A novel heterodimeric cytokine consisting of IL-17 and IL-17F regulates inflammatory responses

The ouroboros of autoimmunity

Human autoimmunity against elements conferring protective immunity can be symbolized by the 'ouroboros', a snake eating its own tail. Underlying infection is autoimmunity against three immunological targets: neutrophils, complement and cytokines. Autoantibodies against neutrophils can cause peripheral neutropenia underlying mild pyogenic bacterial infections. The pathogenic contribution of autoantibodies against molecules of the complement system is often unclear, but autoantibodies specific for C3 convertase can enhance its activity, lowering complement levels and underlying severe bacterial infections. Autoantibodies neutralizing granulocyte-macrophage colony-stimulating factor impair alveolar macrophages, thereby underlying pulmonary proteinosis and airborne infections, type I interferon viral diseases, type II interferon intra-macrophagic infections, interleukin-6 pyogenic bacterial diseases and interleukin-17A/F mucocutaneous candidiasis. Each of these five cytokine autoantibodies underlies a specific range of infectious diseases, phenocopying infections that occur in patients with the corresponding inborn errors. In this Review, we analyze this ouroboros of immunity against immunity and posit that it should be considered as a factor in patients with unexplained infection.

Association of interleukin-17A and chemokine/vascular endothelial growth factor-induced angiogenesis in newly diagnosed patients with bladder cancer

BACKGROUND

The human interleukin-17 (IL-17) family comprises IL-17A to IL-17 F; their receptors are IL-17RA to IL-17RE. Evidence revealed that these cytokines can have a tumor-supportive or anti-tumor impact on human malignancies. The purpose of this study was to assess the expression of CXCR2, IL-17RA, and IL-17RC genes at the mRNA level as well as tissue and serum levels of IL-17A, vascular endothelial growth factor (VEGF), and transforming growth factor β (TGF-β) in patients with bladder cancer (BC) compared to control.

RESULTS

This study showed that gene expression of IL-17RA, IL-17RC, and CXCR2 in the tumoral tissue of BC patients was significantly upregulated compared with normal tissue. The findings disclosed a significant difference in the serum and tissue concentrations of IL-17A, VEGF, and TGF-β between the patient and the control groups, as well as tumor and normal tissues.

CONCLUSION

This study reveals notable dysregulation of CXCR2, IL-17RA, and IL-17RC genes, alongside changes in IL-17A, VEGF, and TGF-β levels in patients with BC than in controls. These findings indicate their possible involvement in BC development and their potential as diagnostic and therapeutic targets.

Signaling pathways and targeted therapies for psoriasis

Psoriasis is a common, chronic, and inflammatory skin disease with a high burden on individuals, health systems, and society worldwide. With the immunological pathologies and pathogenesis of psoriasis becoming gradually revealed, the therapeutic approaches for this disease have gained revolutionary progress. Nevertheless, the mechanisms of less common forms of psoriasis remain elusive. Furthermore, severe adverse effects and the recurrence of disease upon treatment cessation should be noted and addressed during the treatment, which, however, has been rarely explored with the integration of preliminary findings. Therefore, it is crucial to have a comprehensive understanding of the mechanisms behind psoriasis pathogenesis, which might offer new insights for research and lead to more substantive progress in therapeutic approaches and expand clinical options for psoriasis treatment. In this review, we looked to briefly introduce the epidemiology, clinical subtypes, pathophysiology, and comorbidities of psoriasis and systematically discuss the signaling pathways involving extracellular cytokines and intracellular transmission, as well as the cross-talk between them. In the discussion, we also paid more attention to the potential metabolic and epigenetic mechanisms of psoriasis and the molecular mechanistic cascades related to its comorbidities. This review also outlined current treatment for psoriasis, especially targeted therapies and novel therapeutic strategies, as well as the potential mechanism of disease recurrence.

Erythropoietin-mediated IL-17 F attenuates sepsis-induced gut microbiota dysbiosis and barrier dysfunction

Septic gut damage is critical in the progression of sepsis and multiple organ failure, characterized by gut microbiota dysbiosis and epithelium deficiency in the gut barrier. Recent studies highlight the protective effects of Erythropoietin (EPO) on multiple organs. The present study found that EPO treatment significantly alleviated the survival rate, suppressed inflammatory responses, and ameliorated intestine damage in mice with sepsis. EPO treatment also reversed sepsis-induced gut microbiota dysbiosis. The protective role of EPO in the gut barrier and microbiota was impaired after EPOR knockout. Notably, we innovatively demonstrated that IL-17 F screened by transcriptome sequencing could ameliorate sepsis and septic gut damage including gut microbiota dysbiosis and barrier dysfunction, which was verified by IL-17 F-treated fecal microbiota transplantation (FMT) as well. Our findings highlight the protection effects of EPO-mediated IL-17 F in sepsis-induced gut damage by alleviating gut barrier dysfunction and restoring gut microbiota dysbiosis. EPO and IL-17 F may be potential therapeutic targets in septic patients.

Association Between IL-17 and Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

Background

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease characterized by neutrophils airway infiltration. It is currently known that Interleukin-17 (IL-17) is an important pro-inflammatory factor. It can promote the accumulation of neutrophils and participate in the chronic inflammatory process of COPD. However, the value of IL-17 levels in the diagnosis and assessment of COPD remains controversial. In view of this, we conducted a systematic review and meta-analysis to assess its relevance.

Methods

We searched databases such as PubMed, Web of Science, Cochrane Library and Embase to extract original research.

Results

A total of 10 studies with 2268 participants were included in this meta-analysis. The results showed that the level of serum IL-17 in patients with stable COPD was significantly higher than that in healthy controls (standard mean difference SMD, 1.59, 95% CI 0.84-2.34; p<0.001). Compared with the stable COPD group, the serum IL-17 level in acute exacerbation (AECOPD) was significantly higher (SMD, 1.78, 95% CI 1.22-2.33; p<0.001). The level of IL-17 in sputum of COPD patients was also higher than that of healthy controls (SMD, 2.03, 95% CI 0.74-3.31; p<0.001).

Conclusion

Our results showed that IL-17 levels were elevated in serum and sputum in COPD patients compared with healthy controls, and IL-17 levels increased with disease progression. IL-17 serves as a potential biomarker to indicate the persistence of neutrophilic inflammation and exacerbation of COPD.

The Th17/IL-17 Axis and Host Defense Against Fungal Infections

Chronic mucocutaneous candidiasis (CMC) was recognized as a primary immunodeficiency in the early 1970s. However, for almost 40 years, its genetic etiology remained unknown. The progressive molecular and cellular description of inborn errors of immunity (IEI) with syndromic CMC pointed toward a possible role of IL-17-mediated immunity in protecting against fungal infection and CMC. Since 2011, novel IEI affecting either the response to or production of IL-17A and/or IL-17F (IL-17A/F) in patients with isolated or syndromic CMC provided formal proof of the pivotal role of the IL-17 axis in mucocutaneous immunity to Candida spp, and, to a lesser extent, to Staphylococcus aureus in humans. In contrast, IL-17-mediated immunity seems largely redundant against other common microbes in humans. In this review, we outline the current knowledge of IEI associated with impaired IL-17A/F-mediated immunity, highlighting our current understanding of the role of IL-17A/F in human immunity.

Novel Histopathological Biomarkers in Prostate Cancer: Implications and Perspectives

Prostate cancer (PCa) is the second most frequently diagnosed cancer in men. Despite the significant progress in cancer diagnosis and treatment over the last few years, the approach to disease detection and therapy still does not include histopathological biomarkers. The dissemination of PCa is strictly related to the creation of a premetastatic niche, which can be detected by altered levels of specific biomarkers. To date, the risk factors for biochemical recurrence include lymph node status, prostate-specific antigen (PSA), PSA density (PSAD), body mass index (BMI), pathological Gleason score, seminal vesicle invasion, extraprostatic extension, and intraductal carcinoma. In the future, biomarkers might represent another prognostic factor, as discussed in many studies. In this review, we focus on histopathological biomarkers (particularly CD169 macrophages, neuropilin-1, cofilin-1, interleukin-17, signal transducer and activator of transcription protein 3 (STAT3), LIM domain kinase 1 (LIMK1), CD15, AMACR, prostate-specific membrane antigen (PSMA), Appl1, Sortilin, Syndecan-1, and p63) and their potential application in decision making regarding the prognosis and treatment of PCa patients. We refer to studies that found a correlation between the levels of biomarkers and tumor characteristics as well as clinical outcomes. We also hypothesize about the potential use of histopathological markers as a target for novel immunotherapeutic drugs or targeted radionuclide therapy, which may be used as adjuvant therapy in the future.

Therapeutic potential of targeting IL-17 and its receptor signaling in neuroinflammation

T helper 17 cells are thought to significantly contribute to the neuroinflammation process during neurogenerative diseases via their signature cytokine, interleukin (IL)-17. Recently, an emerging key role of IL-17 and its receptors has been documented in inflammatory and autoimmune diseases. The clinical studies conducted on patients with neurodegenerative disease have also shown an increase in IL-17 levels in serum as well as cerebrospinal fluid samples. Therapeutic targeting of either IL-17 receptors or direct IL-17 neutralizing antibodies has shown a promising preclinical and clinical proof of concept for treating chronic autoimmune neurodegenerative diseases such as multiple sclerosis. Thus, IL-17 and its receptors have a central role in regulation of neuroinflammation and can be considered as one of the major therapeutic targets in chronic neuroinflammatory diseases.

Comparative molecular docking analysis for analyzing the inhibitory effect of Anakinra and Ustekinumab against IL17F

Interleukin 17 F is a member of IL-17 cytokine family with a 50% structural homology to IL-17A and plays a significant role either alone or in combination with IL-17A towards inflammation in Rheumatoid arthritis (RA). A growing number of drugs targeting IL-17 pathway are being tested against population specific disease markers. The major objective of this research was to investigate the anti-inflammatory effect of Anakinra (an IL-1 R1 inhibitor) and Ustekinumab (an IL-12 and IL-23 inhibitor) by targeting IL17F. The three dimensional structures of IL17F was taken from PDB while structures of drugs were taken from PubChem database. Docking was performed using MOE and Schrodinger ligand docking software and binding energies, including s-score using London-dG fitness function and glide score using glide internal energy function, between drug and targets were compared. Furthermore, Protein-Drug complex were subjected to 150 ns Molecular Dynamics (MD) Simulations using Schrodinger's Desmond Module. Docking and MD simulation results suggest anakinra as a more potent IL17F inhibitor and forming a more structurally stable complex.Communicated by Ramaswamy H. Sarma.

Bimekizumab Efficacy and Safety in Japanese Patients with Plaque Psoriasis in BE VIVID: A Phase 3, Ustekinumab and Placebo-Controlled Study

INTRODUCTION

Bimekizumab treatment resulted in improved clinical outcomes in patients with moderate-to-severe plaque psoriasis in BE VIVID, a 52-week, phase 3, randomized, ustekinumab and placebo-controlled study. We present data from the BE VIVID Japan patient subpopulation.

METHODS

Globally, patients were randomized to receive bimekizumab 320 mg every 4 weeks (Q4W), ustekinumab (45/90 mg weight-based at baseline and week 4, then every 12 weeks), or placebo (Q4W through week 16, then bimekizumab 320 mg Q4W). Efficacy endpoints included week 16 Psoriasis Area and Severity Index (PASI) 90 and Investigator's Global Assessment (IGA) 0/1, and other outcomes [PASI 100, PASI 75, IGA 0, Dermatology Life Quality Index (DLQI) 0/1, absolute PASI, scalp IGA, Psoriasis Symptoms and Impacts Measure (P-SIM) responses]. Safety analyses were conducted.

RESULTS

There were 108 Japanese randomized patients (bimekizumab: 62; ustekinumab: 29; placebo: 17). At week 16, bimekizumab-treated patients had a higher clinical response versus ustekinumab and placebo (PASI 90: 85.5% versus 51.7% and 5.9%; IGA 0/1: 82.3% versus 48.3% and 0.0%). Over 52 weeks, improved clinical response was maintained with bimekizumab, including patients switching from placebo at week 16. Overall, the safety profile in Japanese patients was consistent with that observed in the global population.

CONCLUSION

Bimekizumab resulted in improved clinical response versus ustekinumab and placebo, and was well-tolerated in Japanese patients.

TRIAL REGISTRATION

NCT03370133.

Th17 Cells: Orchestrators of Mucosal Inflammation and Potential Therapeutic Targets

T helper 17 (Th17) cells represent a specialized subgroup of effector CD4+ T cells known for their role in provoking neutrophil-driven tissue inflammation, particularly within mucosal tissues. Although they are pivotal for defending the host against extracellular bacteria and fungi, they have also been associated with development of various T cell-mediated inflammatory conditions, autoimmune diseases, and even cancer. Notably, Th17 cells exhibit a dual nature, with different Th17 cell subtypes showcasing distinct effector functions and varying capacities to incite autoimmune tissue inflammation. Furthermore, Th17 cells exhibit significant plasticity, which carries important functional implications, both in terms of their expression of cytokines typically associated with other effector T cell subsets and in their interactions with regulatory CD4+ T cells. The intricate balance of Th17 cytokines can also be a double-edged sword in inflammation, autoimmunity, and cancer. Within this article, we delve into the mechanisms that govern the differentiation, function, and adaptability of Th17 cells. We culminate with an exploration of therapeutic potentials in harnessing the power of Th17 cells and their cytokines. Targeted interventions to modulate Th17 responses are emerging as promising strategies for autoimmunity, inflammation, and cancer treatment. By precisely fine-tuning Th17-related pathways, we may unlock new avenues for personalized therapeutic approaches, aiming to restore immune balance, alleviate the challenges of these disorders, and ultimately enhance the quality of life for individuals affected by them.

The Role of Interleukin-17 in Juvenile Idiopathic Arthritis: From Pathogenesis to Treatment

Background and Objectives: Interleukin-17 (IL-17) is a cytokine family consisting of six members and five specific receptors. IL-17A was the first member to be identified in 1993. Since then, several studies have elucidated that IL-17 has predominantly pro-inflammatory activity and that its production is involved in both the defense against pathogens and the genesis of autoimmune processes. Materials and Methods: In this review, we provide an overview of the role of interleukin-17 in the pathogenesis of juvenile idiopathic arthritis (JIA) and its relationship with IL-23, the so-called IL-23-IL-17 axis, by reporting updated findings from the scientific literature. Results: Strong evidence supports the role of interleukin-17A in the pathogenesis of JIA after the deregulated production of this interleukin by both T helper 17 (Th17) cells and cells of innate immunity. The blocking of IL-17A was found to improve the course of JIA, leading to the approval of the use of the human anti-IL17A monoclonal antibody secukinumab in the treatment of the JIA subtypes juvenile psoriatic arthritis (JPsA) and enthesitis-related arthritis (ERA). Conclusions: IL-17A plays a central role in the pathogenesis of JIA. Blocking its production with specific biologic drugs enables the effective treatment of this disabling childhood rheumatic disease.

Interleukin-17 Family Cytokines in Metabolic Disorders and Cancer

Interleukin-17 (IL-17) family cytokines are potent drivers of inflammatory responses. Although IL-17 was originally identified as a cytokine that induces protective effects against bacterial and fungal infections, IL-17 can also promote chronic inflammation in a number of autoimmune diseases. Research in the last decade has also elucidated critical roles of IL-17 during cancer development and treatment. Intriguingly, IL-17 seems to play a role in the risk of cancers that are associated with metabolic disorders. In this review, we summarize our current knowledge on the biochemical basis of IL-17 signaling, IL-17′s involvement in cancers and metabolic disorders, and postulate how IL-17 family cytokines may serve as a bridge between these two types of diseases.

T Cell-Intrinsic Interleukin 17 Receptor A Signaling Supports the Establishment of Chronic Murine Gammaherpesvirus 68 Infection

Gammaherpesviruses, such as human Epstein-Barr virus (EBV) and murine gammaherpesvirus 68 (MHV68), are species-specific, ubiquitous pathogens that are associated with multiple cancers, including B cell lymphomas. These viruses have a natural tropism for B cells and usurp B cell differentiation to drive a unique and robust polyclonal germinal center response to establish a long-term latent reservoir in memory B cells. The robust polyclonal germinal center response driven by gammaherpesvirus infection increases the risk for B cell transformation. Unsurprisingly, many gammaherpesvirus cancers are derived from germinal center or post-germinal center B cells. The viral and host factors that influence the gammaherpesvirus-driven germinal center response are not clearly defined. We previously showed that host interleukin 17 receptor A (IL-17RA) signaling promotes the establishment of chronic MHV68 infection and the MHV68-driven germinal center response. In this study, we found that T cell-intrinsic IL-17RA signaling recapitulates some proviral aspects of global IL-17RA signaling during MHV68 infection. Specifically, we found that T cell-intrinsic IL-17RA signaling supports the MHV68-driven germinal center response, the establishment of latency in the spleen, and viral reactivation in the spleen and peritoneal cavity. Our study unveils an unexpected finding where the T cell-specific IL-17RA signaling supports the establishment of a latent reservoir of a B cell-tropic gammaherpesvirus. IMPORTANCE Gammaherpesviruses, such as human EBV, establish lifelong infection in >95% of adults and are associated with B cell lymphomas. Gammaherpesviruses usurp the germinal center response to establish latent infection, and the germinal center B cells are thought to be the target of viral transformation. We previously found that global expression of IL-17RA promotes the establishment of chronic MHV68 infection and the MHV68-driven germinal center response. In this study, we showed that T cell-intrinsic IL-17RA signaling is necessary to promote the MHV68-driven germinal center response by supporting CD4⁺ T follicular helper cell expansion. We also found that T cell-intrinsic IL-17RA signaling contributes to but is not solely responsible for the systemic proviral role of IL-17RA signaling, highlighting the multifaceted function of IL-17RA signaling during MHV68 infection.

Inhibiting IL-17A and IL-17F in Rheumatic Disease: Therapeutics Help to Elucidate Disease Mechanisms

Purpose of Review

Psoriatic arthritis and ankylosing spondylitis belong to a family of rheumatological diseases that lead to painful joint inflammation that impacts on patient function and quality of life. Recent studies have shown that the pro-inflammatory cytokine IL-17 is involved in the inflammatory joint changes in spondyloarthritides. We will review the pathophysiology of IL-17 and review the biological therapies targeting IL-17.

Recent Findings

IL-17 is produced and released from T cells and is dependent on multiple upstream cytokines, which include IL-23. There are six members of the IL-17 family that are secreted from multiple populations of T cells. The initial biologic medications have been developed against IL-17A, which is the best-studied member of this family. These medications appear to be effective in controlling joint inflammation, improving patient quality of life, and are generally well tolerated. More recently, medications have been developed that target both IL-17A and IL-17F. In addition, brodalumab, an antibody targeting the IL-17 receptor, has had a resurgence after initial concerns for an increased risk of suicide.

Summary

IL-17 is an inflammatory cytokine that is critical in the pathobiology of axial spondyloarthritides. Recent biological therapies targeting IL-17A are effective and well tolerated in patients with axial spondyloarthritis. Specific targeting of the Il-17A/F heterodimer is also effective and provides another viable option in the clinician’s armamentarium.

Singlet oxygen -derived nerve growth factor exacerbates airway hyperresponsiveness in a mouse model of asthma with mixed inflammation

BACKGROUND

Refractory asthma, which is caused by several factors including neutrophil infiltration is a serious complication of bronchial asthma. We previously reported that nerve growth factor (NGF) is involved in AHR. NGF-derived induction of hyperalgesia is dependent on neutrophils; however, this relationship remains unclear in respiratory disease. In this study, we examined the roles of neutrophils and NGF in refractory asthma.

METHODS

Using intranasal house dust mite sensitization, we established a mouse model of asthma with mixed inflammation (Mix-in). AHR, NGF production and hyperinnervation of the lungs were examined with or without different inhibitory treatments. The levels of the singlet oxygen markers, 10- and 12-(Z,E)-hydroxyoctadecadienoic acids (HODE) in the lungs, were measured by liquid chromatography-tandem mass spectrometry. An in vitro experiment was also performed to evaluate the direct effect of singlet oxygen on NGF production.

RESULTS

NGF production and hyperinnervation were higher in Mix-in mice than in conventional eosinophilic-asthmatic mice and were positively correlated with AHR. Asthmatic parameters were inhibited by NGF neutralizing Abs and myeloperoxidase (MPO) inhibition. The 10- and 12-(Z,E)-HODEs levels were increased in the lungs and were positively correlated with MPO activity and NGF production. NGF was produced by bronchial epithelial cells in vitro upon stimulation with singlet oxygen.

CONCLUSIONS

Our findings suggest that neutrophil MPO-derived singlet oxygen induces increased NGF production, leading to AHR and 10- and 12-(Z,E)-HODEs production. These findings may help to develop new therapies targeting this mechanism and to establish a new biomarker for non-type 2 and refractory asthma.

Divergent functions of IL-17-family cytokines in DSS colitis: Insights from a naturally-occurring human mutation in IL-17F

The IL-17 family is structurally distinct from other cytokine subclasses. IL-17A and IL-17F, the most closely related of this family, form homodimers and an IL-17AF heterodimer. While IL-17A and IL-17F exhibit similar activities in many settings, in others their functions are divergent. To better understand the function of IL-17F in vivo, we created mice harboring a mutation in Il17f originally described in humans with unexplained chronic mucosal candidiasis (Ser-65-Leu). We evaluated Il17fS65L/S65L mice in DSS-colitis, as this is one of the few settings where IL-17A and IL-17F exhibit opposing activities. Specifically, IL-17A is protective of the gut epithelium, a finding that was revealed when trials of anti-IL-17A biologics in Crohn's disease failed and recapitulated in many mouse models of colitis. In contrast, mice lacking IL-17F are resistant to DSS-colitis, partly attributable to alterations in intestinal microbiota that mobilize Tregs. Here we report that Il17fS65L/S65L mice do not phenocopy Il17f-/- mice in DSS colitis, but rather exhibited a worsening disease phenotype much like Il17a-/- mice. Gut inflammation in Il17fS65L/S65L mice correlated with reduced Treg accumulation and lowered intestinal levels of Clostridium cluster XIV. Unexpectedly, the protective DSS-colitis phenotype in Il17f-/- mice could be reversed upon co-housing with Il17fS65L/S65L mice, also correlating with Clostridium cluster XIV levels in gut. Thus, the Il17fS65L/S65L phenotype resembles an IL-17A deficiency more closely than IL-17F deficiency in the setting of DSS colitis.

Influence of interleukin 17 A and 17 F polymorphisms in keratoconus

BACKGROUND

Until a few years ago, keratoconus was defined as a noninflammatory degenerative disease. However, recent studies have shown that the altered balance between inflammatory cytokines, proteases, and protease inhibitors, as well as free radicals and oxidants, have a crucial role in the pathogenesis of this disease. The aim of this study is to investigate whether interleukin 17 A G197A (rs2275913) and interleukin 17 F T7488C (rs763780) polymorphisms are associated with keratoconus in patients from a population of the northwestern region of the State of São Paulo, Brazil.

METHODS AND RESULTS

35 patients and 61 controls were enrolled. Genotyping of interleukin 17 A G197A and interleukin 17 F T7488C polymorphisms was carried out using the polymerase chain reaction-restriction fragment length polymorphism technique. Statistical analyses were conducted using the chi-square test, and an odds ratio with a 95% confidence interval was also calculated to evaluate the association between polymorphisms and disease. Evaluating interleukin 17 F T7488C, we found that the TT genotype is associated as a risk factor for keratoconus (P = 0.04; OR = 3.01; CI 1.11-8.14). As for evaluating interleukin 17 A G197A, the allele and genotype frequencies between patients and controls were compared and no statistically significant differences were found.

CONCLUSIONS

Our data showed that the interleukin 17 F T7488C polymorphisms may exert an influence in keratoconus.

Dual inhibition of IL-17A and IL-17F in psoriatic disease

Psoriasis and psoriatic arthritis are chronic immune-mediated disorders with involvement of interleukin (IL)-17 cytokines in their pathogenesis. IL-17A has been considered to be the most biologically active, but IL-17F is also over-expressed in skin and synovial tissues of patients with these diseases. Many therapeutic advances have been made in the past years, but some needs remain unmet. Dual inhibitor and bispecific antibodies simultaneously targeting IL-17A and IL-17F could provide better disease control. Herein we review current evidence on bimekizumab and sonelokimab. The antigen-binding site of bimekizumab neutralizes both IL-17A and IL-17F; phase I, II, and III studies have demonstrated its efficacy and safety in psoriasis and psoriatic arthritis. Sonelokimab is a trivalent nanobody targeting IL-17A and IL-17F; phase I and II studies with this molecule have yielded promising results in psoriasis.

Expression and Function Analysis of Interleukin-17A/F1, 2, and 3 Genes in Yellow Catfish (Pelteobagrus fulvidraco): Distinct Bioactivity of Recombinant IL-17A/F1, 2, and 3

In mammals, Interleukin-17 cytokine family plays critical roles in both acute and chronic inflammatory responses. In fish species, three Interleukin-17A/F (IL-17A/F) genes have been identified to be homologous to mammalian IL-17A and IL-17F, but little is known about their functional activity. In this study, Pf_IL-17A/F1, 2 and 3 genes were cloned from yellow catfish (Pelteobagrus fulvidraco) and they differed in protein structure and exon length, implying that they may have divergent bioactivity. Real-time quantitative PCR analyses revealed that three Pf_IL-17A/F genes were highly expressed in blood and mucosal tissues (skin+mucus and gill) from healthy adult fish. The mRNA expressions of Pf_IL-17A/F1, 2 and 3 genes were significantly up-regulated in the gill, skin+mucus, head kidney and spleen after challenge with Edwardsiella ictaluri and in the isolated peripheral blood leucocytes (PBLs) of yellow catfish after stimulation with phytohaemagglutinin (PHA), lipopolysaccharides (LPS), peptidoglycan (PGN) and polyinosinic-polycytidylic acid (Poly I:C). These results indicate that Pf_IL-17A/F1, 2 and 3 genes may play a vital role in the regulation of immune against pathogens. Additionally, the recombinant (r) Pf_IL-17A/F1, 2 and 3 proteins significantly induced the mRNA expressions of proinflammatory cytokines, chemokines and antibacterial peptides genes, and the rPf_IL-17A/F 2 and 3 proteins promoted phagocytosis of PBLs more powerfully than the rPf_IL-17A/F1. Furthermore, the rPf_IL-17A/F1, 2 and 3 proteins might activate the NF-κB and MAPK signal pathways by IL-17RA, ACT1, TRAF6, TRAF2, TRAF5 and TAK1, indicating that the three Pf_IL-17A/F proteins may play different roles in promoting inflammatory response.

Signalling of multiple interleukin (IL)-17 family cytokines via IL-17 receptor A drives psoriasis-related inflammatory pathways

Background

The interleukin (IL)‐23/IL‐17 immune axis is of central importance in psoriasis. However, the impact of IL‐17 family cytokines other than IL‐17A in psoriasis has not been fully established.

Objectives

To elucidate the contribution of IL‐17 family cytokines in psoriasis.

Methods

To address the expression and localization of IL‐17 family cytokines, lesional and nonlesional skin samples from patients with psoriasis were analysed by several complementary methods, including quantitative polymerase chain reaction, immunoassays, in situ hybridization and immunohistochemistry. Mechanistic studies assessing the functional activity of IL‐17 family cytokines were performed using ex vivo cultured human skin biopsies and primary human keratinocytes.

Results

We demonstrated that IL‐17A, IL‐17F, IL‐17A/F and IL‐17C are expressed at increased levels in psoriasis lesional skin and induce overlapping gene expression responses in ex vivo cultured human skin that correlate with the transcriptomic signature of psoriasis skin. Furthermore, we showed that brodalumab, in contrast to ixekizumab, normalizes gene expression responses induced by the combination of IL‐17A, IL‐17F, IL‐17A/F and IL‐17C in human keratinocytes.

Conclusions

Several IL‐17 ligands signalling through IL‐17RA are overexpressed in psoriasis skin and induce similar psoriasis‐related inflammatory pathways demonstrating their relevance in relation to therapeutic intervention in psoriasis.

What is already known about this topic?

The key role of interleukin (IL)‐17A in psoriasis is well established.

Previous studies have shown that IL‐17A, IL‐17F and IL‐17C are overexpressed in psoriasis skin, whereas contradictory results have been published for IL‐17E.

IL‐17 family cytokines induce secretion of inflammatory mediators such as antimicrobial peptides, chemokines and cytokines involved in the pathophysiology of psoriasis.

What does this study add?

Levels of IL‐17A/F are increased in lesional psoriasis skin but markedly lower than IL‐17A and IL‐17F.

In ex vivo cultured human skin, a physiologically relevant model, IL‐17A, IL‐17F, IL‐17A/F and IL‐17C show functional redundancy in shaping the psoriasis transcriptome.

IL‐17RA antagonism normalizes expression of psoriasis‐related genes in keratinocytes induced by the combination of IL‐17 family cytokines.

What is the translational message?

Overexpression and functional redundancy of IL‐17 family cytokines in psoriasis may explain why some patients with psoriasis with primary or secondary failure of response to secukinumab or ixekizumab achieve a clinical response after switching to brodalumab.

Linked Comment: M. Sugaya. Br J Dermatol 2021; 185:483.

Interleukin-17A Causes Osteoarthritis-Like Transcriptional Changes in Human Osteoarthritis-Derived Chondrocytes and Synovial Fibroblasts In Vitro

Increased interleukin (IL)-17A has been identified in joints affected by osteoarthritis (OA), but it is unclear how IL-17A, and its family members IL-17AF and IL-17F, can contribute to human OA pathophysiology. Therefore, we aimed to evaluate the gene expression and signalling pathway activation effects of the different IL-17 family members in chondrocytes and synovial fibroblasts derived from cartilage and synovium of patients with end-stage knee OA. Immunohistochemistry staining confirmed that IL-17 receptor A (IL-17RA) and IL-17RC are expressed in end-stage OA-derived cartilage and synovium. Chondrocytes and synovial fibroblasts derived from end-stage OA patients were treated with IL-17A, IL-17AF, or IL-17F, and gene expression was assessed with bulk RNA-Seq. Hallmark pathway analysis showed that IL-17 cytokines regulated several OA pathophysiology-related pathways including immune-, angiogenesis-, and complement-pathways in both chondrocytes and synovial fibroblasts derived from end-stage OA patients. While overall IL-17A induced the strongest transcriptional response, followed by IL-17AF and IL-17F, not all genes followed this pattern. Disease-Gene Network analysis revealed that IL-17A-related changes in gene expression in these cells are associated with experimental arthritis, knee arthritis, and musculoskeletal disease gene-sets. Western blot analysis confirmed that IL-17A significantly activates p38 and p65 NF-κB. Incubation of chondrocytes and synovial fibroblasts with anti-IL-17A monoclonal antibody secukinumab significantly inhibited IL-17A-induced gene expression. In conclusion, the association of IL-17-induced transcriptional changes with arthritic gene-sets supports a role for IL-17A in OA pathophysiology. Future studies should further investigate the role of IL-17A in the OA joint to establish whether anti-IL-17 treatment could be a potential therapeutic option in OA patients with an inflammatory phenotype.

Anti-IL-17 Agents in the Treatment of Axial Spondyloarthritis

Axial spondyloarthritis (axSpA) describes a group of chronic inflammatory rheumatic diseases primarily involving the axial skeleton. IL-17 is involved in the pathogenesis of numerous inflammatory diseases, including inflammatory arthritis. Until a few years ago, the only biological agents licensed for the treatment of axSpA and nr-axSpA were TNF inhibitors. However, as some patients did not respond to TNF inhibition or experienced secondary failure, the introduction of the first two IL-17 inhibitors (secukinumab [SEC] and ixekizumab [IXE]) has extended the treatment options, and there are now three others (bimekizumab, brodalumab and netakimab) in various stages of clinical development. The last ten years have seen the development of a number of therapeutic recommendations that aimed at improving the management of axSpA patients. The aim of this narrative review of the published literature concerning the role of IL-17 in the pathogenesis of SpA, and the role of IL-17 inhibitors in the treatment of axSpA, is to provide a comprehensive picture of the clinical efficacy and safety of the drugs themselves, and the treatment strategies recommended in the international guidelines.

Interleukin 17A Derived from γδ T Cell Induces Demyelination of the Brain in Angiostrongylus cantonensis Infection

Angiostrongylus cantonensis infection is a typical cause of eosinophilic encephalitis (EM), which has been reported to induce serious damage in the central nervous system. Both parasite and host factors contribute to the onset of EM, but the related immune-inflammation pathogenesis remains poorly characterised. An A. cantonensis infection model was generated through the infection of mice by gavage. Transmission electron microscopy and immunohistochemistry were used to assess the pathologic changes in the brain. The mRNA expression of inflammatory factors was tested using qRT-PCR. A combination of flow cytometry and western blotting was used to evaluate the alteration of leukocytes and related cytokines. A critical role of IL-17 was found by injecting IL-17A monoclonal antibody into naïve and A. cantonensis-infected mice. A. cantonensis larvae altered the immune homeostasis in the brain, leading to the destruction of myelin sheaths and activation of microglia and macrophage. During this process, IL-17A accumulation was observed, and IL-17RA was expressed in oligodendrocytes and microglia during the infection. Notably, γδ T cell was the major origin of IL-17A production induced by the parasite. After an IL-17A-neutralising antibody was applied, alterations in myelination and the state of the microglia/macrophage were discovered; the neurobehavioural scores of the mice also improved. Our study reveals one unrecognised impact of the γδ T cells in parasitic encephalopathy and emphasises that blocking IL-17A signalling can attenuate microglia and macrophage activation, thus reducing CNS demyelination and ameliorating the neurobehavioural deficit in A. cantonensis-infected mice.

Gammaherpesvirus Usurps Host IL-17 Signaling To Support the Establishment of Chronic Infection

Gammaherpesviruses establish lifelong infections in a majority of humans and are associated with B cell lymphomas. IL-17A is a host cytokine that plays a well-established role in the clearance of bacterial and fungal infections; however, the role of IL-17A in viral infections is poorly understood.

Gammaherpesviruses establish lifelong infection and are associated with a variety of cancers, including B cell lymphomas. These viruses manipulate the B cell differentiation process to establish lifelong infection in memory B cells. Specifically, gammaherpesviruses infect naive B cells and promote entry of both infected and uninfected naive B cells into germinal centers, where the virus usurps rapid proliferation of germinal center B cells to exponentially increase its cellular latent reservoir. In addition to facilitating the establishment of latent infection, germinal center B cells are thought to be the target of viral transformation. In this study, we have uncovered a novel proviral role of host interleukin 17A (IL-17A), a well-established antibacterial and antifungal factor. Loss of IL-17A signaling attenuated the establishment of chronic gammaherpesvirus infection and gammaherpesvirus-driven germinal center response in a route of inoculation-dependent manner. Further, IL-17A treatment directly supported gammaherpesvirus reactivation and de novo lytic infection. This study is the first demonstration of a multifaceted proviral role of IL-17 signaling.

Conformational dynamics in interleukin 17A and 17F functional complexes is a key determinant of receptor A affinity and specificity

The proinflammatory cytokines IL-17A and IL-17F have been identified as key drivers of a range of human inflammatory diseases, such as psoriasis, which has led to several therapeutic antibodies targeted at IL-17A. The two cytokines have been shown to tightly associate as functional homo and hetero dimers, which induce signalling via the formation of a cell surface signalling complex with a single copy of both IL-17RA and IL-17RC. Striking differences in affinity have been observed for IL-17RA binding to IL-17AA, IL-17AF and IL-17FF, however, the functional significance and molecular basis for this has remained unclear. We have obtained comprehensive backbone NMR assignments for full length IL-17AA (79%), IL-17AF (93%) and IL-17FF (89%), which show that the dimers adopt almost identical backbone topologies in solution to those observed in reported crystal structures. Analysis of the line widths and intensities of assigned backbone amide NMR signals has revealed striking differences in the conformational plasticity and dynamics of IL-17AA compared to both IL-17AF and IL-17FF. Our NMR data indicate that a number of regions of IL-17AA are interconverting between at least two distinct conformations on a relatively slow timescale. Such conformational heterogeneity has previously been shown to play an important role in the formation of many high affinity protein-protein complexes. The locations of the affected IL-17AA residues essentially coincides with the regions of both IL-17A and IL-17F previously shown to undergo significant structural changes on binding to IL-17RA. Substantially less conformational exchange was revealed by the NMR data for IL-17FF and IL-17AF. We propose that the markedly different conformational dynamic properties of the distinct functional IL-17 dimers plays a key role in determining their affinities for IL-17RA, with the more dynamic and plastic nature of IL-17AA contributing to the significantly tighter affinity observed for binding to IL-17RA. In contrast, the dynamic properties are expected to have little influence on the affinity of IL-17 dimers for IL-17RC, which has recently been shown to induce only small structural changes in IL-17FF upon binding.

The role of ixekizumab in non-radiographic axial spondyloarthritis

Among patients with axial spondyloarthritis (axSpA), non-radiographic axial spondyloarthritis (nr-axSpA) is distinguished from ankylosing spondylitis (AS) by a lack of obvious radiographic changes in the sacroiliac joint. Tumor necrosis factor inhibitor (TNFi) has been used as a highly effective treatment in patients with AS and has shown good efficacy and safety in clinical trials in patients with nr-axSpA. As the pathophysiological mechanism for axSpA has started to become better recognized, various drugs other than TNFi, all of which are related to the interleukin-17 (IL-17) axis, are being evaluated in patients with axSpA. IL-17 inhibitors, such as secukinumab and ixekizumab, are effective drugs for patients with AS. A recent clinical trial reported that ixekizumab, a monoclonal antibody against IL-17A, was also effective in patients with nr-axSpA. In a COAST-X study, ixekizumab was superior to a placebo for improving signs and symptoms in patients with nr-axSpA at weeks 16 and 52. The adverse events were no different from those found in previous ixekizumab studies, and no new safety signals were identified. However, when considering several IL-17 inhibitors, it is necessary to obtain sufficient data to identify the exacerbation of extra-articular manifestation. In terms of effectiveness and safety, ixekizumab may be an appropriate alternative to TNFi in nr-axSpA patients.

Much More Than IL-17A: Cytokines of the IL-17 Family Between Microbiota and Cancer

The interleukin-(IL-)17 family of cytokines is composed of six members named IL-17A, IL-17B, IL-17C, IL-17D, IL-17E, and IL-17F. IL-17A is the prototype of this family, and it was the first to be discovered and targeted in the clinic. IL-17A is essential for modulating the interplay between commensal microbes and epithelial cells at our borders (i.e., skin and mucosae), and yet, for protecting us from microbial invaders, thus preserving mucosal and skin integrity. Interactions between the microbiota and cells producing IL-17A have also been implicated in the pathogenesis of immune mediated inflammatory diseases and cancer. While interactions between microbiota and IL-17B-to-F have only partially been investigated, they are by no means less relevant. The cellular source of IL-17B-to-F, their main targets, and their function in homeostasis and disease distinguish IL-17B-to-F from IL-17A. Here, we intentionally overlook IL-17A, and we focus instead on the role of the other cytokines of the IL-17 family in the interplay between microbiota and epithelial cells that may contribute to cancer pathogenesis and immune surveillance. We also underscore differences and similarities between IL-17A and IL-17B-to-F in the microbiota-immunity-cancer axis, and we highlight therapeutic strategies that directly or indirectly target IL-17 cytokines in diseases.

The adaptive immune response to Clostridioides difficile: A tricky balance between immunoprotection and immunopathogenesis

Clostridioides difficile (C. difficile) is the major cause of hospital-acquired gastrointestinal infections in individuals following antibiotics treatment. The pathogenesis of C. difficile infection (CDI) is mediated mainly by the production of toxins that induce tissue damage and host inflammatory responses. While innate immunity is well characterized in human and animal models of CDI, adaptive immune responses remain poorly understood. In this review, the current understanding of adaptive immunity is summarized and its influence on pathogenesis and disease outcome is discussed. The perspectives on what we believe to be the main pending questions and the focus of future research are also provided. There is no doubt that the innate immune response provides a first line of defense to CDI. But, is the adaptive immune response a friend or a foe? Probably it depends on the course of the disease. Adaptive immunity is essential for pathogen eradication, but may also trigger uncontrolled or pathological inflammation. Most of the understanding of the role of T cells is based on findings from experimental models. While they are a very valuable tool for research studies, more studies in human are needed to translate these findings into human disease. Another main challenge is to unravel the role of the different T cell populations on protection or induction of immunopathogenesis.

Bimekizumab, a Novel Humanized IgG1 Antibody That Neutralizes Both IL-17A and IL-17F

Interleukin (IL)-17A is a key driver of inflammation and the principal target of anti-IL-17 therapeutic monoclonal antibodies. IL-17A, and its structurally similar family member IL-17F, have been shown to be functionally dysregulated in certain human immune-mediated inflammatory diseases such as psoriasis, psoriatic arthritis, and axial spondyloarthritis. Given the overlapping biology of these two cytokines, we postulated that dual neutralization of IL-17A and IL-17F may provide a greater depth of clinical response in IL-17-mediated diseases than IL-17A inhibition alone. We identified 496.g1, a humanized antibody with strong affinity for IL-17A but poor affinity for IL-17F. Affinity maturation of 496.g1 to 496.g3 greatly enhanced the affinity of the Fab fragment for IL-17F while retaining strong binding to IL-17A. As an IgG1, the affinity for IL-17A and IL-17F was 3.2 pM and 23 pM, respectively. Comparison of 496.g3 IgG1 with the commercially available anti-IL-17A monoclonal antibodies ixekizumab and secukinumab, by surface plasmon resonance and in a human in vitro IL-17A functional assay, showed that 496.g3 and ixekizumab display equivalent affinity for IL-17A, and that both antibodies are markedly more potent than secukinumab. In contrast to ixekizumab and secukinumab, 496.g3 exhibited the unique feature of also being able to neutralize the biological activity of IL-17F. Therefore, antibody 496.g3 was selected for clinical development for its ability to neutralize the biologic function of both IL-17A and IL-17F and was renamed bimekizumab (formerly UCB4940). Early clinical data in patients with psoriasis, in those with psoriatic arthritis, and from the Phase 2 studies in psoriasis, psoriatic arthritis, and ankylosing spondylitis, are encouraging and support the targeted approach of dual neutralization of IL-17A and IL-17F. Taken together, these findings provide the rationale for the continued clinical evaluation of bimekizumab in patients with immune-mediated inflammatory diseases.

Biology of Interleukin-17 and Its Pathophysiological Significance in Sepsis

The interleukin (IL)-17 family includes six structure-related cytokines (A-F). To date, majority of studies have focused on IL-17A. IL-17A plays a pivotal role in various infectious diseases, inflammatory and autoimmune disorders, and cancer. Several recent studies have indicated that IL-17A is a biomarker as well as a therapeutic target in sepsis. In the current review, we summarize the biological functions of IL-17, including IL-17-mediated responses and signal transduction pathways, with particular emphasis on clinical relevance to sepsis.

The effects of phenanthrene exposure on Treg and Th17 cells related cytokines in female rats

Phenanthrene (Phe) female rat model was established to explore the mechanism of Phe on immune impairment. The rats were randomly divided into three groups, including control (C), low (L), and high (H) groups. Phe was supplied to L and H groups at the dose of 180 and 900 mg/kg orally at first day and with the dose of 90 and 450 mg/kg by intraperitoneal injection at the last 2 days. The C group was enriched with the same volume of corn oil. The liver tissue was collected. Then, the protein and mRNA expressions of interleukin (IL)-35 and the concentration IL-17 were detected to evaluate the function of regulatory T cells (Treg cells) and T helper 17 cells (Th17 cells). In addition, IL-1β and interferon-γ (IFN-γ) were analyzed to evaluate the immune impairment. The results showed that the protein and mRNA expressions of IL-35 decreased significantly in H groups (P < 0.05). Meanwhile, there were significant increases in IL-17, IFN-γ and IL-1β in the liver of H group (P < 0.05). This study demonstrated that Phe exposure might be associated with the immune impairment via changing inflammatory mediators including IL-35 and IL-17 in female rats.

The role of interleukin-17 in tumor development and progression

IL-17, a potent proinflammatory cytokine, has been shown to intimately contribute to the formation, growth, and metastasis of a wide range of malignancies. Recent studies implicate IL-17 as a link among inflammation, wound healing, and cancer. While IL-17-mediated production of inflammatory mediators mobilizes immune-suppressive and angiogenic myeloid cells, emerging studies reveal that IL-17 can directly act on tissue stem cells to promote tissue repair and tumorigenesis. Here, we review the pleotropic impacts of IL-17 on cancer biology, focusing how IL-17-mediated inflammatory response and mitogenic signaling are exploited to equip its cancer-promoting function and discussing the implications in therapies.

An IL-17F.S65L Knock-In Mouse Reveals Similarities and Differences in IL-17F Function in Oral Candidiasis: A New Tool to Understand IL-17F

Oropharyngeal candidiasis (OPC) is an opportunistic infection of the oral mucosa caused by the commensal fungus Candida albicans IL-17R signaling is essential to prevent OPC in mice and humans, but the individual roles of its ligands, IL-17A, IL-17F, and IL-17AF, are less clear. A homozygous IL-17F deficiency in mice does not cause OPC susceptibility, whereas mice lacking IL-17A are moderately susceptible. In humans, a rare heterozygous mutation in IL-17F (IL-17F.S65L) was identified that causes chronic mucocutaneous candidiasis, suggesting the existence of essential antifungal pathways mediated by IL-17F and/or IL-17AF. To investigate the role of IL-17F and IL-17AF in more detail, we exploited this "experiment of nature" by creating a mouse line bearing the homologous mutation in IL-17F (Ser65Leu) by CRISPR/Cas9. Unlike Il17f^-/- mice that are resistant to OPC, Il17f^S65L/S65L mice showed increased oral fungal burdens similar to Il17a ^-/- mice. In contrast to humans, however, disease was only evident in homozygous, not heterozygous, mutant mice. The mutation was linked to modestly impaired CXC chemokine expression and neutrophil recruitment to the infected tongue but not to alterations in oral antimicrobial peptide expression. These findings suggest mechanisms by which the enigmatic cytokine IL-17F contributes to host defense against fungi. Moreover, because these mice do not phenocopy Il17f^-/- mice, they may provide a valuable tool to interrogate IL-17F and IL-17AF function in vivo in other settings.

Infectious Complications of Biological and Small Molecule Targeted Immunomodulatory Therapies

The past 2 decades have seen a revolution in our approach to therapeutic immunosuppression. We have moved from relying on broadly active traditional medications, such as prednisolone or methotrexate, toward more specific agents that often target a single receptor, cytokine, or cell type, using monoclonal antibodies, fusion proteins, or targeted small molecules. This change has transformed the treatment of many conditions, including rheumatoid arthritis, cancers, asthma, and inflammatory bowel disease, but along with the benefits have come risks. Contrary to the hope that these more specific agents would have minimal and predictable infectious sequelae, infectious complications have emerged as a major stumbling block for many of these agents. Furthermore, the growing number and complexity of available biologic agents makes it difficult for clinicians to maintain current knowledge, and most review articles focus on a particular target disease or class of agent. In this article, we review the current state of knowledge about infectious complications of biologic and small molecule immunomodulatory agents, aiming to create a single resource relevant to a broad range of clinicians and researchers. For each of 19 classes of agent, we discuss the mechanism of action, the risk and types of infectious complications, and recommendations for prevention of infection.

Interleukin-17 receptor D constitutes an alternative receptor for interleukin-17A important in psoriasis-like skin inflammation

T helper 17 (T_H17) cells and interleukin-17A (IL-17A) produced by them are critical in autoinflammatory diseases, such as psoriasis. IL-17A has been shown to signal through IL-17 receptor A/IL-17 receptor C (IL-17RA/IL-17RC) complex to drive inflammatory responses. However, in a psoriasis model, we found that Il17rc deficiency did not completely ameliorate the disease, suggesting another receptor. In search for another IL-17A-interacting receptor, we found that IL-17RD directly bound IL-17A but not IL-17F or IL-17A/F heterodimer and formed a heterodimer with IL-17RA. IL-17A-, but not IL-17F- or IL-17A/F-, mediated gene expression was defective in Il17rd-deficient keratinocytes. Il17rd deficiency in nonhemopoietic cells attenuated imiquimod-induced psoriasis-like skin inflammation. Although IL-17RC and IL-17RD differentially activated IL-17A-dependent signaling and gene expression, their compound mutation led to complete deficits in keratinocytes. IL-23 was found induced by IL-17A in keratinocytes, dependent on both IL-17RC and IL-17RD, suggesting feed-forward regulation of IL-23/IL-17 axis in psoriasis. Together, IL-17RD constitutes a second functional receptor for IL-17A and, together with IL-17RC, mediates the proinflammatory gene expression downstream of IL-17A.

Development and validation of a survival model for lung adenocarcinoma based on autophagy-associated genes

BACKGROUND

Given that abnormal autophagy is involved in the pathogenesis of cancers, we sought to explore the potential value of autophagy-associated genes in lung adenocarcinoma (LUAD).

METHODS

RNA sequencing and clinical data on tumour and normal samples were acquired from The Cancer Genome Atlas (TCGA) database and randomly assigned to training and testing groups. Differentially expressed autophagy-associated genes (AAGs) were screened. Within the training group, Cox regression and Lasso regression analyses were conducted to screen five prognostic AAGs, which were used to develop a model. Kaplan-Meier (KM) and receiver operating characteristic (ROC) curves were plotted to determine the performance of the model in both groups. Immunohistochemistry was used to demonstrate the differential expression of AAGs in tumour and normal tissues at the protein level. Gene Ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were utilized to further elucidate the roles of AAGs in LUAD.

RESULTS

The data from the TCGA database included 497 tumour and 54 normal samples, within which 30 differentially expressed AAGs were screened. Using Cox regression and Lasso regression analyses for the training group, 5 prognostic AAGs were identified and the prognostic model was constructed. Patients with low risk had better overall survival (OS) in the training group (3-year OS, 73.0% vs 48.0%; 5-year OS, 45.0% vs 33.8%; P = 1.305E-04) and in the testing group (3-year OS, 66.8% vs 41.2%; 5-year OS, 31.7% vs 25.8%; P = 1.027E-03). The areas under the ROC curves (AUC) were significant for both the training and testing groups (3-year AUC, 0.810 vs 0.894; 5-year AUC, 0.792 vs 0.749).

CONCLUSIONS

We developed a survival model for LUAD and validated the performance of the model, which may provide superior outcomes for the patients.

IL-17C/IL-17RE: Emergence of a Unique Axis in TH17 Biology

Therapeutic targeting of IL-17A and its receptor IL-17RA with antibodies has turned out to be a tremendous success in the treatment of several autoimmune conditions. As the IL-17 cytokine family consists of six members (IL-17A to F), it is intriguing to elucidate the biological function of these five other molecules to identify more potential targets. In the past decade, IL-17C has emerged as quite a unique member of this pro-inflammatory cytokine group. In contrast to the well-described IL-17A and IL-17F, IL-17C is upregulated at very early timepoints of several disease settings. Also, the cellular source of the homodimeric cytokine differs from the other members of the family: Epithelial rather than hematopoietic cells were identified as the producers of IL-17C, while its receptor IL-17RE is expressed on T_H17 cells as well as the epithelial cells themselves. Numerous investigations led to the current understanding that IL-17C (a) maintains an autocrine loop in the epithelium reinforcing innate immune barriers and (b) stimulates highly inflammatory T_H17 cells. Functionally, the IL-17C/RE axis has been described to be involved in the pathogenesis of several diseases ranging from infectious and autoimmune conditions to cancer development and progression. This body of evidence has paved the way for the first clinical trials attempting to neutralize IL-17C in patients. Here, we review the latest knowledge about identification, regulation, and function of the IL-17C/IL-17receptor E pathway in inflammation and immunity, with a focus on the mechanisms underlying tissue injury. We also discuss the rationale for the translation of these findings into new therapeutic approaches in patients with immune-mediated disease.

The IL-17 Family of Cytokines in Health and Disease

The interleukin 17 (IL-17) family of cytokines contains 6 structurally related cytokines, IL-17A through IL-17F. IL-17A, the prototypical member of this family, just passed the 25^th anniversary of its discovery. Although less is known about IL-17B-F, IL-17A (commonly known as IL-17) has received much attention for its pro-inflammatory role in autoimmune disease. Over the past decade, however, it has become clear that the functions of IL-17 are far more nuanced than simply turning on inflammation. Accumulating evidence indicates that IL-17 has important context- and tissue-dependent roles in maintaining health during response to injury, physiological stress, and infection. Here, we discuss the functions of the IL-17 family, with a focus on the balance between the pathogenic and protective roles of IL-17 in cancer and autoimmune disease, including results of therapeutic blockade and novel aspects of IL-17 signal transduction regulation.

IL-17 in the immunopathogenesis of spondyloarthritis

Spondyloarthritis (SpA) is a term that refers to a group of inflammatory diseases that includes psoriatic arthritis, axial SpA and nonradiographic axial SpA, reactive arthritis, enteropathic arthritis and undifferentiated SpA. The disease subtypes share clinical and immunological features, including joint inflammation (peripheral and axial skeleton); skin, gut and eye manifestations; and the absence of diagnostic autoantibodies (seronegative). The diseases also share genetic factors. The aetiology of SpA is still the subject of research by many groups worldwide. Evidence from genetic, experimental and clinical studies has accumulated to indicate a clear role for the IL-17 pathway in the pathogenesis of SpA. The IL-17 family consists of IL-17A, IL-17B, IL-17C, IL-17D, IL-17E and IL-17F, of which IL-17A is the best studied. IL-17A is a pro-inflammatory cytokine that also has the capacity to promote angiogenesis and osteoclastogenesis. Of the six family members, IL-17A has the strongest homology with IL-17F. In this Review, we discuss how IL-17A and IL-17F and their cellular sources might contribute to the immunopathology of SpA.

Molecular cloning, expression and biological activity of rhesus macaque interleukin-17A and interleukin-17F

Interleukin-17A (IL-17A) and interleukin-17F (IL-17F) as two potent proinflammatory cytokines and the signature cytokines of Th17 cells play important roles in human autoimmune diseases, inflammation and host defenses. In this study, rhesus macaque IL-17A (rhIL-17A) and IL-17F (rhIL-17F) were cloned and expressed, and their biological activities and in vivo distribution were examined. The resulting data showed that both the rhIL-17A and rhIL-17F genes were consisted of three exons and two introns. RhIL-17A and rhIL-17F shared 96.8% and 93.9% amino acid sequence identity with human IL-17A (huIL-17A) and IL-17F (huIL-17F) respectively and the sequences also shared one N-glycosylation site and six conserved cysteine residues with huIL-17A and huIL-17F. IL-17A and IL-17F transcripts were highly expressed in lymphoid tissues and the intestinal tract of rhesus macaques. Functionally, recombinant rhIL-17A and rhIL-17F showed similar effect on Act1 levels and NF-κB phosphorylation compared with that of commercial human IL-17A and IL-17F. Moreover, the antibacterial proteins (such as β-defensin 2, S100A8, S100A9, RegIIIα and Muc1) and the tight junction associated genes (including CLDN1, CLDN4, OCLN, and ZO1) expressed by Caco-2 cells were largely enhanced after treatment with rhIL-17A and rhIL-17F. Meanwhile, purified rhIL-17A and rhIL-17F could also induce the expression of IL-6 and TNF-α by THP-1 cells. These data indicated that rhesus macaque IL-17A and IL-17F are highly similar to that of humans in both structure and function. Studies on rhIL-17A/rhIL-17F are promising approach to contribute to the understanding of human IL-17A and IL-17F-related intestinal diseases.

Sequence characterization and expression pattern analysis of six kinds of IL-17 family genes in the Asian swamp eel (Monopterus albus)

Interleukin-17 (IL-17) is an important cytokine that plays a critical role in the inflammatory response and host defense against extracellular pathogens. In the present study, six novel IL-17 family genes (MaIL-17) were identified by analyzing Asian swamp eel (Monopterus albus) genome. Sequence analysis revealed that the MaIL-17 family genes shared similar features, comprising a signal peptide, an IL-17 superfamily region, and four conserved cysteines. Phylogenetic analysis showed that the MaIL-17 genes were clustered together with their corresponding IL-17 genes from other species. The similarity and identity of all IL-17 family genes indicated that the MaIL-17 genes are conserved among teleosts, while Ma-IL-17D is more conserved than the other Ma-IL-17s. Except for MaIL-17A/F3 and MaIL-17D, all MaIL-17s shared the same genomic structure as the genes from other fish, namely three exons and two introns. The MaIL-17s showed conserved synteny among fish, and we found that the MaIL-17D locus has a more conserved syntenic relationship with the loci from other fish and humans. These results demonstrated that MaIL-17D and human IL-17D might have evolved from a common ancestral gene and subsequently diverged. The analysis of swamp eel reference genes revealed that EEF1A1 (encoding eukaryotic translation elongation factor 1 alpha 1) was an ideal reference gene for accurate real-time qRT-PCR normalization in the swamp eel. The MaIL-17 genes are widely distributed throughout tissues, suggesting that MaIL-17s carry out their biological functions in immune and non-immune tissues compartments. The transcript of Ma-IL17s exhibited different fold changes in head kidney cells in response to Aeromonas veronii phorbol 12-myristate 13-acetate (PMA) and polyinosinic:polycytidylic acid (poly I:C) challenge, showing that MaIL-17A/F1 has stronger antiviral activities compared with other MaIL-17 family genes, and that MaIL-17A/F3 and MaIL-17A/F2 possess stronger effects against extracellular pathogens compared with the others; however, MaIL-17C2 and MaIL-17D may play vital roles during pathogen infection. The differential immune responses of these genes to Aeromonas veronii, PMA and poly I:C implied distinct mechanisms of host defense against extracellular pathogens.

Association of genetic polymorphism of interleukin-17A & interleukin-17F with susceptibility of psoriasis

Background & objectives:

Psoriasis is a chronic inflammatory skin disease with unknown aetiology. So far studies have confirmed that interleukins, pro-inflammatory factors and T-cell activation play major role in the development of disease. Interleukin-17 (IL-17) a T helper inflammatory cytokine, was found to be positively correlated with severity of psoriasis. However, the specific mechanism has not been clarified. IL-17A and IL-17F are group members of IL17 family cytokines and found to be located adjacent to one another on the same human chromosome, 6p12. The present study was designed to identify the association between IL-17A and IL-17F gene polymorphism with susceptibility of psoriasis in north Indian population.

Methods:

A total of 166 psoriasis patients and 150 healthy controls were genotyped for IL-17A and IL-17F gene polymorphism by amplification refractory mutation system-polymerase chain reaction method. One single nucleotide polymorphism (SNP) was analysed in IL-17A (rs10484879) and one SNP in IL-17F (rs763780) to look for an association with psoriasis.

Results:

Our study indicated decreased frequency of IL-17A (rs10484879) G allele (51.8 vs. 65.0%), and IL-17F (rs763780) C allele (36.5 vs. 45.7%) in psoriatic patients as compared to healthy controls.

Interpretation & conclusions:

The present findings suggest that IL-17A (rs10484879) G/T and IL-17F (rs763780) C/T gene polymorphisms may contribute in pathogenesis of psoriasis. Further studies need to be done to confirm these findings.

Spotlight on brodalumab in the treatment of plaque psoriasis: the evidence to date

The IL-17/IL-23 axis is now understood to influence psoriasis, and the development of novel IL-17 inhibitor medications marks a sea change in the treatment of psoriasis. Brodalumab is a recombinant, fully human immunoglobulin IgG2 monoclonal antibody specifically targeted against IL-17RA. This article discusses the mechanism of action and the efficacy and safety profile of brodalumab presented in the literature. Brodalumab, the latest approved anti-IL-17-class medication, is the only one that exerts its effects on IL-17C as well as on IL-17A and IL-17F, blocking the shared IL-17 receptor A. In this sense, considering the recent evidence, brodalumab could have beneficial effects not only on psoriasis, but also on atopic dermatitis. It could also serve as a therapeutic alternative in patients who develop paradoxical eczematous reactions or atopic-like dermatitis during treatment with other anti-IL-17A (secukinumab, ixekizumab).

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IL-17 inhibition in axial spondyloarthritis: current and future perspectives

INTRODUCTION

Interleukin (IL)-17 is a proinflammatory cytokine considered to play a significant role in the immunopathogenesis of ankylosing spondylitis (AS)/axial spondyloarthritis (axSpA) as well as of other spondyloarthritides. There is a number of substances targeting IL-17, which are at different stages of development in the axSpA indication.

AREAS COVERED

This review summarizes the current evidence on the role of IL-17 in the pathophysiology of axSpA and provided a comprehensive review of clinical and radiographic outcomes as well as of safety data from studies with IL-17A inhibitors secukinumab and ixekizumab. Ongoing studies on other IL-17 inhibitors (bimekizumab, brodalumab and BCD-085) that are being developed are also summarized.

EXPERT OPINION

The development of the IL-17 inhibitors has expanded AS treatment with effective options and confirmed the pathophysiological role of IL-17 in axSpA. IL-17 inhibition showed sufficient efficacy against signs and symptoms of the disease even after the failure of tumor necrosis factor inhibitors, being at the same time reasonably safe.

A randomized, double-blind, placebo-controlled phase 1 study of multiple ascending doses of subcutaneous M1095, an anti-interleukin 17A/F nanobody, in moderate-to-severe psoriasis

BACKGROUND

Interleukin 17 is involved in the pathogenesis of psoriasis, a chronic debilitating disease.

OBJECTIVES

To evaluate the safety/tolerability, immunogenicity, pharmacokinetics/pharmacodynamics, and efficacy of M1095, an anti-interleukin 17A/F nanobody, in moderate-to-severe plaque psoriasis.

METHODS

This multicenter, double-blind, placebo-controlled dose escalation phase 1 study randomized 44 patients 4:1 to treatment with subcutaneous M1095 (30, 60, 120, or 240 mg) or placebo biweekly for 6 weeks, in 4 ascending dose cohorts.

RESULTS

The most frequent treatment-emergent adverse events with M1095 were pruritus (n = 4) and headache (n = 3); 2 patients withdrew owing to adverse events (injection site reaction and elevated liver enzyme levels). The terminal half-life of M1095 was 11 to 12 days. The area under the curve/maximum concentration was dose proportional. Of 10 M1095-treated patients positive for antidrug antibodies, 5 showed treatment-emergent antidrug antibody responses. There was no effect on M1095 exposure. Marked decreases in psoriasis inflammatory markers were observed with M1095. By day 85, 100% and 56% of patients receiving M1095, 240 mg, achieved psoriasis area and severity index 90 and 100, respectively. Improvements in static Physician's Global Assessment and affected body surface area were also seen.

LIMITATIONS

Interpretation of efficacy data is limited by the small sample size.

CONCLUSION

Multiple subcutaneous doses of M1095 showed a favorable safety profile with dose-dependent improvements in psoriasis.

Regulation of IL-17A and implications for TGF-β1 comodulation of airway smooth muscle remodeling in severe asthma

Severe asthma develops as a result of heightened, persistent symptoms that generally coincide with pronounced neutrophilic airway inflammation. In individuals with severe asthma, symptoms are poorly controlled by high-dose inhaled glucocorticoids and often lead to elevated morbidity and mortality rates that underscore the necessity for novel drug target identification that overcomes limitations in disease management. Many incidences of severe asthma are mechanistically associated with T helper 17 (T_H17) cell-derived cytokines and immune factors that mediate neutrophilic influx to the airways. T_H17-secreted interleukin-17A (IL-17A) is an independent risk factor for severe asthma that impacts airway smooth muscle (ASM) remodeling. T_H17-derived cytokines and diverse immune mediators further interact with structural cells of the airway to induce pathophysiological processes that impact ASM functionality. Transforming growth factor-β1 (TGF-β1) is a pivotal mediator involved in airway remodeling that correlates with enhanced T_H17 activity in individuals with severe asthma and is essential to T_H17 differentiation and IL-17A production. IL-17A can also reciprocally enhance activation of TGF-β1 signaling pathways, whereas combined T_H1/T_H17 or T_H2/T_H17 immune responses may additively impact asthma severity. This review seeks to provide a comprehensive summary of cytokine-driven T cell fate determination and T_H17-mediated airway inflammation. It will further review the evidence demonstrating the extent to which IL-17A interacts with various immune factors, specifically TGF-β1, to contribute to ASM remodeling and altered function in T_H17-driven endotypes of severe asthma.

Treating to Target(s) With Interleukin-17 Inhibitors

Background:

The treat-to-target (T2T) strategy has become established in several medical specialties as a key guidance to optimal therapeutic decision making. T2T may be effective in the assessment of the biologic class of agents called interleukin (IL)-17 inhibitors, which are emerging as a safe and effective treatment option for autoimmune inflammatory conditions such as plaque psoriasis, psoriatic arthritis (PsA), and ankylosing spondylitis (AS).

Objective:

The objective of this article is to use a T2T approach for the evaluation of the effectiveness and safety of IL-17 inhibitors in the management of patients with plaque psoriasis, PsA, and AS.

Methods:

Following a comprehensive literature search, a full-day meeting was convened to discuss and identify the T2T targets for psoriasis, PsA, and AS. Clinical trial evidence was presented for the approved IL-17 inhibitors—secukinumab, ixekizumab, and brodalumab—to assess whether these data meet T2T safety and efficacy targets.

Results:

All 3 approved agents were significantly superior to placebo and active controls in the achievement of T2T targets for psoriasis. Secukinumab and ixekizumab were likewise associated with significantly better outcomes than controls in the PsA targets, and secukinumab resulted in significant AS target improvements vs placebo. The IL-17 inhibitors were also associated with low rates of serious adverse events and exacerbations of common comorbid conditions.

Conclusion:

Phase III trial results support the T2T benefit and safety of IL-17 inhibitors according to their specific indications for the management of patients with plaque psoriasis, PsA, and AS.

Transition from metal-DTH resistance to susceptibility is facilitated by NLRP3 inflammasome signaling induced Th17 reactivity: Implications for orthopedic implants

Metal hypersensitivity has been recognized as an adverse biologic reaction that can compromise total joint arthroplasty (TJA) performance. However, the etiology of metal hypersensitivity responses in TJAs remains unclear. Metal implant debris is known to act as a danger signal that drives NLRP3 inflammasome activation. It remains unknown if implant debris induced inflammasome activation regulates T cell lineage in TJA metal hypersensitivity responses. In this study, we show both in vivo and in vitro that the pathogenesis of metal hypersensitivity responses to implant debris are largely dependent on activation of the inflammasome/caspase-1 pathway and subsequent production of IL-17A/F by CD4+ T cells. Inhibiting either the inflammasome pathway or IL-17A bioactivity in vivo and in vitro (in vivo using NLRP3 and Caspase-1 deficient mice or in vitro using blocking agents such as Capase-1 inhibitor, IL-1Ra and anti-IL-17A), significantly (p<0.05) mitigated metal-DTH paw inflammation as well as lymphocyte cytokine (IFN-γ and IL-17) and proliferation responses in metal-sensitized mice and primary human PBMCs. This study provides mechanistic insight into how in vivo exposure to orthopedic implant debris, and metals in general, elicits NLRP3 inflammasome activation that mediates the generation of IL-17A/F producing CD4+ T cells, leading to metal-delayed type hypersensitivity reactions.