Structure and function of interleukin-17 family cytokines

Biomarkers in Detection of Hepatitis C Virus Infection

The hepatitis C virus (HCV) infection affects 58 million people worldwide. In the United States, the incidence rate of acute hepatitis C has doubled since 2014; during 2021, this increased to 5% from 2020. Acute hepatitis C is defined by any symptom of acute viral hepatitis plus either jaundice or elevated serum alanine aminotransferase (ALT) activity with the detection of HCV RNA, the anti-HCV antibody, or hepatitis C virus antigen(s). However, most patients with acute infection are asymptomatic. In addition, ALT activity and HCV RNA levels can fluctuate, and a delayed detection of the anti-HCV antibody can occur among some immunocompromised persons with HCV infection. The detection of specific biomarkers can be of great value in the early detection of HCV infection at an asymptomatic stage. The high rate of HCV replication (which is approximately 1010 to 1012 virions per day) and the lack of proofreading by the viral RNA polymerase leads to enormous genetic diversity, creating a major challenge for the host immune response. This broad genetic diversity contributes to the likelihood of developing chronic infection, thus leading to the development of cirrhosis and liver cancer. Direct-acting antiviral (DAA) therapies for HCV infection are highly effective with a cure rate of up to 99%. At the same time, many patients with HCV infection are unaware of their infection status because of the mostly asymptomatic nature of hepatitis C, so they remain undiagnosed until the liver damage has advanced. Molecular mechanisms induced by HCV have been intensely investigated to find biomarkers for diagnosing the acute and chronic phases of the infection. However, there are no clinically verified biomarkers for patients with hepatitis C. In this review, we discuss the biomarkers that can differentiate acute from chronic hepatitis C, and we summarize the current state of the literature on the useful biomarkers that are detectable during acute and chronic HCV infection, liver fibrosis/cirrhosis, and hepatocellular carcinoma (HCC).

The role of inflammatory mediators and matrix metalloproteinases (MMPs) in the progression of osteoarthritis

Osteoarthritis (OA) is a chronic musculoskeletal disorder characterized by an imbalance between (synthesis) and catabolism (degradation) in altered homeostasis of articular cartilage mediated primarily by the innate immune system. OA degenerates the joints resulting in synovial hyperplasia, degradation of articular cartilage with damage of the structural and functional integrity of the cartilage extracellular matrix, subchondral sclerosis, osteophyte formation, and is characterized by chronic pain, stiffness, and loss of function. Inflammation triggered by factors like biomechanical stress is involved in the development of osteoarthritis. In OA apart from catabolic effects, anti-inflammatory anabolic processes also occur continually. There is also an underlying chronic inflammation present, not only in cartilage tissue but also within the synovium, which perpetuates tissue destruction of the OA joint. The consideration of inflammation in OA considers synovitis and/or other cellular and molecular events in the synovium during the progression of OA. In this review, we have presented the progression of joint degradation that results in OA. The critical role of inflammation in the pathogenesis of OA is discussed in detail along with the dysregulation within the cytokine networks composed of inflammatory and anti-inflammatory cytokines that drive catabolic pathways, inhibit matrix synthesis, and promote cellular apoptosis. OA pathogenesis, fluctuation of synovitis, and its clinical impact on disease progression are presented here along with the role of synovial macrophages in promoting inflammatory and destructive responses in OA. The role of interplay between different cytokines, structure, and function of their receptors in the inter-cellular signaling pathway is further explored. The effect of cytokines in the increased synthesis and release of matrix-decomposing proteolytic enzymes, such as matrix metalloproteinase (MMPs) and a disintegrin-like and metalloproteinase with thrombospondin motif (ADAMTS), is elaborated emphasizing the potential impact of MMPs on the chondrocytes, synovial cells, articular and periarticular tissues, and other immune system cells migrating to the site of inflammation. We also shed light on the pathogenesis of OA via oxidative damage particularly due to nitric oxide (NO) via its angiogenic response to inflammation. We concluded by presenting the current knowledge about the tissue inhibitors of metalloproteinases (TIMPs). Synthetic MMP inhibitors include zinc binding group (ZBG), non-ZBG, and mechanism-based inhibitors, all of which have the potential to be therapeutically beneficial in the treatment of osteoarthritis. Improving our understanding of the signaling pathways and molecular mechanisms that regulate the MMP gene expression, may open up new avenues for the creation of therapies that can stop the joint damage associated with OA.

IL-23/IL-17 in a Paradoxical Association with Primary Membranous Nephropathy

Primary membranous nephropathy (PMN), an autoimmune disease, is the most common cause of nephrotic syndrome in middle-aged non-diabetic adults. PMN pathophysiology includes Th1/Th2 paradigm. The IL-23/IL-17 pathway is implicated in autoimmune kidney disorders, but no study has examined its relationship with PMN. In several unrelated studies, PMN patients reported to have paradoxical IL-17 levels. This manuscript describes the best possible association of IL-23/IL-17 axis with PMN. Biopsy-proven PMN patients and age, gender-matched healthy controls were enrolled. Serum-PLA2R (Euroimmune, Germany), IL-23 and IL-17 (R&D; USA), was measured using ELISA along with biochemical parameters. Appropriate statistical tools were used for analysis. One hundred eighty-nine PMN patients (mean age 41.70 ± 12.53 years) and 100 controls (mean age 43.92 ± 10.93 years) were identified. One hundred forty were PLA2R-related. PMN patients had median proteinuria, serum albumin, and creatinine of 6.12 (3.875, 9.23) g/day, 2.32 (1.96, 2.9) g/dl, and 0.89 (0.7, 1.1) mg/dl, respectively. IL-17, but not IL-23, was significantly increased in PMN patients compared to controls (IL-17, median: 12.07 pg/ml (9.75, 24.56) vs median: 9.75 pg/ml (8.23, 17.03) p = 0.0002); (IL23, median: 6.04 pg/ml (4.22, 10.82) vs median: 5.46 pg/ml (3.34, 9.96) p = 0.142). IL-17 and IL-23 correlated significantly (p 0.05) in PMN patients, and similar trend was seen when grouped into PLA2R-related and -unrelated groups. The levels of IL-23 (p = 0.057) and IL-17 (p = 0.004) were high in MN patients that did not respond to the treatment. The current finding may indicate or suggest the involvement of IL-23/IL-17 PMN pathogenesis. A comprehensive investigation is needed to evaluate IL-23/IL-17 axis with renal infiltrating immune cells, and external stimuli.

Differential effects of interleukin-17A and 17F on cell interactions between immune cells and stromal cells from synovium or skin

We compared the contribution of IL-17A and IL-17F in co-culture systems mimicking cell interactions as found in inflamed synovium and skin. Synoviocytes or skin fibroblasts were co-cultured with activated PBMC, with IL-17A, IL-17 A/F, IL-17F, IL-23, anti-IL-17A, anti-IL-17A/F or anti-IL-17F antibodies. IL-17A, IL-17F, IL-6 and IL-10 production was measured at 48 h. mRNA expression of receptor subunits for IL-23, IL-12 and IL-17 was assessed at 24 h. Both cell activation and interactions were needed for a high IL-17A secretion while IL-17F was stimulated by PHA activation alone and further increased in co-cultures. IL-17F levels were higher than IL-17A in both co-cultures (p < 0.05). IL-17F addition decreased IL-17A secretion (p < 0.05) but IL-17A addition had no effect on IL-17F secretion. Interestingly, IL-17A and IL-17F upregulated IL-17RA and IL-17RC mRNA expression in PBMC/skin fibroblast co-cultures (p < 0.05) while only IL-17F exerted this effect in synoviocytes (p < 0.05). Monocyte exclusion in both co-cultures increased IL-17A and IL-17F (twofold, p < 0.05) while decreasing IL-10 and IL-6 secretion (twofold, p < 0.05). IL-17A and F had differential effects on their receptor expression with a higher sensitivity for skin fibroblasts highlighting the differential contribution of IL-17A and F in joint vs. skin diseases.

The paradigm of IL-23-independent production of IL-17F and IL-17A and their role in chronic inflammatory diseases

Interleukin-17 family (IL-17s) comprises six structurally related members (IL-17A to IL-17F); sequence homology is highest between IL-17A and IL-17F, displaying certain overlapping functions. In general, IL-17A and IL-17F play important roles in chronic inflammation and autoimmunity, controlling bacterial and fungal infections, and signaling mainly through activation of the nuclear factor-kappa B (NF-κB) pathway. The role of IL-17A and IL-17F has been established in chronic immune-mediated inflammatory diseases (IMIDs), such as psoriasis (PsO), psoriatic arthritis (PsA), axial spondylarthritis (axSpA), hidradenitis suppurativa (HS), inflammatory bowel disease (IBD), multiple sclerosis (MS), and asthma. CD4+ helper T cells (Th17) activated by IL-23 are well-studied sources of IL-17A and IL-17F. However, other cellular subtypes can also produce IL-17A and IL-17F, including gamma delta (γδ) T cells, alpha beta (αβ) T cells, type 3 innate lymphoid cells (ILC3), natural killer T cells (NKT), or mucosal associated invariant T cells (MAIT). Interestingly, the production of IL-17A and IL-17F by innate and innate-like lymphocytes can take place in an IL-23 independent manner in addition to IL-23 classical pathway. This would explain the limitations of the inhibition of IL-23 in the treatment of patients with certain rheumatic immune-mediated conditions such as axSpA. Despite their coincident functions, IL-17A and IL-17F contribute independently to chronic tissue inflammation having somehow non-redundant roles. Although IL-17A has been more widely studied, both IL-17A and IL-17F are overexpressed in PsO, PsA, axSpA and HS. Therefore, dual inhibition of IL-17A and IL-17F could provide better outcomes than IL-23 or IL-17A blockade.

A new method for the treatment of myocardial ischemia-reperfusion injury based on γδT cell-mediated immune response

Acute myocardial ischemia is a disease with high morbidity and mortality, and re-perfusion is currently the best intervention. However, re-perfusion may lead to further myocardial injury and increase the area of myocardial infarction. The mechanism of myocardial ischemia-re-perfusion injury is complex, but with more in-depth study, it has been proved that the immune system plays an important role in the process of MIRI. Among them, the γδT cell population has received increasing attention as the main early source of IL-17A in many immune response models. Because γδT cells have the characteristics of linking innate immunity and adaptive immunity,they can rapidly produce IL-17A and produce subsequent immune killing of cardiomyocytes. It can be seen that γδT cells play an important role in MIRI. Therefore, here we review the research progress of immune response in myocardial ischemia-re-perfusion injury, the key characteristics of γδT cells and the role of rapidly produced IL-17 in myocardial ischemia-re-perfusion injury, and propose relevant treatment strategies and prospects for myocardial repair, in order to provide new ideas and methods for clinical treatment of myocardial ischemia-re-perfusion injury.

The protective and pathogenic role of Th17 cell plasticity and function in the tumor microenvironment

At the turn of the century, researchers discovered a unique subtype of T helper cells that secretes IL-17 and defined it as Th17. The latest study found that Th17 cells play both positive and negative definitive roles in the regulation of antitumor immune responses. Although the function of Th17 in the tumor microenvironment remains poorly understood, more and more studies have shown that this paradoxical dual role is closely related to the plasticity of Th17 cells in recent decades. Further understanding of the characteristics of Th17 cells in the tumor microenvironment could yield novel and useful therapeutic approaches to treat cancer. In this review, we further present the high plasticity of Th17 cells and the function of Th17-producing IL-17 in tumor immunity.

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.

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.

Molecular cloning, expression analysis of interleukin 17D (cysteine knot cytokine) from Amphiprion clarkii and their functional characterization and NFκB pathway activation using FHM cells

Interleukin 17D (IL-17D), a pro-inflammatory cytokine, is a signature cytokine of T helper 17 (Th17) cells. However, studies characterizing the functions of IL-17D in teleost are scarce. Therefore, we aimed to characterize the properties of IL-17D in Amphiprion clarkii. We performed spatial and temporal expression, AcIL-17D-mediated antibacterial and inflammatory gene expression, NFκB pathway-related gene expression analyses, and bacterial colony counting and cell protection assays. We found that AcIL-17D contains a 630 bp coding sequence and encodes 210 amino acids. The spatial expression analysis of AcIL-17D in 12 tissues showed ubiquitous expression, with the highest expression in the brain, followed by blood and skin. Temporal expression analysis of AcIL-17D in blood showed upregulated expression at 6 and 24 h (polyinosinic: polycytidylic acid and lipopolysaccharide), 12 h (all stimulants), and 48 h (polyinosinic: polycytidylic acid and Vibrio harveyi). AcIL-17D expression in the blood gradually decreased at later hours in response to all the stimulants. After treatment of fathead minnow (FHM) cells with different recombinant AcIL-17D concentrations, the downstream gene expression analysis showed increased expression of antimicrobial genes in the FHM cells, namely [NK-Lysin (NKL), Hepcidin antimicrobial peptide-1 (HAMP-1), Defensin-β (DEFB1)] and some inflammatory genes such as IL-1β, TNF-α, IL-11, and STAT3. Further nuclear factor κB (NFκB) subunits (NFκB1, NFκB2, RelA, and Rel-B) showed upregulated gene expression at 12 and 24 h. The bacterial colony counting assay using FHM cells showed lower bacterial colony counts in rAcIL-17D-treated cells than in control. Furthermore, the Water-Soluble Tetrazolium Salt (WST -1) assay confirmed the ability of rAcIL-17D in the protection of FHM cells from bacterial infection and conducted the Hoechst 33342 staining upon treatment with rAcIL-17D and rMBP. Therefore, our findings provide important insights into the activation of IL-17D pathway genes in FHM cells, the protective role of AcIL-17D against bacterial infection, and host defense mechanisms in teleost.

Cartilage tissue engineering: From proinflammatory and anti‑inflammatory cytokines to osteoarthritis treatments (Review)

Osteoarthritis (OA), one of the most common joint diseases, is characterized by fibrosis, rhagadia, ulcers and attrition of articular cartilage due to a number of factors. The etiology of OA remains unclear, but its occurrence has been associated with age, obesity, inflammation, trauma and genetic factors. Inflammatory cytokines are crucial for the occurrence and progression of OA. The intra-articular proinflammatory and anti-inflammatory cytokines jointly maintain a dynamic balance, in accordance with the physiological metabolism of articular cartilage. However, dynamic imbalance between proinflammatory and anti-inflammatory cytokines can cause abnormal metabolism in knee articular cartilage, which leads to deformation, loss and abnormal regeneration, and ultimately destroys the normal structure of the knee joint. The ability of articular cartilage to self-repair once damaged is limited, due to its inability to obtain nutrients from blood vessels, nerves and lymphatic vessels, as well as limitations in the extracellular matrix. There are several disadvantages inherent to conventional repair methods, while cartilage tissue engineering (CTE), which combines proinflammatory and anti-inflammatory cytokines, offers a new therapeutic approach for OA. The aim of the present review was to examine the proinflammatory factors implicated in OA, including IL-1β, TNF-α, IL-6, IL-15, IL-17 and IL-18, as well as the key anti-inflammatory factors reducing OA-related articular damage, including IL-4, insulin-like growth factor and TGF-β. The predominance of proinflammatory over anti-inflammatory cytokine effects ultimately leads to the development of OA. CTE, which employs mesenchymal stem cells and scaffolding technology, may prevent OA by maintaining the homeostasis of pro- and anti-inflammatory factors.

The Role of IL-17 Cytokines in Psoriasis

Psoriasis is a chronic inflammatory skin condition associated with immune dysregulation. The immunologic cascade mediated by the interleukin (IL)-17 pathway plays a critically important role in the pathogenesis of psoriasis. The IL-17 effectors (IL-17A, IL-17C, IL-17E, and IL17F) act on keratinocytes, endothelial cells, and immune cells to stimulate epidermal hyperplasia and the pro-inflammatory feed-forward cycle seen within plaque psoriasis. The IL-17 pathway is also hypothesized to modulate the inflammatory responses linking comorbid systemic diseases with psoriasis. Furthermore, the robust clinical response seen with current and emerging therapies targeting IL-17 emphasizes the importance of the IL-17 cytokines in the pathogenesis of psoriasis.

Evaluation of the effect of the interleukin-25 serum concentration on the intensity of the symptoms of atopic dermatitis and epidermal barrier

Introduction

Interleukin 25 (IL-25) is a cytokine with proinflammatory and anti-inflammatory effects, and its biological function of reciprocal epidermal hyperplasia and of inhibiting the filaggrin synthesis points to an essential role connecting the inflammatory process with damage to the epidermal barrier in the course of atopic dermatitis (AD).

Aim

To assess the IL-25 in serum concentration in AD patients and to analyse its possible correlation with the disease intensity and selected epidermal barrier parameters such as transepidermal water loss (TEWL).

Material and methods

The study involved 43 patients with AD and 22 healthy volunteers. The IL-25 concentration was measured using the ELISA method. The intensity of disease symptoms was investigated using W-AZS and EASI indicators. The epidermal barrier was evaluated using a Tewameter TM300 and Corneometer CM825.

Results

The concentration of IL-25 in serum was higher in the study group than in the control group. IL-25 serum concentration correlates with W-AZS/EASI in patients with a severe and moderate course of AD. The concentration of IL-25 affects the TEWL within the affected, evaluated skin surface.

Conclusions

An elevated IL-25 concentration in serum is characteristic for patients with moderate and severe AD intensity. The IL-25 concentration in serum correlates with TEWL and with the moisture level in the affected area. However, further studies are necessary to determine the role played by IL-25 in the course of the disease and how it affects the functional parameters of the epidermal barrier.

The role of interleukin-1β in the immune response to contact allergens

Interleukin-1β (IL-1β) is an important pro-inflammatory cytokine that has an effect on almost every cell lineage in the body. By blocking IL-1β and investigating the IL-1β signaling pathway, several studies have demonstrated a central role of IL-1β in the response to contact allergens. This review summarizes the current literature regarding the basic immunological mechanisms mediated by IL-1β in the different phases of allergic contact dermatitis (ACD) and highlights potential IL-1β-targeted treatment options, which in the future may be relevant in the treatment of patients with ACD. This review is based primarily on studies using various mouse models and human in vitro studies, since clinical studies on the effect of IL-1β in ACD are lacking.

The Evolution and Diversity of Interleukin-17 Highlight an Expansion in Marine Invertebrates and Its Conserved Role in Mucosal Immunity

The interleukin-17 (IL-17) family consists of proinflammatory cytokines conserved during evolution. A comparative genomics approach was applied to examine IL-17 throughout evolution from poriferans to higher vertebrates. Cnidaria was highlighted as the most ancient diverged phylum, and several evolutionary patterns were revealed. Large expansions of the IL-17 repertoire were observed in marine molluscs and echinoderm species. We further studied this expansion in filter-fed Mytilus galloprovincialis, which is a bivalve with a highly effective innate immune system supported by a variable pangenome. We recovered 379 unique IL-17 sequences and 96 receptors from individual genomes that were classified into 23 and 6 isoforms after phylogenetic analyses. Mussel IL-17 isoforms were conserved among individuals and shared between closely related Mytilidae species. Certain isoforms were specifically implicated in the response to a waterborne infection with Vibrio splendidus in mussel gills. The involvement of IL-17 in mucosal immune responses could be conserved in higher vertebrates from these ancestral lineages.

Comparing the efficacy and safety of IL-17 inhibitors for treatment of moderate-to-severe psoriasis: a randomized double blind pilot study with a review of literature

Introduction

Psoriasis is a chronic skin disease in which interleukin-17A (IL-17A) has been found to play an important role. Commercially available anti-IL-17 drugs include brodalumab, ixekizumab (IXE), and secukinumab (SEC).

Aim

To compare the safety and efficacy of IXE and SEC in patients with moderate-to-severe plaque psoriasis.

Material and methods

The patients were randomized to the IXE or SEC group. Effectiveness was estimated by Physician's Global Assessment (PGA), Psoriasis Area and Severity Index (PASI), and Dermatology Life Quality Index (DLQI). Safety was assessed by documentation of adverse effects (AEs), routine laboratory values, and injection-site and allergic reactions.

Results

There were 155 patients in the IXE group and 158 in the SEC group. At week 12, PASI 75 was 76.77% (IXE) vs. 67.09% (SEC); PASI 90 42.58% (IXE) vs. 32.28% (SEC); PGA score of 0 or 1 at week 40 (79.52% vs. 74.4%) and at week 52 (61.83% vs. 58.12%) (p < 0.001). Also, DLQI score improvement was more pronounced in the IXE group. The rates and types of AEs were similar in both groups.

Conclusions

Although both groups demonstrated a robust clinical response, a significant improvement in patient quality of life, and a satisfactory safety profile, the IXE group scored a notch higher.

Interleukin-17 and Interleukin-23: A Narrative Review of Mechanisms of Action in Psoriasis and Associated Comorbidities

Psoriasis is an immune-mediated inflammatory skin disease associated with numerous inflammatory comorbidities, including increased cardiovascular risk. The interleukin (IL)-23/IL-17 axis plays a central role in the immunopathogenesis of psoriasis and related comorbidities by acting to stimulate keratinocyte hyperproliferation and feed-forwarding circuits of perpetual T cell-mediated inflammation. IL-17 plays an important role in the downstream portion of the psoriatic inflammatory cascade. This review discusses the distinct mechanisms of action of IL-17 and IL-23 in the immunopathogenesis of psoriasis and related comorbidities plus the significant therapeutic benefits of selectively inhibiting these cytokines in patients with moderate to severe plaque psoriasis.

Characterization of the Th17 profile immune response in cases of human rabies transmitted by dogs and its interference in the disease pathogenesis

The Th17 profile immune response is influenced by the presence of cytokines such as IL-1, IL-6, TGF-β, IL-17, and IL-23. We sought to characterize the Th17 profile in CNS samples from human rabies cases transmitted by dogs and examine its possible influence on disease pathogenesis. We observed a high expression of TGF-β, followed by IL-23, IL-17 and IL-6, and a low expression of IL-1β and IFN-γ. Those results suggest the participation of Th17 in rabies virus neuroinfection transmitted by dogs. IL-23 probably plays a role in maintaining the Th17 profile, but it can also interfere with the establishment of the Th1 profile and viral clearance.

Th1/Th17 Cytokine Profiles are Associated with Disease Severity and Exacerbation Frequency in COPD Patients

Background

T helper (Th) cell cytokine imbalances have been associated with the pathophysiology of chronic obstructive pulmonary disease (COPD), including the Th1/Th2 and Th17/T regulatory cells (Treg) paradigms. Clarifying cytokine profiles during COPD acute exacerbation (AE) and their relationships with clinical manifestations would help in understanding the pathogenesis of disease and improve clinical management.

Materials and Methods

Eighty seven patients admitted to the hospital with AEs of COPD were included in this study, and follow-up was conducted after discharge (every 30 days, for a total of 120 days). Sputum samples of patients at different time points (including at admission, discharge, and follow-up) were collected, and sputum cytokine profiling (12 cytokines in total) was performed using a Luminex assay.

Results

According to the cytokine profiles at admission, patients were divided into three clusters by a k-means clustering algorithm, namely, Th1_high Th17_high (n=26), Th1_lowTh17_low (n=56), and Th1_high Th17_low (n=5), which revealed distinct clinical characteristics. Patients with Th1_high Th17_low profile had a significantly longer length of non-invasive ventilation time and length of hospital stay than patients with Th1_high Th17_high profile (7 vs 0 days, 22 vs 11 days, respectively, p < 0.05), and had the highest AE frequency. Sputum levels of Th17 cytokines (IL-17A, IL-22, and IL-23) during AE were negatively correlated with AE frequency in the last 12 months (r = −0.258, −0.289 and −0.216, respectively, p < 0.05). Moreover, decreased sputum IL-17A levels were independently associated with increased AE frequency, with an OR (95% CI) of 0.975 (0.958–0.993) and p = 0.006.

Conclusion

Th1/Th17 imbalance during AE is associated with the severity of COPD. Decreased Th17 cytokine expression is correlated with increased AE frequency. The Th1/Th17 balance may be a specific target for the therapeutic manipulation of COPD.

Pathophysiological landscape of osteoarthritis

A sharp rise in osteoarthritis (OA) incidence is expected as over 25% of world population ages in the coming decade. Although OA is considered a degenerative disease, mounting evidence suggests a strong connection with chronic metabolic conditions and low-grade inflammation. OA pathology is increasingly understood as a complex interplay of multiple pathological events including oxidative stress, synovitis and immune responses revealing its intricate nature. Cellular, biochemical and molecular aspects of these pathological events along with major outcomes of the relevant research studies in this area are discussed in the present review. With reference to their published and unpublished work, the authors strongly propose synovitis as a central OA pathology and the key OA pathological events are described in connection with it. Recent research outcomes also have succeeded to establish a linkage between metabolic syndrome and OA, which has been precisely included in the present review. Impact of aging process cannot be neglected in OA. Cell senescence is an important mechanism of aging through which it facilitates development of OA like other degenerative disorders, also discussed within a frame of OA. Conclusively, the reviewers urge low-grade inflammation linked to aging and derailed immune function as a pathological platform for OA development and progression. Thus, interventions targeted to prevent inflammaging hold a promising potential in effective OA management and efforts should be invested in this direction.

IL-17A in Psoriasis and Beyond: Cardiovascular and Metabolic Implications

Interleukin 17A (IL-17A) is one of the currently known six members of the IL-17 cytokine family and is implicated in immune responses to infectious pathogens and in the pathogenesis of inflammatory autoimmune diseases like psoriasis. Psoriatic skin is characterized by high expression of IL-17A and IL-17F, which act on immune and non-immune cell types and strongly contribute to tissue inflammation. In psoriatic lesions, IL-17A, IL-17E, and IL-17F are involved in neutrophil accumulation, followed by the formation of epidermal micro abscesses. IL-17A together with other Th17 cytokines also upregulates the production of several chemokines that are implicated in psoriasis pathogenesis. IL17A-targeting antibodies show an impressive clinical efficacy in patients with psoriasis. Studies have reported an improvement of at least 75% as measured by the psoriasis area and severity index (PASI) in >80% of patients treated with anti-IL-17A therapy. Psoriasis skin manifestations, cardiovascular as well as metabolic disease in psoriasis appear to share pathogenic mechanisms evolving around IL-17A and its proinflammatory role. Thus, anti-IL-17A therapy not only improves skin manifestations of psoriasis, but also cardiovascular inflammation as well as metabolic factors and different domains of psoriatic arthritis (PsA) including peripheral arthritis, enthesitis, dactylitis, and axial involvement. This review summarizes the biological role of IL-17A, before reviewing currently available data on its role in the physiology and pathophysiology of the skin, as well as the cardiovascular and the metabolic system. In conclusion, clinical recommendations for patients with moderate to severe psoriasis based on the current available data are given.

Emerging treatment options for the treatment of moderate to severe plaque psoriasis and psoriatic arthritis: evaluating bimekizumab and its therapeutic potential

Plaque psoriasis (PsO) is a chronic inflammatory skin disorder that may be associated with several comorbidities, including arthritis. The increasing knowledge of psoriasis pathogenesis led to the identification of novel targeted therapeutic interventions. Among them, anti-IL-17A and anti-IL-17F antibodies are currently being investigated for the treatment of PsO and/or psoriatic arthritis (PsA). Bimekizumab is one of these agents, capable ofsimultaneously neutralizing both IL-17A and IL-17F cytokines. In this review we included preclinical and clinical data related to this highly promising agent that shows a peculiar molecular structure differing from other bispecific agents.

Bacteria in Asthma Pathogenesis

The airways are under continuous assault from aerosolized bacteria and oral flora. The bacteria present in the airways and gastrointestinal tract of neonates promote immune maturation and protect against asthma pathogenesis. Later bacterial infections and perturbations to the microbiome can contribute to asthma pathogenesis, persistence, and severity.

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.

Importance of TLR9-IL23-IL17 axis in inflammatory bowel disease development: Gene expression profiling study

BACKGROUND AND AIMS

Mucosal gene expression have not been fully enlightened in inflammatory bowel disease (IBD). Aim of this study was to define IL23A, IL17A, IL17F and TLR9 expression in different IBD phenotypes.

METHODS

Evaluation of mRNA levels was performed in paired non-inflamed and inflamed mucosal biopsies of newly diagnosed 50 Crohn's disease (CD) and 54 ulcerative colitis (UC) patients by quantitative real-time PCR analysis.

RESULTS

IL17A and IL17F expression levels were significantly increased in inflamed IBD mucosa. Inflamed CD ileal and UC mucosa showed increased IL23A, while only inflamed CD ileal samples showed increased TLR9 mRNA level. Correlation between analysed mRNAs levels and endoscopic and clinical disease activity were found in UC, but only with clinical activity in CD.

CONCLUSION

Both CD and UC presented expression of Th17-associated genes. Nevertheless, expression profiles between different disease forms varies which should be taken into account for future research and therapeutics strategies.

Correlation of liver function with intestinal flora, vitamin deficiency and IL-17A in patients with liver cirrhosis

The aim of this study was to investigate the correlation of liver function, intestinal flora, vitamin D and interleukin-17A (IL-17A) levels in patients with liver cirrhosis. A total of 52 patients diagnosed with posthepatitic cirrhosis and admitted into Yantai Infectious Disease Hospital (Yantai, China) from January to December in 2012 (liver cirrhosis group), and 52 patients with chronic hepatitis B (hepatitis group), and 40 healthy volunteers receiving physical examination in the hospital (normal control group) were selected into the study. The liver function, hepatitis B virus (HBV) deoxyribonucleic acid (DNA) level, intestinal flora distribution, vitamin D and IL-17A levels of all patients were detected, and the correlation among them was analyzed via Pearson's analysis. The number of Enterobacteriaceae, Enterococcus, Staphylococcus aureus and Saccharomyces in hepatitis and liver cirrhosis groups was significantly greater than in the normal control group (P<0.05), but the number of Lactobacillus, Bacteroides, Bifidobacterium and Clostridium was significantly decreased (P<0.05); the serum IL-17A levels in hepatitis and liver cirrhosis were obviously higher than that in the normal control group (P<0.05), but the serum vitamin D 25(OH) D and 1,25(OH)2D levels were obviously lower than that in the normal control group (P<0.05). In patients with liver cirrhosis, Enterobacteriaceae was positively correlated with prothrombin time (PT), Enterococcus was positively correlated with alanine aminotransferase and aspartate aminotransferase (AST) levels, Bifidobacterium was negatively correlated with AST, alkline phosphatase (AKP) and HBV DNA levels, and Bacteroides was negatively correlated with AST level and PT. There was a significant negative correlation between serum IL-17A and total bilirubin in patients with liver cirrhosis, and 25(OH) D was negatively correlated with AST, AKP and HBV DNA levels. In patients with liver cirrhosis, there was significant positive correlation between Enterococcus and IL-17A, and between Lactobacillus and 25(OH)D, but other bacteria were not obviously associated with IL-17A and vitamin D. Intestinal flora imbalance, vitamin D deficiency and IL-17A imbalance play an important role in the evolution of liver cirrhosis.

Molecular cloning of chicken interleukin-17B, which induces proinflammatory cytokines through activation of the NF-κB signaling pathway

Interleukin (IL)-17B is a little known member of the IL-17 cytokine family, which plays an important role in immunity by regulating the expression of proinflammatory cytokines. In this study, we determined the coding sequence and biological functions of a novel chicken IL-17B (chIL-17B). The full-length chIL-17B coding sequence includes 567 nucleotides encoding 188 amino acids, which was identified in small intestinal epithelial cells. The chIL-17B protein shares 96.48% amino acid sequence identity with turkey, 92.57% with duck, and 44.92-64.06% with mammalian IL-17B proteins. ChIL-17B shares three exons and two introns with mammals, turkey, and duck. Moreover, IL-17B mRNA was more highly expressed than IL-17A mRNA in several organs of chickens infected with Salmonella and was upregulated in chicken cell lines following LPS stimulation. In addition, in chicken cell lines, chIL-17B induced the mRNA expression of several proinflammatory cytokines, including IL-1β, IL-6, LITAF, and INF-γ, but not IL-17A, and activated MyD88, TAK1, NF-κB1, and SOCS1, which are associated with the NF-κB signaling pathway. Taken together, chicken interleukin-17B plays a critical role in host defense against the bacterial pathogens, and regulates proinflammatory cytokines by activating the NF-κB signaling pathway.

Peritoneal bacterial infection repressed the expression of IL17D in Siberia sturgeon a chondrostean fish in the early immune response

IL17s are pro-inflammatory cytokines that play important roles in host fighting against extracellular bacteria and auto-immune and allergic diseases. IL17D is believed to be the most ancient IL17 member and its functions are far from clarity. Although it has been found in invertebrates, jawless fish, teleosts, and tetrapods, it has not been described in chondrostean fish. Moreover, there are discrepancies concerning its expression pattern in these animals. In this study, we cloned and characterized the cDNA of il17d in Siberia sturgeon (Acipenser baerii), a chondrostean fish and commercially important species in aquaculture. The sturgeon il17d cDNA encodes a deduced protein of 210aa. The classical characteristics of IL17, such as IL17 domain, cysteine and serine residues importantly for cystine-knot formation, and signal peptide, were observed in sturgeon IL17D. Phylogenetic analysis and multiple alignment suggest it is a counterpart of mammalian IL17D. However, in vivo studies demonstrated that the expression pattern of sturgeon il17d mRNA is different from that of other teleosts and jawless fish, and in most cases its expression was down-regulated at the early time points and gradually increasing at late time points when sturgeon were challenged with bacteria (Aernomas hydrophila or Staphylococcus aureus). The In vitro study by using primary spleen cells stimulated with polyI:C revealed a similar expression pattern to that in vivo studies, while the stimulation with β-glucan or LPS, which normally induced expression of il17d mRNA in target cells in vitro in other animals, did not show apparent changes in the expression of il17d mRNA. The results of present study indicated sturgeon IL17D may possess some different characteristics from its counterparts of other fish and invertebrates in the immune response, and may contribute to the understanding of IL17D functions in evolution as well as the potential use in sturgeon aquaculture.

Polymorphisms in the IL-17 Gene (rs2275913 and rs763780) Are Associated with Hepatitis B Virus Infection in the Han Chinese Population

AIM

Interleukin-17 (IL-17) can accelerate the release of many pro-inflammatory cytokines. The purpose of our study was to investigate the potential association between polymorphisms in the IL-17 gene and susceptibility to hepatitis B virus (HBV) infection in the Han Chinese population.

METHODS

We recruited 596 HBV-infected patients and 612 ethnically matched controls, who were then genotyped for the IL-17A and IL-17F polymorphisms, rs2275913 and rs763780, respectively, by using TaqMan probe-based real-time polymerase chain reaction. The frequencies of the alleles and genotypes in patients and controls were compared by the χ² test.

RESULTS

Statistically significant differences in genotypic and allelic frequencies were revealed at both polymorphic sites between HBV-positive patients and controls (rs2275913: genotype χ² = 37.74, p < 0.001 and allele χ² = 22.17, p < 0.001, odds ratio [OR] = 0.654, 95% confidence interval [CI] = 0.548-0.781. rs763780: genotype χ² = 19.80, p < 0.001 and allele χ² = 18.78, p < 0.001, OR = 0.507, 95% CI = 0.371-0.692).

CONCLUSIONS

These results indicate that the IL-17A rs2275913 and IL-17F rs763780 polymorphisms are associated with HBV infection in the Han Chinese population. We conclude that possession of the GG genotype and the G allele at rs2275913, and the TT genotype and the T allele at rs763780 might increase the risk of HBV infection. Larger-scale, multiracial studies are necessary to evaluate the role of IL-17 polymorphisms in relation to an enhanced risk of HBV infection.

IFN-γ induction by neutrophil-derived IL-17A homodimer augments pulmonary antibacterial defense

The role of interleukin-17A (IL-17A) in host defense against Legionella pneumophila remains elusive. To address this issue, we used Il17a(-/-), Il17f(-/-), and Il17a/Il17f(-/-) mice on a C57Bl/6 (non-permissive) background and IL-17 neutralizing Abs in mice on an A/J (permissive) background. Higher bacterial (L. pneumophila) counts in the lung and blood along with reduced neutrophil recruitment were detected in Il17a(-/-), but not Il17f(-/-), mice. We found that neutrophils produce IL-17A homodimer (IL-17A) during L. pneumophila infection, and hematopoietic cell-derived IL-17A is known to be important for bacterial clearance. Thus, intratracheal administration of wild-type neutrophils or recombinant IL-17A restored bacterial clearance and neutrophil recruitment in Il17a(-/-) mice. Furthermore, neutrophil-depleted Rag2(-/-) and Rag2/Il-2rγ(-/-) mice exhibited increased bacterial burden, reduced neutrophil influx and IL-17A production in the lung. Recombinant IFN-γ administration in Il17a(-/-) mice augmented bacterial elimination, whereas IL-17A administration in Ifnγ(-/-) mice did not augment bacterial clearance. IFN-γ is produced by T cells, but not neutrophils or macrophages, suggesting that neutrophil-derived IL-17A induces IFN-γ in a paracrine fashion. Human pneumonic lungs and human neutrophils challenged with L. pneumophila exhibited increased numbers of IL-17A producing cells. These findings display a novel function of neutrophil-derived IL-17A in antibacterial defense via the induction of IFN-γ in a paracrine manner.

Contribution of the IL-17 Pathway to Psoriasis and Psoriatic Arthritis

Investigators have accrued compelling evidence that the IL-17 pathway is central to the pathogenesis of psoriasis and psoriatic arthritis. The evidence comprises genome-wide association studies (GWAS), data from experimental murine models and findings from in vitro studies on patients' cells or tissue biopsies. More recently, the success of drugs blocking the IL-17 pathway in treating both psoriasis (PsO) and psoriatic arthritis (PsA) confirms that IL-17 is a clinically relevant therapeutic target. However, there remain many unanswered questions: is PsA simply an extension of PsO from the skin to the synovial tissue or are there differences in the underlying pathogenesis of these diseases? Which cell type represents the primary source of IL-17 in PsO and PsA? And how are these cells regulated? This review outlines the IL-17 pathway, summarises the evidence supporting its role in PsO and PsA and discusses recent data that may help to address these yet unresolved questions.

Intracranial delivery of interleukin-17A via adeno-associated virus fails to induce physical and learning disabilities and neuroinflammation in mice but improves glucose metabolism through AKT signaling pathway

Interleukin-17A (IL-17A) is generally considered as one of the pathogenic factors involved in multiple sclerosis (MS). Indirect evidence for this is that IL-17A-producing T helper 17 (Th17) cells preferentially accumulate in lesions of MS and experimental autoimmune encephalomyelitis (EAE). However, a direct involvement of IL-17A in MS pathogenesis is still an open question. In this study, we overexpressed IL-17A in the brains of mice (IL-17A-in-Brain mice) via recombinant adeno-associated virus serotype 5 (rAAV5)-mediated gene delivery. In spite of high levels of IL-17A expression in the brain and blood, IL-17A-in-Brain mice exhibit no inflammatory responses and no abnormalities in motor coordination and spatial orientation. Unexpectedly, IL-17A-in-Brain mice show decreases in body weight and adipose tissue mass and an improvement in glucose tolerance and insulin sensitivity. IL-17A enhances glucose uptake in PC12 cells by activation of AKT. Our results provide direct evidence for the first time that IL-17A overexpression in the central nervous system does not cause physical and learning disabilities and neuroinflammation and suggest that IL-17A may regulate glucose metabolism through the AKT signaling pathway.

The maternal interleukin-17a pathway in mice promotes autism-like phenotypes in offspring

Viral infection during pregnancy has been correlated with increased frequency of autism spectrum disorder (ASD) in offspring. This observation has been modeled in rodents subjected to maternal immune activation (MIA). The immune cell populations critical in the MIA model have not been identified. Using both genetic mutants and blocking antibodies in mice, we show that retinoic acid receptor-related orphan nuclear receptor gamma t (RORγt)-dependent effector T lymphocytes [for example, T helper 17 (TH17) cells] and the effector cytokine interleukin-17a (IL-17a) are required in mothers for MIA-induced behavioral abnormalities in offspring. We find that MIA induces an abnormal cortical phenotype, which is also dependent on maternal IL-17a, in the fetal brain. Our data suggest that therapeutic targeting of TH17 cells in susceptible pregnant mothers may reduce the likelihood of bearing children with inflammation-induced ASD-like phenotypes.

Auxiliary subunits of the CKAMP family differentially modulate AMPA receptor properties

AMPA receptor (AMPAR) function is modulated by auxiliary subunits. Here, we report on three AMPAR interacting proteins—namely CKAMP39, CKAMP52 and CKAMP59—that, together with the previously characterized CKAMP44, constitute a novel family of auxiliary subunits distinct from other families of AMPAR interacting proteins. The new members of the CKAMP family display distinct regional and developmental expression profiles in the mouse brain. Notably, despite their structural similarities they exert diverse modulation on AMPAR gating by influencing deactivation, desensitization and recovery from desensitization, as well as glutamate and cyclothiazide potency to AMPARs. This study indicates that AMPAR function is very precisely controlled by the cell-type specific expression of the CKAMP family members.

The brain processes and transmits information through large networks of cells called neurons. A neuron can pass the information it receives to other neurons by releasing chemicals called neurotransmitters across junctions known as synapses. These chemicals bind to receptor proteins on the surface of the neighboring neuron, which triggers changes that affect the activity of this neuron.

Glutamate is the most commonly used neurotransmitter in the brain and binds to receptor proteins called AMPA receptors. If a neuron frequently sends glutamate across a particular synapse, the number of AMPA receptors in the second neuron will increase in response. This makes signaling across the synapse easier – a process known as synaptic strengthening. The ability to change the strength of synapses is important for learning and memory.

Proteins called auxiliary subunits also bind to AMPA receptors and regulate their properties, and hence also affect the strength of the synapse. For instance, some auxiliary subunits increase the number of AMPA receptors at the synapse, while others have an effect on how the receptor protein works. In 2010, researchers identified a new auxiliary protein called CKAMP44 that modifies AMPA receptor activity. Now, Farrow, Khodosevich, Sapir, Schulmann et al. – including some of the researchers involved in the 2010 study – have identified three other auxiliary proteins that are similar to CKAMP44. Collectively, these four proteins are termed the CKAMP family.

The sequences of all four proteins were found to share many common features, especially in the regions that bind to the AMPA receptors. Like CKAMP44, the new members of the CKAMP family are only present in the brain, although each protein is produced in different brain regions. Further investigation revealed that each member of the CKAMP family affects the AMPA receptor channels in a different way.

Taken together, Farrow et al.’s results suggest that the different CKAMP family members allow the activity of the AMPA receptors to be precisely controlled. The next challenge is to understand in more detail how each CKAMP family member influences how AMPA receptors work.

Role of IL-17 Variants in Preeclampsia in Chinese Han Women

Previous studies have suggested an important role for IL-17, mainly secreted by Th17 cells, in the development of systemic inflammation in preeclampsia (PE). This study therefore investigated the association between genetic variants in IL-17A, IL-17F, and IL-17RA and susceptibility to PE in Chinese Han women. We recruited 1,031 PE patients and 1,298 controls of later pregnant women, and used TaqMan allelic discrimination real-time PCR to genotype the polymorphisms of IL17A rs2275913, IL-17F rs763780, and IL-17RA rs4819554. No significant differences in genotypic or allelic frequencies were found at all three polymorphic sites between PE patients and controls (rs2275913: genotype χ2 = 0.218, p = 0.897 and allele χ2 = 0.157, p = 0.692, OR = 1.024, 95%CI 0.911-1.152; rs763780: genotype χ2 = 1.948, p = 0.377 and allele χ2 = 1.242, p = 0.265, OR = 0.897, 95%CI 0.741-1.086; rs4819554: genotype χ2 = 0.633, p = 0.729 and allele χ2 = 0.115, p = 0.735, OR = 1.020, 95%CI 0.908-1.146). There were also no significant differences in genetic distributions between mild/severe PE or early/late-onset PE and control subgroups. Our data indicate that the genetic variants of rs2275913 in IL-17A, rs763780 in IL-17F, and rs4819554 in IL-17RA may not play a role in the pathogenesis of PE in Chinese Han women. However, these findings should be confirmed in other ethnic populations.

Comparative and Evolutionary Analysis of the Interleukin 17 Gene Family in Invertebrates

Interleukin 17 (IL-17) is an important pro-inflammatory cytokine and plays critical roles in the immune response to pathogens and in the pathogenesis of inflammatory and autoimmune diseases. Despite its important functions, the origin and evolution of IL-17 in animal phyla have not been characterized. As determined in this study, the distribution of the IL-17 family among 10 invertebrate species and 7 vertebrate species suggests that the IL-17 gene may have originated from Nematoda but is absent from Saccoglossus kowalevskii (Hemichordata) and Insecta. Moreover, the gene number, protein length and domain number of IL-17 differ widely. A comparison of IL-17-containing domains and conserved motifs indicated somewhat low amino acid sequence similarity but high conservation at the motif level, although some motifs were lost in certain species. The third disulfide bond for the cystine knot fold is formed by two cysteine residues in invertebrates, but these have been replaced by two serine residues in Chordata and vertebrates. One third of invertebrate IL-17 proteins were found to have no predicted signal peptide. Furthermore, an analysis of phylogenetic trees and exon-intron structures indicated that the IL-17 family lacks conservation and displays high divergence. These results suggest that invertebrate IL-17 proteins have undergone complex differentiation and that their members may have developed novel functions during evolution.

Differential regulation of macrophage phenotype by mature and pro-nerve growth factor

To characterize the role of neurotrophin receptors on macrophages, we investigated the ability of nerve growth factor (NGF) and its precursor, proNGF, to regulate human macrophage phenotype. The p75 neurotrophin receptor (p75(NTR)) and TrkA were concentrated within overlapping domains on membrane ruffles. NGF stimulation of macrophages increased membrane ruffling, calcium spiking, phagocytosis and growth factor secretion. In contrast, proNGF induced podosome formation, increased migration, suppressed calcium spikes and increased neurotoxin secretion. These results demonstrate opposing roles of NGF and proNGF in macrophage regulation providing new avenues for pharmacological intervention during neuroinflammation.

Protective effect of a germline, IL-17-neutralizing antibody in murine models of autoimmune inflammatory disease

Monoclonal antibodies (mAbs) inhibiting cytokines have recently emerged as new drug modalities for the treatment of chronic inflammatory diseases. Interleukin-17 (IL-17) is a T-cell-derived central mediator of autoimmunity. Immunization with Qβ-IL-17, a virus-like particle based vaccine, has been shown to produce autoantibodies in mice and was effective in ameliorating disease symptoms in animal models of autoimmunity. To characterize autoantibodies induced by vaccination at the molecular level, we generated mouse mAbs specific for IL-17 and compared them to germline Ig sequences. The variable regions of a selected hypermutated high-affinity anti-IL-17 antibody differed in only three amino acid residues compared to the likely germline progenitor. An antibody, which was backmutated to germline, maintained a surprisingly high affinity (0.5 nM). The ability of the parental hypermutated antibody and the derived germline antibody to block inflammation was subsequently tested in murine models of multiple sclerosis (experimental autoimmune encephalomyelitis), arthritis (collagen-induced arthritis), and psoriasis (imiquimod-induced skin inflammation). Both antibodies were able to delay disease onset and significantly reduced disease severity. Thus, the mouse genome unexpectedly encodes for antibodies with the ability to functionally neutralize IL-17 in vivo.

Coexpressed auxiliary subunits exhibit distinct modulatory profiles on AMPA receptor function

Gating properties and surface trafficking of AMPA receptors (AMPARs) are modulated by auxiliary subunits. Here we studied the function of coexpressed auxiliary subunits belonging to two different classes. We focused on TARP γ-8 and CKAMP44 in dentate gyrus (DG) granule cells, since both subunits are highly expressed in this cell type. TARP γ-8 and CKAMP44 decrease the rate of deactivation but have an opposing influence on receptor desensitization, which accounts for their differential modulation of synaptic short-term plasticity. Furthermore, long-term plasticity (LTP) requires TARP γ-8 but not CKAMP44. The coexpression of both auxiliary subunits is necessary for the efficient targeting of AMPARs to the cell surface of DG granule cells. Finally, electrophysiological and biochemical evidence support the notion that CKAMP44 and TARP γ-8 can be contained in the same AMPAR complex.

Could T cells be involved in lung deterioration and hyperglycemia in cystic fibrosis?

Cystic fibrosis-related diabetes (CFRD) is the most frequent complication of cystic fibrosis (CF) and associated with increased mortality. Why patients have an accelerated loss of lung function before the diagnosis of CFRD remains poorly understood. We reported that patients with or without CFRD had increased glucose excursions when compared to healthy peers. Studies have demonstrated that patients with CF have increased glucose fluctuations and hyperglycemia and that this may affect the clinical course of CF and lead to lymphocyte dysfunction. T-helper 17 (Th17) lymphocytes produce and secrete the pro-inflammatory cytokine IL-17. The Th17 pathway is involved in CF lung inflammation, β-cell destruction in type 1 diabetes (T1D) and Th17 cells of patients with type 2 diabetes have increased production of IL-17 when compared to healthy peers. Also, regulatory T-cells (Tregs) have been shown to be dysfunctional and produce IL-17 in T1D. Furthermore, vitamin D can affect inflammation in CF, diabetes and the differentiation of lymphocytes. In this review, we discuss the potential roles of hyperglycemia on Th17 cells, Tregs and IL-17 as a potential cause for accelerated lung function decline before CFRD and how this could be modulated by vitamin D or by directly intervening in the IL-17A pathway.

Neuroprotection effect of interleukin (IL)-17 secreted by reactive astrocytes is emerged from a high-level IL-17-containing environment during acute neuroinflammation

An increase in interleukin (IL)-17A-producing cells, particularly at sites of tissue inflammation, is observed frequently, yet the mechanism is not fully understood. This study aims to dissect the role of IL-17 in autoimmunity-mediated neuroinflammation. The cytokine milieu containing elevated IL-17, which often appears in active states of autoimmunity, was mimicked in vitro by a supernatant obtained from rat peripheral blood monocytes stimulated with phorbol mystistate acetate (PMA)/ionomycin. The application of such inflammatory media on only primary cultured cerebellar granule neurones resulted in significant apoptosis, but the presence of astrocytes largely prevented the effect. The supernatants of the stimulated astrocytes, especially those that contained the highest level of IL-17, achieved the best protection, and this effect could be blocked by anti-IL-17 antibodies. Protein IL-17 inhibited intracellular calcium increase and protected the neurones under inflammatory attack from apoptosis. IL-17, but not interferon (IFN)-γ, in the inflammatory media contributed to astrocyte secretion of IL-17, which depended on the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway activation. The astrocytes that were treated with IL-17 alone or with prolonged treatment of the inflammatory media failed to produce sufficient levels of IL-17. Moreover, confirmatory data were obtained in vivo in a monophasic experimental autoimmune uveitis (EAU) in Lewis rats; in this preparation, the high-level IL-17-containing the cytokine milieu was demonstrated, along with IL-17 secretion by the resident neural cells. The antagonism of IL-17 at a late stage disturbed the disease resolution and resulted in significant neural apoptosis. Our data show a dynamic role of IL-17 in the maintenance of homeostasis and neuroprotection in active neuroinflammation.

The role of inflammatory and anti-inflammatory cytokines in the pathogenesis of osteoarthritis

Osteoarthritis (OA) is the most common chronic disease of human joints. The basis of pathologic changes involves all the tissues forming the joint; already, at an early stage, it has the nature of inflammation with varying degrees of severity. An analysis of the complex relationships indicates that the processes taking place inside the joint are not merely a set that (seemingly) only includes catabolic effects. Apart from them, anti-inflammatory anabolic processes also occur continually. These phenomena are driven by various mediators, of which the key role is attributed to the interactions within the cytokine network. The most important group controlling the disease seems to be inflammatory cytokines, including IL-1β, TNFα, IL-6, IL-15, IL-17, and IL-18. The second group with antagonistic effect is formed by cytokines known as anti-inflammatory cytokines such as IL-4, IL-10, and IL-13. The role of inflammatory and anti-inflammatory cytokines in the pathogenesis of OA with respect to inter- and intracellular signaling pathways is still under investigation. This paper summarizes the current state of knowledge. The cytokine network in OA is put in the context of cells involved in this degenerative joint disease. The possibilities for further implementation of new therapeutic strategies in OA are also pointed.

Recent progress in host immunity to avian coccidiosis: IL-17 family cytokines as sentinels of the intestinal mucosa

The molecular and cellular mechanisms leading to immune protection against coccidiosis are complex and include multiple aspects of innate and adaptive immunities. Innate immunity is mediated by various subpopulations of immune cells that recognize pathogen associated molecular patterns (PAMPs) through their pattern recognition receptors (PRRs) leading to the secretion of soluble factors with diverse functions. Adaptive immunity, which is important in conferring protection against subsequent reinfections, involves subtypes of T and B lymphocytes that mediate antigen-specific immune responses. Recently, global gene expression microarray analysis has been used in an attempt to dissect this complex network of immune cells and molecules during avian coccidiosis. These new studies emphasized the uniqueness of the innate immune response to Eimeria infection, and directly led to the discovery of previously uncharacterized host genes and proteins whose expression levels were modulated following parasite infection. Among these is the IL-17 family of cytokines. This review highlights recent progress in IL-17 research in the context of host immunity to avian coccidiosis.

The IL17A and IL17F loci have divergent histone modifications and are differentially regulated by prostaglandin E2 in Th17 cells

Prostaglandin E2 (PGE2), IL-23 and IL-1β are implicated in inflammatory bowel disease susceptibility, likely in part by modulating IL-17 producing CD4(+) T helper (Th17) cells. To better understand how these three mediators affect Th17 cell memory responses, we characterized the gene expression profiles of activated human peripheral CD4(+) effector memory T cells and sorted Th17 memory cells from healthy donors concurrent with IL17A mRNA induction mediated by PGE2 and/or IL-23 plus IL-1β. We discovered that PGE2 and IL-23 plus IL-1β differentially regulate Th17 cytokine expression and synergize to induce IL-17A, but not IL-17F. IL-23 plus IL-1β preferentially induce IL-17F expression. The addition of PGE2 to IL-23 plus IL-1β only enhances IL-17A expression as mediated by the PGE2 EP4 receptor, and promotes a switch from an IL-17F to an IL-17A predominant immune response. The human Th17 HuT-102 cell line was also found to constitutively express IL-17A, but not IL-17F. We went on to show that the IL17A and IL17F loci have divergent epigenetic architectures in unstimulated HuT-102 and primary Th17 cells and are poised for preferential expression of IL17A. We conclude that the chromatin for IL17A and IL17F are distinctly regulated, which may play an important role in mucosal health and disease.

Critical role for IL-17A/F in the immunopathogenesis of obliterative airway disease induced by Anti-MHC I antibodies

BACKGROUND

The IL-17 axis is implicated in pathogenesis of chronic rejection after human lung transplantation. Using a murine model of obliterative airway disease (OAD), we recently demonstrated that Abs to MHC class I antigens can induce immune responses to self-antigens that contributes to immunopathogenesis of chronic rejection. Using a murine model of OAD, we determined the role of IL-17 family members in induction of autoimmunity leading to OAD after ligation of MHC class I.

METHODS

Anti-MHC class I or control antibodies (Abs) were administered intrabronchially to wild-type (WT) and IL-17a knock out (IL-17A-/-) C57BL/6.

RESULTS

By day 30, anti-MHC I administered endobronchially in IL-17A-/- mice demonstrated significant reduction in cellular infiltration, a 36.8% reduction in CD4 T cells, 62.7% in CD11b macrophages, 37.5% in degree of fibrosis, 1.94 fold and 2.17 fold decrease in anti-KAT and anti-Col-V, respectively, when compared with wild-type mice. Analysis of lung infiltrating cells in anti-MHC I WT revealed increase in IL-17A (KAT:92+21,Col-V:103+19spm) and IL-17F (KAT:5.03%,Col-V:2.75%) secreting CD4+ T cells. However, administration of anti-MHC I in IL-17A-/- demonstrated increase only in IL-17F for KAT (13.70%) and Col-V (7.08%). Anti-IL-17(A-F) mAb administration after anti-MHC I abrogated OAD in both WT and IL-17A-/-.

CONCLUSION

Our findings indicate that IL-17A and IL-17F secreted by CD4+Th17 cells specific to lung self-antigens are critical mediators of autoimmunity leading to the pathogenesis of OAD.