Activation of cytotoxic lymphocytes through CD6 enhances killing of cancer cells.

Immune checkpoint inhibitors (ICIs) have demonstrated efficacy and improved survival in a growing number of cancers. Despite their success, ICIs are associated with immune-related adverse events that can interfere with their use. Therefore, safer approaches are needed. CD6, expressed by T-lymphocytes and human NK cells, engages in cell-cell interactions by binding to its ligands CD166 (ALCAM) and CD318 (CDCP1). CD6 is a target protein for regulating immune responses and is required for the development of several mouse models of autoimmunity. Interestingly, CD6 is exclusively expressed on immune cells while CD318 is strongly expressed on most cancers. Here we demonstrate that disrupting the CD6-CD318 axis with UMCD6, an anti-CD6 monoclonal antibody, prolongs survival of mice in xenograft mouse models of human breast and prostate cancer, treated with infusions of human lymphocytes. Analysis of tumor-infiltrating immune cells showed that augmentation of lymphocyte cytotoxicity by UMCD6 is due to effects of this antibody on NK, NKT and CD8 + T cells. In particular, tumor-infiltrating cytotoxic lymphocytes from UMCD6-treated mice expressed higher levels of perforin and were found in higher proportions than those from IgG-treated mice. Moreover, RNA-seq analysis of human NK-92 cells treated with UMCD6 revealed that UMCD6 up-regulates the NKG2D-DAP10 receptor complex, important in NK cell activation, as well as its downstream target PI3K. Our results now describe the phenotypic changes that occur on immune cells upon treatment with UMCD6 and further confirm that the CD6-CD318 axis can regulate the activation state of cytotoxic lymphocytes and their positioning within the tumor microenvironment.

Mammalian Glycosylation Patterns Protect Citrullinated Chemokine MCP-1/CCL2 from Partial Degradation.

Monocyte chemoattractant protein-1 (MCP-1/CCL2) is a potent chemotactic agent for monocytes, primarily produced by macrophages and endothelial cells. Significantly elevated levels of MCP-1/CCL2 were found in synovial fluids of patients with rheumatoid arthritis (RA), compared to osteoarthritis or other arthritis patients. Several studies suggested an important role for MCP-1 in the massive inflammation at the damaged joint, in part due to its chemotactic and angiogenic effects. It is a known fact that the post-translational modifications (PTMs) of proteins have a significant impact on their properties. In mammals, arginine residues within proteins can be converted into citrulline by peptidylarginine deiminase (PAD) enzymes. Anti-citrullinated protein antibodies (ACPA), recognizing these PTMs, have become a hallmark for rheumatoid arthritis (RA) and other autoimmune diseases and are important in diagnostics and prognosis. In previous studies, we found that citrullination converts the neutrophil attracting chemokine neutrophil-activating peptide 78 (ENA-78) into a potent macrophage chemoattractant. Here we report that both commercially available and recombinant bacterially produced MCP-1/CCL2 are rapidly (partially) degraded upon in vitro citrullination. However, properly glycosylated MCP-1/CCL2 produced by mammalian cells is protected against degradation during efficient citrullination. Site-directed mutagenesis of the potential glycosylation site at the asparagine-14 residue within human MCP-1 revealed lower expression levels in mammalian expression systems. The glycosylation-mediated recombinant chemokine stabilization allows the production of citrullinated MCP-1/CCL2, which can be effectively used to calibrate crucial assays, such as modified ELISAs.

Angiogenic and Arthritogenic Properties of the Soluble Form of CD13.

Aminopeptidase N/CD13 is expressed by fibroblast-like synoviocytes (FLS) and monocytes (MNs) in inflamed human synovial tissue (ST). This study examined the role of soluble CD13 (sCD13) in angiogenesis, MN migration, phosphorylation of signaling molecules, and induction of arthritis. The contribution of sCD13 was examined in angiogenesis and MN migration using sCD13 and CD13-depleted rheumatoid arthritis (RA) synovial fluids (SFs). An enzymatically inactive mutant CD13 and intact wild-type (WT) CD13 were used to determine whether its enzymatic activity contributes to the arthritis-related functions. CD13-induced phosphorylation of signaling molecules was determined by Western blotting. The effect of sCD13 on cytokine secretion from RA ST and RA FLS was evaluated. sCD13 was injected into C57BL/6 mouse knees to assess its arthritogenicity. sCD13 induced angiogenesis and was a potent chemoattractant for MNs and U937 cells. Inhibitors of Erk1/2, Src, NF-κB, Jnk, and pertussis toxin, a G protein-coupled receptor inhibitor, decreased sCD13-stimulated chemotaxis. CD13-depleted RA SF induced significantly less MN migration than sham-depleted SF, and addition of mutant or WT CD13 to CD13-depleted RA SF equally restored MN migration. sCD13 and recombinant WT or mutant CD13 had similar effects on signaling molecule phosphorylation, indicating that the enzymatic activity of CD13 had no role in these functions. CD13 increased the expression of proinflammatory cytokines by RA FLS, and a CD13 neutralizing Ab inhibited cytokine secretion from RA ST organ culture. Mouse knee joints injected with CD13 exhibited increased circumference and proinflammatory mediator expression. These data support the concept that sCD13 plays a pivotal role in RA and acute inflammatory arthritis.

Pharmacokinetic optimitzation of CCG-203971: Novel inhibitors of the Rho/MRTF/SRF transcriptional pathway as potential antifibrotic therapeutics for systemic scleroderma.

We recently reported the development of a novel inhibitor of Rho-mediated gene transcription (1, CCG-203971) that is efficacious in multiple animal models of acute fibrosis, including scleroderma, when given intraperitoneally. The modest in vivo potency and poor pharmacokinetics (PK) of this lead, however, make it unsuitable for long term efficacy studies. We therefore undertook a systematic medicinal chemistry effort to improve both the metabolic stability and the solubility of 1, resulting in the identification of two analogs achieving over 10-fold increases in plasma exposures in mice. We subsequently showed that one of these analogs (8f, CCG-232601) could inhibit the development of bleomycin-induced dermal fibrosis in mice when administered orally at 50mg/kg, an effect that was comparable to what we had observed earlier with 1 at a 4-fold higher IP dose.

Scleroderma dermal microvascular endothelial cells exhibit defective response to pro-angiogenic chemokines.

OBJECTIVES: Angiogenesis plays a critical role in SSc (scleroderma). The aim of this study was to examine the expression of growth-regulated protein-γ (Gro-γ/CXCL3), granulocyte chemotactic protein 2 (GCP-2/CXCL6) and their receptor CXCR2 in endothelial cells (ECs) isolated from SSc skin and determine whether these cells mount an angiogenic response towards pro-angiogenic chemokines. The downstream signalling pathways as well as the pro-angiogenic transcription factor inhibitor of DNA-binding protein 1 (Id-1) were also examined. METHODS: Skin biopsies were obtained from patients with dcSSc. ECs were isolated via magnetic positive selection. Angiogenesis was measured by EC chemotaxis assay. RESULTS: Gro-γ/CXCL3 and GCP-2/CXCL6 were minimally expressed in both skin types but elevated in SSc serum. Pro-angiogenic chemokine mRNA was greater in SSc ECs than in normal ECs. SSc ECs did not migrate to vascular endothelial growth factor (VEGF), Gro-γ/CXCL3, GCP-2/CXCL6 or CXCL16. The signalling pathways stimulated by these chemokines were also dysregulated. Id-1 mRNA in SSc ECs was lower compared with normal ECs, and overexpression of Id-1 in SSc ECs increased their ability to migrate towards VEGF and CXCL16. CONCLUSION: Our results show that SSc ECs are unable to respond to pro-angiogenic chemokines despite their increased expression in serum and ECs. This might be due to the differences in the signalling pathways activated by these chemokines in normal vs SSc ECs. In addition, the lower expression of Id-1 also decreases the angiogenic response. The inability of pro-angiogenic chemokines to promote EC migration provides an additional mechanism for the impaired angiogenesis that characterizes SSc.

A key role for Fut1-regulated angiogenesis and ICAM-1 expression in K/BxN arthritis.

OBJECTIVES: Angiogenesis contributes to the pathogenesis of rheumatoid arthritis. Fucosyltransferases (Futs) are involved in angiogenesis and tumour growth. Here, we examined the role of Fut1 in angiogenesis and K/BxN serum transfer arthritis. METHODS: We examined Fut1 expression in human dermal microvascular endothelial cells (HMVECs) by quantitative PCR. We performed a number of angiogenesis assays to determine the role of Fut1 using HMVECs, Fut1 null (Fut1(-/-)), and wild type (wt) endothelial cells (ECs) and mice. K/BxN serum transfer arthritis was performed to determine the contribution of Fut1-mediated angiogenesis in Fut1(-/-) and wt mice. A static adhesion assay was implemented with RAW264.7 (mouse macrophage cell line) and mouse ECs. Quantitative PCR, immunofluorescence and flow cytometry were performed with Fut1(-/-) and wt ECs for adhesion molecule expression. RESULTS: Tumour necrosis factor-α induced Fut1 mRNA and protein expression in HMVECs. HMVECs transfected with Fut1 antisense oligodeoxynucleotide and Fut1(-/-) ECs formed significantly fewer tubes on Matrigel. Fut1(-/-) mice had reduced angiogenesis in Matrigel plug and sponge granuloma angiogenesis assays compared with wt mice. Fut1(-/-) mice were resistant to K/BxN serum transfer arthritis and had decreased angiogenesis and leucocyte ingress into inflamed joints. Adhesion of RAW264.7 cells to wt mouse ECs was significantly reduced when Fut1 was lacking. Fut1(-/-) ECs had decreased intercellular adhesion molecule-1 (ICAM-1) expression at mRNA and protein levels compared with wt ECs. ICAM-1 was also decreased in Fut1(-/-) arthritic ankle cryosections compared with wt ankles. CONCLUSIONS: Fut1 plays an important role in regulating angiogenesis and ICAM-1 expression in inflammatory arthritis.

Targeting CD13/aminopeptidase N as a novel therapeutic approach for scleroderma fibrosis.

OBJECTIVE: Systemic sclerosis (SSc) is an autoimmune multisystem disease with poorly understood pathogenesis and ineffective treatment options. Soluble CD13 (sCD13), generated by cleavage of cell surface CD13 via matrix metalloproteinase 14 (MMP14), signals through the bradykinin receptor B1 (B1R) to elicit pro-inflammatory, pro-arthritic, and pro-angiogenic responses. In this study we explored the anti-fibrotic potential of targeting the sCD13-B1R axis in SSc. METHODS: The expression of CD13, B1R and MMP14 was examined in SSc skin and explanted dermal fibroblasts. The efficacy of B1R antagonists in the inhibition on fibrosis was determined in vitro and in vivo. RESULTS: Expression of the genes for CD13, B1R and MMP14 was elevated in skin biopsies from patients with diffuse cutaneous (dc)SSc. Notably, single cell analysis of SSc skin biopsies revealed the highest BDKRB1 expression in COL8A1-positive myofibroblasts, a population exclusively seen in SSc. TGF-ß induced the expression of BDKRB1 and production of sCD13 by dcSSc skin fibroblasts. Treatment of dcSSc fibroblasts with sCD13 promoted fibrotic gene expression, signaling, cell proliferation, migration, and gel contraction. The profibrotic sCD13 or TGFß responses were prevented by a B1R antagonist. Mice lacking Cd13 or Bdkrb1 were resistant to bleomycin-induced skin fibrosis and inflammation. Pharmacological B1R inhibition had a comparable antifibrotic effect. CONCLUSION: These results are the first to demonstrate a key role for sCD13 in SSc skin fibrosis, and suggest that targeting the sCD13-B1R signaling axis is a promising novel therapeutic approach for SSc.

A novel role for inducible Fut2 in angiogenesis.

RATIONALE: Angiogenesis plays an important role in wound healing and tumor growth. Fucosyltransferases synthesize fucosylated glycans and may play a major role in vascular biology. OBJECTIVE: To examine the role of an alpha(1,2) fucosyltransferase (Fut2) in angiogenesis. METHODS AND RESULTS: We found that Fut2 mRNA and protein expression is inducible in human dermal microvascular endothelial cells (HMVECs). After finding that Fut2 is inducible in HMVECs, we examined if Fut2 contributes to angiogenesis. We found that Fut2 null endothelial cell (EC) migration and tube formation were significantly less compared to wild type (wt) ECs. Angiogenesis was impaired in Fut2 null compared to wt mice in the mouse Matrigel plug and the sponge granuloma angiogenesis assays. To assess the characteristics of Fut2 null ECs in vivo, we performed Matrigel plug angiogenesis assays in wt mice using Fut2 null and wt mouse ECs. We found a significant decrease in Fut2 null EC incorporation in neoangiogenesis compared to wt ECs. ERK1/2 activation, fibroblast growth factor receptor2, and vascular endothelial growth factor expression were less in Fut2 null ECs, suggesting a possible mechanism of impaired angiogenesis when Fut2 is lacking. CONCLUSIONS: These data suggest a novel role for Fut2 as a regulator of angiogenesis.

Activation of Cytotoxic Lymphocytes Through CD6 Enhances Killing of Cancer Cells.

Immune checkpoint inhibitors (ICIs) have demonstrated efficacy and improved survival in a growing number of cancers. Despite their success, ICIs are associated with immune-related adverse events that can interfere with their use. Therefore, safer approaches are needed. CD6, expressed by T-lymphocytes and human NK cells, engages in cell-cell interactions by binding to its ligands CD166 (ALCAM) and CD318 (CDCP1). CD6 is a target protein for regulating immune responses and is required for the development of several mouse models of autoimmunity. Interestingly, CD6 is exclusively expressed on immune cells while CD318 is strongly expressed on most cancers. Here we demonstrate that disrupting the CD6-CD318 axis with UMCD6, an anti-CD6 monoclonal antibody, prolongs survival of mice in xenograft models of human breast and prostate cancer, treated with infusions of human lymphocytes. Analysis of tumor-infiltrating immune cells showed that augmentation of lymphocyte cytotoxicity by UMCD6 is due to effects of this antibody on NK, NKT and CD8+ T cells. Tumor-infiltrating cytotoxic lymphocytes were found in higher proportions and were activated in UMCD6-treated mice compared to controls. Similar changes in gene expression were observed by RNA-seq analysis of NK cells treated with UMCD6. Particularly, UMCD6 up-regulated the NKG2D-DAP10 complex and activated PI3K. Thus, the CD6-CD318 axis can regulate the activation state of cytotoxic lymphocytes and their positioning within the tumor microenvironment.

Inhibition of bromodomain extraterminal histone readers alleviates skin fibrosis in experimental models of scleroderma.

Binding of the bromodomain and extraterminal domain proteins (BETs) to acetylated histone residues is critical for gene transcription. We sought to determine the antifibrotic efficacy and potential mechanisms of BET inhibition in systemic sclerosis (SSc). Blockade of BETs was done using a pan-BET inhibitor, JQ1; BRD2 inhibitor, BIC1; or BRD4 inhibitors AZD5153 or ARV825. BET inhibition, specifically BRD4 blockade, showed antifibrotic effects in an animal model of SSc and in patient-derived diffuse cutaneous SSc (dcSSc) fibroblasts. Transcriptome analysis of JQ1-treated dcSSc fibroblasts revealed differentially expressed genes related to extracellular matrix, cell cycle, and calcium (Ca2+) signaling. The antifibrotic effect of BRD4 inhibition was mediated at least in part by downregulation of Ca2+/calmodulin-dependent protein kinase II α and reduction of intracellular Ca2+ concentrations. On the basis of these results, we propose targeting Ca2+ pathways or BRD4 as potentially novel therapeutic approaches for progressive tissue fibrosis.

Soluble CD13 induces inflammatory arthritis by activating the bradykinin receptor B1.

CD13, an ectoenzyme on myeloid and stromal cells, also circulates as a shed, soluble protein (sCD13) with powerful chemoattractant, angiogenic, and arthritogenic properties, which require engagement of a G protein-coupled receptor (GPCR). Here we identify the GPCR that mediates sCD13 arthritogenic actions as the bradykinin receptor B1 (B1R). Immunofluorescence and immunoblotting verified high expression of B1R in rheumatoid arthritis (RA) synovial tissue and fibroblast-like synoviocytes (FLSs), and demonstrated binding of sCD13 to B1R. Chemotaxis, and phosphorylation of Erk1/2, induced by sCD13, were inhibited by B1R antagonists. In ex vivo RA synovial tissue organ cultures, a B1R antagonist reduced secretion of inflammatory cytokines. Several mouse arthritis models, including serum transfer, antigen-induced, and local innate immune stimulation arthritis models, were attenuated in Cd13-/- and B1R-/- mice and were alleviated by B1R antagonism. These results establish a CD13/B1R axis in the pathogenesis of inflammatory arthritis and identify B1R as a compelling therapeutic target in RA and potentially other inflammatory diseases.

Epigallocatechin-3-gallate inhibits IL-6 synthesis and suppresses transsignaling by enhancing soluble gp130 production.

Regulation of IL-6 transsignaling by the administration of soluble gp130 (sgp130) receptor to capture the IL-6/soluble IL-6R complex has shown promise for the treatment of rheumatoid arthritis (RA). However, enhancing endogenous sgp130 via alternative splicing of the gp130 gene has not yet been tested. We found that epigallocatechin-3-gallate (EGCG), an anti-inflammatory compound found in green tea, inhibits IL-1beta-induced IL-6 production and transsignaling in RA synovial fibroblasts by inducing alternative splicing of gp130 mRNA, resulting in enhanced sgp130 production. Results from in vivo studies using a rat adjuvant-induced arthritis model showed specific inhibition of IL-6 levels in the serum and joints of EGCG-treated rats by 28% and 40%, respectively, with concomitant amelioration of rat adjuvant-induced arthritis. We also observed a marked decrease in membrane-bound gp130 protein expression in the joint homogenates of the EGCG-treated group. In contrast, quantitative RT-PCR showed that the gp130/IL-6Ralpha mRNA ratio increased by approximately 2-fold, suggesting a possible mechanism of sgp130 activation by EGCG. Gelatin zymography results showed EGCG inhibits IL-6/soluble IL-6R-induced matrix metalloproteinase-2 activity in RA synovial fibroblasts and in joint homogenates, possibly via up-regulation of sgp130 synthesis. The results of these studies provide previously undescribed evidence of IL-6 synthesis and transsignaling inhibition by EGCG with a unique mechanism of sgp130 up-regulation, and thus hold promise as a potential therapeutic agent for RA.

CD6 is a target for cancer immunotherapy.

Limitations of checkpoint inhibitor cancer immunotherapy include induction of autoimmune syndromes and resistance of many cancers. Since CD318, a novel CD6 ligand, is associated with the aggressiveness and metastatic potential of human cancers, we tested the effect of an anti-CD6 monoclonal antibody, UMCD6, on killing of cancer cells by human lymphocytes. UMCD6 augmented killing of breast, lung, and prostate cancer cells through direct effects on both CD8+ T cells and NK cells, increasing cancer cell death and lowering cancer cell survival in vitro more robustly than monoclonal antibody checkpoint inhibitors that interrupt the programmed cell death 1 (PD-1)/PD-1 ligand 1 (PD-L1) axis. UMCD6 also augmented in vivo killing by human peripheral blood lymphocytes of a human breast cancer line xenotransplanted into immunodeficient mice. Mechanistically, UMCD6 upregulated the expression of the activating receptor NKG2D and downregulated expression of the inhibitory receptor NKG2A on both NK cells and CD8+ T cells, with concurrent increases in perforin and granzyme B production. The combined capability of an anti-CD6 monoclonal antibody to control autoimmunity through effects on CD4+ lymphocyte differentiation while enhancing killing of cancer cells through distinct effects on CD8+ and NK cells opens a potential new approach to cancer immunotherapy that would suppress rather than instigate autoimmunity.

Green tea extract inhibits chemokine production, but up-regulates chemokine receptor expression, in rheumatoid arthritis synovial fibroblasts and rat adjuvant-induced arthritis.

OBJECTIVE: Evaluation of the efficacy of green tea extract (GTE) in regulating chemokine production and chemokine receptor expression in human RA synovial fibroblasts and rat adjuvant-induced arthritis (AIA). METHODS: Fibroblasts isolated from human RA synovium were used in the study. Regulated upon activation normal T cell expressed and secreted (RANTES)/CCL5, monocyte chemoattractant protein (MCP)-1/CCL2, growth-regulated oncogene (GRO)alpha/CXCL1 and IL-8/CXCL8 production was measured by ELISA. Western blotting was used to study the phosphorylation of protein kinase C (PKC)delta and c-Jun N-terminal kinases (JNK). Chemokine and chemokine receptor expression was determined by quantitative RT-PCR. The benefit of GTE administration in rat AIA was determined. RESULTS: GTE (2.5-40 microg/ml) inhibited IL-1beta-induced MCP-1/CCL2 (10 ng/ml), RANTES/CCL5, GROalpha/CXCL1 and IL-8/CXCL8 production in human RA synovial fibroblasts (P < 0.05). However, GTE inhibited MCP-1/CCL2 and GROalpha/CXCL1 mRNA synthesis in RA synovial fibroblasts. Furthermore, GTE also inhibited IL-1beta-induced phosphorylation of PKCdelta, the signalling pathway mediating IL-1beta-induced chemokine production. Interestingly, GTE preincubation enhanced constitutive and IL-1beta-induced CCR1, CCR2b, CCR5, CXCR1 and CXCR2 receptor expression. GTE administration (200 mg/kg/day p.o.) modestly ameliorated rat AIA, which was accompanied by a decrease in MCP-1/CCL2 and GROalpha/CXCL1 levels and enhanced CCR-1, -2, -5 and CXCR1 receptor expression in the joints of GTE administered rats. CONCLUSIONS: Chemokine receptor overexpression with reduced chemokine production by GTE may be one potential mechanism to limit the overall inflammation and joint destruction in RA.

Real time visualization of cancer cell death, survival and proliferation using fluorochrome-transfected cells in an IncuCyte® imaging system.

Cancer immunotherapy is a rapidly advancing and viable approach to treating cancer along with more traditional forms of therapy. Real-time cell analysis technologies that examine the dynamic interactions between cancer cells and the cells of the immune system are becoming more important for assessment of novel therapeutics. In this report, we use the IncuCyte® imaging system to study the killing potential of various immune cells on cancer cell lines. The IncuCyte® system tracks living cells, labeled by a red fluorescent protein, and cell death, as indicated by the caspase-3/7 reagent, which generates a green fluorescent signal upon activation of apoptotic pathways. Despite the power of this approach, obtaining commercially fluorescent cancer cell lines is expensive and limited in the range of cell lines that are available. To overcome this barrier, we developed an inexpensive method using a lentiviral construct expressing nuclear localized mKate2 red fluorescent protein to stably label cancer cells. We demonstrate that this method is effective in labeling a wide variety of cell lines, allowing for analyses of different cancers as well as different cell lines of the same type of cancer.

Attenuation of Murine Collagen-Induced Arthritis by Targeting CD6.

OBJECTIVE: CD6 is an important regulator of T cell function that interacts with the ligands CD166 and CD318. To further clarify the significance of CD6 in rheumatoid arthritis (RA), we examined the effects of targeting CD6 in the mouse model of collagen-induced arthritis (CIA), using CD6-knockout (CD6-KO) mice and CD6-humanized mice that express human CD6 in lieu of mouse CD6 on their T cells. METHODS: We immunized wild-type (WT) and CD6 gene-KO mice with a collagen emulsion to induce CIA. For treatment studies using CD6-humanized mice, mice were immunized similarly and a mouse anti-human CD6 IgG (UMCD6) or control IgG was injected on days 7, 14, and 21. Joint tissues were evaluated for tissue damage, leukocyte infiltration, and local inflammatory cytokine production. Collagen-specific Th1, Th9, and Th17 responses and serum levels of collagen-specific IgG subclasses were also evaluated in WT and CD6-KO mice with CIA. RESULTS: The absence of CD6 reduced 1) collagen-specific Th9 and Th17, but not Th1 responses, 2) the levels of many proinflammatory joint cytokines, and 3) serum levels of collagen-reactive total IgG and IgG1, but not IgG2a and IgG3. Joint homogenate hemoglobin content was significantly reduced in CD6-KO mice with CIA compared to WT mice with CIA (P < 0.05) (reduced angiogenesis). Moreover, treating CD6-humanized mice with mouse anti-human CD6 monoclonal antibody was similarly effective in reducing joint inflammation in CIA. CONCLUSION: Taken together, these data suggest that interaction of CD6 with its ligands is important for the perpetuation of CIA and other inflammatory arthritides that are T cell driven.

Citrullinated Inhibitor of DNA Binding 1 Is a Novel Autoantigen in Rheumatoid Arthritis.

OBJECTIVE: To explore the intrinsic role of inhibitor of DNA binding 1 (ID-1) in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) and to investigate whether ID-1 is citrullinated and autoantigenic in RA. METHODS: RA patient serum ID-1 levels were measured before and after infliximab treatment. RA FLS were transfected with a clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 construct targeting ID-1 to examine the effects of ID-1 deletion. RA synovial fluid (SF) and homogenized synovial tissue (ST) were immunoprecipitated for ID-1 and measured for citrullinated residues using an enzyme-linked immunosorbent assay and Western blotting. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was performed on in vitro-citrullinated recombinant human ID-1 (cit-ID-1) to localize the sites of citrullination. Normal and RA sera and SF were analyzed by immunodot blotting for anti-citrullinated protein antibodies (ACPAs) to cit-ID-1. RESULTS: RA patient serum ID-1 levels positively correlated with several disease parameters and were reduced after infliximab treatment. RA FLS displayed reduced growth and a robust increase in interleukin-6 (IL-6) and IL-8 production upon deletion of ID-1. ID-1 immunodepletion significantly reduced the levels of citrullinated residues in RA SF, and citrullinated ID-1 was detected in homogenized RA ST (n = 5 samples; P < 0.05). Immunodot blot analyses revealed ACPAs to cit-ID-1 but not to native ID-1, in RA peripheral blood (PB) sera (n = 30 samples; P < 0.001) and SF (n = 18 samples; P < 0.05) but not in normal PB sera. Following analyses of LC-MS/MS results for citrullination sites and corresponding reactivity in immunodot assays, we determined the critical arginines in ID-1 for autoantigenicity: R33, R52, and R121. CONCLUSION: Novel roles of ID-1 in RA include regulation of FLS proliferation and cytokine secretion as well as autoantigenicity following citrullination.

5-Aryl-1,3,4-oxadiazol-2-ylthioalkanoic Acids: A Highly Potent New Class of Inhibitors of Rho/Myocardin-Related Transcription Factor (MRTF)/Serum Response Factor (SRF)-Mediated Gene Transcription as Potential Antifibrotic Agents for Scleroderma.

Through a phenotypic high-throughput screen using a serum response element luciferase promoter, we identified a novel 5-aryl-1,3,4-oxadiazol-2-ylthiopropionic acid lead inhibitor of Rho/myocardin-related transcription factor (MRTF)/serum response factor (SRF)-mediated gene transcription with good potency (IC50 = 180 nM). We were able to rapidly improve the cellular potency by 5 orders of magnitude guided by sharply defined and synergistic SAR. The remarkable potency and depth of the SAR, as well as the relatively low molecular weight of the series, suggests, but does not prove, that binding to the unknown molecular target may be occurring through a covalent mechanism. The series nevertheless has no observable cytotoxicity up to 100 µM. Ensuing pharmacokinetic optimization resulted in the development of two potent and orally bioavailable anti-fibrotic agents that were capable of dose-dependently reducing connective tissue growth factor gene expression in vitro as well as significantly reducing the development of bleomycin-induced dermal fibrosis in mice in vivo.

Identification of Pirin as a Molecular Target of the CCG-1423/CCG-203971 Series of Antifibrotic and Antimetastatic Compounds.

A series of compounds (including CCG-1423 and CCG-203971) discovered through an MRTF/SRF-dependent luciferase screen has shown remarkable efficacy in a variety of in vitro and in vivo models, including significant reduction of melanoma metastasis and bleomycin- induced fibrosis. Although these compounds are efficacious in these disease models, the molecular target is unknown. Here, we describe affinity isolation-based target identification efforts which yielded pirin, an iron-dependent cotranscription factor, as a target of this series of compounds. Using biophysical techniques including isothermal titration calorimetry and X-ray crystallography, we verify that pirin binds these compounds in vitro. We also show with genetic approaches that pirin modulates MRTF- dependent luciferase reporter activity. Finally, using both siRNA and a previously validated pirin inhibitor, we show a role for pirin in TGF-ß- induced gene expression in primary dermal fibroblasts. A recently developed analog, CCG-257081, which co crystallizes with pirin, is also effective in the prevention of bleomycin-induced dermal fibrosis.

Monocyte chemoattractant protein-1 and macrophage inflammatory protein-1alpha as possible biomarkers for the chronic pelvic pain syndrome.

PURPOSE: The chronic pelvic pain syndrome is characterized by pelvic pain, voiding symptoms and varying degrees of inflammation within expressed prostatic secretions. We evaluated the chemokines monocyte chemoattractant protein 1 (CCL2) and macrophage inflammatory protein-1alpha (CCL3) in expressed prostatic secretions to identify marker increases associated with inflammatory (IIIA) and noninflammatory (IIIB) chronic pelvic pain syndrome. In addition, chemokine levels were correlated with clinical pain as determined by the National Institutes of Health chronic prostatitis symptom index. MATERIALS AND METHODS: Expressed prostatic secretions were collected by digital rectal examination, and evaluated by enzyme linked immunosorbent assays for monocyte chemoattractant protein 1 and macrophage inflammatory protein-1alpha in 154 patients including controls (13), those with benign prostatic hyperplasia (54), chronic pelvic pain syndrome IIIA (37) and IIIB (50). Monocyte chemoattractant protein 1 and macrophage inflammatory protein-1alpha levels were compared between IIIA, IIIB and the control subgroups, and correlated against the chronic prostatitis symptom index and pain subscore using a Spearman test. RESULTS: Mean levels of monocyte chemoattractant protein 1 in the control, inflammatory benign prostatic hyperplasia, noninflammatory benign prostatic hyperplasia, inflammatory chronic pelvic pain syndrome and noninflammatory chronic pelvic pain syndrome were 599.4, 886.0, 1,636.5, 3,261.2 and 2,272.7 pg/ml, respectively. Mean levels of macrophage inflammatory protein-1alpha in the control, inflammatory benign prostatic hyperplasia, noninflammatory benign prostatic hyperplasia, IIIA chronic pelvic pain syndrome and IIIB chronic pelvic pain syndrome were 140.1, 299.4, 238.7, 1,057.8 and 978.4 pg/ml, respectively. For each cytokine both chronic pelvic pain syndrome subtypes had statistically higher levels than the control group and patients with benign prostatic hyperplasia (p = 0.0002). Receiver operating curves using monocyte chemoattractant protein 1 levels greater than 704 pg/ml and macrophage inflammatory protein-1alpha greater than 146 pg/ml identified patients with chronic pelvic pain syndrome with an accuracy of 90% from control patients. Macrophage inflammatory protein-1alpha levels (p = 0.0007) correlated with the pain subscore of the chronic prostatitis symptom index while monocyte chemoattractant protein 1 (p = 0.71) did not. CONCLUSIONS: Monocyte chemoattractant protein 1 and macrophage inflammatory protein-1alpha within the prostatic fluid in both chronic pelvic pain syndrome subtypes provide candidate future biomarkers for chronic pelvic pain syndrome. In addition, macrophage inflammatory protein-1alpha increase in expressed prostatic secretions provides a new marker for clinical pain in chronic pelvic pain syndrome patients. Given these findings prostatic dysfunction likely has a role in the pathophysiology of this syndrome. These chemokines may serve as effective diagnostic markers and modulators against the chemokines could provide an attractive treatment strategy in individuals with chronic pelvic pain syndrome.