggests potential synergy between this agent and ICIs in the treatment of cutaneous melanoma metastases. Large-scale investigation is warranted to further evaluate this potential novel combination therapeutic approach.

Quercetin alleviates ferroptosis accompanied by reducing M1 macrophage polarization during neutrophilic airway inflammation

Ferroptosis is a kind of regulated cell death, supporting the pathological process of lung inflammation, including asthma. Quercetin (QCT), a kind of natural dietary flavonoid, exerts anti-inflammatory and anti-ferroptosis effects in various diseases. However, the role of QCT in ferroptosis-associated airway inflammation of neutrophilic asthma remains to be described. Our study aimed to investigate the therapeutic effects of QCT on neutrophilic airway inflammation of asthma. Ferrostatin-1 (Fer-1), as a kind of ferroptosis inhibitor, was used to demonstrate whether neutrophilic airway inflammation of asthma relied on ferroptosis. In our study, the alleviation effect of QCT on neutrophilic airway inflammation was similar to Fer-1. Moreover, the significantly decreased levels of ferroptosis anti-oxidant protein (GPX4 and SLC7A11), increased malondialdehyde (MDA) levels, upregulated levels of 4-hydroxynonenal (4-HNE) expression by immunohistochemistry, and distorted mitochondria morphological changes in the lung tissues suggested lung ferroptosis in neutrophilic airway inflammation, which could be reversed by QCT treatment. In vitro experiments showed that QCT reduced LPS-induced ferroptosis through upregulating cell viability and levels of ferroptosis anti-oxidant protein (SLC7A11 and GPX4), reducing inflammatory cytokines, and decreasing the levels of MDA. Furthermore, ferroptosis was accompanied by enhancing M1 phenotype in neutrophilic airway inflammation, and QCT suppressed ferroptosis by inhibiting the pro-inflammatory M1 profile in vitro and in vivo, just as Fer-1 did. In conclusion, our study found that QCT ameliorated ferroptosis-associated neutrophilic airway inflammation accompanied by inhibiting M1 macrophage polarization. QCT may be a promising ferroptosis inhibitor for neutrophilic airway inflammation.

Comprehensive Assessment of Secreted Immuno-Modulatory Cytokines by Serum-Differentiated and Stem-like Glioblastoma Cells Reveals Distinct Differences between Glioblastoma Phenotypes

Glioblastoma is refractory to therapy and presents a significant oncological challenge. Promising immunotherapies have not shown the promise observed in other aggressive cancers. The reasons for this include the highly immuno-suppressive tumour microenvironment controlled by the glioblastoma cells and heterogeneous phenotype of the glioblastoma cells. Here, we wanted to better understand which glioblastoma phenotypes produced the regulatory cytokines, particularly those that are implicated in shaping the immune microenvironment. In this study, we employed nanoString analysis of the glioblastoma transcriptome, and proteomic analysis (proteome profiler arrays and cytokine profiling) of secreted cytokines by different glioblastoma phenotypes. These phenotypes were cultured to reflect a spectrum of glioblastoma cells present in tumours, by culturing an enhanced stem-like phenotype of glioblastoma cells or a more differentiated phenotype following culture with serum. Extensive secretome profiling reveals that there is considerable heterogeneity in secretion patterns between serum-derived and glioblastoma stem-like cells, as well as between individuals. Generally, however, the serum-derived phenotypes appear to be the primary producers of cytokines associated with immune cell recruitment into the tumour microenvironment. Therefore, these glioblastoma cells have considerable importance in shaping the immune landscape in glioblastoma and represent a valuable therapeutic target that should not be ignored.

Comparison of toxicity and cellular responses following pulmonary exposure to different types of nanofibers

Pulmonary effects of inhaled microfibers are an emerging public health concern. In this study, we investigated toxicity following pulmonary exposure to synthetic polyethylene oxide fibroin (PEONF) and silk fibroin (SFNF) nanofibers and the cellular responses. When instilled intratracheally weekly for four weeks, body weight gain was significantly reduced in female mice exposed to the higher dose of SFNF when compared with the control group. The total number of cells in the lungs was more significant in all treated groups than in the control, whereas the relative portion of neutrophils and eosinophils increased significantly only in female mice exposed to SFNF. Both types of nanofibers induced notable pathological changes and increased pulmonary expression of MCP-1α, CXCL1, and TGF-β. More importantly, blood calcium, creatinine kinase, sodium, and chloride concentration were affected significantly, showing sex- and material-dependent differences. The relative portion of eosinophils increased only in SFNF-treated mice. In addition, both types of nanofibers induced necrotic and late apoptotic cell death in alveolar macrophages after 24 h of exposure, with accompanying oxidative stress, increased NO production, cell membrane rupture, intracellular organelle damage, and intracellular calcium accumulation. Additionally, multinucleated giant cells were formed in cells exposed to PEONF or SFNF. Taken together, the findings indicate that inhaled PEONF and SFNF may cause systemic adverse health effects with lung tissue damage, showing differences by sex- and material. Furthermore, PEONF- and SFNF-induced inflammatory response may be partly due to the low clearance of dead (or damaged) pulmonary cells and the excellent durability of PEONF and SFNF.

Atomic-Resolution Experimental Structural Biology and Molecular Dynamics Simulations of Hyaluronan and Its Complexes

This review summarizes the atomic-resolution structural biology of hyaluronan and its complexes available in the Protein Data Bank, as well as published studies of atomic-resolution explicit-solvent molecular dynamics simulations on these and other hyaluronan and hyaluronan-containing systems. Advances in accurate molecular mechanics force fields, simulation methods and software, and computer hardware have supported a recent flourish in such simulations, such that the simulation publications now outnumber the structural biology publications by an order of magnitude. In addition to supplementing the experimental structural biology with computed dynamic and thermodynamic information, the molecular dynamics studies provide a wealth of atomic-resolution information on hyaluronan-containing systems for which there is no atomic-resolution structural biology either available or possible. Examples of these summarized in this review include hyaluronan pairing with other hyaluronan molecules and glycosaminoglycans, with ions, with proteins and peptides, with lipids, and with drugs and drug-like molecules. Despite limitations imposed by present-day computing resources on system size and simulation timescale, atomic-resolution explicit-solvent molecular dynamics simulations have been able to contribute significant insight into hyaluronan's flexibility and capacity for intra- and intermolecular non-covalent interactions.