Critical role for STAT3 in IL-17A-mediated CCL11 expression in human airway smooth muscle cells

The Lung Alveolar Cell (LAC) miRNome and Gene Expression Profile of the SP-A-KO Mice After Infection With and Without Rescue With Human Surfactant Protein-A2 (1A0)

Human surfactant protein (SP)-A1 and SP-A2 exhibit differential qualitative and quantitative effects on the alveolar macrophage (AM), including a differential impact on the AM miRNome. Moreover, SP-A rescue (treatment) of SP-A-knockout (KO) infected mice impoves survival. Here, we studied for the first time the role of exogenous SP-A protein treatment on the regulation of lung alveolar cell (LAC) miRNome, the miRNA-RNA targets, and gene expression of SP-A-KO infected mice of both sexes. Toward this, SP-A-KO mice of both sexes were infected with Klebsiella pneumoniae, and half of them were also treated with SP-A2 (1A⁰). After 6 h of infection/SP-A treatment, the expression levels and pathways of LAC miRNAs, genes, and target miRNA-mRNAs were studied in both groups. We found 1) significant differences in the LAC miRNome, genes, and miRNA-mRNA targets in terms of sex, infection, and infection plus SP-A2 (1A⁰) protein rescue; 2) an increase in the majority of miRNA-mRNA targets in both study groups in KO male vs. female mice and involvement of the miRNA-mRNA targets in pathways of inflammation, antiapoptosis, and cell cycle; 3) genes with significant changes to be involved in TP-53, tumor necrosis factor (TNF), and cell cycle signaling nodes; 4) when significant changes in the expression of molecules from all analyses (miRNAs, miRNA-mRNA targets, and genes) were considered, two signaling pathways, the TNF and cell cycle, referred to as “integrated pathways” were shown to be significant; 5) the cell cycle pathway to be present in all comparisons made. Because SP-A could be used therapeutically in pulmonary diseases, it is important to understand the molecules and pathways involved in response to an SP-A acute treatment. The information obtained contributes to this end and may help to gain insight especially in the case of infection.

Elucidation of the Molecular Pathways Involved in the Protective Effects of AUY-922 in LPS-Induced Inflammation in Mouse Lungs

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) cause thousands of deaths every year and are associated with high mortality rates (~40%) due to the lack of efficient therapies. Understanding the molecular mechanisms associated with those diseases will most probably lead to novel therapeutics. In the present study, we investigated the effects of the Hsp90 inhibitor AUY-922 in the major inflammatory pathways of mouse lungs. Mice were treated with LPS (1.6 mg/kg) via intratracheal instillation for 24 h and were then post-treated intraperitoneally with AUY-922 (10 mg/kg). The animals were examined 48 h after AUY-922 injection. LPS activated the TLR4-mediated signaling pathways, which in turn induced the release of different inflammatory cytokines and chemokines. AUY-922 suppressed the LPS-induced inflammation by inhibiting major pro-inflammatory pathways (e.g., JAK2/STAT3, MAPKs), and downregulated the IL-1β, IL-6, MCP-1 and TNFα. The expression levels of the redox regulator APE1/Ref1, as well as the DNA-damage inducible kinases ATM and ATR, were also increased after LPS treatment. Those effects were counteracted by AUY-922. Interestingly, this Hsp90 inhibitor abolished the LPS-induced pIRE1α suppression, a major component of the unfolded protein response. Our study elucidates the molecular pathways involved in the progression of murine inflammation and supports our efforts on the development of new therapeutics against lung inflammatory diseases and sepsis.

Efficacy of niclosamide on the intra-abdominal inflammatory environment in endometriosis

Endometriosis, a common gynecological disease, causes chronic pelvic pain and infertility in women of reproductive age. Due to the limited efficacy of current therapies, a critical need exists to develop new treatments for endometriosis. Inflammatory dysfunction, instigated by abnormal macrophage (MΦ) function, contributes to disease development and progression. However, the fundamental role of the heterogeneous population of peritoneal MΦ and their potential druggable functions is uncertain. Here we report that GATA6-expressing large peritoneal MΦ (LPM) were increased in the peritoneal cavity following lesion induction. This was associated with increased cytokine and chemokine secretion in the peritoneal fluid (PF), as well as MΦ infiltration, vascularization and innervation in endometriosis-like lesions (ELL). Niclosamide, an FDA-approved anti-helminthic drug, was effective in reducing LPM number, but not small peritoneal MΦ (SPM), in the PF. Niclosamide also inhibits aberrant inflammation in the PF, ELL, pelvic organs (uterus and vagina) and dorsal root ganglion (DRG), as well as MΦ infiltration, vascularization and innervation in the ELL. PF from ELL mice stimulated DRG outgrowth in vitro, whereas the PF from niclosamide-treated ELL mice lacked the strong stimulatory nerve growth response. These results suggest LPM induce aberrant inflammation in endometriosis promoting lesion progression and establishment of the inflammatory environment that sensitizes peripheral nociceptors in the lesions and other pelvic organs, leading to increased hyperalgesia. Our findings provide the rationale for targeting LPM and their functions with niclosamide and its efficacy in endometriosis as a new non-hormonal therapy to reduce aberrant inflammation which may ultimately diminish associated pain.

Causal relationship between humidifier disinfectant exposure and Th17-mediated airway inflammation and hyperresponsiveness

In this study, we investigated whether humidifier disinfectants (HDs) induce asthmatic airway inflammation in an animal model and compared the features of HD-induced inflammatory symptoms with ovalbumin (OVA)-induced allergic asthma. Mice were intratracheally instilled three times with either the control or 0.1, 0.3, or 0.5 mg/kg of polyhexamethylene guanidine phosphate (PHMG-P). To characterize asthmatic features, the following parameters were analyzed: (i) differential cell counts and cytokine expression in the bronchoalveolar lavage fluid (BALF); (ii) presence of mucus-producing goblet cells and pulmonary eosinophilic infiltration in the lungs; (iii) serum immunoglobulin levels; and (iv) airway hyperresponsiveness (AHR). RNA-Seq and bioinformatics tools were used to investigate whether PHMG-P altered asthma-related gene expression in lung tissues. The PHMG-P exposure groups showed higher peribronchial/perivascular inflammation, elevated goblet cell hyperplasia, and inhaled methacholine-induced airway resistance. Additionally, IL-13 and IL-17 in BALF were significantly increased in the PHMG-P exposure groups. However, there were no significant differences in total serum IgE and BALF IL-4 and IL-5 levels in the PHMG-P exposure groups compared to the control group. PHMG-P exposure modulated the expression of genes related to Th17 signaling pathways including the IL-17A, IL-23, and STAT3 signaling pathways, but not the Th2 signaling pathway. Altogether, our results suggest that repeated exposure to low does PHMG-P induces asthma-like symptoms and is thus a possible risk factor for developing asthma. The PHMG-P-induced asthmatic airway inflammation showed a different pattern from that found in typical allergic asthma and may be related to irritant-induced airway inflammation and hyperresponsiveness characterized by Th2-low, Th17-related, IgE-independent, and mixed granulocytic features.

Differential Sex-Dependent Regulation of the Alveolar Macrophage miRNome of SP-A2 and co-ex (SP-A1/SP-A2) and Sex Differences Attenuation after 18 h of Ozone Exposure

Background: Human SP-A1 and SP-A2, encoded by SFTPA1 and SFTPA2, and their genetic variants differentially impact alveolar macrophage (AM) functions and regulation, including the miRNome. We investigated whether miRNome differences previously observed between AM from SP-A2 and SP-A1/SP-A2 mice are due to continued qualitative differences or a delayed response of mice carrying a single gene. Methods: Human transgenic (hTG) mice, carrying SP-A2 or both SP-A genes, and SP-A-KO mice were exposed to filtered air (FA) or ozone (O₃)_. AM miRNA levels, target gene expression, and pathways determined 18 h after O₃ exposure. RESULTS: We found (a) differences in miRNome due to sex, SP-A genotype, and exposure; (b) miRNome of both sexes was largely downregulated by O₃, and co-ex had fewer changed (≥2-fold) miRNAs than either group; (c) the number and direction of the expression of genes with significant changes in males and females in co-ex are almost the opposite of those in SP-A2; (d) the same pathways were found in the studied groups; and (e) O₃ exposure attenuated sex differences with a higher number of genotype-dependent and genotype-independent miRNAs common in both sexes after O₃ exposure. Conclusion: Qualitative differences between SP-A2 and co-ex persist 18 h post-O₃, and O₃ attenuates sex differences.

Interleukin-33 activates regulatory T cells to suppress innate γδ T cell responses in the lung

Foxp3⁺ regulatory T (T_reg) cells expressing the interleukin (IL)-33 receptor ST2 mediate tissue repair in response to IL-33. Whether T_reg cells also respond to the alarmin IL-33 to regulate specific aspects of the immune response is not known. Here we describe an unexpected function of ST2⁺ T_reg cells in suppressing the innate immune response in the lung to environmental allergens without altering the adaptive immune response. Following allergen exposure, ST2⁺ T_reg cells were activated by IL-33 to suppress IL-17-producing γδ T cells. ST2 signaling in T_reg cells induced Ebi3, a component of the heterodimeric cytokine IL-35 that was required for T_reg cell-mediated suppression of γδ T cells. This response resulted in fewer eosinophil-attracting chemokines and reduced eosinophil recruitment into the lung, which was beneficial to the host in reducing allergen-induced inflammation. Thus, we define a fundamental role for ST2⁺ T_reg cells in the lung as a negative regulator of the early innate γδ T cell response to mucosal injury.

Interleukin-17A up-regulates thymic stromal lymphopoietin production by nasal fibroblasts from patients with allergic rhinitis

PURPOSE

Emerging evidence has shown that interleukin (IL)-17A is implicated in the pathogenesis of allergic rhinitis (AR). Thymic stromal lymphopoietin (TSLP) orchestrates the immune response toward a Th2 phenotype. Although increased TSLP is found in AR, the contribution of IL-17A in TSLP production by nasal fibroblasts is not well understood. We aimed to investigate the effect and mechanism of IL-17A on TSLP production by human nasal fibroblasts (HNFs) from AR patients.

METHODS

HNFs from AR patients were cultured and stimulated with IL-17A in the absence or presence of a Janus kinase (JAK) 2 or JAK1/3 inhibitor. Western blotting was used to assay phosphorylated signal transducer and activator of transcription 3 (p-STAT3) and nuclear factor-kappa B (NF-κB) p65 in HNFs. The TSLP expression in the cells and culture supernatants was evaluated by real-time polymerase chain reaction and enzyme-linked immunoassay.

RESULTS

Stimulation with IL-17A induced STAT3 phosphorylation, which was inhibited by the pretreatment with JAK2 inhibitor AZD1480 or JAK1/3 inhibitor tofacitinib. IL-17A promoted the nuclear translocation of NF-κBp65 protein, leading to increased TSLP production, while the pre-incubation with AZD1480 prior to IL-17A attenuated these effects. However, the pre-incubation with tofacitinib before IL-17A stimulation had no impact on the expression of NF-κBp65 and TSLP.

CONCLUSIONS

IL-17A up-regulated TSLP production by HNFs through JAK2/NF-κB pathway. Although IL-17A induced STAT3 activation through JAK1/2/3, IL-17A-mediated TSLP expression was not dependent on STAT3 signaling. These observations would provide mechanistic insight into therapeutic strategies to improve the immune and inflammation associated with Th17A in the management of AR.

Muscarinic Toxin 7 Signals Via Ca2+/Calmodulin-Dependent Protein Kinase Kinase β to Augment Mitochondrial Function and Prevent Neurodegeneration

Mitochondrial dysfunction is implicated in a variety of neurodegenerative diseases of the nervous system. Peroxisome proliferator–activated receptor-γ coactivator-1α (PGC-1α) is a regulator of mitochondrial function in multiple cell types. In sensory neurons, AMP-activated protein kinase (AMPK) augments PGC-1α activity and this pathway is depressed in diabetes leading to mitochondrial dysfunction and neurodegeneration. Antimuscarinic drugs targeting the muscarinic acetylcholine type 1 receptor (M₁R) prevent/reverse neurodegeneration by inducing nerve regeneration in rodent models of diabetes and chemotherapy-induced peripheral neuropathy (CIPN). Ca²⁺/calmodulin-dependent protein kinase kinase β (CaMKKβ) is an upstream regulator of AMPK activity. We hypothesized that antimuscarinic drugs modulate CaMKKβ to enhance activity of AMPK, and PGC-1α, increase mitochondrial function and thus protect from neurodegeneration. We used the specific M₁R antagonist muscarinic toxin 7 (MT7) to manipulate muscarinic signaling in the dorsal root ganglia (DRG) neurons of normal rats or rats with streptozotocin-induced diabetes. DRG neurons treated with MT7 (100 nM) or a selective muscarinic antagonist, pirenzepine (1 μM), for 24 h showed increased neurite outgrowth that was blocked by the CaMKK inhibitor STO-609 (1 μM) or short hairpin RNA to CaMKKβ. MT7 enhanced AMPK phosphorylation which was blocked by STO-609 (1 μM). PGC-1α reporter activity was augmented up to 2-fold (p < 0.05) by MT7 and blocked by STO-609. Mitochondrial maximal respiration and spare respiratory capacity were elevated after 3 h of exposure to MT7 (p < 0.05). Diabetes and CIPN induced a significant (p < 0.05) decrease in corneal nerve density which was corrected by topical delivery of MT7. We reveal a novel M₁R-modulated, CaMKKβ-dependent pathway in neurons that represents a therapeutic target to enhance nerve repair in two of the most common forms of peripheral neuropathy.

Proinflammatory Pathways in the Pathogenesis of Asthma

There are multiple proinflammatory pathways in the pathogenesis of asthma. These include both innate and adaptive inflammation, in addition to inflammatory and physiologic responses mediated by eicosanoids. An important component of the innate allergic immune response is ILC2 activated by interleukin (IL)-33, thymic stromal lymphopoietin, and IL-25 to produce IL-5 and IL-13. In terms of the adaptive T-lymphocyte immunity, CD4+ Th2 and IL-17-producing cells are critical in the inflammatory responses in asthma. Last, eicosanoids involved in asthma pathogenesis include prostaglandin D₂ and the cysteinyl leukotrienes that promote smooth muscle constriction and inflammation that propagate allergic responses.

IL-17A secreted from lymphatic endothelial cells promotes tumorigenesis by upregulation of PD-L1 in hepatoma stem cells

BACKGROUND & AIMS

The microenvironment regulates hepatoma stem cell behavior. However, the contributions of lymphatic endothelial cells to the hepatoma stem cell niche remain largely unknown; we aimed to analyze this contribution and elucidate the mechanisms behind it.

METHODS

Associations between lymphatic endothelial cells and CD133⁺ hepatoma stem cells were analyzed by immunofluorescence and adhesion assays; with the effects of their association on IL-17A expression examined using western blot, quantitative reverse transcription PCR and luciferase reporter assay. The effects of IL-17A on the self-renewal and tumorigenesis of hepatoma stem cells were examined using sphere and tumor formation assays. The role of IL-17A in immune escape by hepatoma stem cells was examined using flow cytometry. The expression of IL-17A in hepatoma tissues was examined using immunohistochemistry.

RESULTS

CD133⁺ hepatoma stem cells preferentially interact with lymphatic endothelial cells. The interaction between the mannose receptor and high-mannose type N-glycans mediates the interaction between CD133⁺ hepatoma stem cells and lymphatic endothelial cells. This interaction activates cytokine IL-17A expression in lymphatic endothelial cells. IL-17A promotes the self-renewal of hepatoma stem cells. It also promotes their immune escape, partly through upregulation of PD-L1.

CONCLUSION

Interactions between lymphatic endothelial cells and hepatoma stem cells promote the self-renewal and immune escape of hepatoma stem cells, by activating IL-17A signaling. Thus, inhibiting IL-17A signaling may be a promising approach for hepatoma treatment.

LAY SUMMARY

The microenvironment is crucial for the self-renewal and development of hepatoma stem cells, which lead to the development of liver cancer. Lymphatic endothelial cells are an important component of this niche microenvironment, helping hepatoma stem cells to self-renew and escape immune attack, by upregulating IL-17A signaling. Thus, targeting IL-17A signaling is a potential strategy for the treatment of hepatoma.

A Combined Set of Four Serum Inflammatory Biomarkers Reliably Predicts Endoscopic Disease Activity in Inflammatory Bowel Disease

Introduction: Blood C-reactive protein (CRP) and fecal calprotectin levels are routinely measured as surrogate markers of disease activity in Inflammatory Bowel Disease (IBD), but often do not correlate well with the degree of mucosal inflammation in the intestine as established by endoscopy. Therefore, novel predictive biomarkers are urgently needed that better reflect mucosal disease activity in IBD. The aim of this study was to identify a combination of serum inflammatory biomarkers predictive for endoscopic disease activity. Methods: Serum concentrations of 10 inflammatory biomarkers were analyzed in 118 IBD patients [64 Crohn's disease (CD), 54 ulcerative colitis (UC)] and 20 healthy controls. In a subset of 71 IBD patients, endoscopic disease activity was established. Non-parametric ROC estimation with bootstrap inference was used to establish the best combination of inflammatory biomarkers predicting endoscopic disease activity. Results: Six (6) inflammatory biomarkers (serum amyloid A (SAA), Eotaxin-1, IL-6, IL-8, IL-17A, and TNF-α) showed better prediction of IBD disease activity than routine measures (CRP, fecal calprotectin and HBI/SCCAI scores). The best combination of predictive inflammatory biomarkers consisted of serum SAA, IL-6, IL-8, and Eotaxin-1, showing an optimism-adjusted area under the ROC (AuROC) curve of 0.84 (95% CI: 0.73-0.94, P < 0.0001), which predicted significantly better (P = 0.002) than serum CRP levels with an AuROC of 0.57 (95% CI: 0.43-0.72, P = 0.32). Conclusion: The combination of SAA, IL-6, IL-8, and Eotaxin-1 reliably predicts endoscopic disease activity in IBD and might be valuable for monitoring disease activity and management of the disease.

Crosstalk Between Signaling Pathways Involved in the Regulation of Airway Smooth Muscle Cell Hyperplasia

Increased ASM mass, primarily due to ASM hyperplasia, has been recognized as a hallmark of airway remodeling in asthma. Increased ASM mass is the major contributor to the airway narrowing, thus worsening the bronchoconstriction in response to stimuli. Inflammatory mediators and growth factors released during inflammation induce increased ASM mass surrounding airway wall via increased ASM proliferation, diminished ASM apoptosis and increased ASM migration. Several major pathways, such as MAPKs, PI3K/AKT, JAK2/STAT3 and Rho kinase, have been reported to regulate these cellular activities in ASM and were reported to be interrelated at certain points. This article aims to provide an overview of the signaling pathways/molecules involved in ASM hyperplasia as well as the mapping of the interplay/crosstalk between these major pathways in mediating ASM hyperplasia. A more comprehensive understanding of the complexity of cellular signaling in ASM cells will enable more specific and safer drug development in the control of asthma.

Interleukin-Mediated Pendrin Transcriptional Regulation in Airway and Esophageal Epithelia

Pendrin (SLC26A4), a Cl⁻/anion exchanger, is expressed at high levels in kidney, thyroid, and inner ear epithelia, where it has an essential role in bicarbonate secretion/chloride reabsorption, iodide accumulation, and endolymph ion balance, respectively. Pendrin is expressed at lower levels in other tissues, such as airways and esophageal epithelia, where it is transcriptionally regulated by the inflammatory cytokines interleukin (IL)-4 and IL-13 through a signal transducer and activator of transcription 6 (STAT6)-mediated pathway. In the airway epithelium, increased pendrin expression during inflammatory diseases leads to imbalances in airway surface liquid thickness and mucin release, while, in the esophageal epithelium, dysregulated pendrin expression is supposed to impact the intracellular pH regulation system. In this review, we discuss some of the recent findings on interleukin-mediated transcriptional regulation of pendrin and how this dysregulation impacts airway and esophagus epithelial homeostasis during inflammatory diseases.

Type 3 ILCs in Lung Disease

The lungs represent a complex immune setting, balancing external environmental signals with a poised immune response that must protect from infection, mediate tissue repair, and maintain lung function. Innate lymphoid cells (ILCs) play a central role in tissue repair and homeostasis, and mediate protective immunity in a variety of mucosal tissues, including the lung. All three ILC subsets are present in the airways of both mice and humans; and ILC2s shown to have pivotal roles in asthma, airway hyper-responsiveness, and parasitic worm infection. The involvement of ILC3s in respiratory diseases is less well-defined, but they are known to be critical in homeostasis, infection and inflammation at other mucosal barriers, such as the gut. Moreover, they are important players in the IL17/IL22 axis, which is key to lung health. In this review, we discuss the emerging role of ILC3s in the context of infectious and inflammatory lung diseases, with a focus on data from human subjects.

Mechanisms and functions of IL-17 signaling in renal autoimmune diseases

Immune-mediated glomerular diseases (glomerulonephritis) encompass a heterogeneous collection of diseases that cause inflammation within the glomerulus and other renal compartments with significant morbidity and mortality. In general, CD4⁺ T cells orchestrate the immune response and play a unique role in autoimmune and chronic inflammatory diseases. In particular, the characterization of a distinct, IL-17 cytokines producing CD4⁺ T cell subset named T_H17 cells has significantly advanced the current understanding of the pathogenic mechanisms of organ-specific immunity. Our group and others have shown that the recruitment of T_H17 cells to the inflamed kidney drives renal tissue injury in experimental and possibly human crescentic glomerulonephritis (GN), but much remains to be understood about the biological functions, regulation, and signaling pathways of the T_H17/IL-17 axis leading to organ damage. Here we review our current knowledge about the mechanisms and functions of IL-17 signaling in renal autoimmune diseases, with a special focus on experimental and human crescentic GN.

Th17 response in patients with cervical cancer

Persistent infection by high-risk human papillomavirus (HR-HPV) is the main risk factor for uterine cervical cancer (UCC). However, viral infection alone is not sufficient for the development and progression of premalignant cervical lesions for cancer. In previous years it has been suggested that the adaptive immune response triggered by the differentiation of naïve helper T cells in Th17 cells may serve an important role in disease development. It has been hypothesized that Th17 cells may be involved in the promotion of UCC, as high levels of interleukin 17 (IL17) expression have been detected in the mucosa of the uterine cervix of patients affected by the disease. However, the role of Th17 cells in the tumor development and progression remains unclear. It is believed that the immune response of the Th17 type during persistent infection of the genital tract with HR-HPV triggers chronic inflammation with a long duration with the production of IL17 and other pro-inflammatory cytokines, creating a favorable environment for tumor development. These cytokines are produced by immune system cells in addition to tumor cells and appear to function by modulating the host immune system, resulting in an immunosuppressive response as opposed to inducing an effective protective immune response, thus contributing to the growth and progression of the tumor. In the present review, the latest advances are presented about the function of Th17 cells and the cytokines produced by them in the development and progression of UCC.

MicroRNA-590-5p represses proliferation of human fetal airway smooth muscle cells by targeting signal transducer and activator of transcription 3

INTRODUCTION

Pediatric asthma has remained a health threat to children in recent years. The abnormal proliferation of airway smooth muscle (ASM) cells contributes to airway remodeling during development of asthma. MicroRNAs (miRNAs) are critical regulators of ASM cell proliferation during airway remodeling. miR-590-5p has been reported to regulate cell proliferation in various cell types. However, it remains unclear whether miR-590-5p regulates ASM cell proliferation. In this study, we aimed to investigate the potential role of miR-590-5p in regulating fetal ASM cell proliferation in vitro stimulated by platelet-derived growth factor (PDGF).

MATERIAL AND METHODS

miRNA, mRNA, and protein expression was detected by real-time quantitative polymerase chain reaction and western blot. Cell proliferation was detected by CCK-8 and BrdU assays. The target of miR-590-5p was confirmed by dual-luciferase reporter assay.

RESULTS

MiR-590-5p expression was significantly down-regulated in fetal ASM cells stimulated with PDGF (p < 0.05). Overexpression of miR-590-5p inhibited cell proliferation (p < 0.05), whereas the suppression of miR-590-5p promoted cell proliferation of fetal ASM cells stimulated with PDGF (p < 0.05). Signal transducer and activator of transcription 3 (STAT3) was identified as a target gene of miR-590-5p. In addition, miR-590-5p negatively regulated STAT3 expression (p < 0.05). Moreover, miR-590-5p also modulated downstream genes of STAT3 including cyclin D3 and p27 (p < 0.05). The restoration of STAT3 significantly reversed the inhibitory effect of miR-590-5p on fetal ASM cell proliferation.

CONCLUSIONS

MiR-590-5p inhibits proliferation of fetal ASM cells by down-regulating STAT3, thereby suggesting a novel therapeutic target for the treatment of pediatric asthma.

A proteomics analysis reveals that A2M might be regulated by STAT3 in persistent allergic rhinitis

BACKGROUND

Proteomics tools can be used to identify the differentially expressed proteins related to allergic rhinitis (AR). However, the large numbers of proteins related to AR have not yet been explored using an advanced quantitative proteomics approach, known as isobaric tags for relative and absolute quantitation (iTRAQ).

OBJECTIVES

To identify differentially expressed proteins in persistent AR patients and to explore the regulatory signalling pathways involving the identified proteins.

METHODS

Forty-five persistent AR patients and 20 healthy controls were recruited for this study. iTRAQ was used to identify the proteins that were differentially expressed between these two groups, and a bioinformatics analysis was then conducted to identify the signalling pathways associated with the identified proteins. Immunofluorescence labelling was performed to detect alpha-2-macroglobulin (A2M), STAT3, p-STAT3 and IL17 in the nasal mucosa.

RESULTS

A total of 133 differentially expressed proteins were identified. We then determined the top 10 regulatory pathways associated with these proteins and found that the blood coagulation pathway had the most significant association. A2M, a protein involved in the blood coagulation pathway, was found to be differentially expressed in the serum of AR patients. The bioinformatics analysis indicated that STAT3 is an upstream transcription factor that might regulate A2M expression. An immunofluorescence study further confirmed that STAT3 and A2M are co-localized in nasal mucosa cells. Additionally, A2M, STAT3, p-STAT3, and IL17 are elevated in AR patients. The expressional level of A2M is positively related to IL17 and the symptom of the congestion in AR subjects.

CONCLUSIONS

The blood coagulation pathway may be a key regulatory network pathway contributing to the allergic inflammatory response in AR patients. A2M, which is regulated by STAT3, may be an important protein in the pathogenesis of allergic rhinitis in AR patients.

The FGF21-CCL11 Axis Mediates Beiging of White Adipose Tissues by Coupling Sympathetic Nervous System to Type 2 Immunity

Type 2 cytokines are important signals triggering biogenesis of thermogenic beige adipocytes in white adipose tissue (WAT) during cold acclimation. However, how cold activates type 2 immunity in WAT remains obscure. Here we show that cold-induced type 2 immune responses and beiging in subcutaneous WAT (scWAT) are abrogated in mice with adipose-selective ablation of FGF21 or its co-receptor β-Klotho, whereas such impairments are reversed by replenishment with chemokine CCL11. Mechanistically, FGF21 acts on adipocytes in an autocrine manner to promote the expression and secretion of CCL11 via activation of ERK1/2, which drives recruitment of eosinophils into scWAT, leading to increases in accumulation of M2 macrophages, and proliferation and commitment of adipocyte precursors into beige adipocytes. These FGF21-elicited type 2 immune responses and beiging are blocked by CCL11 neutralization. Thus, the adipose-derived FGF21-CCL11 axis triggers cold-induced beiging and thermogenesis by coupling sympathetic nervous system to activation of type 2 immunity in scWAT.

Interleukin-26 Production in Human Primary Bronchial Epithelial Cells in Response to Viral Stimulation: Modulation by Th17 cytokines

Interleukin (IL)-26 is abundant in human airways and this cytokine is involved in the local immune response to a bacterial stimulus in vivo. Specifically, local exposure to the toll-like receptor (TLR) 4 agonist endotoxin does increase IL-26 in human airways and this cytokine potentiates chemotactic responses in human neutrophils. In addition to T-helper (Th) 17 cells, alveolar macrophages can produce IL-26, but it remains unknown whether this cytokine can also be produced in the airway mucosa per se in response to a viral stimulus. Here, we evaluated whether this is the case using primary bronchial epithelial cells from the airway epithelium in vitro, and exploring the signaling mechanisms involved, including the modulatory effects of additional Th17 cytokines. Finally, we assessed IL-26 and its archetype signaling responses in healthy human airways in vivo. We found increased transcription and release of IL-26 protein after stimulation with the viral-related double stranded (ds) RNA polyinosinic-polycytidylic acid (poly-IC) and showed that this IL-26 release involved mitogen-activated protein (MAP) kinases and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). The release of IL-26 in response to a viral stimulus was modulated by additional Th17 cytokines. Moreover, there was transcription of IL26 mRNA and expression of the protein in epithelial cells of bronchial brush and tissue biopsies respectively after harvest in vivo. In addition, the extracellular IL-26 protein concentrations in bronchoalveolar lavage (BAL) samples did correlate with increased epithelial cell transcription of an archetype intracellular signaling molecule downstream of the IL-26-receptor complex, STAT1, in the bronchial brush biopsies. Thus, our study suggests that viral stimulation causes the production of IL-26 in lining epithelial cells of human airway structural cells that constitute a critical immune barrier and that this production is modulated by Th17 cytokines.

Emerging role of Interleukins IL-23/IL-17 axis and biochemical markers in the pathogenesis of Type 2 Diabetes: Association with age and gender in human subjects

Chronic hyperglycaemia in type 2 diabetes (T2D) is associated with increased oxidative stress and inflammation. Keeping the above fact into consideration we analyse the effect of age and gender on oxidative stress biomarkers and pro-inflammatory cytokines in T2D patients. The study included 148 diabetic and 110 healthy subjects, grouped on the basis of age and gender. Plasma malondialdehyde, protein carbonyl content and nitric oxide levels were elevated significantly in diabetic patients, with significant decrease in Ferric reducing ability of plasma, vitamin C, reduced glutathione, erythrocyte thiol groups and erythrocyte antioxidant enzyme activity and these changes were even more pronounced as age progressed. Serum IL-1β, IL-6, IL-17A, IL-22 levels and TNF-α mRNA expression was significantly upregulated in all the age groups whereas IL-23 mRNA was upregulated only in the higher age group. Female diabetic patients experienced higher oxidative stress and greater serum IL-6 levels and TNF-α mRNA expression as compared to their male counterparts. This study suggested that diabetes onset is accompanied with increased oxidative stress and elevated levels of inflammatory mediators. The effect was more prominent in aged patients. Female patients experienced greater oxidative stress as compared to males of those age groups with slightly higher levels of inflammatory cytokines.

The Role of IL-17 and Related Cytokines in Inflammatory Autoimmune Diseases

Interleukin-17 (IL-17) induces the production of granulocyte colony-stimulating factor (G-CSF) and chemokines such as CXCL1 and CXCL2 and is a cytokine that acts as an inflammation mediator. During infection, IL-17 is needed to eliminate extracellular bacteria and fungi, by inducing antimicrobial peptides such as defensin. This cytokine also plays an important role in chronic inflammation that occurs during the pathogenesis of autoimmune diseases and allergies such as human rheumatoid arthritis (RA) for which a mouse model of collagen-induced arthritis (CIA) is available. In autoimmune diseases such as RA and multiple sclerosis (MS), IL-17 is produced by helper T (Th) cells that are stimulated by IL-1β and IL-6 derived from phagocytes such as macrophages and from tissue cells. IL-17 contributes to various lesions that are produced by Th17 cells, one subset of helper T cells, and by γδ T cells and innate lymphoid cells. It strongly contributes to autoimmune diseases that are accompanied by chronic inflammation. Thus, a functional understanding of Th17 cells is extremely important. In this review, we highlight the roles of cytokines that promote the development and maintenance of pathogenic Th17 cells in autoimmune diseases.

Combination of Interleukin-27 and MicroRNA for Enhancing Expression of Anti-Inflammatory and Proosteogenic Genes

Remission of inflammation has become an achievable goal in inflammatory or rheumatoid arthritis (RA); however, bone erosion continues in many patients. Interleukin- (IL-) 27 regulates immune and bone cell balance and also suppresses activities of several inflammatory cell types in RA. Despite its promise, challenges to clinical translation of IL-27 have been its partial effects in vivo. Due to their ability to modulate plasticity of bone and immune cell differentiation, we examined the potential for several microRNA (miR) candidates in enhancing the effects of IL-27. Using differentiation, luciferase, and real time quantitative PCR assays, we show that IL-27 promotes osteoblast differentiation, reduces expression of osteoblast inhibitory genes, and reduces osteoclast differentiation, and results suggest a potential coordination with TGFβ/BMP/SMAD and JAK/STAT pathways. We selected miRNA regulators of these and related pathways to examine whether the effects of IL-27 could be augmented for therapeutic applications. miR-29b and miR-21 augmented IL-27 proosteogenic while downregulating osteoclastogenic signals and also worked to reduce inflammatory signaling in activated macrophages, while miR-21 and miR-20b worked with IL-27 to reduce inflammatory gene expression in fibroblasts and T cells. It appears that several miRNAs can be utilized to enhance IL-27's impact on modulating osteogenesis and reducing proinflammatory signaling.

Innate Immune Cytokines, Fibroblast Phenotypes, and Regulation of Extracellular Matrix in Lung

Chronic inflammation can be caused by adaptive immune responses in autoimmune and allergic conditions, driven by a T lymphocyte subset balance (TH1, TH2, Th17, Th22, and/or Treg) and skewed cellular profiles in an antigen-specific manner. However, several chronic inflammatory diseases have no clearly defined adaptive immune mechanisms that drive chronicity. These conditions include those that affect the lung such as nonatopic asthma or idiopathic pulmonary fibrosis comprising significant health problems. The remodeling of extracellular matrix (ECM) causes organ dysfunction, and it is largely generated by fibroblasts as the major cell controlling net ECM. As such, these are potential targets of treatment approaches in the context of ECM pathology. Fibroblast phenotypes contribute to ECM and inflammatory cell accumulation, and they are integrated into chronic disease mechanisms including cancer. Evidence suggests that innate cytokine responses may be critical in nonallergic/nonautoimmune disease, and they enable environmental agent exposure mechanisms that are independent of adaptive immunity. Innate immune cytokines derived from macrophage subsets (M1/M2) and innate lymphoid cell (ILC) subsets can directly regulate fibroblast function. We also suggest that STAT3-activating gp130 cytokines can sensitize fibroblasts to the innate cytokine milieu to drive phenotypes and exacerbate existing adaptive responses. Here, we review evidence exploring innate cytokine regulation of fibroblast behavior.

IL-35 Suppresses Lipopolysaccharide-Induced Airway Eosinophilia in EBI3-Deficient Mice

EBI3 functions as the subunit of immune-regulatory cytokines, such as IL-27 and IL-35, by pairing with p28 and p35, respectively. We treated wild-type and EBI3-deficient mice with intratracheal administration of LPS and obtained bronchoalveolar lavage fluid (BALF) 24 h later. Although neutrophils were the predominant cells in BALF from both groups of mice, eosinophils were highly enriched and there was increased production of eosinophil-attracting chemokines CCL11 and CCL24 in BALF of EBI3-deficient mice. The bronchial epithelial cells and alveolar macrophages were the major producers of CCL11 and CCL24. Because no such increases in eosinophils were seen in BALF of p28/IL-27-deficient mice or WSX-1/IL-27Rα subunit-deficient mice upon intratracheal stimulation with LPS, we considered that the lack of IL-35 was responsible for the enhanced airway eosinophilia in EBI3-deficient mice. In vitro, IL-35 potently suppressed production of CCL11 and CCL24 by human lung epithelial cell lines treated with TNF-α and IL-1β. IL-35 also suppressed phosphorylation of STAT1 and STAT3 and induced suppressor of cytokine signaling 3. In vivo, rIL-35 dramatically reduced LPS-induced airway eosinophilia in EBI3-deficient mice, with concomitant reduction of CCL11 and CCL24, whereas neutralization of IL-35 significantly increased airway eosinophils in LPS-treated wild-type mice. Collectively, our results suggest that IL-35 negatively regulates airway eosinophilia, at least in part by reducing the production of CCL11 and CCL24.

IgE regulates airway smooth muscle phenotype: Future perspectives in allergic asthma

The purpose of this commentary is to highlight the emerging role of IgE on airway smooth muscle (ASM) cells function through activation of the high-affinity Fc receptor for IgE. We discuss the potential implications of IgE-mediated ASM sensitization in airway inflammation and remodeling, the hallmark features of allergic asthma.

An asthma-associated IL4R variant exacerbates airway inflammation by promoting conversion of regulatory T cells to TH17-like cells

Mechanisms by which regulatory T (Treg) cells fail to control inflammation in asthma remain poorly understood. We show that a severe asthma-associated polymorphism in the gene encoding the interleukin (IL)-4 receptor alpha chain (Il4ra(R576)) promotes conversion of induced Treg (iTreg) cells toward a T helper 17 (TH17) cell fate. This skewing is mediated by the recruitment by IL-4Rα(R576) of the growth-factor-receptor-bound protein 2 (GRB2) adaptor protein, which drives IL-17 expression by activating a pathway that involves extracellular-signal-regulated kinase, IL-6 and the transcription factor STAT3. Treg cell-specific deletion of genes that regulate TH17 cell differentiation, including Il6ra and RAR-related orphan receptor gamma (Rorc), but not of Il4 or Il13, prevented exacerbated airway inflammation in mice expressing Il4ra(R576) (hereafter referred to as Il4ra(R576) mice). Furthermore, treatment of Il4ra(R576) mice with a neutralizing IL-6-specific antibody prevented iTreg cell reprogramming into TH17-like cells and protected against severe airway inflammation. These findings identify a previously unknown mechanism for the development of mixed TH2-TH17 cell inflammation in genetically prone individuals and point to interventions that stabilize iTreg cells as potentially effective therapeutic strategies.

Regulation of IL-17A responses in human airway smooth muscle cells by Oncostatin M

Background

Regulation of human airway smooth muscle cells (HASMC) by cytokines contributes to chemotactic factor levels and thus to inflammatory cell accumulation in lung diseases. Cytokines such as the gp130 family member Oncostatin M (OSM) can act synergistically with Th2 cytokines (IL-4 and IL-13) to modulate lung cells, however whether IL-17A responses by HASMC can be altered is not known.

Objective

To determine the effects of recombinant OSM, or other gp130 cytokines (LIF, IL-31, and IL-6) in regulating HASMC responses to IL-17A, assessing MCP-1/CCL2 and IL-6 expression and cell signaling pathways.

Methods

Cell responses of primary HASMC cultures were measured by the assessment of protein levels in supernatants (ELISA) and mRNA levels (qRT-PCR) in cell extracts. Activation of STAT, MAPK (p38) and Akt pathways were measured by immunoblot. Pharmacological agents were used to assess the effects of inhibition of these pathways.

Results

OSM but not LIF, IL-31 or IL-6 could induce detectable responses in HASMC, elevating MCP-1/CCL2, IL-6 levels and activation of STAT-1, 3, 5, p38 and Akt cell signaling pathways. OSM induced synergistic action with IL-17A enhancing MCP-1/CCL-2 and IL-6 mRNA and protein expression, but not eotaxin-1 expression, while OSM in combination with IL-4 or IL-13 synergistically induced eotaxin-1 and MCP-1/CCL2. OSM elevated steady state mRNA levels of IL-4Rα, OSMRβ and gp130, but not IL-17RA or IL-17RC. Pharmacologic inhibition of STAT3 activation using Stattic down-regulated OSM, OSM/IL-4 or OSM/IL-13, and OSM/IL-17A synergistic responses of MCP-1/CCL-2 induction, whereas, inhibitors of Akt and p38 MAPK resulted in less reduction in MCP-1/CCL2 levels. IL-6 expression was more sensitive to inhibition of p38 (using SB203580) and was affected by Stattic in response to IL-17A/OSM stimulation.

Conclusions

Oncostatin M can regulate HASMC responses alone or in synergy with IL-17A. OSM/IL-17A combinations enhance MCP-1/CCL2 and IL-6 but not eotaxin-1. Thus, OSM through STAT3 activation of HASMC may participate in inflammatory cell recruitment in inflammatory airway disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0164-4) contains supplementary material, which is available to authorized users.

Th17 differentiation and their pro-inflammation function

CD4(+) T helper cells are classical but constantly reinterpreted T-cell subset, playing critical roles in a diverse range of inflammatory responses or diseases. Depending on the cytokines they release and the immune responses they mediate, CD4(+) T cells are classically divided into two major cell populations: Th1 and Th2 cells. However, recent studies challenged this Th1/Th2 paradigm by discovering several T-helper cell subsets with specific differentiation program and functions, including Th17 cells, Treg cells, and Tfh cells. In this chapter, we summarize the current understanding and recent progresses on the Th17 lineage differentiation and its effector impacts on variety of inflammatory responses or disease pathogenesis.

IL-17RA in intestinal inflammation: structure, signaling, function, and clinical application

: Interleukin-17 receptor A (IL-17RA) is responsible for both IL-17A and IL-25 (IL-17E) signaling pathways. Current evidences suggest distinct but interactive responses between IL-17A and IL-25 signaling, both of which are critical for intestinal immune homeostasis. IL-17RA is assumed to regulate this counterbalance and therefore becomes a crucial molecule in mucosal immunology. In this review, we will describe the structure of IL-17RA, compare IL-17A and IL-25 signaling pathways, and emphasize on the function of IL-17RA in intestinal inflammation and discuss current evidences of accomplished and ongoing clinical trials with monoclonal antibodies targeting Th17 pathway, especially IL-17RA.

Dysregulation of the IL-23/IL-17 axis and myeloid factors in secondary progressive MS

OBJECTIVE

In the current exploratory study, we longitudinally measured immune parameters in the blood of individuals with relapsing-remitting multiple sclerosis (RRMS) and secondary progressive multiple sclerosis (SPMS), and investigated their relationship to disease duration and clinical and radiologic measures of CNS injury.

METHODS

Peripheral blood mononuclear cells (PBMCs) and plasma were obtained from subjects with RRMS, SPMS, and from healthy controls on a monthly basis over the course of 1 year. MRI and Expanded Disability Status Scale evaluations were performed serially. PBMCs were analyzed by enzyme-linked immunosorbent spot assay to enumerate myelin basic protein-specific interleukin (IL)-17- and interferon (IFN)-γ-producing cells. Plasma concentrations of proinflammatory factors were measured using customized Luminex panels.

RESULTS

Frequencies of myelin basic protein-specific IL-17- and IFN-γ-producing PBMCs were higher in individuals with RRMS and SPMS compared to healthy controls. Patients with SPMS expressed elevated levels of IL-17-inducible chemokines that activate and recruit myeloid cells. In the cohort of patients with SPMS without inflammatory activity, upregulation of myeloid-related factors correlated directly with MRI T2 lesion burden and inversely with brain parenchymal tissue volume.

CONCLUSIONS

The results of this exploratory study raise the possibility that Th17 responses and IL-17-inducible myeloid factors are elevated during SPMS compared with RRMS, and correlate with lesion burden. Our data endorse further investigation of Th17- and myeloid-related factors as candidate therapeutic targets in SPMS.

Wheezing and itching: The requirement for STAT proteins in allergic inflammation

The development of allergic inflammation requires the orchestration of gene expression from the inflamed tissue and from the infiltrating immune cells. Since many of the cytokines that promote allergic inflammation signal through hematopoietin family receptors, the Signal Transducer and Activator of Transcription (STAT) family have obligate roles in pro-allergic cytokine-induced gene regulation in multiple cell types. In this review, we summarize work defining the contribution of each of the STAT family members to the development of allergic inflammation, using data from mouse models of allergic inflammation, studies on patient samples and correlations with single nucleotide polymorphisms in STAT genes.

Thymic stromal lymphopoietin induces migration in human airway smooth muscle cells

Airway remodeling due to increased airway smooth muscle (ASM) mass, likely due to enhanced migration and proliferation, has been shown to be highly associated with decline in lung function in asthma. Thymic stromal lymphopoietin (TSLP) is an IL-7-like, pro-allergic cytokine that has been shown to be necessary and sufficient for the development of allergic asthma. Human ASM (HASM) cells express TSLP receptor (TSLPR), the activation of which leads to enhanced release of proinflammatory mediators such as IL-6, CCL11/eotaxin-1, and CXCL8/IL-8. We show here that TSLP induces HASM cell migration through STAT3 activation since lentiviral-shRNA inhibition of STAT3 abrogated the TSLP-induced cell migration. Moreover, TSLP induced multiple cytoskeleton changes in HASM cells such as actin polymerization, cell polarization, and activation of small GTPase Rac1. Collectively, our data suggest a pro-migratory function of TSLP in ASM remodeling and provides better rationale for targeting TSLP/TSLPR pathway for therapeutic approaches in allergic asthma.

Th17-associated cytokines as a therapeutic target for steroid-insensitive asthma

Steroid-insensitive asthma is an infrequent but problematic airway disease that presents with persistent symptoms, airflow limitation, or recurrent exacerbations even when treated with steroid-based therapies. Because of unsatisfactory results obtained from currently available therapies for steroid-insensitive asthma, a better understanding of its pathogenesis and the development of new targeted molecular therapies are warranted. Recent studies indicated that levels of interleukin (IL)-17 are increased and both eosinophils and neutrophils infiltrate the airways of severe asthmatics. IL-17 is a proinflammatory cytokine mainly secreted from helper T (Th) 17 cells and is important for the induction of neutrophil recruitment and migration at sites of inflammation. This review focuses on the pathogenetic role of Th17 cells and their associated cytokines in steroid-insensitive asthma and discusses the prospects of novel therapeutic options targeting the Th17 signaling pathway.

Diabetes impairs an interleukin-1β-dependent pathway that enhances neurite outgrowth through JAK/STAT3 modulation of mitochondrial bioenergetics in adult sensory neurons

Background

A luminex-based screen of cytokine expression in dorsal root ganglia (DRG) and nerve of type 1 diabetic rodents revealed interleukin-1 (IL-1α) and IL-1β to be significantly depressed. We, therefore, tested the hypothesis that impaired IL-1α and IL-1β expression in DRG may contribute to aberrant axon regeneration and plasticity seen in diabetic sensory neuropathy. In addition, we determined if these cytokines could optimize mitochondrial bioenergetics since mitochondrial dysfunction is a key etiological factor in diabetic neuropathy.

Results

Cytokines IL-1α and IL-1β were reduced 2-fold (p<0.05) in DRG and/or nerve of 2 and 5 month streptozotocin (STZ)-diabetic rats. IL-2 and IL-10 were unchanged. IL-1α and IL-1β induced similar 2 to 3-fold increases in neurite outgrowth in cultures derived from control or diabetic rats (p<0.05). STAT3 phosphorylation on Tyr705 or Ser727 was depressed in DRG from STZ-diabetic mice and treatment of cultures derived from STZ-diabetic rats with IL-1β for 30 min raised phosphorylation of STAT3 on Tyr705 and Ser727 by 1.5 to 2-fold (p<0.05). shRNA-based or AG490 inhibition of STAT3 activity or shRNA blockade of endogenous IL-1β expression completely blocked neurite outgrowth. Cultured neurons derived from STZ-diabetic mice were treated for 24 hr with IL-1β and maximal oxygen consumption rate and spare respiratory capacity, both key measures of bioenergetic fidelity that were depressed in diabetic compared with control neurons, were enhanced 2-fold. This effect was blocked by AG490.

Conclusions

Endogenous synthesis of IL-1β is diminished in nerve tissue in type 1 diabetes and we propose this defect triggers reduced STAT3 signaling and mitochondrial function leading to sup-optimal axonal regeneration and plasticity.

IgE induces proliferation in human airway smooth muscle cells: role of MAPK and STAT3 pathways

Airway remodeling is not specifically targeted by current asthma medications, partly owing to the lack of understanding of remodeling mechanisms, altogether posing great challenges in asthma treatment. Increased airway smooth muscle (ASM) mass due to hyperplasia/hypertrophy contributes significantly to overall airway remodeling and correlates with decline in lung function. Recent evidence suggests that IgE sensitization can enhance the survival and mediator release in inflammatory cells. Human ASM (HASM) cells express both low affinity (FcεRII/CD23) and high affinity IgE Fc receptors (FcεRI), and IgE can modulate the contractile and synthetic function of HASM cells. IgE was recently shown to induce HASM cell proliferation but the detailed mechanisms remain unknown. We report here that IgE sensitization induces HASM cell proliferation, as measured by ³H-thymidine, EdU incorporation, and manual cell counting. As an upstream signature component of FcεRI signaling, inhibition of spleen tyrosine kinase (Syk) abrogated the IgE-induced HASM proliferation. Further analysis of IgE-induced signaling depicted an IgE-mediated activation of Erk 1/2, p38, JNK MAPK, and Akt kinases. Lastly, lentiviral-shRNA-mediated STAT3 silencing completely abolished the IgE-mediated HASM cell proliferation. Collectively, our data provide mechanisms of a novel function of IgE which may contribute, at least in part, to airway remodeling observed in allergic asthma by directly inducing HASM cell proliferation.

STAT3 modulates cigarette smoke-induced inflammation and protease expression

Signal transducer and activator of transcription-3 (STAT3) regulates inflammation, apoptosis, and protease expression, which are critical processes associated with airway injury and lung tissue destruction. However, the precise role of STAT3 in the development of airway diseases such as chronic obstructive pulmonary disease (COPD) has not been established. This study shows that cigarette smoke activates STAT3 in the lungs of mice. Since cigarette smoke activated STAT3 in the lung, we then evaluated how the loss of STAT3 would impact on smoke-mediated lung inflammation, protease expression, and apoptosis. STAT3^+/+ and STAT3^−/− mice were exposed to 8 days of cigarette smoke. Compared to the STAT3^+/+ mice bronchoalveolar lavage fluid (BALF) cellularity was significantly elevated in the STAT3^−/− mice both before and after cigarette smoke exposure, with the increase in cells primarily macrophages. In addition, smoke exposure induced significantly higher BALF protein levels of Interleukin-1α (IL-1α), and monocyte chemotactic protein-1 (MCP-1) and higher tissue expression of keratinocyte chemoattractant (KC) in the STAT3^−/− mice. Lung mRNA expression of MMP-12 was increased in STAT3^−/− at baseline. However, the smoke-induced increase in MMP-10 expression seen in the STAT3^+/+ mice was not observed in the STAT3^−/− mice. Moreover, lung protein levels of the anti-inflammatory proteins SOCS3 and IL-10 were markedly lower in the STAT3^−/− mice compared to the STAT3^+/+ mice. Lastly, apoptosis, as determined by caspase 3/7 activity assay, was increased in the STAT3^−/− at baseline to levels comparable to those observed in the smoke-exposed STAT3^+/+ mice. Together, these results indicate that the smoke-mediated induction of lung STAT3 activity may play a critical role in maintaining normal lung homeostasis and function.

IL-17 family cytokines mediated signaling in the pathogenesis of inflammatory diseases

Inflammation is the immediate protective response of the body to pathogen invasions, allergen challenges, chemical exposures or physical injuries. Acute inflammation usually accompanies with transient infiltration of leukocytes, removal of danger signals and eventually tissue repair, while persistent and uncontrolled inflammation becomes a major stimulator in the progression of many chronic diseases in human, including autoimmune diseases, metabolic disorders and cancer. Interleukin (IL)-17 family is a recent classified subset of cytokines, playing critical roles in both acute and chronic inflammatory responses. In this review, we will summarize recent progresses on the signalings of this family cytokines and their impacts on the inflammatory responses or disorders.

IL-17A plays a critical role in the pathogenesis of liver fibrosis through hepatic stellate cell activation

Liver fibrosis is a severe, life-threatening clinical condition resulting from nonresolving hepatitis of different origins. IL-17A is critical in inflammation, but its relation to liver fibrosis remains elusive. We find increased IL-17A expression in fibrotic livers from HBV-infected patients undergoing partial hepatectomy because of cirrhosis-related early-stage hepatocellular carcinoma in comparison with control nonfibrotic livers from uninfected patients with hepatic hemangioma. In fibrotic livers, IL-17A immunoreactivity localizes to the inflammatory infiltrate. In experimental carbon tetrachloride-induced liver fibrosis of IL-17RA-deficient mice, we observe reduced neutrophil influx, proinflammatory cytokines, hepatocellular necrosis, inflammation, and fibrosis as compared with control C57BL/6 mice. IL-17A is produced by neutrophils and T lymphocytes expressing the Th17 lineage-specific transcription factor Retinoic acid receptor-related orphan receptor γt. Furthermore, hepatic stellate cells (HSCs) isolated from naive C57BL/6 mice respond to IL-17A with increased IL-6, α-smooth muscle actin, collagen, and TGF-β mRNA expression, suggesting an IL-17A-driven fibrotic process. Pharmacologic ERK1/2 or p38 inhibition significantly attenuated IL-17A-induced HSC activation and collagen expression. In conclusion, IL-17A(+) Retinoic acid receptor-related orphan receptor γt(+) neutrophils and T cells are recruited into the injured liver driving a chronic, fibrotic hepatitis. IL-17A-dependent HSC activation may be critical for liver fibrosis. Thus, blockade of IL-17A could potentially benefit patients with chronic hepatitis and liver fibrosis.

Intestinal CCL11 and eosinophilic inflammation is regulated by myeloid cell-specific RelA/p65 in mice

In inflammatory bowel diseases (IBDs), particularly ulcerative colitis, intestinal macrophages (MΦs), eosinophils, and the eosinophil-selective chemokine CCL11, have been associated with disease pathogenesis. MΦs, a source of CCL11, have been reported to be of a mixed classical (NF-κB-mediated) and alternatively activated (STAT-6-mediated) phenotype. The importance of NF-κB and STAT-6 pathways to the intestinal MΦ/CCL11 response and eosinophilic inflammation in the histopathology of experimental colitis is not yet understood. Our gene array analyses demonstrated elevated STAT-6- and NF-κB-dependent genes in pediatric ulcerative colitis colonic biopsies. Dextran sodium sulfate (DSS) exposure induced STAT-6 and NF-κB activation in mouse intestinal F4/80(+)CD11b(+)Ly6C(hi) (inflammatory) MΦs. DSS-induced CCL11 expression, eosinophilic inflammation, and histopathology were attenuated in RelA/p65(Δmye) mice, but not in the absence of STAT-6. Deletion of p65 in myeloid cells did not affect inflammatory MΦ recruitment or alter apoptosis, but did attenuate LPS-induced cytokine production (IL-6) and Ccl11 expression in purified F4/80(+)CD11b(+)Ly6C(hi) inflammatory MΦs. Molecular and cellular analyses revealed a link between expression of calprotectin (S100a8/S100a9), Ccl11 expression, and eosinophil numbers in the DSS-treated colon. In vitro studies of bone marrow-derived MΦs showed calprotectin-induced CCL11 production via a p65-dependent mechanism. Our results indicate that myeloid cell-specific NF-κB-dependent pathways play an unexpected role in CCL11 expression and maintenance of eosinophilic inflammation in experimental colitis. These data indicate that targeting myeloid cells and NF-κB-dependent pathways may be of therapeutic benefit for the treatment of eosinophilic inflammation and histopathology in IBD.

Expression of IL-33 in the epidermis: The mechanism of induction by IL-17

BACKGROUND

Interleukin (IL)-33 is a dual functional, IL-1 family member cytokine, whose exact roles in inflammatory skin diseases are still unknown. IL-17A is a key cytokine in the pathogenesis of psoriasis.

OBJECTIVES

We investigated if IL-17A could induce IL-33 in epidermal keratinocytes, and the signaling mechanisms involved.

METHODS

IL-33 levels were evaluated by RT-PCR and western blot in human keratinocytes following IL-17A simulation. IL-33 immunohistochemical staining of psoriatic skin samples was also performed and compared with that of control tissues. The role of signaling pathways downstream of IL-17A was investigated using small molecule inhibitors of EGFR, ERK, p38, and JAK. Adenovirus vector expressing dominant negative STAT1 was also utilized.

RESULTS

IL-33 and its receptor, ST2L, were expressed in the psoriatic epidermis, and the associated infiltrating cells. IL-17A induced IL-33 expression at mRNA and protein levels in a time- and concentration-dependent manner. IL-17A caused phosphorylation of EGFR, ERK, p38, and STAT1. IL-17A-induced IL-33 expression was blocked by the addition of EGFR, ERK, p38, and JAK inhibitors, and dominant negative STAT1-expressing adenovirus vector.

CONCLUSION

IL-17A induced IL-33 in NHEKs through EGFR, ERK, p38, and JAK/STAT1 pathways, which were necessary for the induction of IL-33. IL-33, induced by IL-17A in epidermal keratinocytes, may be involved in the pathophysiology of inflammatory skin diseases, including psoriasis.

The activation and regulation of IL-17 receptor mediated signaling

Interleukin-17 (IL-17), the signature cytokine produced by T helper 17 (Th17) cells, plays pivotal roles in host defense responses against microbial invasion, as well as in the pathogenesis of autoimmune diseases and allergic syndromes. IL-17 activates several downstream signaling pathways including NF-κB, MAPKs and C/EBPs to induce gene expression of antibacterial peptides, proinflammatory chemokines and cytokines and matrix metalloproteinases (MMPs). IL-17 can also stabilize mRNAs of genes induced by TNFα. Although the physiological and pathological functions of IL-17 have been studied for many years, the landscape of its signaling transduction has not been described until recently. The cytosolic adaptor molecule Act1 (also known as CIKS) is considered as the master mediator of IL-17 signaling. In this review, we will summarize recent progress on activation and regulation of IL-17 mediated signal transduction, especially on Act1 mediated regulation of the signaling.

IL-17-mediated Bcl-2 expression regulates survival of fibroblast-like synoviocytes in rheumatoid arthritis through STAT3 activation

Introduction

Fibroblast-like synoviocytes (FLSs) are a major cell population of the pannus that invades adjacent cartilage and bone in rheumatoid arthritis (RA). The study was undertaken to determine the effect of interleukin-17 (IL-17) on the survival and/or proliferation of FLSs from RA patients and to investigate whether signal tranducer and activator of transcription 3 (STAT3) is implicated in this process.

Methods

Bcl-2 and Bax expression in FLSs was determined using the real-time PCR and western blot analysis. The expression of Bcl-2 and phosphoSTAT3 in synovial tissues was investigated by confocal microscope. Apoptosis of FLSs was detected by Annexin V/propidium iodide staining and/or phase contrast microscopy. The proliferation of FLSs was determined by CCK-8 ELISA assay.

Results

The pro-apoptotic Bax is decreased and anti-apoptotic Bcl-2 is increased in FLSs from RA patients compared with those from patients with osteoarthritis (OA). IL-17 upregulated the expression of Bcl-2 in FLSs from RA patients, but not in FLSs from OA patients. STAT3 was found to mediate IL-17-induced Bcl-2 upregulation in FLSs from RA patients. Additionally, IL-17 promoted the survival and proliferation of FLSs from RA patients. Most importantly, treatment with STAT3 inhibitor reversed the protective effect of IL-17 on FLSs apoptosis induced by sodium nitroprusside (SNP).

Conclusions

Our data demonstrate that STAT3 is critical in IL-17-induced survival of FLS from RA patients. Therefore, therapeutic strategies that target the IL-17/STAT3 pathway might be strong candidates for RA treatment modalities.