Emerging Role of the IL-36/IL-36R Axis in Multiple Inflammatory Skin Diseases.

IL-36 is a most recent member of the IL-1 cytokine family, primarily expressed at barrier sites of the body such as the skin, lungs, and intestine. It plays a vital role in inflammation and is implicated in the development of various cutaneous; intestinal; and pulmonary disorders, including psoriasis, inflammatory bowel disease, and chronic obstructive pulmonary disease. IL-36 comprises 4 isoforms: the proinflammatory IL-36α, IL-36ß, and IL-36γ and the anti-inflammatory IL-36R antagonist. An imbalance between proinflammatory and anti-inflammatory IL-36 isoforms can contribute to the inflammatory fate of cells and tissues. IL-36 cytokines signal through an IL-36R heterodimer mediating their function through canonical signaling cacade, including the NF-B pathway. Prominent for its role in psoriasis, IL-36 has recently been associated with disease mechanisms in atopic dermatitis, hidradenitis suppurativa, neutrophilic dermatoses, autoimmune blistering disease, and Netherton syndrome. The major cutaneous source of IL-36 cytokines is keratinocytes, pointing to its role in the communication between the epidermis, innate (neutrophils, dendritic cells) immune system, and adaptive (T helper [Th]1 cells, Th17) immune system. Thus, cutaneous IL-36 signaling is crucial for the immunopathological outcome of various skin diseases. Consequently, the IL-36/IL-36R axis has recently been recognized as a promising drug target for the treatment of inflammatory disorders beyond psoriasis. This review summarizes the current update on IL-36 cytokines in inflammatory skin diseases.

Azithromycin downregulates ICOS (CD278) and OX40 (CD134) expression and mTOR activity of TCR-activated T cells to inhibit proliferation.

The precise mechanism of macrolide antibiotic azithromycin (AZM) mediated CD4+ T cell suppression is not fully understood. Given the crucial role of co-stimulatory signaling in T-lymphocyte function, we tested in vitro effects of AZM on two of the most extensively investigated costimulatory molecules, ICOS and OX40 in context to CD4+ T cell proliferation. Using multi-color flow cytometry approach on TCR-activated healthy donor peripheral blood mononuclear cells, we observed a marked reduction in the frequencies and surface expression of ICOS and OX40 receptors following AZM treatment. Functionally, in contrast to ICOS- and OX40- CD3+ CD4+ T cells, AZM treated ICOS+ and OX40+ displayed profound reduction in cell proliferation. Furthermore, AZM treated T cells displaying reduced levels of ICOS and OX40 found to be associated with suppressed mTOR activity as detected by phosphorylation levels of S6 ribosomal protein. This study provides new insights on potential mechanism of AZM mediated inhibition of T cell proliferation by targeting costimulatory pathways.

Upregulation of interleukin-19 in saliva of patients with COVID-19.

Cytokines are major players in orchestrating inflammation, disease pathogenesis and severity during COVID-19 disease. However, the role of IL-19 in COVID-19 pathogenesis remains elusive. Herein, through the analysis of transcriptomic datasets of SARS-CoV-2 infected lung cells, nasopharyngeal swabs, and lung autopsies of COVID-19 patients, we report that expression levels of IL-19 and its receptor, IL-20R2, were upregulated following SARS-CoV-2 infection. Of 202 adult COVID-19 patients, IL-19 protein level was significantly higher in blood and saliva of asymptomatic patients compared to healthy controls when adjusted for patients' demographics (P < 0.001). Interestingly, high saliva IL-19 level was also associated with COVID-19 severity (P < 0.0001), need for mechanical ventilation (P = 0.002), and/or death (P = 0.010) within 29 days of admission, after adjusting for patients' demographics, diabetes mellitus comorbidity, and COVID-19 serum markers of severity such as D-dimer, C-reactive protein, and ferritin. Moreover, patients who received interferon beta during their hospital stay had lower plasma IL-19 concentrations (24 pg mL-1) than those who received tocilizumab (39.2 pg mL-1) or corticosteroids (42.5 pg mL-1). Our findings indicate that high saliva IL-19 level was associated with COVID-19 infectivity and disease severity.

Interleukin-17, a salivary biomarker for COVID-19 severity.

OBJECTIVES: T-helper 17 cell-mediated response and their effector IL-17 cytokine induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a major cause of COVID-19 disease severity and death. Therefore, the study aimed to determine if IL-17 level in saliva mirrors its circulatory level and hence can be used as a non-invasive biomarker for disease severity. METHODS: Interleukin-17 (IL-17) level was evaluated by ELISA in saliva and blood of 201 adult COVID-19 patients with different levels of severity. The IL-17 saliva level was also associated with COVID-19 disease severity, and need for mechanical ventilation and/or death within 29 days after admission of severe COVID-19 patients. RESULTS: We found that IL-17 level in saliva of COVID-19 patients reflected its circulatory level. High IL-17 level in saliva was associated with COVID-19 severity (P<0.001), need for mechanical ventilation (P = 0.002), and/or death by 29 days (P = 0.002), after adjusting for patients' demographics, comorbidity, and COVID-19 serum severity markers such as D-Dimer, C-reactive protein, and ferritin. CONCLUSION: We propose that saliva IL-17 level could be used as a biomarker to identify patients at risk of developing severe COVID-19.

Epigenetic regulation of CXCR4 signaling in cancer pathogenesis and progression.

Signaling involving chemokine receptor CXCR4 and its ligand SDF-1/CXL12 has been investigated for many years for its possible role in cancer progression and pathogenesis. Evidence emerging from clinical studies in recent years has further established diagnostic as well as prognostic importance of CXCR4 signaling. CXCR4 and SDF-1 are routinely reported to be elevated in tumors, distant metastases, which correlates with poor survival of patients. These findings have kindled interest in the mechanisms that regulate CXCR4/SDF-1 expression. Of note, there is a particular interest in the epigenetic regulation of CXCR4 signaling that may be responsible for upregulated CXCR4 in primary as well as metastatic cancers. This review first lists the clinical evidence supporting CXCR4 signaling as putative cancer diagnostic and/or prognostic biomarker, followed by a discussion on reported epigenetic mechanisms that affect CXCR4 expression. These mechanisms include regulation by non-coding RNAs, such as, microRNAs, long non-coding RNAs and circular RNAs. Additionally, we also discuss the regulation of CXCR4 expression through methylation and acetylation. Better understanding and appreciation of epigenetic regulation of CXCR4 signaling can invariably lead to identification of novel therapeutic targets as well as therapies to regulate this oncogenic signaling.

Upregulation of interleukin-19 in severe asthma: a potential saliva biomarker for asthma severity.

Interleukin (IL)-19, a designated IL-20 subfamily cytokine, has been implicated in inflammatory disorders including rheumatoid arthritis, psoriasis and, lately, asthma. Here, through the analysis of transcriptomic datasets of lung tissue of large asthma cohorts, we report that IL-19 expression is upregulated in asthma and correlates with disease severity. The gene expression of IL-19 was significantly higher in lung tissue from patients with severe and mild/moderate asthma compared to healthy controls. IL-19 protein level, however, was significantly higher in the blood and saliva of patients with severe asthma compared to mild/moderate subgroups as measured by ELISA assay. IL-19 protein level was not affected by corticosteroid treatment in plasma. Our data provide insights into the potential use of IL-19 as a saliva marker for asthma severity and a potential therapeutic target.

Systems Immunology Analysis Reveals an Immunomodulatory Effect of Snail-p53 Binding on Neutrophil- and T Cell-Mediated Immunity in KRAS Mutant Non-Small Cell Lung Cancer.

Immunomodulation and chronic inflammation are important mechanisms utilized by cancer cells to evade the immune defense and promote tumor progression. Therefore, various efforts were focused on the development of approaches to reprogram the immune response to increase the immune detection of cancer cells and enhance patient response to various types of therapy. A number of regulatory proteins were investigated and proposed as potential targets for immunomodulatory therapeutic approaches including p53 and Snail. In this study, we investigated the immunomodulatory effect of disrupting Snail-p53 binding induced by the oncogenic KRAS to suppress p53 signaling. We analyzed the transcriptomic profile mediated by Snail-p53 binding inhibitor GN25 in non-small cell lung cancer cells (A549) using Next generation whole RNA-sequencing. Notably, we observed a significant enrichment in transcripts involved in immune response pathways especially those contributing to neutrophil (IL8) and T-cell mediated immunity (BCL6, and CD81). Moreover, transcripts associated with NF-κB signaling were also enriched which may play an important role in the immunomodulatory effect of Snail-p53 binding. Further analysis revealed that the immune expression signature of GN25 overlaps with the signature of other therapeutic compounds known to exhibit immunomodulatory effects validating the immunomodulatory potential of targeting Snail-p53 binding. The effects of GN25 on the immune response pathways suggest that targeting Snail-p53 binding might be a potentially effective therapeutic strategy.

Azithromycin Differentially Alters TCR-Activated Helper T Cell Subset Phenotype and Effector Function.

In addition to their antibiotic activities, azithromycin (AZM) exhibits anti-inflammatory effects in various respiratory diseases. One of the potent anti-inflammatory mechanisms is through inhibition of CD4+ helper T (Th) cell effector function. However, their impact on specific Th subset is obscure. Herein, we demonstrate the cellular basis of phenotypic and functional alterations associated with Th subsets following AZM treatment in vitro. Using well-characterized Th subset specific chemokine receptors, we report significant suppression of T cell receptor (TCR)-stimulated hyperactivated CCR4+CXCR3+ (Th0) expansion compared to CCR4-CXCR3+ (Th1-like) and CCR4+CXCR3- (Th2-like) cells. Interestingly, this effect was associated with diminished cell proliferation. Furthermore, AZM significantly inhibited the inflammatory cytokines IFN-γ and IL-4 production, CCR4 and CXCR3 receptor expression, and viability of Th0, Th1-like, and Th2-like subsets. Our findings suggest that AZM differentially affects TCR-activated Th subsets phenotype and function, and CCR4 and CXCR3 downregulation and suppressed Th0 subset expansion could potentially influence their trafficking and differentiation into cytokine-producing effector cells.

IL-17 Induced Autophagy Regulates Mitochondrial Dysfunction and Fibrosis in Severe Asthmatic Bronchial Fibroblasts.

The accumulation of fibroblasts, their synthesis of extracellular matrix (ECM) proteins and their innate resistance to apoptosis are characteristics of subepithelial fibrosis observed in severe asthma. Interleukin-17 (IL-17) is an important regulator of airway remodeling in asthma. However, the contribution of IL-17 to the pro-fibrotic phenotype of bronchial fibroblasts is not well-characterized. In this study, we investigated whether IL-17 induced autophagy regulates mitochondrial and pro-fibrotic function in bronchial fibroblasts. The primary cultured bronchial fibroblasts isolated from non-asthmatic (NHBF) and severe asthmatic (DHBF) subjects were treated with IL-17 in order to ascertain its effect on mitochondrial function, mitochondrial quality control, and apoptosis using immunoblotting and flow cytometric analyses. At baseline, DHBF exhibited higher levels of mitophagy and mitochondrial biogenesis compared to NHBF. Immunohistochemical evaluation of bronchial biopsies showed intense PINK1 immunoreactivity in severe asthma than in control. IL-17 intensified the mitochondrial dysfunction and impaired the mitochondrial quality control machinery in NHBF and DHBF. Moreover, IL-17 augmented a pro-fibrotic and anti-apoptotic response in both group of fibroblasts. Inhibition of autophagy using bafilomycin-A1 reduced PINK1 expression in NHBF and restored the IL-17 mediated changes in PINK1 to their basal levels in DHBF. Bafilomycin-A1 also reversed the IL-17 associated fibrotic response in these fibroblasts, suggesting a role for IL-17 induced autophagy in the induction of fibrosis in bronchial fibroblasts. Taken together, our findings suggest that IL-17 induced autophagy promotes mitochondrial dysfunction and fibrosis in bronchial fibroblasts from both non-asthmatic and severe asthmatic subjects. Our study provides insights into the therapeutic potential of targeting autophagy in ameliorating fibrosis, particularly in severe asthmatic individuals.

Prednisolone mediated suppression of HIV-1 viral load strongly correlates with C-C chemokine CCL2: In vivo and in vitro findings.

CCL2 (MCP-1) is a proinflammatory chemokine induced in HIV-1 infection. We have previously demonstrated a significant correlation of CCL2 gene expression with HIV-1 viremia. In this study we investigated the effect of prednisolone on CCL2 gene expression and viral load in an HIV-1-infected patient receiving high-dose prednisolone for severe uveitis. We observed a >1 log reduction of HIV-1 viral load, associated with more than hundred fold reduction of CCL2 expression at day 3 of prednisolone treatment. In vitro HIV-1 infection of PBMC demonstrated reduced HIV-1 replication in the presence of prednisolone. Flow cytometric analysis revealed 50% reduction of LTR driven GFP activity by prednisolone in GHOST cells. These findings indicate that prednisolone suppresses both HIV-1 viral load and CCL2 mRNA expression, an association which might be exploited for future anti-inflammatory therapeutic strategies in HIV-1 infection.

Host chemokine (C-C motif) ligand-2 (CCL2) is differentially regulated in HIV type 1 (HIV-1)-infected individuals.

Several cytokines and chemokines including chemokine (C-C motif) ligand-2 (CCL2) are induced in HIV-1 infection. However, the impact of HIV-1 viremia on CCL2 regulation is largely unknown. We utilized a DNA oligonucleotide microarray covering 110 inflammatory genes. Five genes were induced by at least 2-fold in PBMCs of HIV-1 viremic (>100,000 RNA copies ml(-1)) as compared with aviremic (<50 RNA copies ml(-1)) individuals. These genes were CCL2, CXC chemokine ligand-10, IFN-gamma, GTP-cyclohydrolase-1 and C-C chemokine receptor-1. In addition to microarray data verification by real-time PCR, analysis of independent patient samples revealed a similar expression pattern. CCL2 was the most strongly regulated gene at mRNA level and its serum concentration was significantly elevated in viremic compared with aviremic and HIV-1 seronegative controls, indicating a positive correlation between viremia and CCL2. Flow cytometric studies demonstrated a higher percentage of CCL2-expressing CD14(+) monocytes in viremic compared with aviremic individuals. These results suggest a highly restricted modulation of host inflammatory gene response by HIV. Genes up-regulated in the viremic state, in particular CCL2, presumably serve as potential enhancing factors in HIV-1 replication, represented by high viral load in HIV-1 viremic patients. Inhibition of increased CCL2 production could provide a new therapeutic intervention in HIV-1 infection.