Targeting CD226/DNAX accessory molecule-1 (DNAM-1) in collagen-induced arthritis mouse models

Genetic variability of three common NK and γδ T cell receptor genes (FCγ3R, NCR3, and DNAM-1) and their role in Polish patients with rheumatoid arthritis and ankylosing spondylitis

Various lymphocyte subpopulations, including NK cells as well as γδ T cells, have been considered an important element in the pathogenesis of autoimmune, inflammatory, rheumatic diseases, such as rheumatoid arthritis (RA) and ankylosing spondylitis (AS). The aim of this study was to assess the potential role of polymorphic variations in the genes coding for three NK and γδ T cell receptors: NCR3, FCγR3A, and DNAM-1 (rs1052248, rs396991, and rs763361, respectively) in the disease susceptibility and the efficacy of treatment with TNF inhibitors. The study included 461 patients with RA, 168 patients with AS, and 235 voluntary blood donors as controls. The NCR3 rs1052248 AA homozygosity prevailed in RA in patients lacking rheumatoid factor (p = 0.044) as well as in those who manifested the disease at a younger age (p = 0.005) and had higher CRP levels after 12 weeks of anti-TNF therapy (p = 0.021). The FCγR3A rs396991 polymorphism was associated with pain visual analogue scale (VAS) values before the initiation of anti-TNF treatment. Lower VAS values were observed in the GG homozygous RA patients (p = 0.024) and in AS patients with the TT genotype (p = 0.012). Moreover, AS heterozygous patients with the TG genotype presented higher CRP levels in the 12th week of anti-TNF treatment (p = 0.021). The findings suggest that the NCR3 rs1052248 AA homozygosity may have an adverse effect on RA, while the T allele potentially plays a protective role in the development of AS. Moreover, the rs1052248 T allele and TT genotype appear to have a favorable impact on the response to anti-TNF therapy in RA patients.

Nectin Family Ligands Trigger Immune Effector Functions in Health and Autoimmunity

The superfamily of immunoglobulin cell-adhesion molecules (IgCAMs) is a well-known family of cell-adhesion molecules used for immune-cell extravasation and cell–cell interaction. Amongst others, this family includes DNAX accessory molecule 1 (DNAM-1/CD226), class-I-restricted T-cell-associated molecule (CRTAM/CD355), T-cell-activated increased late expression (Tactile/CD96), T-cell immunoreceptor with Ig and ITIM domains (TIGIT), Nectins and Nectin-like molecules (Necls). Besides using these molecules to migrate towards inflammatory sites, their interactions within the immune system can support the immunological synapse with antigen-presenting cells or target cells for cytotoxicity, and trigger diverse effector functions. Although their role is generally described in oncoimmunity, this review emphasizes recent advances in the (dys)function of Nectin-family ligands in health, chronic inflammatory conditions and autoimmune diseases. In addition, this review provides a detailed overview on the expression pattern of Nectins and Necls and their ligands on different immune-cell types by focusing on human cell systems.

Loss of CD226 protects apolipoprotein E-deficient mice from diet-induced atherosclerosis

CD226 is a costimulatory molecule that regulates immune cell functions in T cells, natural killer cells, and macrophages. Because macrophage-derived foam cell formation is a crucial factor contributing to the development of atherosclerosis, we aimed to evaluate the potential roles of CD226 in the pathogenesis of atherosclerosis. The effects of CD226 on atherosclerosis were investigated in CD226 and apolipoprotein E double-knockout (CD226^-/- ApoE^-/-) mice fed with a high-cholesterol atherogenic diet. CD226 expression in macrophages was evaluated using flow cytometry. Histopathological analysis was performed to evaluate the atherosclerotic lesions. Inflammatory cell infiltration was detected using immunofluorescence staining. Bone marrow-derived macrophages (BMDMs) and peritoneal macrophages (PEMs) were isolated from the mice and used to explore the mechanism in vitro. The in vivo results indicated that CD226 knockdown protected against atherosclerosis in ApoE^-/- mice, evidenced by reduced plaque accumulation in the brachiocephalic artery, aortic roots, and main aortic tree. CD226 gene-deficient macrophages showed reduced foam cell formation under ox-low density lipoprotein stimulation compared with wild-type (WT) cells. CD226 deficiency also decreased the expression of CD36 and scavenger receptor (SR)-A (responsible for lipoprotein uptake) but increased the expression of ATP-binding cassette transporter A1 and G1 (two transporters for cholesterol efflux). Therefore, loss of CD226 hinders foam cell formation and atherosclerosis progression, suggesting that CD226 is a promising new therapeutic target for atherosclerosis.

CD226 Deletion Reduces Type 1 Diabetes in the NOD Mouse by Impairing Thymocyte Development and Peripheral T Cell Activation

The costimulatory molecule CD226 is highly expressed on effector/memory T cells and natural killer cells. Costimulatory signals received by T cells can impact both central and peripheral tolerance mechanisms. Genetic polymorphisms in CD226 have been associated with susceptibility to type 1 diabetes and other autoimmune diseases. We hypothesized that genetic deletion of Cd226 in the non-obese diabetic (NOD) mouse would impact type 1 diabetes incidence by altering T cell activation. CD226 knockout (KO) NOD mice displayed decreased disease incidence and insulitis in comparison to wild-type (WT) controls. Although female CD226 KO mice had similar levels of sialoadenitis as WT controls, male CD226 KO mice showed protection from dacryoadenitis. Moreover, CD226 KO T cells were less capable of adoptively transferring disease compared to WT NOD T cells. Of note, CD226 KO mice demonstrated increased CD8⁺ single positive (SP) thymocytes, leading to increased numbers of CD8⁺ T cells in the spleen. Decreased percentages of memory CD8⁺CD44⁺CD62L^- T cells were observed in the pancreatic lymph nodes of CD226 KO mice. Intriguingly, CD8⁺ T cells in CD226 KO mice showed decreased islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)-tetramer and CD5 staining, suggesting reduced T cell receptor affinity for this immunodominant antigen. These data support an important role for CD226 in type 1 diabetes development by modulating thymic T cell selection as well as impacting peripheral memory/effector CD8⁺ T cell activation and function.

CD226: An Emerging Role in Immunologic Diseases

CD226, a member of the immunoglobulin superfamily, is a functional protein initially expressed on natural killer and T cells. In recent years, the function of CD226 has been increasingly realized and researched. Accumulating evidence shows that CD226 is closely related to the occurrence of autoimmune diseases, infectious diseases, and tumors. Because of the CD226’s increasing importance, the author herein discusses the structure, mechanism of action, and role of CD226 in various pathophysiological environments, allowing for further understanding of the function of CD226 and providing the basis for further research in related diseases.

CD19+CD24hiCD38hi regulatory B cells: a potential immune predictive marker of severity and therapeutic responsiveness of hepatitis C

OBJECTIVES

Hepatitis C virus (HCV) infection is associated with abnormal immune responses. Since regulatory T (Tregs) and B (Bregs) cells modulate the progression of infectious diseases, this study aimed at examining how these cells are involved with the development of HCV infection.

METHODS

The frequencies of circulating Bregs and Tregs were characterized using flow cytometry. Both the association and dynamic changes of these cells with related clinical parameters were analyzed after Direct-Acting Antiviral (DAA) agent treatments. Additionally, both regulatory B and T and naïve B and T cells were sorted and stimulated with healthy or HCV sera in vitro.

RESULTS

Bregs frequency in HCV-infected patients increased significantly and were positively correlated with levels of sera HCV RNA load, Alanine aminotransferase (AST) and total bilirubin (TBILI). Additionally, the increased Bregs returned to normal levels after DAA treatment. However, Tregs increased markedly in patients with HCV-cirrhosis and were significantly associated with Aspartate aminotransferase to Platelet Ratio Index (APRI) and Fibrosis 4 (FIB-4) scores. Furthermore, HCV sera doesn't expand either Tregs or Bregs, however, it does induce the IL-10 expression in B cells although it fails to induce FOXP3 expression in CD4+ T cells.

CONCLUSIONS

Increased Bregs not only may be associated with poor viral eradication and liver injury but also may provide a predictive marker of HCV disease therapeutic efficacy following DAA-treatment. HCV sera may selectively induce Bregs. Tregs probably do not control disease status in the early stages but may contribute to the progression of liver fibrosis in the late stages of HCV infection.

Helios but not CD226, TIGIT and Foxp3 is a Potential Marker for CD4+ Treg Cells in Patients with Rheumatoid Arthritis

BACKGROUND/AIMS

Rheumatoid arthritis (RA) is a progressive, chronic, even disabling systemic autoimmune disease. Imbalance between pathogenic immune cells and immunosuppressive cells is associated with the pathogenesis and development of RA and other autoimmune diseases. As Foxp3 is also expressed on activated CD4⁺ cells in the presence of inflammation, the identification of Treg cells in patients with RA remains a challenge.

METHODS

Comprehensive analyses were carried out by Flow cytometry. Expression of Helios, CD226, T cell immunoreceptor with Ig and ITIM domains clinical samples and healthy controls.

RESULTS

We have systemically examined three potential markers, Helios, CD226 and TIGIT, that are possibly related to Treg identification, and found that Helios expression on CD4⁺Foxp3⁺cells was decreased and negatively correlated with the disease activity of RA patients, while CD226 and TIGIT both showed elevated expression levels in CD4⁺Foxp3⁺cells in RA patients and they were not associated with disease activity of RA patients.

CONCLUSION

Taken together, our findings indicate that CD4⁺CD25^hiCD127^low/-Foxp3⁺Helios⁺ may represent the real Treg cell population in patients with RA.

Astragalin Suppresses Inflammatory Responses and Bone Destruction in Mice With Collagen-Induced Arthritis and in Human Fibroblast-Like Synoviocytes

Astragalin, as a bioactive flavonoid with anti-inflammatory, antioxidant, and protective properties, provides a potential agent for rheumatoid arthritis (RA). In this study, its therapeutic efficacy and the underlying mechanisms were explored using DBA/1J mice with collagen-induced arthritis (CIA). It was demonstrated that astragalin could significantly attenuate inflammation of CIA mice. The effects were associated with decreased severity of arthritis (based on the arthritis index), joint swelling and reduced bone erosion and destruction. Furthermore, astragalin treatment suppressed the production of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-8), and inhibited the expression of matrix metalloproteinases (MMP-1, MMP-3, and MMP-13) in chondrocytes and synovial cells of CIA mice. Fibroblast-like synoviocytes derived from RA patients (MH7A cells) were applied to verify these effects. In vitro, astragalin inhibited the expression of matrix metalloproteinases (MMP-1, MMP-3, and MMP-13) dose-dependently in TNF-α-induced MH7A cells, with no apparent cytotoxicity. Furthermore, astragalin suppressed the phosphorylation of p38, JNK, and the activation of c-Jun/AP-1 in TNF-α-induced MH7A cells. In conclusion, it has proven that astragalin could attenuate synovial inflammation and joint destruction in RA at least partially by restraining the phosphorylation of MAPKs and the activating of c-Jun/AP-1. Therefore, astragalin can be a potential therapeutic agent for RA.

The paired receptors TIGIT and DNAM-1 as targets for therapeutic antibodies

One of the most exciting fields in modern medicine is immunotherapy, treatment which looks to harness the power of the immune system to fight disease. A particularly effective strategy uses antibodies designed to influence the activity levels of the immune system. Here we look at two receptors - TIGIT and DNAM-1 - which bind the same ligands but have opposite effects on immune cells, earning them the label `paired receptors'. Importantly, natural killer cells and cytotoxic T cells express both of these receptors, and in certain cases their effector functions are dictated by TIGIT or DNAM-1 signaling. Agonist and antagonist antibodies targeting either TIGIT or DNAM-1 present many therapeutic options for diseases spanning from cancer to auto-immunity. In this review we present cases in which the modulation of these receptors holds potential for the development of novel therapies.

Lysyl oxidase is involved in synovial hyperplasia and angiogenesis in rats with collagen‑induced arthritis

Lysyl oxidase (LOX) serves an important role in remodeling the extracellular matrix and angiogenesis in various types of cancer; however, whether LOX is involved in the pathogenesis of rheumatoid arthritis remains unknown. In order to investigate this in the present study, β-aminopropionitrile, an inhibitor of LOX, was injected intraperitoneally into rats with type II collagen-induced arthritis (CIA). Subsequently, synovial hyperplasia was examined by hematoxyl in and eosin staining, and the microvascular density (MVD) and expression levels of LOX, matrix metalloproteinase (MMP)-2 and MMP-9 in the synovial membrane and fluid were determined by immunohistochemistry and ELISA, respectively. The enzyme activity of LOX was evaluated by the Amplex Red Hydrogen Peroxide method. The results demonstrated an increased amount of rough synovial membranes, higher MVD in these membranes and more synovial cell layers in CIA rats compared with in the control rats. In addition, higher enzymatic activity of LOX and higher expression levels of MMP-2 and MMP-9 were revealed in CIA rats compared with in the control rats. Notably, β-aminopropionitrile inhibited paw swelling and the decreased the arthritis index, the MVD in the synovial membranes and the expression levels of MMP-2 and MMP-9. Furthermore, the expression level of LOX in the synovial membranes was positively associated with the MVD and the expression levels of MMP-2 and MMP-9, suggesting that LOX promotes synovial hyperplasia and angiogenesis and that LOX may be a potential therapeutic target for rheumatoid arthritis.

A Truncated IL-17RC Peptide Ameliorates Synovitis and Bone Destruction of Arthritic Mice

Peptide-based therapy, such as modified peptides, has attracted increased attention. IL-17 is a promising therapeutic target for autoimmune diseases, and levels of circulating bioactive IL-17 are associated with rheumatoid arthritis severity. In this study, a modified truncated IL-17RC is generated to ameliorate inflammation and bone destruction in arthritis. The truncated IL-17RC binds to both IL-17A and IL-17F with higher binding capacity compared to nonmodified IL-17RC. In addition, the truncated IL-17RC reduces the secretion of inflammatory and osteoclastogenic factors induced by IL-17A/F in vitro. Moreover, the administration of truncated IL-17RC dramatically improves symptoms of inflammation and inhibited bone destruction in collagen-induced arthritis mice. Collectively, these data demonstrate that modified truncated IL-17RC peptide may be a more effective treatment strategy in the simultaneous inhibition of both IL-17A and IL-17F signaling, whereas the existing agents neutralize IL-17A or IL-17F alone. These suggest that the truncated IL-17RC may be a potential candidate in the treatment of inflammatory associated bone diseases.

The establishment of a porcine rheumatoid arthritis model: Collagen induced arthritis minipig model

Rheumatoid arthritis (RA) research has been largely dependent on collagen induced arthritis (CIA) rodent models, however, they may not translate well to humans due to innate differences in the size, physiology and lifespan. The present study aimed to establish a CIA porcine model with the physical, hematological, histopathological and etiological properties closer to their human equivalent in an attempt to better meet the needs of RA research. Three month old minipigs were administered of bovine type II collagen (CII) emulsified with complete Freund's adjuvants on Day 1 and incomplete Freund's adjuvants on Day 22, via an intradermal or intra-articular route. The clinical, radiological and hematological assessments of immunized animals were made periodically until Day 43, during which period the onset and progression of arthritis was recorded and characterized. In addition, the histopathological and micro-tomographic assessments of the cartilage degradation with regard to mononuclear cell infiltration, and joint deformity indicated a higher severity in the intradermal injection group over the intra-articular group. With confirmation of the susceptibility to heterogeneous CII for arthritis induction in minipig, the potential suitability of this test system as a large animal model for RA has been demonstrated.

Critical roles of co-activation receptor DNAX accessory molecule-1 in natural killer cell immunity

Natural killer (NK) cells, which can exert early and powerful anti-tumour and anti-viral responses, are important components of the innate immune system. DNAX accessory molecule-1 (DNAM-1) is an activating receptor molecule expressed on the surface of NK cells. Recent findings suggest that DNAM-1 is a critical regulator of NK cell biology. DNAM-1 is involved in NK cell education and differentiation, and also plays a pivotal role in the development of cancer, viral infections and immune-related diseases. However, tumours and viruses have developed multiple mechanisms to evade the immune system. They are able to impair DNAM-1 activity by targeting the DNAM-1 receptor-ligand system. We have reviewed the roles of DNAM-1, and its biological functions, with respect to NK cell biology and DNAM-1 chimeric antigen receptor-based immunotherapy.