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Transplantation outcomes are affected by the increase in rejection associated with ischemia reperfusion injury (IRI). Fractalkine (FKN), a chemokine for recruitment of CX3CR1+ leukocytes, contributes to the pathogenesis of various inflammatory diseases. Herein, we evaluated the importance of the FKN-CX3CR1 axis during IRIrelated rejections using a mouse heterotopic heart transplantation model. FKN expression and graft survival was compared between wild-type C57BL/6 recipients transplanted with BALB/c hearts preserved for 8 (WT-IRI) and 0.5 h (WT-control) at 4°C. Graft survival of WTIRI was shorter than that of WT-control. FKN was expressed on the vascular endothelium in WT-IRI allografts, but minimally in WT-control. The role of the FKN-CX3CR1 axis in IRIrelated rejection was directly investigated using the transplant model with CX3CR1-deficient recipients (CX3CR1 KO-IRI) or treatment with anti-mouse FKN monoclonal antibodies. Graft survival of CX3CR1 KO-IRI was longer than that of WT-IRI; antibody treatment prolonged graft survival. The contribution of CX3CR1+ monocytes to IRI-related rejection was evaluated by adoptive transfer to CX3CR1 KO-IRI. Adoptive transfer of CX3CR1+ monocytes attenuated the effect of prolonged graft survival in CX3CR1 KO-IRI. Overall, the FKN-CX3CR1 axis plays a major role during IRI-related rejection; its blockade has the potential to improve the outcomes of deceased donor transplantation. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the safety and efficacy of E6011, a novel humanized anti-fractalkine monoclonal antibody, in patients with active rheumatoid arthritis (RA) with an inadequate response to biological disease-modifying antirheumatic drugs (DMARDs). Methods: Active RA patients inadequately responding to biological DMARDs were randomly assigned to placebo or E6011 400-mg group at a 1:1 ratio, and administered E6011 at weeks 0, 1, 2, and subsequently every 2 weeks. Primary endpoint was American College of Rheumatology (ACR)20 response at week 12. Results: Of 64, 33 received placebo, 31 received E6011 400-mg. The ACR20 response rate at week 12 (non-responder imputation) was 27.3% and 22.6% in the placebo and E6011 groups, respectively. ACR50, ACR70 response rates at week 12 were 3.0%, 0% in the placebo and 9.7%, 3.2% in the E6011 group. Exploratory PK exposure analysis revealed that the effect of E6011 tended to be clearer in patients with higher serum trough E6011 concentration. E6011 was well tolerated with no notable safety concerns. Conclusions: E6011 400-mg was well tolerated but had no clear efficacy at week 12 in RA patients with inadequate response to biologics. Further investigations are warranted to determine the optimal clinical dose and evaluation period for E6011. [ABSTRACT FROM AUTHOR]

Objective: Fractalkine (CX3CL1/FKN) is a chemokine that regulates chemotaxis and adhesion of CX3C chemokine receptor 1 (CX3CR1)-expressing inflammatory cells. We conducted the first phase 1/2, openlabel, multiple ascending dose study of E6011, a humanized anti-FKN monoclonal antibody, in Japanese rheumatoid arthritis (RA) patients (clinicaltrial.gov identifier: NCT02196558). Methods: Active RA patients with an inadequate response or intolerance to methotrexate or tumor necrosis factor (TNF) inhibitor received E6011 at week 0, 1, 2, and thereafter every 2 weeks for 12 weeks. Results: Twelve, 15, and 10 subjects were enrolled in the 100, 200, and 400mg cohorts, respectively. No severe adverse events (AEs) or deaths occurred, and no major differences were observed in the incidence or severity of AEs across the cohorts. Serum E6011 concentrations increased dose dependently. American College of Rheumatology (ACR) 20, 50, and 70 responses at week 12 were 75.0%, 33.3%, and 8.3% in the 100mg cohort; 66.7%, 20.0%, and 13.3% in the 200mg cohort; and 60.0%, 30.0%, and 20.0% in the 400mg cohort, respectively. Conclusions: E6011 appeared to be safe and well tolerated in RA patients during this 12-week treatment period, suggesting that E6011 has an effective clinical response in active RA patients. [ABSTRACT FROM AUTHOR]

Osteopontin (OPN) is a secreted phosphoglycoprotein, and is a transcriptional target of aberrant Wnt signaling. OPN is upregulated in human colon cancers, and is suggested to enhance cancer progression. In this study, the effect of deficiency of OPN on intestinal tumor development in Apc-deficient Min mice was investigated. At 16 weeks of age, the number of small intestinal polyps in Min/OPN(+/−) and Min/OPN(−/−) mice was lower than that of Min/OPN(+/+) mice. Colorectal tumor incidences and multiplicities in Min/OPN(+/−) and Min/OPN(−/−) mice were significantly lower than those in Min/OPN(+/+) mice, being 48% and 0.6 ± 0.8, 50% and 0.8 ± 0.9 vs. 80% and 1.6 ± 1.7, respectively. OPN expression in colorectal tumors was strongly upregulated in Min/OPN(+/+) compared to adjacent non-tumor parts, but was decreased in Min/OPN(+/−) and not detected in Min/OPN(−/−). Targets of OPN, matrix metalloproteinases (MMPs)-3, -9, and -13 were lowered by OPN deficiency. Macrophage marker F4/80 in colorectal tumors was also lowered by OPN deficiency. MMP-9 expression was observed in tumor cells and tumor-infiltrating neutrophils. These results indicate that induction of OPN by aberrant Wnt signaling could enhance colorectal tumor development in part by upregulation of MMP-3, -9, and -13 and infiltration of macrophage and neutrophils. Suppression of OPN expression could contribute to tumor prevention, but complete deficiency of OPN may cause some adverse effects. [ABSTRACT FROM AUTHOR]

Fractalkine is a CX3C chemokine that exists in both membrane-bound and soluble forms. Interaction between fractalkine and its unique receptor (CX3CR1) induces cell adhesion, chemotaxis, crawling, "accessory cell" activity, and survival. The serum level of fractalkine is elevated in patients with rheumatoid arthritis (RA) and is correlated with disease activity. Peripheral blood CD16+ monocytes and a subset of T cells express CX3CR1, while fractalkine is expressed on fibroblast-like synoviocytes and endothelial cells in the synovial tissue of patients with RA. Fractalkine expression is enhanced by tumor necrosis factor-a and interferon-g, and it promotes the migration of monocytes, T cells, and osteoclast precursors into RA synovial tissue. Fractalkine also induces the production of inflammatory mediators by macrophages, T cells, and fibroblast-like synoviocytes. Moreover, fractalkine promotes angiogenesis and osteoclastogenesis. In an animal model of RA, arthritis was improved by the abrogation of fractalkine. Recently, a clinical trial of an anti-fractalkine monoclonal antibody for the treatment of RA commenced in Japan. We review the multiple roles of fractalkine in the pathogenesis of RA and its potential as a therapeutic target for this disease. [ABSTRACT FROM AUTHOR]

Patients with rheumatoid arthritis (RA) accumulate prematurely aged T cells that have acquired a new profile of regulatory receptors. Many of the de novo–expressed receptors are typically found on natural killer cells, including CX3CR1, the receptor for the chemokine fractalkine (FKN). This study explored whether interactions between CX3CR1 and FKN are relevant for T cell functions in rheumatoid synovitis. FKN expression was examined by real‐time polymerase chain reaction and immunohistochemistry. CX3CR1 expression on peripheral blood T cells was analyzed by flow cytometry. T cell activation was quantified by determining proliferative responses, interferon‐γ (IFNγ) secretion, and granule release. Fibroblast‐like synoviocyte (FLS)/T cell adhesion was measured by the retention of 5‐carboxyfluorescein diacetate succinimidyl ester–labeled T cells on FLS monolayers.FKN was expressed on cultured synovial fibroblasts and hyperplastic synoviocytes in the rheumatoid tissue. Among CD4+ T cells, only senescent CD28− T cells were positive for CX3CR1 (P < 0.001). Such CD4+,CD28−,CX3CR1+ T cells strongly adhered to FLS, with soluble FKN blocking the interaction. FKN expressed on FLS costimulated T cell–activating signals and amplified proliferation, IFNγ production, and expulsion of cytoplasmic granules.Senescent CD4+ T cells that accumulate in rheumatoid arthritis aberrantly express CX3CR1. FKN, which is membrane‐anchored on synoviocytes, enhances CD4+ T cell adhesion, provides survival signals, and costimulates the production of proinflammatory cytokines as well as the release of granules. By virtue of their altered receptor profile, senescent CD4+ T cells receive strong stimulatory signals from nonprofessional antigen‐presenting cells in the synovial microenvironment. [ABSTRACT FROM AUTHOR]

Lupus nephritis is characterized by immune complex deposition and inflammatory cell infiltration into the renal glomeruli. Local generation of chemokines and the presence of chemokine receptors on the infiltrating cells may be involved in this process. Fractalkine (Fkn)/CX3CL1 and its receptor, CX3CR1, form one such chemokine system. We therefore undertook this study to investigate whether Fkn antagonist inhibits the initiation and progression of lupus nephritis in MRL/lpr mice. NH2‐ terminally truncated Fkn/CX3CL1 analogs were transfected into a nonmetastatic fibroblastoid cell line, MRL/N‐1, and injected subcutaneously into MRL/lpr mice.Fkn analogs truncated by ≥4 amino acid residues from the N‐ terminus failed to induce chemotaxis and calcium influx by CX3CR1‐expressing cells. Of these, the most potent antagonist (Fkn‐AT) lacked the 4 N‐ terminal amino acid residues. Fkn expression in the glomerulus was significantly increased in 12‐ week‐ old MRL/lpr mice. Expression was localized predominantly in the glomerular endothelial cells, but was occasionally observed in the mesangial cells and, to a lesser extent, in the interstitial microvasculature. Inoculation of MRL/lpr mice with Fkn‐AT before the onset or during the early stages of lupus nephritis significantly reduced glomerular hypercellularity, glomerulosclerosis, crescent formation, and vasculitis compared with control mice. This seemed to be due to a marked reduction in macrophage accumulation. In contrast, Fkn antagonist did not affect pneumonitis, sialadenitis, lymphadenopathy, or splenomegaly. We prepared a novel potent Fkn antagonist and demonstrated its ability to delay the initiation and ameliorate the progression of lupus nephritis. This agent may therefore provide a new therapeutic approach to lupus nephritis. [ABSTRACT FROM AUTHOR]

Short-term dextran sodium sulfate (DSS) treatment has been shown to notably accelerate colorectal tumor development in rats initiated with 1,2-dimethylhydrazine (DMH). In the present study, to clarify mechanisms underlying the DSS influence, time-course studies of histopathological and immunohistochemical characteristics and β-catenin gene mutations in colorectal mucosa in early stages of this model were conducted. F344 males were given three subcutaneous injections of DMH (40 mg/kg body wt) within a week, followed by free access to drinking water containing 1% DSS for a week. At weeks 1, 4, 6 and 8 after the DSS treatment, rats were euthanized and colorectal samples were collected. At week 1, the colorectal mucosa demonstrated extensive erosion along with significant inflammatory cell infiltration and neighboring reactive hyperplasia. By week 4, the mucosal damage was repaired and regenerative mucosa, partly characterized by Paneth cell metaplasia and altered subcellular localization of β-catenin, was apparent. Areas with Paneth cells/β-catenin accumulation were significantly more likely to be accompanied by interstitial inflammation and 17 of 24 dysplastic foci were found in regenerative mucosa with Paneth cells. Furthermore, adenomas/carcinomas frequently featured various degrees of Paneth cell differentiation. Point mutations mainly in codons 34 and 41 of β-catenin gene were detected in 6 of 27 samples of regenerative mucosa with Paneth cells and four of nine dysplastic foci/adenomas/carcinomas. These findings indicate that inflammation-associated regenerative mucosa with Paneth cell metaplasia and alteration in the APC/β-catenin/Tcf signal transduction pathway are possibly involved in the acceleration of colorectal carcinogenesis in this DMH–DSS rat model. [ABSTRACT FROM AUTHOR]