Life before seventeen: cloning of the IL-17 receptor

Sarah Gaffen: I thrive on turning my vision for the lab into reality

Sarah Gaffen, PhD, is a professor of medicine and rheumatology and holds the Gerald P. Rodnan endowed chair at the University of Pittsburgh. Her lab explores the biological function of IL-17 and its receptor in the context of fungal host defense and autoimmunity. We spoke to Sarah about where her interest in cytokines began, the importance of saying no in your career, and her interest in paleogenetics.

Shengu granules ameliorate ovariectomy-induced osteoporosis by the gut-bone-immune axis

Introduction

Postmenopausal osteoporosis (PMOP) is a common chronic disease, and the loss of bone density and bone strength after menopause are its main symptoms. Effective treatments for PMOP are still uncertain, but Chinese medicine has some advantages in slowing down bone loss. Shengu granules are often used clinically to treat PMOP. It has been shown to be an effective prescription for the treatment of PMOP, and there is evidence that gut flora may play an important role. However, whether Shengu granules attenuate PMOP by modulating gut flora and related mechanisms remains unclear.

Methods

In this study, we mainly examined the bone strength of the femur, the structure of the intestinal microbiota, SCFAs in the feces and the level of FOXP3 cells in the colon. To further learn about the inflammation response, the condition of the mucosa and the level of cytokines in the serum also included in the testing. In addition, to get the information of the protein expression, the protein expression of OPG and RANKL in the femur and the protein expression of ZO-1 and Occludin in the colon were taken into account.

Results

The osteoporosis was significantly improved in the SG group compared with the OVX group, and the diversity of intestinal flora, the secretion level of SCFAs and the expression level of FOXP3 were significantly increased compared with the OVX group. In terms of inflammatory indicators, the intestinal inflammation scores of the SG group was significantly lower than those in the OVX group. Additionally, the serum expression levels of IL-10 and TGF-β in the SG group were significantly increased compared with the OVX group, and the expression levels of IL-17 and TNF-α were significantly decreased compared with the OVX group. In terms of protein expression, the expression levels of ZO-1, Occluding and OPG were significantly increased in the SG group compared with the OVX group, and the expression level of RANKL was significantly decreased compared with the OVX group.

Discussion

Shengu granules treatment can improve the imbalance of intestinal flora, increase the secretion of SCFAs and the expression of FOXP3, which reduces the inflammatory response and repairs the intestinal barrier, as well as regulates the expression of OPG/RANKL signaling axis. Overall, Shengu granules ameliorate ovariectomy-induced osteoporosis by the gut-bone-immune axis.

Advances in the study of IL-17 in neurological diseases and mental disorders

Interleukin-17 (IL-17), a cytokine characteristically secreted by T helper 17 (Th17) cells, has attracted increasing attention in recent years because of its importance in the pathogenesis of many autoimmune or chronic inflammatory diseases. Recent studies have shown that neurological diseases and mental disorders are closely related to immune function, and varying degrees of immune dysregulation may disrupt normal expression of immune molecules at critical stages of neural development. Starting from relevant mechanisms affecting immune regulation, this article reviews the research progress of IL-17 in a selected group of neurological diseases and mental disorders (autism spectrum disorder, Alzheimer's disease, epilepsy, and depression) from the perspective of neuroinflammation and the microbiota-gut-brain axis, summarizes the commonalities, and provides a prospective outlook of target application in disease treatment.

SARS-CoV-2 ORF8 Mediates Signals in Macrophages and Monocytes through MyD88 Independently of the IL-17 Receptor

SARS-CoV-2 has caused an estimated 7 million deaths worldwide to date. A secreted SARS-CoV-2 accessory protein, known as open reading frame 8 (ORF8), elicits inflammatory pulmonary cytokine responses and is associated with disease severity in COVID-19 patients. Recent reports proposed that ORF8 mediates downstream signals in macrophages and monocytes through the IL-17 receptor complex (IL-17RA, IL-17RC). However, generally IL-17 signals are found to be restricted to the nonhematopoietic compartment, thought to be due to rate-limiting expression of IL-17RC. Accordingly, we revisited the capacity of IL-17 and ORF8 to induce cytokine gene expression in mouse and human macrophages and monocytes. In SARS-CoV-2-infected human and mouse lungs, IL17RC mRNA was undetectable in monocyte/macrophage populations. In cultured mouse and human monocytes and macrophages, ORF8 but not IL-17 led to elevated expression of target cytokines. ORF8-induced signaling was fully preserved in the presence of anti-IL-17RA/RC neutralizing Abs and in Il17ra-/- cells. ORF8 signaling was also operative in Il1r1-/- bone marrow-derived macrophages. However, the TLR/IL-1R family adaptor MyD88, which is dispensable for IL-17R signaling, was required for ORF8 activity yet MyD88 is not required for IL-17 signaling. Thus, we conclude that ORF8 transduces inflammatory signaling in monocytes and macrophages via MyD88 independently of the IL-17R.

Analysis of gene expression profiles and experimental validations of a rat chronic cervical cord compression model

Cervical spondylotic myelopathy (CSM) is a severe non-traumatic spinal cord injury (SCI) wherein the spinal canal and cervical cord are compressed due to the degeneration of cervical tissues. To explore the mechanism of CSM, the ideal model of chronic cervical cord compression in rats was constructed by embedding a polyvinyl alcohol polyacrylamide hydrogel in lamina space. Then, the RNA sequencing technology was used to screen the differentially expressed genes (DEGs) and enriched pathways among intact and compressed spinal cords. A total of 444 DEGs were filtered out based on the value of log₂(Compression/Sham); these were associated with IL-17, PI3K-AKT, TGF-β, and Hippo signaling pathways according to the GSEA, KEGG, and GO analyses. Transmission electron microscopy indicated the changes in mitochondrial morphology. Western blot and immunofluorescent staining revealed neuronal apoptosis, astrogliosis and microglial neuroinflammation in the lesion area. Specifically, the expression of apoptotic indicators, such as Bax and cleaved caspase-3, and inflammatory cytokines, such as IL-1β, IL-6, and TNF-α, were upregulated. The activation of IL-17 signaling pathways was observed in microglia instead of neurons or astrocytes, the activation of TGF-β and inhibition of Hippo signaling pathways were detected in astrocytes instead of neurons or microglia, and the inhibition of PI3K-AKT signaling pathway was discovered in neurons rather than microglia of astrocytes in the lesion area. In conclusion, this study indicated that neuronal apoptosis was accompanied by inhibiting of the PI3K-AKT pathway. Then, the activation of microglia IL-17 pathway and NLRP3 inflammasome effectuated the neuroinflammation, and astrogliosis was ascribed to the activation of TGF-β and the inhibition of the Hippo pathway in the chronic cervical cord of compression. Therefore, therapeutic methods targeting these pathways in nerve cells could be promising CSM treatments.

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.

Transcriptomic Evidence of the Immune Response Activation in Individuals With Limb Girdle Muscular Dystrophy Dominant 2 (LGMDD2) Contributes to Resistance to HIV-1 Infection

LGMDD2 is a rare form of muscular dystrophy characterized by one of the three heterozygous deletions described within the TNPO3 gene that result in the addition of a 15-amino acid tail in the C-terminus.TNPO3 is involved in the nuclear import of splicing factors and acts as a host cofactor for HIV-1 infection by mechanisms not yet deciphered. Further characterization of the crosstalk between HIV-1 infection and LGMDD2 disease may contribute to a better understanding of both the cellular alterations occurring in LGMDD2 patients and the role of TNPO3 in the HIV-1 cycle. To this regard, transcriptome profiling of PBMCs from LGMDD2 patients carrying the deletion c.2771delA in the TNPO3 gene was compared to healthy controls. A total of 545 differentially expressed genes were detected between LGMDD2 patients and healthy controls, with a high representation of G protein-coupled receptor binding chemokines and metallopeptidases among the most upregulated genes in LGMDD2 patients. Plasma levels of IFN-β and IFN-γ were 4.7- and 2.7-fold higher in LGMDD2 patients, respectively. An increase of 2.3-fold in the expression of the interferon-stimulated gene MxA was observed in activated PBMCs from LGMDD2 patients after ex vivo HIV-1 pseudovirus infection. Thus, the analysis suggests a pro-inflammatory state in LGMDD2 patients also described for other muscular dystrophies, that is characterized by the alteration of IL-17 signaling pathway and the consequent increase of metallopeptidases activity and TNF response. In summary, the increase in interferons and inflammatory mediators suggests an antiviral environment and resistance to HIV-1 infection but that could also impair muscular function in LGMDD2 patients, worsening disease evolution. Biomarkers of disease progression and therapeutic strategies based on these genes and mechanisms should be further investigated for this type of muscular dystrophy.

Interleukin-17 Links Inflammatory Cross-Talks Between Comorbid Psoriasis and Atherosclerosis

Psoriasis is a chronic, systemic, immune-mediated inflammatory disorder that is associated with a significantly increased risk of cardiovascular disease (CVD). Studies have shown that psoriasis often coexists with atherosclerosis, a chronic inflammatory disease of large and medium-sized arteries, which is a major cause of CVD. Although the molecular mechanisms underlying this comorbidity are not fully understood, clinical studies have shown that when interleukin (IL)-17A inhibitors effectively improve psoriatic lesions, atherosclerotic symptoms are also ameliorated in patients with both psoriasis and atherosclerosis. Also, IL-17A levels are highly expressed in the psoriatic lesions and atherosclerotic plaques. These clinical observations implicit that IL-17A could be a crucial link for psoriasis and atherosclerosis and IL-17A-induced inflammatory responses are the major contribution to the pathogenesis of comorbid psoriasis and atherosclerosis. In this review, the current literature related to epidemiology, genetic predisposition, and inflammatory mechanisms of comorbidity of psoriasis and atherosclerosis is summarized. We focus on the immunopathological effects of IL-17A in both diseases. The goal of this review is to provide the theoretical base for future preventing or treating psoriasis patients with atherosclerosis comorbidity. The current evidence support the notion that treatments targeting IL-17 seem to be hold some promise to reduce cardiovascular risk in patients with psoriasis.

The role of Th17 cells/IL-17A in AD, PD, ALS and the strategic therapy targeting on IL-17A

Neurodegenerative diseases are a group of disorders characterized by progressive loss of certain populations of neurons, which eventually lead to dysfunction. These diseases include Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS). Immune pathway dysregulation is one of the common features of neurodegeneration. Recently, there is growing interest in the specific role of T helper Th 17 cells and Interleukin-17A (IL-17A), the most important cytokine of Th 17 cells, in the pathogenesis of the central nervous system (CNS) of neurodegenerative diseases. In the present study, we summarized current knowledge about the function of Th17/IL-17A, the physiology of Th17/IL-17A in diseases, and the contribution of Th17/IL-17A in AD, PD, and ALS. We also update the findings on IL-17A-targeting drugs as potentially immunomodulatory therapeutic agents for neurodegenerative diseases. Although the specific mechanism of Th17/IL-17A in this group of diseases is still controversial, uncovering the molecular pathways of Th17/IL-17A in neurodegeneration allows the identification of suitable targets to modulate these cellular processes. Therapeutics targeting IL-17A might represent potentially novel anti-neurodegeneration drugs.

Clinical Implementation of Biologics and Small Molecules in the Treatment of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic, recurrent, auto-inflammatory skin disease originating from the hair follicles. The typical inflammatory nodules, abscesses, and draining sinus tracts (tunnels) are characterized by a massive influx of neutrophils, macrophages, B-cells, plasma cells, T helper (Th)1, Th17 cells and upregulation of pro-inflammatory cytokines such as IL-1, IL-17, IL-12/23, and TNF-α. Over the last decades, several clinical trials evaluated the clinical efficacy of different biologics targeting these pro-inflammatory cytokines, in particular TNF-α and IL-1. However, adalimumab is still the only registered drug for HS. This review discusses biologics and small molecules with high level of evidence for their clinical application, provides guidance on when and how to use these biologics and small molecules in clinical practice, and elaborates on the combination with medical and surgical treatment options beyond the current guidelines. Furthermore this review provides an overview of potential biologics and small molecules currently under investigation for novel targets in HS such as IL-36, C5a, Janus kinase family members, CD-40, LTA4 and CXCR1/2.

Interleukin-17A: The Key Cytokine in Neurodegenerative Diseases

Neurodegenerative diseases are characterized by the loss of neurons and/or myelin sheath, which deteriorate over time and cause dysfunction. Interleukin 17A is the signature cytokine of a subset of CD4⁺ helper T cells known as Th17 cells, and the IL-17 cytokine family contains six cytokines and five receptors. Recently, several studies have suggested a pivotal role for the interleukin-17A (IL-17A) cytokine family in human inflammatory or autoimmune diseases and neurodegenerative diseases, including psoriasis, rheumatoid arthritis (RA), Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and glaucoma. Studies in recent years have shown that the mechanism of action of IL-17A is more subtle than simply causing inflammation. Although the specific mechanism of IL-17A in neurodegenerative diseases is still controversial, it is generally accepted now that IL-17A causes diseases by activating glial cells. In this review article, we will focus on the function of IL-17A, in particular the proposed roles of IL-17A, in the pathogenesis of neurodegenerative diseases.

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.

Th17 Cells and the IL-23/IL-17 Axis in the Pathogenesis of Periodontitis and Immune-Mediated Inflammatory Diseases

Innate immunity represents the semi-specific first line of defense and provides the initial host response to tissue injury, trauma, and pathogens. Innate immunity activates the adaptive immunity, and both act highly regulated together to establish and maintain tissue homeostasis. Any dysregulation of this interaction can result in chronic inflammation and autoimmunity and is thought to be a major underlying cause in the initiation and progression of highly prevalent immune-mediated inflammatory diseases (IMIDs) such as psoriasis, rheumatoid arthritis, inflammatory bowel diseases among others, and periodontitis. Th1 and Th2 cells of the adaptive immune system are the major players in the pathogenesis of IMIDs. In addition, Th17 cells, their key cytokine IL-17, and IL-23 seem to play pivotal roles. This review aims to provide an overview of the current knowledge about the differentiation of Th17 cells and the role of the IL-17/IL-23 axis in the pathogenesis of IMIDs. Moreover, it aims to review the association of these IMIDs with periodontitis and briefly discusses the therapeutic potential of agents that modulate the IL-17/IL-23 axis.

The Interleukin-17 Family of Cytokines in Breast Cancer

Breast cancer (BC) is the most common cancer in women worldwide and remains a major cause of mortality with an expected 137,000 death this year in Europe. Standard management of metastatic BC comprises hormonotherapy, chemotherapy, and targeted therapies. Cyclin dependent kinase (CDK) and mammalian target of rapamycin (mTOR) inhibitors have recently proved their efficiency in hormonal receptor expressing BC. Checkpoint proteins inhibition is being evaluated in phase 3 studies. Since inflammation is constantly present in cancers, research teams have focused their attention on the interleukin-17 (IL-17) family of proinflammatory cytokines. Preclinical experiments have reported both pro and antitumor effects depending on the conditions. In the present article, we review the accumulating evidences about the roles of IL-17 in BC and discuss whether this family of cytokines could be a new target in anticancer treatments.