IL-17 induces monocyte migration in rheumatoid arthritis

Periodontal inflammatory and microbial profiles in healthy young African Americans and Caucasians

AIM

This study aimed to compare microbial and inflammatory profiles in periodontally/systemically healthy African American (AA) and Caucasian (C) individuals.

MATERIALS AND METHODS

Thirty-seven C and 46 AA aged from 5 to 25 years were evaluated regarding periodontal disease, caries, microbial subgingival profile via 16-s sequencing, as well as salivary and gingival crevicular fluid (GCF) inflammatory profile via multiplex assay.

RESULTS

Greater probing depth percentage was detected in AA (p = .0075), while a higher percentage of caries index (p = .0069) and decayed, missing, filled teeth (DMFT) index (p = .0089) was observed in C, after adjusting for number of teeth, sex and age. Salivary levels of IL-6, IL-8 and TNFα were higher for C, whereas GCF levels of eotaxin, IL-12p40, IL-12p70, IL-2 and MIP-1α were higher in AA (p < .05). Different microbial profiles were observed between the races (p = .02). AA presented higher abundance of periodontopathogens (such as Tanerella forsythia, Treponema denticola, Filifactor alocis, among others), and C presented more caries-associated bacteria (such as Streptococcus mutans and Prevotella species). Bacillaceae and Lactobacillus species were associated with higher DMFT index, whereas Fusobacterium and Tanerella species with periodontal disease parameters.

CONCLUSIONS

A different inflammatory and bacterial profile was observed between healthy AA and C, which may predispose these races to higher susceptibility to specific oral diseases.

Rac1 plays a crucial role in MCP-1-induced monocyte adhesion and migration

Monocyte migration is an important process in inflammation and atherogenesis. Identification of the key signalling pathways that regulate monocyte migration can provide prospective targets for prophylactic treatments in inflammatory diseases. Previous research showed that the focal adhesion kinase Pyk2, Src kinase and MAP kinases play an important role in MCP-1-induced monocyte migration. In this study, we demonstrate that MCP-1 induces iPLA2 activity, which is regulated by PKCβ and affects downstream activation of Rac1 and Pyk2. Rac1 interacts directly with iPLA2 and Pyk2, and plays a crucial role in MCP-1-mediated monocyte migration by modulating downstream Pyk2 and p38 MAPK activation. Furthermore, Rac1 is necessary for cell spreading and F-actin polymerization during monocyte adhesion to fibronectin. Finally, we provide evidence that Rac1 controls the secretion of inflammatory mediator vimentin from MCP-1-stimulated monocytes. Altogether, this study demonstrates that the PKCβ/iPLA2/Rac1/Pyk2/p38 MAPK signalling cascade is essential for MCP-1-induced monocyte adhesion and migration.

Th17 Cell and Inflammatory Infiltrate Interactions in Cutaneous Leishmaniasis: Unraveling Immunopathogenic Mechanisms

The inflammatory response during cutaneous leishmaniasis (CL) involves immune and non-immune cell cooperation to contain and eliminate Leishmania parasites. The orchestration of these responses is coordinated primarily by CD4+ T cells; however, the disease outcome depends on the Th cell predominant phenotype. Although Th1 and Th2 phenotypes are the most addressed as steers for the resolution or perpetuation of the disease, Th17 cell activities, especially IL-17 release, are recognized to be vital during CL development. Th17 cells perform vital functions during both acute and chronic phases of CL. Overall, Th17 cells induce the migration of phagocytes (neutrophils, macrophages) to the infection site and CD8+ T cells and NK cell activation. They also provoke granzyme and perforin secretion from CD8+ T cells, macrophage differentiation towards an M2 phenotype, and expansion of B and Treg cells. Likewise, immune cells from the inflammatory infiltrate have modulatory activities over Th17 cells involving their differentiation from naive CD4+ T cells and further expansion by generating a microenvironment rich in optimal cytokines such as IL-1β, TGF-β, IL-6, and IL-21. Th17 cell activities and synergies are crucial for the resistance of the infection during the early and acute stages; however, if unchecked, Th17 cells might lead to a chronic stage. This review discusses the synergies between Th17 cells and the inflammatory infiltrate and how these interactions might destine the course of CL.

EnILs: A General Ensemble Computational Approach for Predicting Inducing Peptides of Multiple Interleukins

Interleukins (ILs) are a group of multifunctional cytokines, which play important roles in immune regulations and inflammatory responses. Recently, IL-6 has been found to affect the development of COVID-19, and significantly elevated levels of IL-6 cytokines have been reported in patients with severe COVID-19. IL-10 and IL-17 are anti-inflammatory and proinflammatory cytokines, respectively, which play multiple protective roles in host defense against pathogens. At present, a number of machine learning methods have been proposed to predict ILs inducing peptides, but their predictive performance needs to be further improved, and the inducing peptides of different ILs are predicted separately, rather than using a general approach. In our work, we combine the statistical features of peptide sequence with word embedding to design a general ensemble model named EnILs to predict inducing peptides of different ILs, in which the predictive probabilities of random forest, eXtreme Gradient Boosting and neural network are integrated in an average way. Compared with the state-of-the-art machine learning methods, EnILs shows considerable performance in the prediction of IL-6, IL-10, and IL-17 inducing peptides. In addition, we predict the most promising IL-6 inducing peptides in Severe Acute Respiratory Syndrome Coronavirus 2 spike protein in the case study for further experimental verification.

A newly developed PLD1 inhibitor ameliorates rheumatoid arthritis by regulating pathogenic T and B cells and inhibiting osteoclast differentiation

Phospholipase D1 (PLD1), which catalyzes the hydrolysis of phosphatidylcholine to phosphatidic acid and choline, plays multiple roles in inflammation. We investigated the therapeutic effects of the newly developed PLD1 inhibitors A2998, A3000, and A3773 in vitro and in vivo rheumatoid arthritis (RA) model. A3373 reduced the levels of LPS-induced TNF-α, IL-6, and IgG in murine splenocytes in vitro. A3373 also decreased the levels of IFN-γ and IL-17 and the frequencies of Th1, Th17 cells and germinal-center B cells, in splenocytes in vitro. A3373 ameliorated the severity of collagen-induced arthritis (CIA) and suppressed infiltration of inflammatory cells into the joint tissues of mice with CIA compared with vehicle-treated mice. Moreover, A3373 prevented systemic bone demineralization in mice with CIA and suppressed osteoclast differentiation and the mRNA levels of osteoclastogenesis markers in vitro. These results suggest that A3373 has therapeutic potential for RA.

Circulating and Synovial Monocytes in Arthritis and Ex-Vivo Model to Evaluate Therapeutic Modulation of Synovial Monocytes

Monocytes are innate immune cells that play a dual role in protection of host against pathogens and initiation and perpetuation of inflammatory disorders including joint diseases. During inflammation, monocytes migrate from peripheral blood to tissues via chemokine receptors where they produce inflammatory factors. Monocytes are classified into three subsets, namely: classical, intermediate and non-classical, each subset has particular function. Synovium of patients with inflammatory joint diseases, such as rheumatoid arthritis and psoriatic arthritis as well as osteoarthritis, is enriched by monocytes that differ from circulatory ones by distinct subsets distribution. Several therapeutic agents used systemically or locally through intra-articular injections in arthritis management modulate monocyte subsets. This scoping review summarized the existing literature delineating the effect of common therapeutic agents used in arthritis management on circulating and synovial monocytes/macrophages. As certain agents have an inhibitory effect on monocytes, we propose to test their potential to inhibit synovial monocytes via an ex-vivo platform based on cultured synovial fluid mononuclear cells derived from patients with rheumatic diseases. Information obtained from the ex-vivo platform can be applied to explore the therapeutic potential of medications in clinical practice.

Contact lens-induced corneal parainflammation involving Ly6G+ cell infiltration requires IL-17A and γδ T cells

PURPOSE

Previously, using a murine model, we reported that contact lens (CL) wear induced corneal parainflammation involving CD11c+ cells after 24 h and Ly6G+ cells (neutrophils) after 5-6 days. Here, we investigated the role of IL-17 and γδ T cells in the CL-induced neutrophil response.

METHODS

CL-wearing C57BL/6 wild-type (WT) mice were compared to lens-wearing IL-17A/F single or double gene knock-out mice, or mice treated with UC7-13D5 monoclonal antibody to functionally deplete γδ T cells. Contralateral eyes served as no lens wear controls. Corneal Ly6G+ and γδ T cell responses were quantified as was expression of genes encoding pro-inflammatory cytokines IL-17A/F, IL-β, IL-18 and expression of IL-17A/F protein.

RESULTS

After 6 days lens wear, WT corneas showed Ly6G+ cell infiltration while remaining free of visible pathology. In contrast, lens-wearing corneas of IL-17AF (-/-), IL-17A (-/-) mice and γδ T cell-depleted mice showed little or no Ly6G+ cell infiltration. No Ly6G+ cell infiltration was detected in contralateral eye controls. Lens-wearing WT corneas also showed a significant increase in γδ T cells after 24 h that was maintained after 6 days of wear, and significantly increased cytokine gene expression after 6 days versus contralateral controls: IL-18 & IL-17A (∼3.9 fold) and IL-23 (∼6.5-fold). Increased IL-17A protein (∼4-fold) was detected after 6 days lens wear. γδ T cell-depletion abrogated these lens-induced changes in cytokine gene and protein expression.

CONCLUSION

Together, these data show that IL-17A and γδ T cells are required for Ly6G+ cell (neutrophil) infiltration of the cornea during contact lens-induced parainflammation.

Blocking common γ chain cytokine signaling ameliorates T cell-mediated pathogenesis in disease models

The common γ chain (γc; IL-2RG) is a subunit of the interleukin (IL) receptors for the γc cytokines IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21. The lack of appropriate neutralizing antibodies recognizing IL-2RG has made it difficult to thoroughly interrogate the role of γc cytokines in inflammatory and autoimmune disease settings. Here, we generated a γc cytokine receptor antibody, REGN7257, to determine whether γc cytokines might be targeted for T cell-mediated disease prevention and treatment. Biochemical, structural, and in vitro analysis showed that REGN7257 binds with high affinity to IL-2RG and potently blocks signaling of all γc cytokines. In nonhuman primates, REGN7257 efficiently suppressed T cells without affecting granulocytes, platelets, or red blood cells. Using REGN7257, we showed that γc cytokines drive T cell-mediated disease in mouse models of graft-versus-host disease (GVHD) and multiple sclerosis by affecting multiple aspects of the pathogenic response. We found that our xenogeneic GVHD mouse model recapitulates hallmarks of acute and chronic GVHD, with T cell expansion/infiltration into tissues and liver fibrosis, as well as hallmarks of immune aplastic anemia, with bone marrow aplasia and peripheral cytopenia. Our findings indicate that γc cytokines contribute to GVHD and aplastic anemia pathology by promoting these characteristic features. By demonstrating that broad inhibition of γc cytokine signaling with REGN7257 protects from immune-mediated disorders, our data provide evidence of γc cytokines as key drivers of pathogenic T cell responses, offering a potential strategy for the management of T cell-mediated diseases.

Sex Difference in Amebiasis

Infection with the protozoan parasite Entamoeba histolytica is much more likely to cause severe, focal liver damage in males than females, although the infection rate is the same in both sexes. The differences in disease susceptibility may be due to modulation of key mechanisms of the innate immune response by sex hormones. Complement-mediated mechanisms and estrogen-dependent activated natural killer T cells lead to early elimination of the parasite in females, whereas a pathological immune axis is triggered in males. Testosterone, which is generally thought to have more immunosuppressive properties on cells of the immune response, leads to overwhelming activation of monocytes and host-dependent destruction of liver tissue in males resulting in worse outcomes.

NFIL3 and its immunoregulatory role in rheumatoid arthritis patients

Nuclear-factor, interleukin 3 regulated (NFIL3) is an immune regulator that plays an essential role in autoimmune diseases. However, the relationship between rheumatoid arthritis (RA) and NFIL3 remains largely unknown. In this study, we examined NFIL3 expression in RA patients and its potential molecular mechanisms in RA. Increased NFIL3 expression levels were identified in peripheral blood mononuclear cells (PBMCs) from 62 initially diagnosed RA patients and 75 healthy controls (HCs) by quantitative real-time PCR (qRT-PCR). No correlation between NFIL3 and disease activity was observed. In addition, NFIL3 expression was significantly upregulated in RA synovial tissues analyzed in the Gene Expression Omnibus (GEO) dataset (GSE89408). Then, we classified synovial tissues into NFIL3-high (≥75%) and NFIL3-low (≤25%) groups according to NFIL3 expression levels. Four hundred five differentially expressed genes (DEGs) between the NFIL3-high and NFIL3-low groups were screened out using the “limma” R package. Enrichment analysis showed that most of the enriched genes were primarily involved in the TNF signaling pathway via NFκB, IL-17 signaling pathway, and rheumatoid arthritis pathways. Then, 10 genes (IL6, IL1β, CXCL8, CCL2, PTGS2, MMP3, MMP1, FOS, SPP1, and ADIPOQ) were identified as hub genes, and most of them play a key role in RA. Positive correlations between the hub genes and NFIL3 were revealed by qRT-PCR in RA PBMCs. An NFIL3-related protein–protein interaction (PPI) network was constructed using the STRING database, and four clusters (mainly participating in the inflammatory response, lipid metabolism process, extracellular matrix organization, and circadian rhythm) were constructed with MCODE in Cytoscape. Furthermore, 29 DEGs overlapped with RA-related genes from the RADB database and were mainly enriched in IL-17 signaling pathways. Thus, our study revealed the elevated expression of NFIL3 in both RA peripheral blood and synovial tissues, and the high expression of NFIL3 correlated with the abnormal inflammatory cytokines and inflammatory responses, which potentially contributed to RA progression.

Significance of IL-7 and IL-7R in RA and autoimmunity

While physiological levels of IL-7 are essential for T cell proliferation, survival and co-stimulation, its escalated concentration has been associated with autoimmune diseases such as Rheumatoid arthritis (RA). Expression of IL-7 and IL-7R in RA monocytes is linked to disease activity score and TNF transcription. TNF stimulation can modulate IL-7 secretion and IL-7R frequency in myeloid cells, however, only IL-7R transcription levels are downregulated in anti-TNF responsive patients. Elevated levels of IL-7 in RA synovial tissue and fluid are involved in attracting RA monocytes into the inflammatory joints and remodeling them into proinflammatory macrophages and mature osteoclasts. Further, IL-7 amplification of RA Th1 cell differentiation and IFNγ secretion, can directly prime myeloid IL-7R expression and thereby exacerbate IL-7-mediated joint inflammatory and erosive imprints. In parallel, IL-7 accentuates joint angiogenesis by expanding the production of proangiogenic factors from RA macrophages and endothelial cells. In preclinical models, blockade of IL-7 or IL-7R can effectively impair joint inflammation, osteoclast formation, and neovascularization primarily by impeding monocyte and endothelial cell infiltration as well as inhibition of pro-inflammatory macrophage and Th1/Th17 cell differentiation. In conclusion, disruption of IL-7/IL-7R signaling can uniquely intercept the crosstalk between RA myeloid and lymphoid cells in their ability to trigger neovascularization.

Immunological effects of anti-IL-17/12/23 therapy in patients with psoriasis complicated by Candida infections

Biologics that block the T-helper-17 pathway are very effective in the treatment of psoriasis and other inflammatory diseases. However, interleukin-17 is also crucial for antifungal host defense, and clinical trial data suggest an increase in the incidence of Candida infections during IL-17 inhibitor (IL-17i) therapy. We investigated the innate and adaptive immune responses of psoriasis patients with a history of skin and/or mucosal candidiasis during IL-17i or IL-12/23i therapy, comparing those responses to healthy controls. Psoriasis patients with IL-17i showed significantly lower CD4+Th1-like (CCR6^-CXCR3⁺CCR4^-) and Th1Th17-like (CD4⁺CCR6⁺CXCR3⁺CCR4^-) cell percentages. Patient cells stimulated with Candida albicans produced significantly lower IL-6 in the IL-12/23i group and IL-1β production in the IL-17i group, while the release of TNF-α and ROS was similar between patients and controls. IFN-γ and IL-10 production in response to several stimuli after 7 days was particularly decreased in patients receiving IL-17i therapy. Finally, after stimulation with the polarizing cytokines IL-1β and IL-23, the Th17 cytokine response was significantly lower in the IL-17i patient group. These innate and adaptive immune response defects can diminish antifungal host immune response and thereby increase susceptibility to candidiasis in patients treated with IL-17i or IL-12/23i.

Dynamic synovial fibroblasts are modulated by NBCn1 as a potential target in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by aggressive fibroblast-like synoviocytes (FLSs) and pannus formation. Various therapeutic strategies have been developed against inflammatory cytokines in RA in recent decades. Based on the migratory features of FLSs, we examined whether modulation of the migratory module attenuates RA severity. In this study, inflamed synovial fluid-stimulated FLSs exhibited enhanced migration and migratory apparatus expression, and sodium bicarbonate cotransporter n1 (NBCn1) was identified in primary cultured RA-FLSs for the first time. The NBC inhibitor S0859 attenuated the migration of FLSs induced with synovial fluid from patients with RA or with TNF-α stimulation. Inhibition of NBCs with S0859 in a collagen-induced arthritis (CIA) mouse model reduced joint swelling and destruction without blood, hepatic, or renal toxicity. Primary FLSs isolated from the CIA-induced mouse model also showed reduced migration in the presence of S0859. Our results suggest that inflammatory mediators in synovial fluid, including TNF-α, recruit NBCn1 to the plasma membrane of FLSs to provide dynamic properties and that modulation of NBCn1 could be developed into a therapeutic strategy for RA.

Interleukin-17 contributes to Ross River virus-induced arthritis and myositis

Arthritogenic alphaviruses are mosquito-borne viruses that are a major cause of infectious arthropathies worldwide, and recent outbreaks of chikungunya virus and Ross River virus (RRV) infections highlight the need for robust intervention strategies. Alphaviral arthritis can persist for months after the initial acute disease, and is mediated by cellular immune responses. A common strategy to limit inflammation and pathology is to dampen the overwhelming inflammatory responses by modulating proinflammatory cytokine pathways. Here, we investigate the contribution of interleukin-17 (IL-17), a cytokine involved in arthropathies such as rheumatoid arthritis, in the development RRV-induced arthritis and myositis. IL-17 was quantified in serum from RRV-infected patients, and mice were infected with RRV and joints and muscle tissues collected to analyse cellular infiltrates, tissue mRNA, cytokine expression, and joint and muscle histopathology. IL-17 expression was increased in musculoskeletal tissues and serum of RRV-infected mice and humans, respectively. IL-17–producing T cells and neutrophils contributed to the cellular infiltrate in the joint and muscle tissue during acute RRV disease in mice. Blockade of IL-17A/F using a monoclonal antibody (mAb) reduced disease severity in RRV-infected mice and led to decreased proinflammatory proteins, cellular infiltration in synovial tissues and cartilage damage, without affecting viral titers in inflamed tissues. IL-17A/F blockade triggered a shift in transcriptional profile of both leukocyte infiltrates and musculoskeletal stromal cells by downregulating proinflammatory genes. This study highlights a previously uncharacterized role for an effector cytokine in alphaviral pathology and points towards potential therapeutic benefit in targeting IL-17 to treat patients presenting with RRV-induced arthropathy.

Some viruses transmitted by mosquitoes cause painful and debilitating arthritis, which manifests both as an acute form shortly following infection, and a chronic form long after the initial symptoms have subsided. These viruses, termed arboviruses, are difficult to control and there are currently no specific treatments to alleviate the pain and loss of mobility. Arthritis caused by arboviruses shares similarities with a non-infectious, autoimmune form of arthritis called rheumatoid arthritis (RA). In RA, an immune molecule termed interleukin-17, or IL-17, has been shown to drive arthritis and treatments that target or block IL-17 are being developed to treat RA. Here, we asked whether arthritis caused by an arbovirus, Ross River virus (RRV), was also associated with elevated IL-17 in humans and mice. Disease severity in mice was associated with high IL-17 expression in the feet and muscle, and blocking IL-17 using an anti-IL-17 monoclonal antibody ameliorated disease in mice infected with RRV. Our study provides new information on a molecule that is implicated in arthritic inflammation, and could be targeted to treat disease caused by arthritogenic arboviruses.

Psychological Stress During Childhood and Adolescence and Its Association With Inflammation Across the Lifespan: A Critical Review and Meta-Analysis

Psychological stress during childhood and adolescence increases risk of health problems across the lifecourse, and inflammation is implicated as an underlying mechanism. To evaluate the viability of this hypothesis, we used meta-analysis to quantify the association between childhood/adolescent stress and inflammation over the lifecourse. Furthermore, we addressed three unresolved conceptual questions: (a) Does the strength of this association change over the lifecourse? (b) Are different types of childhood/adolescent stressors differentially associated with inflammation? (c) And which components of the inflammatory response are involved? A systematic search identified 187 articles reporting 922 associations. Meta-analyses were conducted using a three-level multilevel approach and controlled for study quality, conversion confidence, and whether effect sizes were unadjusted or adjusted (n = 662, 72%). Results indicated a small but reliable overall adjusted association ( r ^ = .04 ) . The magnitude of the association strengthened across the lifecourse-effect sizes were smallest in studies that measured inflammation in childhoodr ^ = .02 and became progressively larger in studies of adolescencer ^ = .04 and adulthoodr ^ = .05 , suggesting the impact of early stress strengthens with time. By contrast, effect sizes did not vary by adversity type (socioeconomic disadvantage, maltreatment, other interpersonal stressors, and cumulative exposure across stressors), or component of inflammation (circulating biomarkers of low-grade inflammation vs. cytokine responses to microbial stimuli). Implications and future directions are discussed.

Association of Inflammatory Markers/Cytokines with Cardiovascular Risk Manifestation in Patients with Endometriosis

This study is aimed at determining the association of inflammatory markers and proinflammatory cytokines with cardiovascular risk manifestation in women with endometriosis as compared to healthy controls. A total of 181 females of reproductive age with the absence of other inflammatory or autoimmune disorders and a lack of hormonal therapy for at least 6 months voluntarily participated in this investigation. Patients were 81 females, laparoscopically diagnosed with endometriosis, while the control group comprised 80 healthy females without any pelvic pathology. All subjects were 20-40 years of age. Exclusion criteria were diabetes, obesity, hypertension, metabolic diseases, cardiovascular, and renal disorders. C-reactive protein, fibrinogen, homocysteine, interleukin-17, and interleukin-33 were analyzed using commercially available ELISA kits. For statistical interpretation, the unpaired Student “t” test was used. All inflammatory markers and cytokines demonstrated elevated levels (P < 0.001) in endometriosis patients as compared to healthy controls. The results of the study revealed that the patients with endometriosis demonstrate a hypercoagulable status due to inflammation, which initiates atherosclerosis and associated complications. Hence, endometriosis can cause a risk of cardiovascular disorders in these patients.

Radiotherapy to Enhance Chimeric Antigen Receptor T-Cell Therapeutic Efficacy in Solid Tumors: A Narrative Review

Importance

Immunotherapy has emerged as a new pillar of cancer therapy over the past decade. Adoptive immunotherapy in particular has become a major area of research interest, with advances seen in the development of T-cell engineering. As a result, chimeric antigen receptor (CAR) T-cell therapy has become a new and highly effective treatment option, especially for patients with refractory or resistant blood cell cancers. However, CAR T-cell therapy has shown limited efficacy for the treatment of solid tumors thus far.

Observations

Combinatorial treatment approaches, such as addition of radiotherapy to CAR T cells, may provide a strategy to prevent resistance to CAR T-cell therapy of solid tumors. These approaches need to overcome obstacles that include abnormal vessels and adhesion molecule expression on tumor vasculature, leading to reduced transmigration of effector immune cells, including CAR T cells, and immunosuppressive cues in the tumor microenvironment, including regional hypoxia.

Conclusions and Relevance

This review provides an overview of the current developments in CAR T-cell therapy and highlights the unique opportunities and challenges in combining CAR T-cell therapy with radiotherapy.

A Tale of Two Immune Cells in Rheumatoid Arthritis: The Crosstalk Between Macrophages and T Cells in the Synovium

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease. Joint inflammation of RA is closely related to infiltration of immune cells, synovium hyperplasia, and superfluous secretion of proinflammatory cytokines, which lead to cartilage degradation and bone erosion. The joint synovium of RA patients contains a variety of immune cellular types, among which monocytes/macrophages and T cells are two essential cellular components. Monocytes/macrophages can recruit and promote the differentiation of T cells into inflammatory phenotypes in RA synovium. Similarly, different subtypes of T cells can recruit monocytes/macrophages and promote osteoblast differentiation and production of inflammatory cytokines. In this review, we will discuss how T cell-monocyte/macrophage interactions promote the development of RA, which will provide new perspectives on RA pathogenesis and the development of targeted therapy.

Interplay of Microbiota and Citrullination in the Immunopathogenesis of Rheumatoid Arthritis

Microbiota is a balanced ecosystem that has important functions to the host health including development, defense, digestion, and absorption of dietary fibers and minerals, vitamin synthesizes, protection, and training the host immune system. On the other hand, its dysbiosis is linked to many human diseases such as rheumatoid arthritis (RA). The RA is an inflammatory autoimmune disorder caused by genetic and environmental factors; microbiota may be considered as a risk environmental factor for it. Citrullination is a post-translation modification (PMT) that converts the amino acid arginine to amino acid citrulline in certain proteins. These citrullinated proteins are recognized as a foreign antigen by the immune system resulting in the upregulation of inflammatory action such as in RA. The current work highlights the effect of both gut and oral microbiota dysbiosis on the development of RA, as well as discusses how the alteration in microbiota composition leads to the overgrowth of some bacterial species that entangled in RA pathogenicity. The evidence suggested that some oral and gut microbial species such as Porphyromonas gingivalis and Prevotella copri, respectively, contribute to RA pathogenesis. During dysbiosis, these bacteria can mediate the citrullination of either human or bacteria proteins to trigger an immune response that leads to the generation of autoantibodies.

Impact of Three Different Serum Sources on Functional Properties of Equine Mesenchymal Stromal Cells

Culture and expansion of equine mesenchymal stromal cells (MSCs) are routinely performed using fetal bovine serum (FBS) as a source of growth factors, nutrients, and extracellular matrix proteins. However, the desire to minimize introduction of xenogeneic bovine proteins or pathogens and to standardize cellular products intended for clinical application has driven evaluation of alternatives to FBS. Replacement of FBS in culture for several days before administration has been proposed to reduce antigenicity and potentially prolong survival after injection. However, the functional consequences of MSC culture in different serum types have not been fully evaluated. The objective of this study was to compare the immunomodulatory and antibacterial properties of MSCs cultured in three serum sources: FBS or autologous or allogeneic equine serum. We hypothesized that continuous culture in FBS would generate MSCs with improved functionality compared to equine serum and that there would not be important differences between MSCs cultured in autologous vs. allogeneic equine serum. To address these questions, MSCs from three healthy donor horses were expanded in medium with FBS and then switched to culture in FBS or autologous or allogeneic equine serum for 72 h. The impact of this 72-h culture period in different sera on cell viability, cell doubling time, cell morphology, bactericidal capability, chondrogenic differentiation, and production of cytokines and antimicrobial peptides was assessed. Altering serum source did not affect cell viability or morphology. However, cells cultured in FBS had shorter cell doubling times and secreted more interleukin 4 (IL-4), IL-5, IL-17, RANTES, granulocyte–macrophage colony-stimulating factor, fibroblast growth factor 2, eotaxin, and antimicrobial peptide cathelicidin/LL-37 than cells cultured in either source of equine serum. Cells cultured in FBS also exhibited greater spontaneous bactericidal activity. Notably, significant differences in any of these parameters were not observed when autologous vs. allogeneic equine serum was used for cell culture. Chondrogenic differentiation was not different between different serum sources. These results indicate that MSC culture in FBS will generate more functional cells based on a number of parameters and that the theoretical risks of FBS use in MSC culture should be weighed against the loss of MSC function likely to be incurred from culture in equine serum.

New Insights Into Novel Therapeutic Targets in ANCA-Associated Vasculitis

Biologics targeting inflammation-related molecules in the immune system have been developed to treat rheumatoid arthritis (RA), and these RA treatments have provided revolutionary advances. Biologics may also be an effective treatment for anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis, particularly in patients with resistance to standard treatments. Despite the accumulation of clinical experience and the increasing understanding of the pathogenesis of vasculitis, it is becoming more difficult to cure vasculitis. The treatment of vasculitis with biologics has been examined in clinical trials, and this has also enhanced our understanding of the pathogenesis of vasculitis. A humanized anti-interleukin-5 monoclonal antibody known as mepolizumab was recently demonstrated to provide clinical benefit in the management of eosinophilic granulomatosis with polyangiitis in refractory and relapsing disease, and additional new drugs for vasculitis are being tested in clinical trials, while others are in abeyance. This review presents the new findings regarding biologics in addition to the conventional immunosuppressive therapy for ANCA-associated vasculitis.

The Evolving Knowledge on T and NK Cells in Classic Hodgkin Lymphoma: Insights into Novel Subsets Populating the Immune Microenvironment

Simple Summary

In classic Hodgkin lymphoma, T and NK cells constitute a significant fraction of the reactive microenvironment established by malignant Hodgkin Reed–Sternberg cells. Despite their abundance, T and NK cells remain largely ineffective because of two coordinated levels of immune evasion. The first is based on the acquisition of regulatory properties or exhausted phenotypes that cripple their antitumor activity. The second is represented by their peculiar spatial distribution, with the most immunosuppressive subpopulations lying in close proximity of neoplastic cells. Recent discoveries about the functional role and the spatial orientation of T and NK cells in classic Hodgkin lymphoma are the focus of this review.

Abstract

Classic Hodgkin lymphoma (cHL) is a unique lymphoid neoplasm characterized by extensive immune infiltrates surrounding rare malignant Hodgkin Reed–Sternberg (HRS) cells. Different subsets of T and NK cells have long been recognized in the cHL microenvironment, yet their distinct contribution to disease pathogenesis has remained enigmatic. Very recently, novel platforms for high dimensional analysis of immune cells, such as single-cell RNA sequencing and mass cytometry, have revealed unanticipated insights into the composition of T- and NK-cell compartments in cHL. Advances in imaging techniques have better defined specific T-helper subpopulations physically interacting with neoplastic cells. In addition, the identification of novel cytotoxic subsets with an exhausted phenotype, typically enriched in cHL milieu, is shedding light on previously unrecognized immune evasion mechanisms. This review examines the immunological features and the functional properties of T and NK subsets recently identified in the cHL microenvironment, highlighting their pathological interplay with HRS cells. We also discuss how this knowledge can be exploited to predict response to immunotherapy and to design novel strategies to improve PD-1 blockade efficacy.

Prune-1 drives polarization of tumor-associated macrophages (TAMs) within the lung metastatic niche in triple-negative breast cancer

M2-tumor-associated macrophages (M2-TAMs) in the tumor microenvironment represent a prognostic indicator for poor outcome in triple-negative breast cancer (TNBC).

Here we show that Prune-1 overexpression in human TNBC patients has positive correlation to lung metastasis and infiltrating M2-TAMs. Thus, we demonstrate that Prune-1 promotes lung metastasis in a genetically engineered mouse model of metastatic TNBC augmenting M2-polarization of TAMs within the tumor microenvironment. Thus, this occurs through TGF-β enhancement, IL-17F secretion, and extracellular vesicle protein content modulation.

We also find murine inactivating gene variants in human TNBC patient cohorts that are involved in activation of the innate immune response, cell adhesion, apoptotic pathways, and DNA repair. Altogether, we indicate that the overexpression of Prune-1, IL-10, COL4A1, ILR1, and PDGFB, together with inactivating mutations of PDE9A, CD244, Sirpb1b, SV140, Iqca1, and PIP5K1B genes, might represent a route of metastatic lung dissemination that need future prognostic validations.

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Prune-1 correlates to M2-TAMs confirming lung metastatic dissemination in GEMM

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Cytokines and EV proteins are responsible of M2-TAMs polarization processes

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A small molecule with immunomodulatory properties ameliorates metastatic dissemination

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Identification of gene variants within immune response and cell adhesion in TNBC

Innate Lymphocytes in Inflammatory Arthritis

Inflammatory arthritis (IA) refers to a group of chronic diseases, including rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis (AS), and other spondyloarthritis (SpA). IA is characterized by autoimmune-mediated joint inflammation and is associated with inflammatory cytokine networks. Innate lymphocytes, including innate-like lymphocytes (ILLs) expressing T or B cell receptors and innate lymphoid cells (ILCs), play important roles in the initiation of host immune responses against self-antigens and rapidly produce large amounts of cytokines upon stimulation. TNF (Tumor Necrosis Factor)-α, IFN (Interferon)-γ, Th2-related cytokines (IL-4, IL-9, IL-10, and IL-13), IL-17A, IL-22, and GM-CSF are involved in IA and are secreted by ILLs and ILCs. In this review, we focus on the current knowledge of ILL and ILC phenotypes, cytokine production and functions in IA. A better understanding of the roles of ILLs and ILCs in IA initiation and development will ultimately provide insights into developing effective strategies for the clinical treatment of IA patients.

IL-17A as a Potential Therapeutic Target for Patients on Peritoneal Dialysis

Chronic kidney disease (CKD) is a health problem reaching epidemic proportions. There is no cure for CKD, and patients may progress to end-stage renal disease (ESRD). Peritoneal dialysis (PD) is a current replacement therapy option for ESRD patients until renal transplantation can be achieved. One important problem in long-term PD patients is peritoneal membrane failure. The mechanisms involved in peritoneal damage include activation of the inflammatory and immune responses, associated with submesothelial immune infiltrates, angiogenesis, loss of the mesothelial layer due to cell death and mesothelial to mesenchymal transition, and collagen accumulation in the submesothelial compact zone. These processes lead to fibrosis and loss of peritoneal membrane function. Peritoneal inflammation and membrane failure are strongly associated with additional problems in PD patients, mainly with a very high risk of cardiovascular disease. Among the inflammatory mediators involved in peritoneal damage, cytokine IL-17A has recently been proposed as a potential therapeutic target for chronic inflammatory diseases, including CKD. Although IL-17A is the hallmark cytokine of Th17 immune cells, many other cells can also produce or secrete IL-17A. In the peritoneum of PD patients, IL-17A-secreting cells comprise Th17 cells, γδ T cells, mast cells, and neutrophils. Experimental studies demonstrated that IL-17A blockade ameliorated peritoneal damage caused by exposure to PD fluids. This article provides a comprehensive review of recent advances on the role of IL-17A in peritoneal membrane injury during PD and other PD-associated complications.

IL-17A Modulates Peritoneal Macrophage Recruitment and M2 Polarization in Endometriosis

Endometriosis is a debilitating gynecological disease characterized by the extrauterine presence of endometrial-like tissues located on the peritoneal membrane and organs of the pelvic cavity. Notably, dysfunctional immune activation in women with endometriosis could also contribute to the development of disease. In particular, alternatively activated (M2) peritoneal macrophages are shown to aid peritoneal lesion development by promoting remodeling of extracellular matrix and neovascularization of lesions. However, the stimuli responsible for polarizing M2 macrophages in endometriosis remain elusive. Interleukin-17A (IL-17A) can induce M2 macrophage polarization in other disease models and IL-17A is elevated in the plasma and endometriotic lesions of women with endometriosis. In this study, we investigated whether IL-17A could induce macrophage recruitment and M2 polarization, while promoting endometriotic lesion growth through enhanced vascularization. By utilizing a co-culture of macrophage-like THP-1 cells with an endometriotic epithelial cell line, our in vitro results suggest that IL-17A indirectly induces M2 markers CCL17 and CD206 by interacting with endometriotic epithelial cells. Further, in a syngeneic mouse model of endometriosis, IL-17A treatment increased macrophages in the peritoneum, which were also M2 in phenotype. However, IL-17A treatment did not augment proliferation or vascularization of the lesion in the study time frame. These findings suggest that IL-17A may be a stimulus inducing the pathogenic polarization of macrophages into the M2 phenotype by first acting on the endometriotic lesion itself.

Could IL-17A Be a Novel Therapeutic Target in Diabetic Nephropathy?

Chronic kidney disease has become a major medical issue in recent years due to its high prevalence worldwide, its association with premature mortality, and its social and economic implications. A number of patients gradually progress to end-stage renal disease (ESRD), requiring then dialysis and kidney transplantation. Currently, approximately 40% of patients with diabetes develop kidney disease, making it the most prevalent cause of ESRD. Thus, more effective therapies for diabetic nephropathy are needed. In preclinical studies of diabetes, anti-inflammatory therapeutic strategies have been used to protect the kidneys. Recent evidence supports that immune cells play an active role in the pathogenesis of diabetic nephropathy. Th17 immune cells and their effector cytokine IL-17A have recently emerged as promising targets in several clinical conditions, including renal diseases. Here, we review current knowledge regarding the involvement of Th17/IL-17A in the genesis of diabetic renal injury, as well as the rationale behind targeting IL-17A as an additional therapy in patients with diabetic nephropathy.

Interleukin 17A Participates in Renal Inflammation Associated to Experimental and Human Hypertension

Hypertension is now considered as an inflammatory disease, and the kidney is a key end-organ target. Experimental and clinical studies suggest that interleukin 17A (IL-17A) is a promising therapeutic target in immune and chronic inflammatory diseases, including hypertension and kidney disease. Elevated circulating IL-17A levels have been observed in hypertensive patients. Our aim was to investigate whether chronically elevated circulating IL-17A levels could contribute to kidney damage, using a murine model of systemic IL-17A administration. Blood pressure increased after 14 days of IL-17A infusion in mice when compared with that in control mice, and this was associated to kidney infiltration by inflammatory cells, including CD3⁺ and CD4⁺ lymphocytes and neutrophils. Moreover, proinflammatory factors and inflammatory-related intracellular mechanisms were upregulated in kidneys from IL-17A-infused mice. In line with these findings, in the model of angiotensin II infusion in mice, IL-17A blockade, using an anti-IL17A neutralizing antibody, reduced kidney inflammatory cell infiltrates and chemokine overexpression. In kidney biopsies from patients with hypertensive nephrosclerosis, IL-17A positive cells, mainly Th17 and γδ T lymphocytes, were found. Overall, the results support a pathogenic role of IL-17A in hypertensive kidney disease-associated inflammation. Therapeutic approaches targeting this cytokine should be explored to prevent hypertension-induced kidney injury.

Classical Hodgkin lymphoma cells may promote an IL-17-enriched microenvironment

In classical Hodgkin lymphoma (cHL), the significance of the interplay between Hodgkin and Reed-Sternberg cells (HRS) and reactive T cells remains poorly defined. By immunohistochemistry on bioptic cHL specimens, we found that HRS and surrounding T lymphocytes stained positive for IL-17 in 40% of cases. IL-17 was detectable in a similar proportion of patients' sera and correlated with disease burden. Supernatants of KM-H2 and HDLM-2 cHL cell lines guided preferential chemotaxis of CCR6⁺ T lymphocytes. Coculture of cHL cell lines with PBMC promoted the enrichment of Th17 lymphocytes and Foxp3⁺/IL-17⁺ cells, whereas T regulatory cells slightly decreased. Soluble CD30 downmodulated membrane CD30 expression on T cells and contributed to their polarization shift by stimulating IL-17 production and reducing IFN-γ synthesis. Thus, HRS and a number of reactive CD4⁺ T cells, attracted by tumor-secreted chemokines, produce an IL-17 tumor-shaped inflammatory milieu in a cHL subset.

Ethanolic extract of Kaempferia parviflora interrupts the mechanisms-associated rheumatoid arthritis in SW982 culture model via p38/STAT1 and STAT3 pathways

BACKGROUND

Kaempferia parviflora Wall. ex Baker (KP) has long been used in traditional medicine to treat various diseases because active compounds in rhizome extracts are important anti-inflammatory agents.

PURPOSE

This study aims to investigate the effects of an ethanolic extract of KP on the molecular mechanisms associated with rheumatoid arthritis (RA), which was induced by a combination of proinflammatory cytokines (IL-1β or TNF-α with IL-17A) in a human synovial sarcoma cell line (SW982) culture model.

METHODS

SW982 cells pretreated with cytokines were incubated with KP extract at 3-30 µg/ml, or three major compounds of KP (5,7-dimethoxyflavone, 5,7,4'-trimethoxyflavone, and 3,5,7,3',4'-pentamethoxyflavone) for up to 72 h. Dexamethasone was used as positive control. RA-associated genes and inflammatory products were measured in parallel with cell death genes. Apoptosis by flow cytometry and migration assay were also analyzed. Western blotting was used to examine the effects on intracellular signaling mechanisms.

RESULTS

KP extract markedly reduced the expression of genes and levels of proinflammatory cytokines, inflammatory mediators, and matrix-degraded enzymes, but neither induced apoptosis nor altered the cell cycle. Its major constituents differently exerted suppressive effects on inflammatory genes. The KP extract downregulated the expression of genes associated with autophagosome and necroptosome formations. The extract also inhibited cell migration, reduced the mRNA expression of cadherin-11, and selectively reduced the phosphorylation of p38 MAPK, STAT1, and STAT3 signaling molecules, but did not interfere with the NF-κB pathway.

CONCLUSION

These results suggest that the anti-arthritic potential of KP extract results from anti-inflammation and anti-migration via the suppression of the cytokines-induced p38/STAT1 and STAT3 pathways.

Macrophages as regulators of tumour immunity and immunotherapy

Macrophages are critical mediators of tissue homeostasis, with tumours distorting this proclivity to stimulate proliferation, angiogenesis and metastasis. This had led to an interest in targeting macrophages in cancer, and preclinical studies have demonstrated efficacy across therapeutic modalities and tumour types. Much of the observed efficacy can be traced to the suppressive capacity of macrophages, driven by microenvironmental cues such as hypoxia and fibrosis. As a result, tumour macrophages display an ability to suppress T cell recruitment and function as well as to regulate other aspects of tumour immunity. With the increasing impact of cancer immunotherapy, macrophage targeting is now being evaluated in this context. Here, we discuss the results of clinical trials and the future of combinatorial immunotherapy.

MicroRNA Post-transcriptional Regulation of the NLRP3 Inflammasome in Immunopathologies

Inflammation has a crucial role in protection against various pathogens. The inflammasome is an intracellular multiprotein signaling complex that is linked to pathogen sensing and initiation of the inflammatory response in physiological and pathological conditions. The most characterized inflammasome is the NLRP3 inflammasome, which is a known sensor of cell stress and is tightly regulated in resting cells. However, altered regulation of the NLRP3 inflammasome is found in several pathological conditions, including autoimmune disease and cancer. NLRP3 expression was shown to be post-transcriptionally regulated and multiple miRNA have been implicated in post-transcriptional regulation of the inflammasome. Therefore, in recent years, miRNA based post-transcriptional control of NLRP3 has become a focus of much research, especially as a potential therapeutic approach. In this review, we provide a summary of the recent investigations on the role of miRNA in the post-transcriptional control of the NLRP3 inflammasome, a key regulator of pro-inflammatory IL-1β and IL-18 cytokine production. Current approaches to targeting the inflammasome product were shown to be an effective treatment for diseases linked to NLRP3 overexpression. Although utilizing NLRP3 targeting miRNAs was shown to be a successful therapeutic approach in several animal models, their therapeutic application in patients remains to be determined.

The purinergic receptor P2X5 contributes to bone loss in experimental periodontitis

Purinergic receptor signaling is increasingly recognized as an important regulator of inflammation. The P2X family purinergic receptors P2X5 and P2X7 have both been implicated in bone biology, and it has been suggested recently that P2X5 may be a significant regulator of inflammatory bone loss. However, a role for P2X5 in periodontitis is unknown. The present study aimed to evaluate the functional role of P2X5 in ligature-induced periodontitis in mice. Five days after placement of ligature, analysis of alveolar bone revealed decreased bone loss in P2rx5^−/− mice compared to P2rx7^−/− and WT control mice. Gene expression analysis of the gingival tissue of ligated mice showed that IL1b, IL6, IL17a and Tnfsf11 expression levels were significantly reduced in P2rx5^−/− compared to WT mice. These results suggest the P2X5 receptor may regulate bone loss related to periodontitis and it may thus be a novel therapeutic target in this oral disease.

Engineering CAR-T Cells for Improved Function Against Solid Tumors

Genetic engineering T cells to create clinically applied chimeric antigen receptor (CAR) T cells has led to improved patient outcomes for some forms of hematopoietic malignancies. While this has inspired the biomedical community to develop similar strategies to treat solid tumor patients, challenges such as the immunosuppressive character of the tumor microenvironment, CAR-T cell persistence and trafficking to the tumor seem to limit CAR-T cell efficacy in solid cancers. This review provides an overview of mechanisms that tumors exploit to evade eradication by CAR-T cells as well as emerging approaches that incorporate genetic engineering technologies to improve CAR-T cell activity against solid tumors.

Monocytes in rheumatoid arthritis: Circulating precursors of macrophages and osteoclasts and, their heterogeneity and plasticity role in RA pathogenesis

Rheumatoid arthritis (RA) is a chronic systemic, autoimmune and inflammatory disease represented as synovitis, pannus formation, adjacent bone erosions, and joint destruction. The major cells involved in the perpetuation of RA pathogenesis are CD4⁺ T-cells (mainly Th1 cells and Th17 cells), fibroblasts like synoviocytes (FLS), macrophages and B cells. Other autoimmune cells such as dendritic cells, neutrophils, mast cells, and monocytes also contribute to RA pathogenesis. Monocytes are mainly bone marrow (BM) derived cells in the circulation. The chemokine receptors CCR2 and CX3CR1 expressed by monocytes interact with chemokine ligands CCL2 (MCP-1) and CX3CL1 (fractalkine) respectively produced by FLS and this interaction promotes their migration and recruitment into RA synovium. Activated monocytes on their surface exhibit upregulated antigenic expressions such as CD14, CD16, HLA-DR, toll-like receptors (TLRs), and adhesion molecules B1 and B2 integrins. RA monocytes interconnect with other cells in a positive loop manner in the propagation of the rheumatoid process. They skew towards mainly intermediate monocyte subsets (CD14⁺⁺ CD16⁺) which produce proinflammatory cytokines such as TNF-α, IL-1β, and IL-6. Moreover, the predominant intermediate monocytes in RA differentiate into M1-macrophages which play a major role in synovial inflammation. Demonstrations suggest monocytes with CD14⁺ and CD16^- expression (classical monocytes?) differentiate to osteoclasts which are the cells responsible for bone erosion in RA synovial joints. Th17 cells induce the production of RANKL by FLS which promotes osteoclastogenesis. Cytokines mainly TNF-α, IL-1β, and IL-6 amplify osteoclastogenesis. Hence, monocytes are the circulating precursors of macrophages and osteoclasts in RA. AIM OF THE REVIEW: To enlighten the identity of monocytes, the antigenic expression on monocyte surface and their cytokines role in RA. We also emphasize about the chemokine receptors expressed by monocytes subsets and chemotaxis of circulating monocytes into RA synovium. Additionally, we review monocytes as the circulating precursors of macrophages and osteoclasts in RA joints and their heterogeneity and plasticity role in RA.

Chemotaxis Model for Breast Cancer Cells Based on Signal/Noise Ratio

Chemotaxis, a biased migration of cells under a chemical gradient, plays a significant role in diverse biological phenomena including cancer metastasis. Stromal cells release signaling proteins to induce chemotaxis, which leads to organ-specific metastasis. Epidermal growth factor (EGF) is an example of the chemical attractants, and its gradient stimulates metastasis of breast cancer cells. Hence, the interactions between EGF and breast cancer cells have long been a subject of interest for oncologists and clinicians. However, most current approaches do not systematically separate the effects of gradient and absolute concentration of EGF on chemotaxis of breast cancer cells. In this work, we develop a theoretical model based on signal/noise ratio to represent stochastic properties and report our microfluidic experiments to verify the analytical predictions from the model. The results demonstrate that even under the same EGF concentration gradients (0-50 or 0-150 ng/mL), breast cancer cells reveal a more evident chemotaxis pattern when the absolute EGF concentrations are low. Moreover, we found that reducing the number of EGF receptors (EGFRs) with addition of EGFR antibody (1 ng/mL) can promote chemotaxis at an EGF gradient of 0-1 ng/mL as shown by chemotaxis index (0.121 ± 0.037, reduced EGFRs vs. 0.003 ± 0.041, control). This counterintuitive finding suggests that EGFR-targeted therapy may stimulate metastasis of breast cancer because the partial suppression of the receptors makes the number of receptors close to the optimal one for chemotaxis. This analysis should be considered in anticancer drug design.

From neuroimunomodulation to bioelectronic treatment of rheumatoid arthritis

Neuronal stimulation is an emerging field in modern medicine to control organ function and reestablish physiological homeostasis during illness. The nervous system innervates most of the peripheral organs and provides a fine tune to control the immune system. Most of these studies have focused on vagus nerve stimulation and the physiological, cellular and molecular mechanisms regulating the immune system. Here, we review the new results revealing afferent vagal signaling pathways, immunomodulatory brain structures, spinal cord-dependent circuits, neural and non-neural cholinergic/catecholaminergic signals and their respective receptors contributing to neuromodulation of inflammation in rheumatoid arthritis. These new neuromodulatory networks and structures will allow the design of innovative bioelectronic or pharmacological approaches for safer and low-cost treatment of arthritis and related inflammatory disorders.

Angiotensin II-induced Hypertension is Reduced by Deficiency of P-selectin Glycoprotein Ligand-1

Identification of inflammatory mediators that regulate the vascular response to vasopressor molecules may aid in the development of novel therapeutic agents to treat or prevent hypertensive vascular diseases. Leukocytes have recently been shown to be capable of modifying blood pressure responses to vasopressor molecules. The purpose of this study was to test the hypothesis that deficiency of the leukocyte ligand, Psgl-1, would reduce the pressor response to angiotensin II (Ang II). Mice deficient in Psgl-1 (Psgl-1^−/−) along with wild-type (WT) controls were treated for 2 weeks with a continuous infusion of Ang II. No differences in blood pressure between the groups were noted at baseline, however after 5 days of Ang II infusion, systolic blood pressures were higher in WT compared to Psgl-1^−/− mice. The pressor response to acute administration of high dose Ang II was also attenuated in Psgl-1^−/− compared to WT mice. Chimeric mice with hematopoietic deficiency of Psgl-1 similarly showed a reduced pressor response to Ang II. This effect was associated with reduced plasma interleukin-17 (IL-17) levels in Psgl-1^−/− mice and the reduced pressor response was restored by administration of recombinant IL-17. In conclusion, hematopoietic deficiency of Psgl-1 attenuates Ang II-induced hypertension, an effect that may be mediated by reduced IL-17.

Activation of IL-17 receptor leads to increased oxidative inflammation in peripheral monocytes of autistic children

Millions of children are affected by different neurodevelopmental disorders, out of which autism spectrum disorder (ASD) poses a major hurdle to normal life style due to associated behavioral abnormalities. Several studies have shown an increased expression/release of Th17 related cytokine, IL-17A in ASD. IL-17A may enhance neuroinflammation via its IL-17A receptor, i.e. IL-17RA expressed in immune cells (such as monocytes) of autistic children. Increased oxidative stress has been implicated in a number of neuropsychiatric disorders including ASD. However, whether IL-17A/IL-17RA signaling contributes to oxidative inflammation in monocytes of autistic children has not been explored previously. With this background, we performed this study in peripheral monocytes of ASD patients and age-matched typically developing children. Our study shows that ASD individuals have increased IL-17RA expression in monocytes which is associated with increased nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) pathway and inducible nitric oxide synthase (iNOS)/nitrotyrosine expression as compared to typically developing children. Moreover, in vitro activation of IL-17 receptor by IL-17A in monocytes isolated from ASD individuals leads to enhanced iNOS expression via NFκB pathway. IL-17RA antibody treatment in vitro reversed IL-17A-induced increase in NFκB and iNOS/nitrotyrosine expression in monocytes isolated from ASD subjects. These data connect increased IL-17A/IL-17RA signaling in ASD patients with enhanced oxidative inflammation in monocytes. Therefore, IL-17 receptor signaling in monocytes may potentiate the effects of IL-17A released by other immune cells and may aggravate neuroinflammation in ASD. Our study further suggests that blockade of IL-17A/IL-17 receptor signaling may be beneficial in the children with ASD.

CD14+ Cells with the Phenotype of Infiltrated Monocytes Consist of Distinct Populations Characterized by Anti-inflammatory as well as Pro-inflammatory Activity in Gouty Arthritis

It has been suggested that inflammasome-mediated IL-1β production in monocytic cells is responsible for the acute inflammatory response in gouty arthritis. However, phenotypical and functional analyses of monocytes during gouty arthritis have yet to be conducted. Therefore, we investigated the characteristics of monocytes/macrophages in the synovial fluid cells of patients with acute gout. The number and frequency of monocytes/macrophages in the synovial fluid mononuclear cells (SFMCs) of patients was examined. The expression of markers for monocyte recruitment and tissue-resident macrophages, the production of pro-inflammatory and anti-inflammatory cytokines, and phagocytosis were analyzed in the monocytes/macrophages of patients with acute gout attacks. The number and frequency of CD14⁺CD3⁻CD19⁻CD56⁻ monocytes/macrophages was markedly increased in the SFMCs of patients with gout compared to those of patients with rheumatoid arthritis (RA). CD14⁺ cells showed the phenotypes of infiltrated monocytes rather than tissue-resident macrophages, characterized by a high expression of CCR2, MRP8, and MRP14, but a low expression of MERTK and 25F9. These cells had the capacity to produce pro-inflammatory cytokines such as TNF-α and IL-1β after stimulation with lipopolysaccharides. In addition, anti-inflammatory features, including CD163 expression and IL-10 production from CD14⁺ cells, were significantly higher in patients with gout than in those with RA. CD14⁺ cells with phenotype of M2 macrophages had high phagocytic activity for monosodium urate crystals. Thus, our results indicate that monocytes/macrophages from patients with gout have the phenotype of infiltrated monocytes, and these cells consist of different populations characterized by anti-inflammatory activities as well as pro-inflammatory functions.

Biologics that inhibit the Th17 pathway and related cytokines to treat inflammatory disorders

INTRODUCTION

Advances in the understanding of TNF-α and IL-17 synergistic functions have recently led to the concept that patients who do not respond or who respond inadequately to TNF-α inhibitors may have IL-17-driven diseases, opening up the way for a new class of therapeutic development: Th17-inhibitors. Areas covered: In this review, the authors discuss the central role that the IL-23/Th17 axis plays in the pathogenesis of several inflammatory diseases, such as psoriasis, highlighting its position as a relevant therapeutic target. In particular, the authors start by giving a brief historical excursus on biologic agent development up until the success of TNF-α inhibitors, and continue with an overview of IL12/23 pathway inhibition. Next, they describe Th17 cell biology, focusing on the role of IL-17 in host defense and in human immune-inflammatory diseases, discussing the use and side effects of IL-17 inhibitors. Expert opinion: The IL-23/Th17 signaling pathway plays a central role in the pathogenesis of several inflammatory diseases, such as psoriasis. Recent data has demonstrated that biologics neutralizing IL-17 (ixekizumab, secukinumab) or its receptor (brodalumab) are highly effective with a positive safety profile in treating moderate to severe psoriasis, offering new treatment possibilities, especially for patients who do not respond adequately to anti-TNF-α therapies.

Impacts of Interleukin-17 Neutralization on the Inflammatory Response in a Healing Ligament

In this study, we sought to improve ligament healing by modulating the inflammatory response after acute injury through the neutralization of Interleukin-17 (IL-17), which we hypothesized would decrease inflammatory cell infiltration and cytokine production. Administration of an Interleukin-17 neutralizing antibody (IL-17 NA) immediately following a rat medial collateral ligament (MCL) transection resulted in alterations in inflammatory cell populations and cytokine expression within the healing ligament, but did not reduce inflammation. Specifically, treatment resulted in a decrease in M2 (anti-inflammatory) macrophages, an increase in T cells, and an increase in the levels of IL-2, IL-6, and IL-12 in the MCL 7 days post injury. IL-17NA treatment, and subsequent immunomodulation, did not result in improved ligament healing, as measured by collagen composition and wound size.