The critical role of C5a as an initiator of neutrophil-mediated autoimmune inflammation of the joint and skin.

The deposition of IgG autoantibodies in peripheral tissues and the subsequent activation of the complement system, which leads to the accumulation of the anaphylatoxin C5a in these tissues, is a common hallmark of diverse autoimmune diseases, including rheumatoid arthritis (RA) and pemphigoid diseases (PDs). C5a is a potent chemoattractant for granulocytes and mice deficient in its precursor C5 or its receptor C5aR1 are resistant to granulocyte recruitment and, consequently, to tissue inflammation in several models of autoimmune diseases. However, the mechanism whereby C5a/C5aR regulates granulocyte recruitment in these diseases has remained elusive. Mechanistic studies over the past five years into the role of C5a/C5aR1 in the K/BxN serum arthritis mouse model have provided novel insights into the mechanisms C5a/C5aR1 engages to initiate granulocyte recruitment into the joint. It is now established that the critical actions of C5a/C5aR1 do not proceed in the joint itself, but on the luminal endothelial surface of the joint vasculature, where C5a/C5aR1 mediate the arrest of neutrophils on the endothelium by activating ß2 integrin. Then, C5a/C5aR1 induces the release of leukotriene B4 (LTB4) from the arrested neutrophils. The latter, subsequently, initiates by autocrine/paracrine actions via its receptor BLT1 the egress of neutrophils from the blood vessel lumen into the interstitial. Compelling evidence suggests that this C5a/C5aR1-LTB4/BLT1 axis driving granulocyte recruitment in arthritis may represent a more generalizable biological principle critically regulating effector cell recruitment in other IgG autoantibody-induced diseases, such as in pemphigoid diseases. Thus, dual inhibition of C5a and LTB4, as implemented in nature by the lipocalin coversin in the soft-tick Ornithodoros moubata, may constitute a most effective therapeutic principle for the treatment of IgG autoantibody-driven diseases.

LTB4 and BLT1 in inflammatory arthritis.

Inflammatory arthritis, including rheumatoid arthritis (RA), is characterized by infiltration of inflammatory cells into the joints. Biological agents targeting TNF-α and IL-6 dramatically improve RA. However, some RA patients do not respond to current treatments and these broadly active upstream biological agents increase the risk of severe infection. Therefore, there remains a need for other effective and safe treatments for RA. Many studies have implicated that blockade of leukotriene B4 (LTB4) and its high affinity receptor BLT1 dramatically suppress arthritis in animal models. In addition, levels of LTB4 in serum, synovial fluid and synovial tissue are increased in RA patients compared to healthy donors or osteoarthritis patients. These data suggest that LTB4 and BLT1 likely contribute to the pathogenesis of human RA. However, several clinical trials inhibiting BLT1 in RA were not successful. Our recent data revealed that LTB4 is a key mediator in a complement, lipid, cytokine and chemokine cascade that first initiates and then sustains neutrophilic inflammation in inflammatory arthritis. These new mechanistic studies suggest novel ways to target the LTB4-BLT1 pathway for the treatment of RA and other inflammatory diseases.

An expanded population of pathogenic regulatory T cells in giant cell arteritis is abrogated by IL-6 blockade therapy.

OBJECTIVES: Randomised-controlled trials have recently proven the efficacy of the interleukin (IL)-6 receptor antagonist tocilizumab (TCZ) in giant cell arteritis (GCA). However, the mechanism of action of IL-6 blockade in this disease is unknown. Moreover, the role of regulatory T (Treg) cells in the pathogenesis of GCA remains underexplored. Given the plasticity of Tregs and the importance of IL-6 in their biology, we hypothesised that TCZ might modulate the Treg response in GCA. We therefore characterised the Treg compartment of patients with GCA treated with TCZ. METHODS: We classified 41 patients with GCA into three groups: active disease (aGCA, n=11), disease remission on corticosteroids (rGCA-CS, n=19) and disease remission on TCZ (rGCA-TCZ, n=11). Healthy controls (HCs) were included for comparison. We determined the frequency, phenotype and function of peripheral blood Tregs. RESULTS: Patients with aGCA demonstrated a hypoproliferating Treg compartment enriched in IL-17-secreting Tregs (IL-17+Tregs). Tregs in patients with aGCA disproportionally expressed a hypofunctional isoform of Foxp3 that lacks exon 2 (Foxp3Δ2). Foxp3Δ2-expressing Tregs coexpressed CD161, a marker commonly associated with the Th17 linage, significantly more often than full-length Foxp3-expressing Tregs. Compared with those of HCs, GCA-derived Tregs demonstrated impaired suppressor capacity. Treatment with TCZ, in contrast to CS therapy, corrected the Treg abnormalities observed in aGCA. In addition, TCZ treatment increased the numbers of activated Tregs (CD45RA-Foxp3high) and the Treg expression of markers of trafficking (CCR4) and terminal differentiation (CTLA-4). CONCLUSIONS: TCZ may exert its therapeutic effects in GCA by increasing the proliferation and activation of Tregs, and by reverting the pathogenic Treg phenotype seen during active disease.

A sphingosine 1-phosphate receptor agonist ameliorates animal model of vasculitis.

OBJECTIVES: Sphingosine 1-phosphate (S1P) is a bioactive lipid that binds to cell surface receptors (S1P1-5). In this study, we examined the effect of S1P1 agonist, ONO-W061, on murine Candida albicans water-soluble fraction (CAWS)-induced vasculitis. METHODS: Mice were administered ONO-W061, and the number of peripheral blood cells was counted. Vasculitis was induced by an intraperitoneal injection of CAWS. Expression of S1P receptors and CXCL1 was analyzed by quantitative RT-PCR. ONO-W061 was orally administered, and vasculitis was evaluated histologically. Number of neutrophils, macrophages and T cells in the vasculitis tissue was counted using flow cytometry. Production of chemokines from S1P-stimulated human umbilical vein endothelial cells (HUVECs) was measured by ELISA. RESULTS: Number of peripheral blood lymphocytes was decreased by ONO-W061. Expression of CXCL1 and S1P1 was enhanced in CAWS-induced vasculitis tissue. Vasculitis score, CXCL1 and number of neutrophils in the vasculitis tissue were lower in ONO-W061-treated mice. Treatment of HUVECs with S1P upregulated the production of CXCL1 and IL-8 in vitro, and this was inhibited by ONO-W061. CONCLUSIONS: ONO-W061 significantly improved CAWS-induced vasculitis. This effect may be partly exerted through the inhibited production of chemokines by endothelial cells, which in turn could induce neutrophil recruitment into inflamed vessels.

Could retinoids be a potential treatment for rheumatic diseases?

Retinoid, a derivative of vitamin A, is a general term used to describe compounds that bind to and activate retinoic acid receptors [RARs (RARα, RARß, and RARγ)] and/or retinoid X receptors [RXRs (RXRα, RXRß, and RXRγ)]. They have been shown to surpress the differentiation of Th1/Th17 cells and induce the development of Th1/regulatory T cells. They also affect the proliferation of B cells as both an inducer and suppressor. Furthermore, retinoids may induce the maturation of dendritic cells and production of interleukin-10 from monocytes/macrophages. We recently demonstrated that retinoids suppressed the production of reactive oxygen species, the release of elastase from neutrophils by inhibiting mitogen-activated protein kinase signals, and both the migration speed and chemotaxis directionality of neutrophils. Retinoids, such as all-trans retinoic acid and tamibarotene, were previously shown to have positive effects on animal models of several rheumatic diseases, including arthritis, myositis, and vasculitis in vivo. Moreover, retinoids have been used in a pilot study to effectively treat patients with lupus nephritis and systemic sclerosis. We herein reviewed the effects of retinoids on immune cells, animal models of rheumatic diseases, and rheumatic patients.

Necessity of lysophosphatidic acid receptor 1 for development of arthritis.

OBJECTIVE: Lysophosphatidic acid (LPA) is a bioactive lipid that binds to a group of cell surface G protein-coupled receptors (LPA receptors 1-6 [LPA1-6 ]) and has been implicated as an important mediator of angiogenesis, inflammation, and cancer growth. This study was undertaken to analyze the effects of LPA1 on the development of arthritis. METHODS: Expression of LPA receptors on synovial tissue was analyzed by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction. The effects of abrogation of LPA1 on collagen-induced arthritis (CIA) were evaluated using LPA1 -deficient mice or LPA1 antagonist. Migrating fluorescence-labeled CD11b+ splenocytes, which were transferred into the synovium of mice with CIA, were counted. CD4+ naive T cells were incubated under Th1-, Th2-, or Th17-polarizing conditions, and T helper cell differentiation was assessed. Osteoclast formation from bone marrow cells was examined. RESULTS: LPA1 was highly expressed in the synovium of patients with rheumatoid arthritis (RA) compared with that of patients with osteoarthritis. LPA1 -deficient mice did not develop arthritis following immunization with type II collagen (CII). LPA1 antagonist also ameliorated murine CIA. Abrogation of LPA1 was associated with reductions in cell infiltration, bone destruction in the joints, and interleukin-17 production from CII-stimulated splenocytes. Infiltration of transferred CD11b+ macrophages from LPA1 -deficient mice into the synovium was suppressed compared with infiltration of macrophages from wild-type mice. LPA1 antagonist inhibited the infiltration of macrophages from wild-type mice. Differentiation into Th17, but not Th1 or Th2, and osteoclast formation were also suppressed under conditions of LPA1 deficiency or LPA1 inhibition in vitro. CONCLUSION: Collectively, these results indicate that LPA/LPA1 signaling contributes to the development of arthritis via cellular infiltration, Th17 differentiation, and osteoclastogenesis. Thus, LPA1 may be a promising target molecule for RA therapy.

Am80, a retinoic acid receptor agonist, ameliorates murine vasculitis through the suppression of neutrophil migration and activation.

OBJECTIVE: Vasculitis is characterized by leukocyte infiltration in the vessel walls, with destructive damage to mural structures. Retinoids are compounds that bind to retinoic acid receptors and exert biologic activities similar to those of vitamin A, including modulatory effects on cell proliferation and differentiation. This study was undertaken to examine the therapeutic effects of a synthetic retinoid, Am80, in a murine model of vasculitis induced by Candida albicans water-soluble fraction (CAWS). METHODS: Vasculitis was induced in BALB/c mice by intraperitoneal injection of CAWS. Neutrophils were depleted by injection of antineutrophil antibody-positive serum. Am80 was administered orally once daily. Vasculitis was evaluated histologically. Migration of labeled adoptively transferred cells was quantified. Chemotaxis was assessed by cell mobility analysis. Production of reactive oxygen species (ROS) and phosphorylation of MAPKs were measured by flow cytometry. Concentrations of elastase were measured by enzyme-linked immunosorbent assay. RESULTS: Administration of CAWS induced vasculitis in the coronary arteries and aortic root, with abundant neutrophil infiltration. Depletion of neutrophils reduced CAWS-induced vasculitis. Treatment with Am80 led to a significant attenuation of the vasculitis score and inhibition of the migration of transferred neutrophils into the site of vasculitis. In vitro, Am80 suppressed fMLP-induced chemotaxis of human peripheral blood neutrophils. ROS production and elastase release by stimulated neutrophils were reduced by AM80 treatment, and Am80 also inhibited phosphorylation of ERK-1/2 and p38 in neutrophils stimulated with fMLP plus lipopolysaccharide. CONCLUSION: Am80 significantly suppressed CAWS-induced vasculitis. This effect was presumably exerted via inhibition of neutrophil migration and activation.

Cannabinoid receptor 2 as a potential therapeutic target in rheumatoid arthritis.

BACKGROUND: Some of cannabinoids, which are chemical compounds contained in marijuana, are immunosuppressive. One of the receptors, CB receptor 1 (CB1), is expressed predominantly by the cells in the central nervous system, whereas CB receptor 2 (CB(2)) is expressed primarily by immune cells. Theoretically, selective CB(2) agonists should be devoid of psychoactive effects. In this study, we investigated therapeutic effects of a selective CB(2) agonist on arthritis. METHODS: The expression of CB(2) was analyzed with immunohistochemistry and Western blotting. Interleukin (IL)-6, matrix metalloproteinase-3 (MMP-3), and chemokine (C-C motif) ligand 2 (CCL2) were quantified with enzyme-linked immunosorbent assays (ELISA). Osteoclastogenesis was assessed with tartrate-resistant acid phosphatase staining and the resorption of coated-calcium phosphate. Effect of JWH133, a selective CB(2) agonist, on murine collagen type II (CII)-induced arthritis (CIA) was evaluated with arthritis score, and histological and radiographic changes. IFN-γ and IL-17 production by CII-stimulated splenocytes and serum anti-CII Ab were analyzed by ELISA. RESULTS: Immunohistochemistry showed that CB(2) was expressed more in the synovial tissues from the rheumatoid joints than in those from the osteoarthritis joints. CB(2) expression on RA FLS was confirmed with Western blot analysis. JWH133 inhibited IL-6, MMP-3, and CCL2 production from tumor necrosis factor-α-stimulated fibroblast-like synoviocytes (FLS) derived from the rheumatoid joints, and osteoclastogenesis of peripheral blood monocytes. Administration of JWH133 to CIA mice reduced the arthritis score, inflammatory cell infiltration, bone destruction, and anti-CII IgG1 production. CONCLUSION: The present study suggests that a selective CB(2) agonist could be a new therapy for RA that inhibits production of inflammatory mediators from FLS, and osteoclastogenesis.

Clodronate liposome treatment contributes to the nerve regeneration in corneal nerve involvement of diabetic mice.

The dense nerve and thin vascular structure of the corneal tissue provide the refractive function in healthy eyes. Diabetes mellitus causes ocular complications including corneal opacification because of corneal nerve degeneration. Diabetic neurotrophic keratopathy is characterized by reduced corneal sensitivity, delayed corneal wound healing, and nerve degeneration. Neurotization and vascularization inhibit each other in the cornea. Macrophages contribute to the corneal neovascularization. To investigate the role of macrophage in neurotrophic keratopathy, clodronate liposome was subconjunctivally injected into diabetic db/db mice with neurotrophic keratopathy. The clodronate liposome treatment decreased F4/80+ macrophage infiltration into the corneal epithelium, and improved corneal nerve involvement in diabetic db/db mice. Furthermore, we found that interleukin (IL)-1ß and IL-34 mRNA expression was increased in the corneal epithelium of clodronate-treated diabetic db/db mice. These cytokines contribute to the maintenance of nerve tissues via microglia and nerve regeneration; however, their role in corneal nerve involvement remains unknown. Notably, the intraocular injection of recombinant IL-1ß and IL-34 promoted nerve regeneration in the cornea of diabetic db/db mice. These results suggest that clodronate liposome treatment contributes to nerve regeneration during corneal involvement via IL-1ß and IL-34 signaling.

Streptococcal infection and autoimmune diseases.

Excessive activation of immune cells by environmental factors, such as infection or individual genetic risk, causes various autoimmune diseases. Streptococcus species are gram-positive bacteria that colonize the nasopharynx, respiratory tract, gastrointestinal tract, genitourinary tract, and skin. Group A Streptococcus (GAS) species cause various symptoms, ranging from mild infections, such as tonsillitis and pharyngitis, to serious infections, such as necrotizing fasciitis and streptococcal toxic shock syndrome. The contribution of GAS infections to several autoimmune diseases, including acute rheumatic fever, vasculitis, and neuropsychiatric disorders, has been studied. In this review, we focus on the association between streptococcal infections and autoimmune diseases, and discuss current research on the mechanisms underlying the initiation and progression of autoimmune diseases.

Lysosomal degradation of PD-L1 is associated with immune-related adverse events during anti-PD-L1 immunotherapy in NSCLC patients.

Background: Immune checkpoint inhibitors (ICIs) can induce immune-related adverse events (irAEs). Liquid biomarkers to predict irAE occurrence are urgently needed. We previously developed an ELISA system to specifically detect soluble PD-L1 (sPD-L1) with PD-1-binding capacity (bsPD-L1). Here, we investigated the relationship between sPD-L1 and bsPD-L1 in gastric cancer (GC) and non-small cell lung cancer (NSCLC) treated with PD-1/PD-L1 blockade and their association with irAEs. Methods: We examined sPD-L1, bsPD-L1, matrix metalloproteinases (MMPs), and proinflammatory cytokine levels by ELISA in plasma samples from 117 GC patients prior to surgery and 72 NSCLC patients prior to and at 2 months after ICI treatment (anti-PD-1, n = 48; anti-PD-L1, n = 24). In mice treated with anti-PD-1/PD-L1 antibodies (Abs), sPD-L1 levels and localization of Abs were examined by ELISA and immunohistochemistry, respectively. Results:sPD-L1 was detected with higher frequency in GC patients than in NSCLC patients, whereas bsPD-L1 was detected with similar frequencies in GC and NSCLC patients. sPD-L1 levels were correlated with IL-1α, IL-1ß, TNF-α, and IL-6 levels, while bsPD-L1 levels were correlated with MMP13, MMP3, and IFN-γ levels. In NSCLC patients, anti-PD-L1, but not anti-PD-1, treatment increased sPD-L1, which was associated with irAE development, but not with clinical outcomes. In mice, trafficking of anti-PD-L1 Abs to lysosomes in F4/80+ macrophages resulted in sPD-L1 production, which was suppressed by treatment with lysosomal degradation inhibitor chloroquine and macrophage depletion. Conclusion: Anti-PD-L1-mediated lysosomal degradation induces sPD-L1 production, which can serve as an indicator to predict irAE development during anti-PD-L1 treatment.

Combination of plasma MMPs and PD-1-binding soluble PD-L1 predicts recurrence in gastric cancer and the efficacy of immune checkpoint inhibitors in non-small cell lung cancer.

Background: The tumor microenvironment (TME) impacts the therapeutic efficacy of immune checkpoint inhibitors (ICIs). No liquid biomarkers are available to evaluate TME heterogeneity. Here, we investigated the clinical significance of PD-1-binding soluble PD-L1 (bsPD-L1) in gastric cancer (GC) patients and non-small cell lung cancer (NSCLC) patients treated with PD-1/PD-L1 blockade. Methods: We examined bsPD-L1, matrix metalloproteinases (MMPs), and IFN-γ levels in plasma samples from GC patients (n = 117) prior to surgery and NSCLC patients (n = 72) prior to and 2 months after ICI treatment. We also examined extracellular matrix (ECM) integrity, PD-L1 expression, and T cell infiltration in tumor tissues from 25 GC patients by Elastica Masson-Goldner staining and immunohistochemical staining for PD-L1 and CD3, respectively. Results: bsPD-L1 was detected in 17/117 GC patients and 16/72 NSCLC patients. bsPD-L1 showed strong or moderate correlations with plasma MMP13 or MMP3 levels, respectively, in both GC and NSCLC patients. bsPD-L1 expression in GC was associated with IFN-γ levels and intra-tumoral T cell infiltration, whereas MMP13 levels were associated with loss of ECM integrity, allowing tumor cells to access blood vessels. Plasma MMP3 and MMP13 levels were altered during ICI treatment. Combined bsPD-L1 and MMP status had higher predictive accuracy to identify two patient groups with favorable and poor prognosis than tumor PD-L1 expression: bsPD-L1+MMP13high in GC and bsPD-L1+(MMP3 and MMP13)increased in NSCLC were associated with poor prognosis, whereas bsPD-L1+MMP13low in GC and bsPD-L1+(MMP3 or MMP13)decreased in NSCLC were associated with favorable prognosis. Conclusion: Plasma bsPD-L1 and MMP13 levels indicate T cell response and loss of ECM integrity, respectively, in the TME. The combination of bsPD-L1 and MMPs may represent a non-invasive tool to predict recurrence in GC and the efficacy of ICIs in NSCLC.

Chemokines and chemokine receptors as promising targets in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease that commonly causes inflammation and bone destruction in multiple joints. Inflammatory cytokines, such as IL-6 and TNF-α, play important roles in RA development and pathogenesis. Biological therapies targeting these cytokines have revolutionized RA therapy. However, approximately 50% of the patients are non-responders to these therapies. Therefore, there is an ongoing need to identify new therapeutic targets and therapies for patients with RA. In this review, we focus on the pathogenic roles of chemokines and their G-protein-coupled receptors (GPCRs) in RA. Inflamed tissues in RA, such as the synovium, highly express various chemokines to promote leukocyte migration, tightly controlled by chemokine ligand-receptor interactions. Because the inhibition of these signaling pathways results in inflammatory response regulation, chemokines and their receptors could be promising targets for RA therapy. The blockade of various chemokines and/or their receptors has yielded prospective results in preclinical trials using animal models of inflammatory arthritis. However, some of these strategies have failed in clinical trials. Nonetheless, some blockades showed promising results in early-phase clinical trials, suggesting that chemokine ligand-receptor interactions remain a promising therapeutic target for RA and other autoimmune diseases.

Innate immune responses in Behçet disease and relapsing polychondritis.

Behçet disease (BD) and relapsing polychondritis (RP) are chronic multisystem disorders characterized by recurrent flare-ups of tissue inflammation. Major clinical manifestations of BD are oral aphthae, genital aphthous ulcers, skin lesions, arthritis, and uveitis. Patients with BD may develop rare but serious neural, intestinal, and vascular complications, with high relapse rates. Meanwhile, RP is characterized by the inflammation of the cartilaginous tissues of the ears, nose, peripheral joints, and tracheobronchial tree. Additionally, it affects the proteoglycan-rich structures in the eyes, inner ear, heart, blood vessels, and kidneys. The mouth and genital ulcers with inflamed cartilage (MAGIC) syndrome is a common characteristic of BD and RP. The immunopathology of these two diseases may be closely related. It is established that the genetic predisposition to BD is related to the human leukocyte antigen (HLA)-B51 gene. Skin histopathology demonstrates the overactivation of innate immunity, such as neutrophilic dermatitis/panniculitis, in patients with BD. Monocytes and neutrophils frequently infiltrate cartilaginous tissues of patients with RP. Somatic mutations in UBA1, which encodes a ubiquitylation-related enzyme, cause vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome (VEXAS) with severe systemic inflammation and activation of myeloid cells. VEXAS prompts auricular and/or nasal chondritis, with neutrophilic infiltration around the cartilage in 52-60% of patients. Thus, innate immune cells may play an important role in the initiation of inflammatory processes underlying both diseases. This review summarizes the recent advances in our understanding of the innate cell-mediated immunopathology of BD and RP, with a focus on the common and distinct features of these mechanisms.

Alteration of microbial composition in the skin and blood in vasculitis.

Vasculitis is a systemic autoimmune disease characterized by leukocyte infiltration into blood vessels. Various microorganisms have been associated with the pathogenesis of vasculitis; however, the causal microbial agents and underlying mechanisms are not fully understood, possibly because of the technical limitations of pathogen detection. In the present study, we characterized the microbiome profile of patients with cutaneous vasculitis using comprehensive metagenome shotgun sequencing. We found that the abundance of the SEN virus was increased in the affected skin and serum of patients with vasculitis compared to healthy donors. In particular, the abundance of SEN virus reads was increased in the sera of patients with cutaneous arteritis. Among the bacteria identified, Corynebacteriales was the most differentially associated with vasculitis. Linear discriminant analysis effect size also indicated differences in the microbial taxa between patients with vasculitis and healthy donors. These findings demonstrate that vasculitis is associated with considerable alteration of the microbiome in the blood and skin and suggest a role for the infectious trigger in vasculitis.

Pathogenic role of CXCR7 in rheumatoid arthritis.

OBJECTIVE: The interaction between CXCL12 and its receptor, CXCR4, in the synovium of patients with rheumatoid arthritis (RA) is important for local inflammatory cell recruitment, angiogenesis, and cytokine production. CXCR7 was recently identified as an alternative receptor for CXCL12. We undertook this study to analyze the expression of CXCR7 in RA synovium and the pathogenic role of the CXCL12/CXCR7 pathway in RA. METHODS: CXCR7 expression in RA synovial tissue was analyzed using immunohistochemistry, while expression of CXCR4 and CXCR7 on human umbilical vein endothelial cells (HUVECs) was examined using quantitative reverse transcription-polymerase chain reaction, and CXCR7 expression was also analyzed by flow cytometry. Tube formation and rat aortic ring angiogenesis assays were used to assess the effects of CCX733 (a CXCR7 antagonist) and AMD3100 (a CXCR4 antagonist) on CXCL12-induced angiogenesis. The effect of anti-CXCR4 monoclonal antibody (mAb) was also analyzed using a tube formation assay. The effects of CCX733 in a murine model of collagen-induced arthritis (CIA) were also evaluated. RESULTS: CXCR7 was expressed on endothelial cells in RA synovium and also on unstimulated HUVECs. The expression of CXCR7 on HUVECs was markedly up-regulated by interleukin-1ß (IL-1ß) stimulation, and this overexpression was further enhanced by CXCL12 treatment. Incubation with CXCL12 also promoted angiogenic activity, with addition of IL-1ß again augmenting the effect. CXCL12-induced angiogenesis was inhibited by both CXCR4 and CXCR7 antagonists and by anti-CXCR4 mAb. Furthermore, treatment with CCX733 significantly reduced the clinical arthritis scores and the numbers of vessels in the inflamed synovial tissue in mice with CIA. CONCLUSION: CXCR7 and CXCR4 are both important for angiogenesis in RA synovium, making CXCR7 another potential target molecule for novel RA angiogenesis-blocking therapies.

Successful treatment of cyclosporine-A-resistant cytophagic histiocytic panniculitis with tacrolimus.

A 34-year-old woman with discoid lupus erythematosus and lupus profundus was admitted to our hospital showing signs of a fever, malaise, and abdominal swelling. Diagnosis of cytophagic histiocytic panniculitis (CHP) was made based on lobular panniculitis with a hemophagocytosis. Treatment with high doses of prednisolone combined with cyclosporine A (CsA) was not effective enough. However, after changing CsA to tacrolimus (TAC), CHP improved. Our case demonstrates that TAC may be a novel therapy for CHP.

Pathogens in Vasculitis: Is It Really Idiopathic?

Vasculitis is an autoimmune disease characterized by the infiltration of leukocytes in blood vessels. An increasing number of studies on human and animal models have implicated various microorganisms in the pathogenesis of vasculitis. Previous studies have shown the presence of infectious agents, including viruses, bacteria, and fungi, in diseased vessels. However, despite continued research, the link between infection and vasculitis is not fully understood, possibly owing to the lack of appropriate animal models that mirror human disease and the technical limitations of pathogen detection in blood vessels. Among the pathogen-induced animal models, Candida albicans water-soluble fraction (CAWS)-induced coronary arteritis is currently considered one of the representative models of Kawasaki (KD) disease. Advances in metagenomic next-generation sequencing have enabled the detection of all nucleic acids in tissue, which can help identify candidate pathogens, including previously unidentified viruses. In this review, we discuss the findings from reports on pathogen-associated vasculitis in animal models and humans, with a specific focus on the investigation of the pathogenesis of vasculitis. Further studies on animal models and microbes in diseased vessels may provide important insights into the pathogenesis of vasculitis, which is often considered an idiopathic disease.

Immune checkpoint molecule expression is altered in the skin and peripheral blood in vasculitis.

Dysfunction of immunoinhibitory signals and persistent T cell activation reportedly play important roles in the development of vasculitis. The skin is one of the most accessible organs, and it is suitable for the characterization of immune cell signatures. However, the inhibitory checkpoint molecules in the skin and their relevance to vasculitis have not been studied. Here, we investigated the profile of immune checkpoint molecules in the skin and peripheral blood of patients with vasculitis and healthy donors. We found that some of the inhibitory checkpoint molecules, including programmed cell death 1 receptor (PD-1), were elevated in T-cells in the blood of patients with systemic and cutaneous vasculitis. In addition, programmed death-ligand 1 (PD-L1) expression was elevated in the skin of patients with cutaneous vasculitis. Histologically, PD-L1 was highly expressed in the vessels in the skin along with CD4+ and CD8+ T-cell infiltration in patients with cutaneous vasculitis. Notably, plasma soluble PD-L1 levels were increased, and these correlated with C-reactive protein in patients with systemic vasculitis. Our findings suggest that inhibitory checkpoint molecules might be differentially modulated in the skin and peripheral blood of patients with vasculitis, and that the alteration of the PD-L1/PD-1 axis may be associated with the regulation of T-cell activation in vasculitis.