Combined Blockade of TNF-α and IL-17A Alleviates Progression of Collagen-Induced Arthritis without Causing Serious Infections in Mice

Helminth-induced impairment of humoral immunity differently contribute to their anti-arthritic effects in mice: Comparison of Schistosoma mansoni and Trichinella spiralis

AIMS

We have previously reported reduction of anti-type II collagen (IIC) IgG levels in collagen-induced arthritis (CIA) by Schistosoma mansoni (Sm) and Trichinella spiralis (Ts). To clarify the contribution of the impairment of humoral immunity to their anti-arthritic activities, we herein investigated the relationship between anti-IIC IgG levels and arthritic swelling in Sm- or Ts-infected mice.

METHODS AND RESULTS

Male DBA/1J mice were infected with Sm cercariae or Ts muscle larvae prior to the IIC immunization. In the Sm-infected mice, paw swelling and anti-IIC IgG levels were continuously lower than those of non-infected control group. In contrast, arthritic swelling in the Ts-infected mice only decreased in the early phase of CIA progression, despite the continued impairment of anti-IIC IgG production throughout the experimental period. Correlation coefficients between residual paw swelling and anti-IIC IgG titers were similar or higher in the Sm group than in the control group, but were similar or lower in the Ts group than in the control group.

CONCLUSION

The down-modulations of anti-IIC IgG levels by the two parasitic infections and the correlation analyses suggest that the anti-arthritic activity of Sm was primarily attributed to the modulation of IgG-independent arthritogenic mechanisms and secondarily to the impairment of anti-IIC IgG production. In contrast, Ts could alleviate CIA mainly via the impairment of antibody production.

Combinational strategy using albumin-based nanoparticles to enable synergetic anti-rheumatic efficacy and reduced hepatotoxicity

Methotrexate (MTX) is recognized as the golden standard for rheumatoid arthritis (RA) treatment. However, it can cause liver damage in long-term application. Although nanomedicines can target to inflamed sites, most of them tend to accumulate in liver. Glycyrrhizinic acid (GA) holds potential to reverse MTX-associated hepatotoxicity. The combination of GA and MTX might achieve a synergistic anti-inflammatory efficacy and reduced hepatotoxicity. As MTX and GA have totally different in vivo performance, it is necessary to co-encapsulate them in one carrier to coordinate their in vivo fates. Here, we co-delivered MTX and GA to arthritic joints using a human serum albumin-based nanoparticle (HSN). We found the dual drug-loaded albumin nanoparticles (HSN/MTX/GA) could preferentially distribute in inflamed joints, where GA can extend MTX retention by inhibiting the expression of efflux pumps for MTX, thereby exerting synergistic therapeutic effect. In liver tissues, GA was able to reverse the MTX-induced liver damage by activating anti-oxidant defense Nrf2/HO-1 and anti-apoptosis Bcl-2/Bax signaling. We offer a combinational strategy to effectively overcome the MTX-induced hepatotoxicity and enhance the anti-rheumatic efficacy simultaneously. Furthermore, we verified the underlying mechanism about how GA cooperated with MTX in vivo for the first time. Our findings can provide valuable insights for long-term treatment of RA.

Anti-Inflammatory Effects of a Novel Nuclear Factor-κB Inhibitory Derivative Derived from Pyrazolo[3,4-d]Pyrimidine in Three Inflammation Models

Nuclear factor-κB (NF-κB) plays a central role in inflammatory responses, and its physiologic functions are essential for cell survival and proliferation. Currently, drugs targeting NF-κB inhibition have not yet been applied in clinical practice. We investigated the physiologic effect of a novel NF-κB inhibitory compound, 1H-pyrazolo[3,4-d]pyrimidin-4-amine derivative (INH #1), on three inflammatory animal models. The pharmacokinetics were measured by liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. Acute hepatitis was induced by administrating lipopolysaccharide (LPS) and D-(+)-galactosamine hydrochloride followed by the analysis of survival time and inflammatory mediators. Collagen-induced arthritis (CIA) was induced by immunization with type II collagen (CII), and serum-transfer arthritis (STA) was caused by injecting K/BxN mice serum. Clinical and histologic scores were evaluated in both arthritis models. Immune cell subset analysis, CII-induced interferon-gamma (IFN-γ) production and proliferation, and measurement of anti-CII IgG antibodies were performed in the CIA model. In the acute hepatitis model, INH #1 suppressed tumor necrosis factor-α (TNF-α) production and prevented early death in a dose-dependent manner. INH #1 significantly attenuated arthritis scores and joint inflammation in both arthritis models. Additionally, in the CIA model, dendritic cells (DCs) in the regional lymph nodes were decreased in the treated mice and antigen-induced IFN-γ production and cell proliferation in splenocytes were inhibited, whereas the titers of anti-CII IgG antibodies were comparable regardless of the treatment. Here we revealed that INH #1 exerted anti-inflammatory effects in vivo via inhibition of inflammatory mediators and suppression of cellular immune responses. This compound could be a novel candidate for inhibition of NF-κB in certain inflammatory diseases. SIGNIFICANCE STATEMENT: A novel nuclear factor-κB (NF-κB) inhibitory compound, 1H-pyrazolo[3,4-d]pyrimidin-4-amine derivative (INH #1), which retains physiologically essential NF-κB bioactivity, suppressed inflammation in three different mouse models: the acute hepatitis model, the collagen-induced arthritis model, and the K/BxN serum-transfer arthritis model. These results suggest that this compound could be a novel and potent anti-inflammatory agent.

Dual targeted therapy in patients with psoriatic arthritis and spondyloarthritis: a real-world multicenter experience from Spain

Dual targeted therapy (DTT) has emerged as a promising approach in patients with refractory spondyloarthritis (SpA) or psoriatic arthritis (PsA) and extra-musculoskeletal manifestations of both diseases, but its effectiveness/safety ratio still remains unclear. This is a retrospective, real-world multicenter study in refractory SpA and PsA patients with simultaneous use of two biological or synthetic targeted agents. Effectiveness was assessed using Ankylosing Spondylitis Disease Activity Score with C-reactive protein (ASDAS-CRP) and Disease Activity in Psoriatic Arthritis (DAPSA) Score. We identified 39 different DTT combinations in 36 patients (22 SpA; 14 PsA), 25 of them with concomitant inflammatory bowel disease. The most commonly used combinations were TNF inhibitor plus antagonist of the IL12/23 pathway, followed by TNF inhibitor plus IL-17 antagonist. During a median exposure of 14.86 months (IQR 8-20.2), DTT retention rate was 69.4% (n=25/36; 19 SpA, 6 PsA). Major clinical improvement (change in ASDAS-CRP > 2 or improvement > 85% in DAPSA) was achieved in 69.4% of patients (n=25/36 therapeutical combinations; 17/21 SpA, 8/15 PsA), with a 58.3% (n=21/36 combinations; 15/20 SpA, 6/13 PsA) low-activity/remission rate. Of the patients who were receiving glucocorticoids, 55% managed to withdraw them during follow-up. Interestingly, only four serious adverse events in three patients were observed, leading to DTT discontinuation.

Apoptotic cell death in disease-Current understanding of the NCCD 2023

Apoptosis is a form of regulated cell death (RCD) that involves proteases of the caspase family. Pharmacological and genetic strategies that experimentally inhibit or delay apoptosis in mammalian systems have elucidated the key contribution of this process not only to (post-)embryonic development and adult tissue homeostasis, but also to the etiology of multiple human disorders. Consistent with this notion, while defects in the molecular machinery for apoptotic cell death impair organismal development and promote oncogenesis, the unwarranted activation of apoptosis promotes cell loss and tissue damage in the context of various neurological, cardiovascular, renal, hepatic, infectious, neoplastic and inflammatory conditions. Here, the Nomenclature Committee on Cell Death (NCCD) gathered to critically summarize an abundant pre-clinical literature mechanistically linking the core apoptotic apparatus to organismal homeostasis in the context of disease.

The forgotten key players in rheumatoid arthritis: IL-8 and IL-17 - Unmet needs and therapeutic perspectives

Despite the relevant advances in our understanding of the pathogenetic mechanisms regulating inflammation in rheumatoid arthritis (RA) and the development of effective therapeutics, to date, there is still a proportion of patients with RA who do not respond to treatment and end up progressing toward the development of joint damage, extra-articular complications, and disability. This is mainly due to the inter-individual heterogeneity of the molecular and cellular taxonomy of the synovial membrane, which represents the target tissue of RA inflammation. Tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6) are crucial key players in RA pathogenesis fueling the inflammatory cascade, as supported by experimental evidence derived from in vivo animal models and the effectiveness of biologic-Disease Modifying Anti-Rheumatic Drugs (b-DMARDs) in patients with RA. However, additional inflammatory soluble mediators such as IL-8 and IL-17 exert their pathogenetic actions promoting the detrimental activation of immune and stromal cells in RA synovial membrane, tendons, and extra-articular sites, as well as blood vessels and lungs, causing extra-articular complications, which might be excluded by the action of anti-TNFα and anti-IL6R targeted therapies. In this narrative review, we will discuss the role of IL-8 and IL-17 in promoting inflammation in multiple biological compartments (i.e., synovial membrane, blood vessels, and lung, respectively) in animal models of arthritis and patients with RA and how their selective targeting could improve the management of treatment resistance in patients.

TNFα Blockade Inhibits Both Initial and Continued Control of Pulmonary Coccidioides

Tumor necrosis factor alpha (TNFα) is a pluripotent cytokine that is important in many infections, though its role in Coccidioides infection remains poorly understood. The need to understand TNFα in Coccidioides infection has increased recently with the widespread use of TNFα inhibitors for a wide variety of autoimmune conditions. Here, we couple the newly developed Coccidioides infection model using strain Cp1038 and C57BL/6 × DBA/2J F1 (B6D2F1) mice. B6D2F1 mice develop long-lasting control of Cp1038. Treatment of B6D2F1 mice with anti-TNFα antibodies permits significant fungal proliferation and death. Additionally, we show that antibody treatment limited to the first 2 weeks of infection was sufficient to induce this same loss of fungal control. Importantly, anti-TNFα antibody treatment initiated after fungal control leads to a loss of host control. These results highlight the importance of TNFα in both the initial control of murine Coccidioides and ongoing suppression of the fungal disease.

Non-lethal rodent malarial infection prevents collagen-induced arthritis in mice via anti-arthritic immunomodulation

AIMS

Immunomodulatory effects of parasitic infections on the outcomes of allergic or autoimmune disorders have been addressed in many experimental studies. We examined the effects of Plasmodium yoelii 17X NL (Py) infection on collagen-induced arthritis (CIA).

METHODS AND RESULTS

Male DBA/1J mice were immunized with bovine type II collagen (IIC). Py inoculation was induced at three different time points (1, 4 weeks after or 4 weeks before the immunization). Only the inoculation at 4 weeks after IIC immunization significantly inhibited arthritis development. Non-malarial anaemia induced by phenylhydrazine hydrochloride (PHZ) did not affect arthritis development. In the infected mice, anti-IIC IgG levels were transiently reduced. In addition, splenic production of pro-arthritic cytokines (IL-17 and TNF-α) and IFN-γ decreased, whereas IL-10 production increased. Flow cytometric analysis clarified that the main IL-10 producers in Py-infected mice had the CD4⁺ CD25^- Foxp3^- phenotype, presumably Tr1 cells.

CONCLUSION

We demonstrated that experimental malarial infection alleviated autoimmune arthritis via immunomodulation, suggesting the importance of malaria in the hygiene hypothesis and the significance of searching for therapeutic immunomodulatory molecules from malarial parasites.

Lactobacillus rhamnosus GG attenuates the pathology of Chlamydial muridarium in the upper genital tract in mice

OBJECTIVES

Chlamydia trachomatis is a pathogen which can cause hydrosalpinx and tubal fibrosis when infecting the urogenital tract. However, the mechanism is still not clear. There is growing evidence that the gut microbiota is associated with the pathogenesis of both intestinal and extra-intestinal disorders, such as cardiovascular disease, hepatocirrhosis, allergy, respiratory tract infection, polycystic ovary syndrome, endometriosis, and bacterial vaginitis. Lactobacillus rhamnosus GG (LGG) is one of the most extensively studied and widely used probiotic bacteria, the benefits of LGG including the treatment in gastrointestinal disorders and immunomodulation are well demonstrated, and it can also alleviate hypersensitivity reaction and diarrhoea, inhibit a variety of respiratory and urogenital diseases. Chlamydia muridarium (Cm) infection is a good model for the study on human Chlamydia pathogenicity in genitourinary tract. The mice infected with Cm were used as animal models to preliminarily explore the mechanism for the effect of LGG on upper reproductive tract infection in the mice, and to provide experimental basis for the pathogenesis of Chlamydia trachomatis genitourinary tract infection and the new idea for the treatment of Chlamydia trachomatis infection.

METHODS

Five to six weeks-old C57BL/6J mice were divided into 2 groups: An experimental group and a control group. The experimental group were administrated with 5×108 colony forming units (CFU) LGG for 19 consecutive days, while the control group were feed PBS. The mice in the 2 group were subcutaneously injected with 2.5 mg progesterone on Day 9 and infected with 1×105 inclusion body forming unit of Cm via the vaginal tract on Day 14. Vaginal and rectal swabs were taken every 7 days to infect HeLa cells for 24 hours, then the indirect immunofluorescence assay was used and the number of inclusion bodies of Chlamydia were calculated. Mice were euthanized on Day 14 and Day 63 after Cm inoculation, the vaginal tracts were dissected, and the tissue homogenates were prepared to culture the pathogens for 24 hours. The Cm bearing capacity in the bilateral uterine horn, tubal ovary, and cervical vaginal tissues in the 2 groups were calculated. The spleen cells were harvested to assay the intracellular IFN-γ, IL-5, and IL-17 by flow cytometry. On Day 63 after the Chlamydia infection, the pathology injury in the bilateral uterine horn and oviduct was observed, and the pathological sections and HE staining in the various part of genital tract were performed. The inflammatory cell infiltration and lumen dilatation was assessed. The specific IgM and IgG in sera were detected by indirect ELISA on Day 14 and 63 after infection.

RESULTS

There was no effect of LGG on the clearing of Cm from the urogenital tract, the Chlamydia ascending to fallopian tube or the uterine horn, and the organism dissemination and colonization to the gastrointestinal tract (all P>0.05). On Day 14 after Cm infection via the vagina, the IL-17 expression level in the experimental group was significant decreased than that in the control group (t=2.486, P<0.05), but there was no significant difference between the 2 groups in the CD4+ T rate in spleen and IgM and IgG levels in serum after Cm intravaginal infection (all P>0.05). On Day 63 after Cm infection, there was no difference in the severity of inflammation in the uterine horns and fallopian tubes between the 2 groups (P>0.05), but the dilation of the fallopian tubes and hydrosalpinx was attenuated in the experimental group compared with the control group (P<0.05).

CONCLUSIONS

Oral administration of LGG has no effect on inhibiting Cm ascending to upper genital tract and preventing the dissemination and colonization of Cm to the gastrointestinal tract, which also cannot affect the secretion of specific IgM and IgG in sera. Oral administration of LGG can suppress the production of IL-17 in the spleen cells and attenuate hydrosalpinx development when following Cm intravaginal infection in mice.

Evaluating the Role of the Interleukin-23/17 Axis in Critically Ill COVID-19 Patients

Studies have hypothesized a potential role of the interleukin (IL)-23/17 axis in coronavirus disease 2019 (COVID-19). However, to date, levels of IL-23 and 17 have not been compared between critically ill COVID-19 patients and critically ill non-COVID-19 patients. IL-23 and 17 were measured on admission to the intensive care unit (ICU) in critically ill COVID-19 (N = 38) and critically ill non-COVID-19 (N = 34) patients with an equal critical illness severity. Critically ill non-COVID-19 patients did not have sepsis or septic shock on ICU admission. None of the enrolled patients had previously received corticosteroids. In our study, circulating IL-17 levels were higher in the COVID-19 patients. More specifically, critically ill COVID-19 patients had levels of 0.78 (0.05-1.8) pg/mL compared to 0.11 (0.05-0.9) pg/mL in the critically ill non-COVID-19 patients (p = 0.04). In contrast, IL-23 levels were comparable between groups. A group of patients hospitalized in the specialized COVID-19 clinic (N = 16) was also used to evaluate IL-17 and IL-23 levels with respect to COVID-19 severity. Non-critically ill COVID-19 patients had undetectable levels of both cytokines. Our results support the notion of inhibiting IL-17 in critical COVID-19 infection.

Autoimmunity in 2019

Based on the PubMed data, we have been performing a yearly evaluation of the publications related to autoimmune diseases and immunology to ascertain the relative weight of the former in the scientific literature. It is particularly intriguing to observe that despite the numerous new avenues of immune-related mechanisms, such as cancer immunotherapy, the proportion of immunology manuscripts related to autoimmunity continues to increase and has been approaching 20% in 2019. As in the previous 13 years, we performed an arbitrary selection of the peer-reviewed articles published by the major dedicated Journals and discussed the common themes which continue to outnumber peculiarites in autoimmune diseases. The investigated areas included systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), psoriatic arthritis (PsA), autoantibodies (autoAbs), and common therapeutic avenues and novel pathogenic mechanisms for autoimmune conditions. Some examples include new pathogenetic evidence which is well represented by IL21 or P2X7 receptor (P2X7R) in SLE or the application of single-cell RNA sequencing (scRNA-seq), mass cytometry, bulk RNA sequencing (RNA-seq), and flow cytometry for the analysis of different cellular populations in RA. Cumulatively and of interest to the clinicians, a large number of findings continue to underline the importance of a strict relationship between basic and clinical science to define new pathogenetic and therapeutic developments. The therapeutic pipeline in autoimmunity continues to grow and maintain a constant flow of new molecules, as well illustrated in RA and PsA, and this is most certainly derived from the new basic evidence and the high-throughput tools applied to autoimmune diseases.

The m6A reader IMP2 directs autoimmune inflammation through an IL-17- and TNFα-dependent C/EBP transcription factor axis

Excessive cytokine activity underlies many autoimmune conditions, particularly through the interleukin-17 (IL-17) and tumor necrosis factor-α (TNFα) signaling axis. Both cytokines activate nuclear factor κB, but appropriate induction of downstream effector genes requires coordinated activation of other transcription factors, notably, CCAAT/enhancer binding proteins (C/EBPs). Here, we demonstrate the unexpected involvement of a posttranscriptional "epitranscriptomic" mRNA modification [N6-methyladenosine (m6A)] in regulating C/EBPβ and C/EBPδ in response to IL-17A, as well as IL-17F and TNFα. Prompted by the observation that C/EBPβ/δ-encoding transcripts contain m6A consensus sites, we show that Cebpd and Cebpb mRNAs are subject to m6A modification. Induction of C/EBPs is enhanced by an m6A methylase "writer" and suppressed by a demethylase "eraser." The only m6A "reader" found to be involved in this pathway was IGF2BP2 (IMP2), and IMP2 occupancy of Cebpd and Cebpb mRNA was enhanced by m6A modification. IMP2 facilitated IL-17-mediated Cebpd mRNA stabilization and promoted translation of C/EBPβ/δ in response to IL-17A, IL-17F, and TNFα. RNA sequencing revealed transcriptome-wide IL-17-induced transcripts that are IMP2 influenced, and RNA immunoprecipitation sequencing identified the subset of mRNAs that are directly occupied by IMP2, which included Cebpb and Cebpd Lipocalin-2 (Lcn2), a hallmark of autoimmune kidney injury, was strongly dependent on IL-17, IMP2, and C/EBPβ/δ. Imp2-/- mice were resistant to autoantibody-induced glomerulonephritis (AGN), showing impaired renal expression of C/EBPs and Lcn2 Moreover, IMP2 deletion initiated only after AGN onset ameliorated disease. Thus, posttranscriptional regulation of C/EBPs through m6A/IMP2 represents a previously unidentified paradigm of cytokine-driven autoimmune inflammation.

Gut microbiota mediated the protective effects of tuna oil on collagen-induced arthritis in mice

Rheumatoid arthritis is emerging as a chronic autoimmune disease worldwide. In this study, the beneficial effects of tuna oil (TO) on collagen-induced arthritis (CIA) mice were investigated. Dietary administration of TO relieved arthritis severity and joint bone erosion, and ameliorated systemic inflammation. Furthermore, TO treatments regulated the phosphorylation of nuclear factor-kappa B (NF-κB) and Wnt1/β-catenin signaling pathways in the joint, enhanced osteoblastogenesis biomarkers and suppressed osteoclastogenesis biomarkers, and subsequently re-balanced bone remodeling. Moreover, the impaired intestinal epithelial barrier was repaired after TO treatments, along with gut microbiota modulation. By employing fecal microbiota transplantation, we clarified that the beneficial effects of TO in CIA alleviation were mediated by the modulated gut microbiota. These results indicated that gut microbiota mediated the protective effects of tuna oil on collagen-induced arthritis in mice.

Insights Into Host Cell Cytokines in Chlamydia Infection

Chlamydial infection causes a number of clinically relevant diseases and induces significant morbidity in humans. Immune and inflammatory responses contribute to both the clearance of Chlamydia infection and pathology in host tissues. Chlamydia infection stimulates host cells to produce a large number of cytokines that trigger and regulate host immune responses against Chlamydia. However, inappropriate responses can occur with excessive production of cytokines, resulting in overreactive inflammatory responses and alterations in host or Chlamydia metabolism. As a result, Chlamydia persists and causes wound healing delays, leading to more severe tissue damage and triggering long-lasting fibrotic sequelae. Here, we summarize the roles of cytokines in Chlamydia infection and pathogenesis, thus advancing our understanding chlamydial infection biology and the pathogenic mechanisms involved.

Interleukin-17A Interweaves the Skeletal and Immune Systems

The complex crosstalk between the immune and the skeletal systems plays an indispensable role in the maintenance of skeletal homeostasis. Various cytokines are involved, including interleukin (IL)-17A. A variety of immune and inflammatory cells produces IL-17A, especially Th17 cells, a subtype of CD4⁺ T cells. IL-17A orchestrates diverse inflammatory and immune processes. IL-17A induces direct and indirect effects on osteoclasts. The dual role of IL-17A on osteoclasts partly depends on its concentrations and interactions with other factors. Interestingly, IL-17A exerts a dual role in osteoblasts in vitro. IL-17A is a bone-destroying cytokine in numerous immune-mediated bone diseases including postmenopausal osteoporosis (PMOP), rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondylarthritis (axSpA). This review will summarize and discuss the pathophysiological roles of IL-17A on the skeletal system and its potential strategies for application in immune-mediated bone diseases.

The pathogenic importance of CCL21 and CCR7 in rheumatoid arthritis

Innate and adaptive immunity regulate the inflammatory and erosive phenotypes observed in rheumatoid arthritis (RA) patients. Hence, identifying novel pathways that participate in different stages of RA pathology will provide valuable insights concerning the mechanistic behavior of different joint leukocytes and the strategy to restrain their activity. Recent findings have revealed that CCL21 poses as a risk factor for RA and expression of its receptor, CCR7, on circulating monocytes is representative of the patient's disease activity score. Expression of CCR7 was found to be the hallmark of RA synovial fluid (SF) M1 macrophages (MФs) and its levels were potentiated in response to M1 mediating factors and curtailed by M2 mediators in naïve MФs. Intriguingly, although both CCR7 ligands, CCL19 and CCL21, are elevated in RA specimens, only CCL21 was predominately responsible for CCR7's pathological manifestation of RA. Unique subset of MФs differentiated in response to CCL21 stimulation, exhibited upregulation in Th17-polarizing monokines. Moreover, CCL21-activated monokines were capable of differentiating naïve T cells into joint Th17 cells, which also partook in RA osteoclastogenesis. Finally, to conserve chronic inflammation, SF CCL21 amplified RA neovascularization directly and indirectly by promoting RA FLS and MΦs to secrete proangiogenic factors, VEGF and IL-17. This review aims to shed light on the broad pathogenic impact of CCL21, linking immunostimulatory MФs with Th17 cells, while concurrently advancing RA bone destruction and neovascularization.

The Neutrophil: Constant Defender and First Responder

The role of polymorphonuclear neutrophils (PMNs) in biology is often recognized during pathogenesis associated with PMN hyper- or hypo-functionality in various disease states. However, in the vast majority of cases, PMNs contribute to resilience and tissue homeostasis, with continuous PMN-mediated actions required for the maintenance of health, particularly in mucosal tissues. PMNs are extraordinarily well-adapted to respond to and diminish the damaging effects of a vast repertoire of infectious agents and injurious processes that are encountered throughout life. The commensal biofilm, a symbiotic polymicrobial ecosystem that lines the mucosal surfaces, is the first line of defense against pathogenic strains that might otherwise dominate, and is therefore of critical importance for health. PMNs regularly interact with the commensal flora at the mucosal tissues in health and limit their growth without developing an overt inflammatory reaction to them. These PMNs exhibit what is called a para-inflammatory phenotype, and have reduced inflammatory output. When biofilm growth and makeup are disrupted (i.e., dysbiosis), clinical symptoms associated with acute and chronic inflammatory responses to these changes may include pain, erythema and swelling. However, in most cases, these responses indicate that the immune system is functioning properly to re-establish homeostasis and protect the status quo. Defects in this healthy everyday function occur as a result of PMN subversion by pathological microbial strains, genetic defects or crosstalk with other chronic inflammatory conditions, including cancer and rheumatic disease, and this can provide some avenues for therapeutic targeting of PMN function. In other cases, targeting PMN functions could worsen the disease state. Certain PMN-mediated responses to pathogens, for example Neutrophil Extracellular Traps (NETs), might lead to undesirable symptoms such as pain or swelling and tissue damage/fibrosis. Despite collateral damage, these PMN responses limit pathogen dissemination and more severe damage that would otherwise occur. New data suggests the existence of unique PMN subsets, commonly associated with functional diversification in response to particular inflammatory challenges. PMN-directed therapeutic approaches depend on a greater understanding of this diversity. Here we outline the current understanding of PMNs in health and disease, with an emphasis on the positive manifestations of tissue and organ-protective PMN-mediated inflammation.

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.

Characterization of concurrent target suppression by JNJ-61178104, a bispecific antibody against human tumor necrosis factor and interleukin-17A

Tumor necrosis factor (TNF) and interleukin (IL)-17A are pleiotropic cytokines implicated in the pathogenesis of several autoimmune diseases including rheumatoid arthritis (RA) and psoriatic arthritis (PsA). JNJ-61178104 is a novel human anti-TNF and anti-IL-17A monovalent, bispecific antibody that binds to both human TNF and human IL-17A with high affinities and blocks the binding of TNF and IL-17A to their receptors in vitro. JNJ-61178104 also potently neutralizes TNF and IL-17A-mediated downstream effects in multiple cell-based assays. In vivo, treatment with JNJ-61178104 resulted in dose-dependent inhibition of cellular influx in a human IL-17A/TNF-induced murine lung neutrophilia model and the inhibitory effects of JNJ-61178104 were more potent than the treatment with bivalent parental anti-TNF or anti-IL-17A antibodies. JNJ-61178104 was shown to engage its targets, TNF and IL-17A, in systemic circulation measured as drug/target complex formation in normal cynomolgus monkeys (cyno). Surprisingly, quantitative target engagement assessment suggested lower apparent in vivo target-binding affinities for JNJ-61178104 compared to its bivalent parental antibodies, despite their similar in vitro target-binding affinities. The target engagement profiles of JNJ-61178104 in humans were in general agreement with the predicted profiles based on cyno data, suggesting similar differences in the apparent in vivo target-binding affinities. These findings show that in vivo target engagement of monovalent bispecific antibody does not necessarily recapitulate that of the molar-equivalent dose of its bivalent parental antibody. Our results also offer valuable insights into the understanding of the pharmacokinetics/pharmacodynamics and target engagement of other bispecific biologics against dimeric and/or trimeric soluble targets in vivo.

Oral epithelial IL-22/STAT3 signaling licenses IL-17-mediated immunity to oral mucosal candidiasis

Oropharyngeal candidiasis (OPC; thrush) is an opportunistic infection caused by the commensal fungus Candida albicans Interleukin-17 (IL-17) and IL-22 are cytokines produced by type 17 lymphocytes. Both cytokines mediate antifungal immunity yet activate quite distinct downstream signaling pathways. While much is now understood about how IL-17 promotes immunity in OPC, the activities of IL-22 are far less well delineated. We show that, despite having similar requirements for induction from type 17 cells, IL-22 and IL-17 function nonredundantly during OPC. We find that the IL-22 and IL-17 receptors are required in anatomically distinct locations within the oral mucosa; loss of IL-22RA1 or signal transducer and activator of transcription 3 (STAT3) in the oral basal epithelial layer (BEL) causes susceptibility to OPC, whereas IL-17RA is needed in the suprabasal epithelial layer (SEL). Transcriptional profiling of the tongue linked IL-22/STAT3 not only to oral epithelial cell proliferation and survival but also, unexpectedly, to driving an IL-17-specific gene signature. We show that IL-22 mediates regenerative signals on the BEL that replenish the IL-17RA-expressing SEL, thereby restoring the ability of the oral epithelium to respond to IL-17 and thus to mediate antifungal events. Consequently, IL-22 signaling in BEL "licenses" IL-17 signaling in the oral mucosa, revealing spatially distinct yet cooperative activities of IL-22 and IL-17 in oral candidiasis.

Not your average joint: Towards precision medicine in psoriatic arthritis

Precision medicine, propelled by advances in multi-omics methods and analytics, aims to revolutionize patient care by using clinically-actionable molecular markers to guide diagnostic and therapeutic decisions. We describe the applications of precision medicine in risk stratification, drug selection, and treatment response prediction in psoriatic arthritis, for which targeted, personalized approaches are steadily emerging.

[Role of tumor necrosis factor-α in Chlamydia Muridarum infection in the urogenital tract of mice]

OBJECTIVE

To explore the role of tumor necrosis factor-α (TNF-α) in immune response to urogenital chlamydial infection and urogenital pathology in mice.

METHODS

Fifteen female wild-type (WT) C57BL/6J mice and 15 TNF-α receptor knockout (TNF-αR KO) mice were inoculated intravaginally with 1×104 inclusion forming units (IFUs) of live C. muridarum. At 56 days after the first inoculation, 8 mice from each group were subjected to a second inoculation at the same dose. Vaginal swabs were taken every 3 or 4 days to detect the number of inclusion bodies of chlamydia. On day 80 after the first inoculation, the mice were euthanized and peritoneal macrophages were collected and the vaginal tract and spleen were dissected. The pathologies in the fallopian tube and the uterine horn were observed and the severity of inflammatory cell infiltration and lumen dilatation were semi-quantitatively scored. The levels of interleukin-6 (IL-6), IL-8, IL-1α, IL-1β and TNF-α in the supernatant of the peritoneal macrophage were detected. Spleen cell suspension was prepared, and after stimulation with chlamydia EB in vitro, the levels of the cytokines including IL-4, IL-5, IL-17 and interferon-γ (IFN-γ) were determined in the cells.

RESULTS

The clearance rate of Chlamydia from the urogenital tract was similar between TNF-αR KO mice and WT mice regardless of the primary or second infection. The severity of inflammation in the fallopian tube and the uterine horn did not differ significantly between the two groups, but TNF-αR KO mice had significantly milder dilation of the fallopian tubes (P < 0.05). The peritoneal macrophages from TNF-αR KO mice produced a significantly higher level of TNF-α than those from WT mice (P < 0.05); the spleen cells from the two groups both produced high levels of IFN-γ, but IL-17 production by the spleen cells was significantly lower in TNF-αR KO mice than in WT mice (P < 0.05).

CONCLUSIONS

TNF-α is not associated with protective immune response against C. muridarum infection, and can worsen the inflammatory damages of the urogenital tract caused by C. muridarum in mice.

Regulation of host-microbe interactions at oral mucosal barriers by type 17 immunity

The oral mucosa is a primary barrier site and a portal for entry of microbes, food, and airborne particles into the gastrointestinal tract. Nonetheless, mucosal immunity at this barrier remains understudied compared with other anatomical barrier sites. Here, we review basic aspects of oral mucosal histology, the oral microbiome, and common and clinically significant diseases that present at oral mucosal barriers. We particularly focus on the role of interleukin-17 (IL-17)/T helper 17 (TH17) responses in protective immunity and inflammation in the oral mucosa. IL-17/TH17 responses are highly relevant to maintaining barrier integrity and preventing pathogenic infections by the oral commensal fungus Candida albicans On the other hand, aberrant IL-17/TH17 responses are implicated in driving the pathogenesis of periodontitis and consequent bone and tooth loss. We discuss distinct IL-17-secreting T cell subsets, emphasizing their regulation and function in oropharyngeal candidiasis and periodontitis.