Immunity to the microbiota promotes sensory neuron regeneration.

Tissue immunity and responses to injury depend on the coordinated action and communication among physiological systems. Here, we show that, upon injury, adaptive responses to the microbiota directly promote sensory neuron regeneration. At homeostasis, tissue-resident commensal-specific T cells colocalize with sensory nerve fibers within the dermis, express a transcriptional program associated with neuronal interaction and repair, and promote axon growth and local nerve regeneration following injury. Mechanistically, our data reveal that the cytokine interleukin-17A (IL-17A) released by commensal-specific Th17 cells upon injury directly signals to sensory neurons via IL-17 receptor A, the transcription of which is specifically upregulated in injured neurons. Collectively, our work reveals that in the context of tissue damage, preemptive immunity to the microbiota can rapidly bridge biological systems by directly promoting neuronal repair, while also identifying IL-17A as a major determinant of this fundamental process.

Maternal gut bacteria drive intestinal inflammation in offspring with neurodevelopmental disorders by altering the chromatin landscape of CD4+ T cells.

Children with autism spectrum disorders often display dysregulated immune responses and related gastrointestinal symptoms. However, the underlying mechanisms leading to the development of both phenotypes have not been elucidated. Here, we show that mouse offspring exhibiting autism-like phenotypes due to prenatal exposure to maternal inflammation were more susceptible to developing intestinal inflammation following challenges later in life. In contrast to its prenatal role in neurodevelopmental phenotypes, interleukin-17A (IL-17A) generated immune-primed phenotypes in offspring through changes in the maternal gut microbiota that led to postnatal alterations in the chromatin landscape of naive CD4+ T cells. The transfer of stool samples from pregnant mice with enhanced IL-17A responses into germ-free dams produced immune-primed phenotypes in offspring. Our study provides mechanistic insights into why children exposed to heightened inflammation in the womb might have an increased risk of developing inflammatory diseases in addition to neurodevelopmental disorders.

Dysregulated Lung Commensal Bacteria Drive Interleukin-17B Production to Promote Pulmonary Fibrosis through Their Outer Membrane Vesicles.

Idiopathic pulmonary fibrosis (IPF) is a severe form of lung fibrosis with a high mortality rate. However, the etiology of IPF remains unknown. Here, we report that alterations in lung microbiota critically promote pulmonary fibrosis pathogenesis. We found that lung microbiota was dysregulated, and the dysregulated microbiota in turn induced production of interleukin-17B (IL-17B) during bleomycin-induced mouse lung fibrosis. Either lung-microbiota depletion or IL-17B deficiency ameliorated the disease progression. IL-17B cooperated with tumor necrosis factor-α to induce expression of neutrophil-recruiting genes and T helper 17 (Th17)-cell-promoting genes. Three pulmonary commensal microbes, which belong to the genera Bacteroides and Prevotella, were identified to promote fibrotic pathogenesis through IL-17R signaling. We further defined that the outer membrane vesicles (OMVs) that were derived from the identified commensal microbes induced IL-17B production through Toll-like receptor-Myd88 adaptor signaling. Together our data demonstrate that specific pulmonary symbiotic commensals can promote lung fibrosis by regulating a profibrotic inflammatory cytokine network.

Staphylococcus aureus proteases trigger eosinophil-mediated skin inflammation.

Staphylococcus aureus skin colonization and eosinophil infiltration are associated with many inflammatory skin disorders, including atopic dermatitis, bullous pemphigoid, Netherton's syndrome, and prurigo nodularis. However, whether there is a relationship between S. aureus and eosinophils and how this interaction influences skin inflammation is largely undefined. We show in a preclinical mouse model that S. aureus epicutaneous exposure induced eosinophil-recruiting chemokines and eosinophil infiltration into the skin. Remarkably, we found that eosinophils had a comparable contribution to the skin inflammation as T cells, in a manner dependent on eosinophil-derived IL-17A and IL-17F production. Importantly, IL-36R signaling induced CCL7-mediated eosinophil recruitment to the inflamed skin. Last, S. aureus proteases induced IL-36α expression in keratinocytes, which promoted infiltration of IL-17-producing eosinophils. Collectively, we uncovered a mechanism for S. aureus proteases to trigger eosinophil-mediated skin inflammation, which has implications in the pathogenesis of inflammatory skin diseases.

IL-17A-producing γδ T cells: A novel target in stroke immunotherapy.

The activation of the immune system is crucial for the fate of the ischemic brain tissue and neurological outcome in experimental stroke. Rapidly after stroke γδ (γδ17), T cells release IL-17A in the ischemic brain and thereby amplify the early detrimental immune response. Notably, IL-17A levels in γδ17 T cells are modulated by the intestinal microbiota which is, in turn, shaped by the diet. Importantly, besides their proinflammatory effects, meningeal γδ17 T cells have been recently implicated in regulating neuronal signaling, behavior, and cognition under homeostatic and pathological conditions at the brain-meningeal interface. Against this background, we propose that a dietary intervention represents a promising treatment option to improve poststroke outcomes by the modulation of the microbiota composition and IL-17A levels in γδ T cells.

Cutting edge: interleukin-17a prompts HIF1α for wound healing.

IL-17a is widely considered an inflammatory cytokine, linked to the development and severity of autoimmune diseases such as inflammatory bowel disease and psoriasis. However, a recent report by Konieczny et al. sheds light on a novel protective role of IL-17a in wound healing, adding to the growing list of studies highlighting a noninflammatory function for IL-17a.

Attenuation of relapsing fever neuroborreliosis in mice by IL-17A blockade.

Relapsing fever due to Borrelia hermsii is characterized by recurrent bacteremia episodes. However, infection of B. hermsii, if not treated early, can spread to various organs including the central nervous system (CNS). CNS disease manifestations are commonly referred to as relapsing fever neuroborreliosis (RFNB). In the mouse model of B. hermsii infection, we have previously shown that the development of RFNB requires innate immune cells as well as T cells. Here, we found that prior to the onset of RFNB, an increase in the systemic proinflammatory cytokine response followed by sustained levels of IP-10 concurrent with the CNS disease phase. RNA sequencing analysis of the spinal cord tissue during the disease phase revealed an association of the interleukin (IL)-17 signaling pathway in RFNB. To test a possible role for IL-17 in RFNB, we compared B. hermsii infection in wild-type and IL-17A-/- mice. Although the onset of bacteremia and protective anti-B. hermsii antibody responses occurred similarly, the blood-brain barrier permeability, proinflammatory cytokine levels, immune cell infiltration in the spinal cord, and RFNB manifestations were significantly diminished in IL-17A-/- mice compared to wild-type mice. Treatment of B. hermsii-infected wild-type mice with anti-IL-17A antibody ameliorated the severity of spinal cord inflammation, microglial cell activation, and RFNB. These data suggest that the IL-17 signaling pathway plays a major role in the pathogenesis of RFNB, and IL-17A blockade may be a therapeutic modality for controlling neuroborreliosis.

Susceptibility and resistance in leprosy: Studies in the mouse model.

Leprosy is a chronic granulomatous infectious disease caused by the pathogen, Mycobacterium leprae, and the more recently discovered, M. lepromatosis. Described in 1873, M. leprae was among the first microorganisms to be proposed as a cause of a human infectious disease. As an obligate intracellular bacterium, it has still not thus far been reproducibly cultivated in axenic medium or cell cultures. Shepard's mouse footpad assay, therefore, was truly a breakthrough in leprosy research. The generation of immunosuppressed and genetically engineered mice, along with advances in molecular and cellular techniques, has since offered more tools for the study of the M. leprae-induced granuloma. While far from perfect, these new mouse models have provided insights into the immunoregulatory mechanisms responsible for the spectrum of this complex disease.

IL-17 receptor A functions to help maintain barrier integrity and limit activation of immunopathogenic response to H. pylori infection.

Activation of Th17 cell responses, including the production of IL-17A and IL-21, contributes to host defense and inflammatory responses by coordinating adaptive and innate immune responses. IL-17A and IL-17F signal through a multimeric receptor, which includes the IL-17 receptor A (IL-17RA) subunit and the IL-17RC subunit. IL-17RA is expressed by many cell types, and data from previous studies suggest that loss of IL-17 receptor is required to limit immunopathology in the Helicobacter pylori model of infection. Here, an Il17ra-/- mouse was generated on the FVB/n background, and the role of IL-17 signaling in the maintenance of barrier responses to H. pylori was investigated. Generating the Il17ra-/- on the FVB/n background allowed for the examination of responses in the paragastric lymph node and will allow for future investigation into carcinogenesis. While uninfected Il17ra-/- mice do not develop spontaneous gastritis following H. pylori infection, Il17ra-/- mice develop severe gastric inflammation accompanied by lymphoid follicle production and exacerbated production of Th17 cytokines. Increased inflammation in the tissue, increased IgA levels in the lumen, and reduced production of Muc5ac in the corpus correlate with increased H. pylori-induced paragastric lymph node activation. These data suggest that the cross talk between immune cells and epithelial cells regulates mucin production, IgA production, and translocation, impacting the integrity of the gastric mucosa and therefore activating of the adaptive immune response.

Amiloride lowers plasma TNF and interleukin-6 but not interleukin-17A in patients with hypertension and type 2 diabetes.

Interleukin (IL)-17A contributes to hypertension in preclinical models. T helper 17 and dendritic cells are activated by NaCl, which could involve the epithelial Na+ channel (ENaC). We hypothesized that the ENaC blocker amiloride reduces plasma IL-17A and related cytokines in patients with hypertension. Concentrations of IL-17A, IFN-γ, TNF, IL-6, IL-1ß, and IL-10 were determined by immunoassays in plasma from two patient cohorts before and after amiloride treatment: 1) patients with type 2 diabetes mellitus (T2DM) and treatment-resistant hypertension (n = 69, amiloride 5-10 mg/day for 8 wk) and 2) patients with hypertension and type 1 diabetes mellitus (T1DM) (n = 29) on standardized salt intake (amiloride 20-40 mg/day, 2 days). Plasma and tissue from ANG II-hypertensive mice with T1DM treated with amiloride (2 mg/kg/day, 4 days) were analyzed. The effect of amiloride and benzamil on macrophage cytokines was determined in vitro. Plasma cytokines showed higher concentrations (IL-17A ∼40-fold) in patients with T2DM compared with T1DM. In patients with T2DM, amiloride had no effect on IL-17A but lowered TNF and IL-6. In patients with T1DM, amiloride had no effect on IL-17A but increased TNF. In both cohorts, blood pressure decline and plasma K+ increase did not relate to plasma cytokine changes. In mice, amiloride exerted no effect on IL-17A in the plasma, kidney, aorta, or left cardiac ventricle but increased TNF in cardiac and kidney tissues. In lipopolysaccharide-stimulated human THP-1 macrophages, amiloride and benzamil (from 1 nmol/L) decreased TNF, IL-6, IL-10, and IL-1ß. In conclusion, inhibition of ENaC by amiloride reduces proinflammatory cytokines TNF and IL-6 but not IL-17A in patients with T2DM, potentially by a direct action on macrophages.NEW & NOTEWORTHY ENaC activity may contribute to macrophage-derived cytokine release, since amiloride exerts anti-inflammatory effects by suppression of TNF and IL-6 cytokines in patients with resistant hypertension and type 2 diabetes and in THP-1-derived macrophages in vitro.

Involvement of IL-17 A/IL-17 Receptor A with Neutrophil Recruitment and the Severity of Coronary Arteritis in Kawasaki Disease.

PURPOSE: To assess the role of the interleukin (IL)-17 A/IL-17 receptor A (IL-17RA) in Kawasaki disease (KD)-related coronary arteritis (CA). METHODS: In human study, the plasma levels of IL-17 A and coronary arteries were concurrently examined in acute KD patients. In vitro responses of human coronary endothelial cells to plasma stimulation were investigated with and without IL-17RA neutralization. A murine model of Lactobacillus casei cell-wall extract (LCWE)-induced CA using wild-type Balb/c and Il17ra-deficient mice were also inspected. RESULTS: The plasma levels of IL-17 A were significantly higher in KD patients before intravenous immunoglobulin therapy, especially in those with coronary artery lesion. The pre-IVIG IL-17 A levels positively correlated with maximal z scores of coronary diameters and plasma-induced endothelial mRNA levels of chemokine (C-X-C motif) ligand-1, IL-8, and IL-17RA. IL-17RA blockade significantly reduced such endothelial upregulations of aforementioned three genes and inducible nitric oxide synthase, and neutrophil transmigration. IL-17RA expression was enhanced on peripheral blood mononuclear cells in pre-IVIG KD patients, and in the aortic rings and spleens of the LCWE-stimulated mice. LCWE-induced CA composed of dual-positive Ly6G- and IL-17 A-stained infiltrates. Il17ra-deficient mice showed reduced CA severity with the fewer number of neutrophils and lower early inducible nitric oxide synthase and chemokine (C-X-C motif) ligand-1 mRNA expressions than Il17ra+/+ littermates, and absent IL-17RA upregulation at aortic roots. CONCLUSION: IL-17 A/IL-17RA axis may play a role in mediating aortic neutrophil chemoattraction, thus contributory to the severity of CA in both humans and mice. These findings may help to develop a new therapeutic strategy toward ameliorating KD-related CA.

Endothelial IL17RD promotes Western diet-induced aortic myeloid cell infiltration.

The Interleukin-17 (IL17) family is a group of cytokines implicated in the etiology of several inflammatory diseases. Interleukin-17 receptor D (IL17RD), also known as Sef (similar expression to fibroblast growth factor) belonging to the family of IL17 receptors, has been shown to modulate IL17A-associated inflammatory phenotypes. The objective of this study was to test the hypothesis that IL17RD promotes endothelial cell activation and consequent leukocyte adhesion. We utilized primary human aortic endothelial cells and demonstrated that RNAi targeting of IL17RD suppressed transcript levels by 83 % compared to non-targeted controls. Further, RNAi knockdown of IL17RD decreased the adhesion of THP-1 monocytic cells onto a monolayer of aortic endothelial cells in response to IL17A. Additionally, we determined that IL17A did not significantly enhance the activation of canonical MAPK and NFκB pathways in endothelial cells, and further did not significantly affect the expression of VCAM-1 and ICAM-1 in aortic endothelial cells, which is contrary to previous findings. We also determined the functional relevance of our findings in vivo by comparing the expression of endothelial VCAM-1 and ICAM-1 and leukocyte infiltration in the aorta in Western diet-fed Il17rd null versus wild-type mice. Our results showed that although Il17rd null mice do not have significant alteration in aortic expression of VCAM-1 and ICAM-1 in endothelial cells, they exhibit decreased accumulation of proinflammatory monocytes and neutrophils, suggesting that endothelial IL17RD induced in vivo myeloid cell accumulation is not dependent on upregulation of VCAM-1 and ICAM-1 expression. We further performed proteomics analysis to identify potential molecular mediators of the IL17A/IL17RD signaling axis. Collectively, our results underscore a critical role for Il17rd in the regulation of aortic myeloid cell infiltration in the context of Western diet feeding.

IL-21, not IL-17A, exacerbates murine primary biliary cholangitis.

Primary biliary cholangitis (PBC) is a chronic autoimmune liver disease caused by intrahepatic bile duct injuries, resulting in fibrosis, cirrhosis, and eventually liver failure. T helper (Th) 17 cells are proposed to involve in the pathogenesis of PBC. However, how and which Th17 cell-derived cytokines affect PBC remains unclear. In this study, we investigated the effects of Th17 effector cytokines, including interleukin (IL)-17A, IL-17F, and IL-21 in PBC using a xenobiotic-induced mouse model of autoimmune cholangitis (inducible chemical xenobiotic models of PBC) treated with cytokine-expressing adeno-associated virus. Our results showed that administration of IL-17A, the well-known main cytokine produced by Th17 cells, did not augment liver inflammation or fibrosis. In contrast, we noted IL-17A-treated mice had lower hepatic Th1 cell numbers and higher hepatic CD11b+Ly6G+ polymorphonuclear myeloid-derived suppressor cell numbers. IL-17F did not alter liver inflammation or fibrosis. However, the administration of IL-21 exacerbated liver inflammatory responses and portal cell infiltration. IL-21 markedly increased the numbers of activated CD8+ T cells and liver tissue-resident memory CD8+ T cells. Moreover, IL-21 aggravates liver fibrosis in mice with autoimmune cholangitis. These results emphasized that not IL-17A but IL-21 in Th17 cell-derived cytokines affected the pathogenesis of PBC. IL-21 enhanced liver inflammation and progression to fibrosis by enhancing the numbers and effector activities of CD8+ T cells. Delineation of the effects of different Th17 effector cytokines in PBC offers clues for developing new therapeutic approaches.

Low uveitis rates in patients with axial spondyloarthritis treated with bimekizumab: pooled results from phase 2b/3 trials.

OBJECTIVES: Acute anterior uveitis ('uveitis') is a common axial spondyloarthritis (axSpA) extramusculoskeletal manifestation. Interleukin (IL)-17 is implicated in its pathogenesis, however, there is conflicting evidence for IL-17A inhibition in uveitis management. We report pooled analyses of uveitis incidence in patients receiving bimekizumab (BKZ), a monoclonal IgG1 antibody that selectively inhibits IL-17F in addition to IL-17A, from phase 2b/3 trials. METHODS: Data were pooled for patients receiving BKZ 160 mg or placebo in the double-blind treatment period of the phase 3 BE MOBILE 1 (NCT03928704; non-radiographic axSpA) and BE MOBILE 2 (NCT03928743; radiographic axSpA) trials. Data were separately pooled for patients treated with at least one BKZ dose in the BE MOBILE trials and their ongoing open-label extension (OLE; NCT04436640), and the phase 2b BE AGILE trial (NCT02963506; radiographic axSpA) and its ongoing OLE (NCT03355573). Uveitis rates and exposure-adjusted incidence rates (EAIR)/100 patient-years (PYs) are reported. RESULTS: In the BE MOBILE 1 and 2 double-blind treatment period, 0.6% (2/349) of patients receiving BKZ experienced uveitis vs 4.6% (11/237) receiving placebo (nominal p=0.001; EAIR (95% CI): 1.8/100 PYs (0.2 to 6.7) vs 15.4/100 PYs (95% CI 7.7 to 27.5)). In patients with history of uveitis, EAIR was lower in patients receiving BKZ (6.2/100 PYs (95% CI 0.2 to 34.8); 1.9%) vs placebo (70.4/100 PYs (95% CI 32.2 to 133.7); 20.0%; nominal p=0.004). In the phase 2b/3 pool (N=848; BKZ exposure: 2034.4 PYs), EAIR remained low (1.2/100 PYs (95% CI 0.8 to 1.8)). CONCLUSIONS: Bimekizumab, a dual-IL-17A/F inhibitor, may confer protective effects for uveitis in patients with axSpA.

Comparative risk of incident and recurrent acute anterior uveitis across different biological agents in patients with ankylosing spondylitis.

OBJECTIVE: To evaluate the comparative risk of incident and recurrent acute anterior uveitis (AAU) across different biological disease-modifying anti-rheumatic drugs (bDMARDs) in patients with ankylosing spondylitis (AS). METHODS: A retrospective nationwide cohort study was conducted on 34 621 patients with AS without a previous history of AAU using a national claims database. Patients were followed-up from 2010 to 2021. The comparative risk of incident and recurrent AAU across different bDMARDs was examined using multivariable time-dependent Cox models and counting process (AG) models, respectively. RESULTS: The adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for incident AAU (bDMARDs non-exposure as reference) were: adalimumab 0.674 (0.581-0.891), etanercept 1.760 (1.540-2.012), golimumab 0.771 (0.620-0.959), infliximab 0.891 (0.741-1.071), and secukinumab 1.324 (0.794-2.209). Compared with adalimumab exposure, etanercept (aHR = 2.553 [2.114-3.083]), infliximab (aHR = 1.303 [1.039-1.634]), and secukinumab exposures (aHR = 2.173 [1.273-3.710]) showed a higher risk of incident AAU. The aHRs and 95% CIs for recurrent AAU (bDMARDs non-exposure as reference) were: adalimumab 0.798 (0.659-0.968), etanercept 1.416 (1.185-1.693), golimumab 0.874 (0.645-1.185), infliximab 0.926 (0.729-1.177), and secukinumab 1.257 (0.670-2.359). Compared with adalimumab exposure, etanercept exposure (aHR = 1.793 [1.403-2.292]) was associated with a higher risk of recurrent AAU. CONCLUSION: Our data suggest preference for bDMARDs in the following order: adalimumab/golimumab > infliximab > secukinumab > etanercept (for incident AAU prevention) and adalimumab > golimumab/infliximab/secukinumab > etanercept (for recurrent AAU prevention).

Dual blockade of interleukin-17A and interleukin-17F as a therapeutic strategy for liver fibrosis: Investigating the potential effect and mechanism of brodalumab.

Liver fibrosis is a terminal manifestation of various chronic liver diseases. There are no drugs that can reverse the condition. Recently, the importance of interleukin-17 (IL17) in the pathophysiology has been revealed and has attracted attention as a therapeutic target. We aimed to reveal the roles of IL17A and IL17F in liver fibrosis, and to validate the potential of their dual blockade as therapeutic strategy. First, we retrospectively reviewed the longitudinal change of FIB-4 index, a clinical indicator of liver fibrosis, among psoriasis patients treated by brodalumab, which blocks IL17 receptor A (IL17RA). Next, we examined anti-fibrotic efficacy of anti-IL17RA antibody (Ab) in two murine liver fibrosis models by histopathological investigation and real-time reverse transcription polymerase chain reaction (RT-PCR). Finally, we analyzed the effect of IL17A and IL17F upon human hepatic stellate cells with RNA sequencing, real-time RT-PCR, western blotting, chromatin immunoprecipitation, and flow cytometry. Clinical data showed that FIB-4 index significantly decreased among psoriasis patients treated by brodalumab. In vivo studies additionally demonstrated that anti-IL17RA Ab ameliorates liver fibrosis induced by tetrachloride and methionine-choline deficient diet. Furthermore, in vitro experiments revealed that both IL17A and IL17F enhance cell-surface expression of transforming growth factor-ß receptor II and promote pro-fibrotic gene expression via the JUN pathway in human hepatic stellate cells. Our insights suggest that IL17A and IL17F share their pro-fibrotic function in the context of liver fibrosis, and moreover, dual blockade of IL17A and IL17F by anti-IL17RA Ab would be a promising strategy for the management of liver fibrosis.

In vivo overexpression of the avian interleukin-17 in a necrotic enteritis disease model modulates the expression of antimicrobial peptides in the small intestine of broilers.

In humans and mice, the induction of interleukin (IL)-17 expression enhances epithelial barrier integrity through the secretion of antimicrobial peptides (AMP), thereby improving antibacterial defense. However, it is unclear whether IL-17 has similar antibacterial effects in chickens by modulating the expression of AMPs, such as avian beta-defensins (also known as gallinacins) and cathelicidins. This study evaluated the in vivo effects of inoculating 20-day-old broiler chickens with two doses of a plasmid encoding chicken IL-17 (pCDNA3.1/rchIL-17-V5-HIS TOPO plasmid [pCDNA3.1-IL-17]; 5 or 10 µg/bird). On day 23 of age, all broilers, except those in the negative control group, were orally challenged with a virulent Clostridium perfringens strain for three days. To investigate IL-17-mediated effects against C. perfringens infection, the expression of avian beta-defensin 1 (avBD1), avBD2, avBD4, avBD6, cathelicidins, and inducible nitric oxide synthase (iNOS) genes were quantified, and gross necrotic enteritis (NE) lesion scores were assessed in the small intestine. The results showed that broilers receiving the higher dose of pCDNA3.1-IL-17 (10 µg) had significantly lower NE lesion scores compared to those receiving the lower dose (5 µg), the vector control, and the positive control groups. Furthermore, the expression of all avian beta-defensins and cathelicidin genes was detectable across all groups, regardless of treatment and time points. IL-17 treatment led to significantly higher expression of avBD1, avBD2, avBD4, avBD6, cathelicidin, and iNOS in the duodenum, jejunum, and ileum compared to control chickens. In C. perfringens-infected chickens, the expression of avBD1, avBD2, avBD4, cathelicidin, and iNOS in the ileum was significantly higher than in control chickens. Pre-treatment with the higher dose of pCDNA3.1-IL-17 (10 µg) in infected chickens was associated with reduced NE lesion severity and increased expression of avBD1, avBD2, cathelicidin, and iNOS in the ileum, but not avBD4 and avBD6. These findings provide new insights into the potential effect of IL-17 and reduction in NE lesion severity by modulating AMP expression which may be involved in mediating protective immunity against intestinal infection with C. perfringens.

Role of Interleukin-17 cytokine family in human T-cell lymphotropic virus type 1 (HTLV-1) infection and associated diseases.

BACKGROUND: Human T-lymphotropic virus (HTLV-1) is a neglected virus with worldwide distribution of over 10 million people and is the cause of two main associated diseases Adult T cell Leukemia-Lymphoma (ATLL), and HTLV-1-associated Myelopathy/Tropical Spastic paraparesis (HAM/TSP). The IL-17 cytokine family plays a crucial role in the host immunity against HTLV-1 and the development of associated disease. A systematic review was conducted to analyze all research reporting on the levels or expression of the IL-17 HTLV-1 infection and associated diseases. METHODS: The literature search was conducted in electronic databases including PubMed/Medline and Web of Sciences until January 31st, 2024, followed by the PRISMA guidelines. RESULTS: Our search revealed 20 eligible articles to be included in our study. The total number of cases studied was 1420, of which 386 were carriers without any symptoms, and were 176 ATLL and 237 HAM/TSP. The IL-17 cytokine family production or mRNA expression was higher in HAM/TSP patients but showed a trend toward reduction in the case of ATLL. CONCLUSIONS: Our results showed that while The IL-17 cytokine family plays a significant role in the immunopathogenesis of disease and clinical status of patients with inflammatory disorders such as HAM/TSP, IL-17 production is diminished and the RORC/IL-17 signaling pathway is downregulated during ATLL. Our data suggest that boosting the RORC/IL-17 signaling pathway in ATLL and using anti-IL-17 agents in HAM/TSP and other HTLV-related inflammatory conditions might benefit patients and improve their outcomes.

Impact of IL-6 rs1800795 and IL-17A rs2275913 gene polymorphisms on the COVID-19 prognosis and susceptibility in a sample of Iranian patients.

BACKGROUND: From asymptomatic to acute and life-threatening pulmonary infection, the clinical manifestations of COVID-19 are highly variable. Interleukin (IL)-6 and IL-17A are key drivers of hyper inflammation status in COVID-19, and their elevated levels are hallmarks of the infection progression. To explore whether prognosis and susceptibility to COVID-19 are linked to IL-6 rs1800795 and IL-17A rs2275913, these single-nucleotide polymorphisms (SNPs) were assessed in a sample of Iranian COVID-19 patients. METHODS: This study enrolled two hundred and eighty COVID-19 patients (140 non-severe and 140 severe). Genotyping for IL-6 rs1800795 and IL-17A rs2275913 was performed using tetra primer-amplification refractory mutation system-polymerase chain reaction (tetra-ARMS-PCR). IL-6 and IL-17A circulating levels were measured using enzyme-linked immunosorbent assay (ELISA). Also, mortality predictors of COVID-19 were investigated. RESULTS: The rs1800795 GG genotype (78/140 (55.7 %)) and G allele (205/280 (73.2 %)) were significantly associated with a positive risk of COVID-19 severe infection (OR = 2.19, 95 %CI: 1.35-3.54, P =.006 and OR = 1.79, 95 %CI: 1.25-2.56, P <.001, respectively). Also, rs1800795 GG genotype was significantly linked to disease mortality (OR = 1.95, 95 %CI: 1.06-3.61, P =.04). The rs2275913 GA genotype was protective against severe COVID-19 (OR = 0.5, 95 %CI: 0.31--0.80, P =.012). However, the present study did not reveal any significant link between rs2275913 genotypes with disease mortality. INR ≥ 1.2 (OR = 2.19, 95 %CI: 1.61-3.78, P =.007), D-dimer ≥ 565.5 ng/mL (OR = 3.12, 95 %CI: 1.27-5.68, P =.019), respiratory rate ≥ 29 (OR = 1.19, 95 %CI: 1.12-1.28, P =.001), IL-6 serum concentration ≥ 28.5 pg/mL (OR = 1.97, 95 %CI: 1.942-2.06, P =.013), and IL-6 rs1800795 GG genotype (OR = 1.95, 95 %CI: 1.06-3.61, P =.04) were predictive of COVID-19 mortality. CONCLUSION: The rs1800795 GG genotype and G allele were associated with disease severity, and INR, D-dimer, respiratory rate, IL-6 serum concentration, and IL-6 rs1800795 GG genotype were predictive of COVID-19 mortality.

Involvement of IL17A and IL17RA variants in interleukin-17A levels and disease activity in ulcerative colitis.

Ulcerative colitis (UC) is characterized by chronic inflammation of the large intestine with involvement of Th17 cells and interleukin (IL)-17A. The role of IL17A and IL17A receptor (IL17RA) variants in pathophysiology of UC still remains inconclusive. The aim was to evaluate the association between IL17A and IL17RA variants with susceptibility, IL-17A plasma levels, and endoscopic activity in UC. The study included 104 patients with UC and 213 controls. Patients were divided according to endoscopic activity (remission/mild and moderate/severe). The IL17A rs3819024 A>G and rs3819025 G>A, and IL17RA rs2241043 C>T, rs2241049 A>G, and rs6518661 G>A variants were genotyped using real time polymerase chain reaction. IL-17A plasma levels were determined using immunofluorimetric assay. Neither IL17A nor IL17RA variants were associated with UC susceptibility. The IL17A rs3819024 AG genotype was associated to high levels of IL-17 only in patients. Patients with the G allele of IL17RA rs2241049 showed 2.944 more chance of developing moderate/severe disease. The haplotype analysis showed that IL17RA rs2241049 and rs6518661 was not associated with UC susceptibility and haplotypes constituted with G allele of these variants were not associated with disease severity (p = 0.09). In conclusion, the IL17A rs3819024 AG genotype was associated with elevated IL-17A plasma levels in patients with UC but not in controls and the IL17RA rs2241049 AG+GG genotypes were associated to severity of UC. These results suggest a possible hidden interaction between the IL17A rs3819024 variant and other genetic, environmental, and epigenetic factors in the IL-17A expression that is present only in patients with UC.