Sidong Xiong

Coxsackievirus Group B Type 3 Infection Upregulates Expression of Monocyte Chemoattractant Protein 1 in Cardiac Myocytes, Which Leads to Enhanced Migration of Mononuclear Cells in Viral Myocarditis

ABSTRACT Coxsackievirus group B type 3 (CVB3) is an important cause of viral myocarditis. The infiltration of mononuclear cells into the myocardial tissue is one of the key events in viral myocarditis. Immediately after CVB3 infects the heart, the expression of chemokine(s) by infected myocardial cells may be the first trigger for inflammatory infiltration and immune response. However, it is unknown whether CVB3 can induce the chemokine expression in cardiac myocytes. Monocyte chemoattractant protein 1 (MCP-1) is a potent chemokine that stimulates the migration of mononuclear cells. The objective of the present study was to investigate the effect of CVB3 infection on MCP-1 expression in murine cardiac myocytes and the role of MCP-1 in migration of mononuclear cells in viral myocarditis. Our results showed that the expression of MCP-1 was significantly increased in cardiac myocytes after wild-type CVB3 infection in a time- and dose-dependent manner, which resulted in enhanced migration of mononuclear cells in mice with viral myocarditis. The migration of mononuclear cells was partially abolished by antibodies specific for MCP-1 in vivo and in vitro. Administration of anti-MCP-1 antibody prevented infiltration of mononuclear cells bearing the MCP-1 receptor CCR2 in mice with viral myocarditis. Infection by UV-irradiated CVB3 induced rapid and transient expression of MCP-1 in cardiac myocytes. In conclusion, our results indicate that CVB3 infection stimulates the expression of MCP-1 in myocardial cells, which subsequently leads to migration of mononuclear cells in viral myocarditis.

Targeted in vivo expression of IFN-γ-inducible protein 10 induces specific antitumor activity

Although it is known that the chemoattractant effect of IFN‐γ inducible protein 10 (IP‐10), a CXC chemokine (CXCL10), plays an important role in T cell‐mediated antitumor immunity in vivo, whether IP‐10 is involved in modulating the proliferation, survival and functional activation of tumor‐specific T cells remains poorly investigated. Using an experimental mouse tumor model, we demonstrated that the in vivo growth of 4T1 tumor cells harboring IP‐10 gene (4T1‐IP‐10) was inhibited. Mice inoculated with 4T1‐IP‐10 tumor cells expressing functional IP‐10 survived over 90 days, whereas mice injected with control parental 4T1 cells and mice of control 4T1 cells transduced with control plasmid all succumbed to the tumor by day 38 after tumor inoculation. Mechanical analysis showed that targeted expression of IP‐10 in 4T1 tumor cells markedly enhanced the infiltration of tumor‐specific T cells into the 4T1‐IP‐10 tumor. These tumor infiltrating T lymphocytes (TILs) recruited by IP‐10 were potent cytolytic killers against 4T1 tumor cells and were able to proliferate and produce high levels of IFN‐γ in response to 4T1 cells. In vivo administration of IP‐10‐recruited TILs induced vigorous proliferation of these TILs in situ in the 4T1‐IP‐10 tumor but not in the 4T1‐pcDNA3 and parental 4T1 tumors. Furthermore, culture of TILs together with recombinant IP‐10 significantly enhanced the proliferation and expansion of IP‐10‐recruited TILs in response to 4T1 tumor antigens. These results suggest that IP‐10 is not only able to chemoattract tumor‐specific T cells into the local tissue, but also enhance the proliferation, survival, and functional activation of these TILs, leading to the tumor regression. Thus, targeted expression of IP‐10 in vivo will allow for the development of a novel approach for immunotherapy of tumor.

In situ expression of IFN-gamma-inducible T cell alpha chemoattractant in breast cancer mounts an enhanced specific anti-tumor immunity which leads to tumor regression.

Increased evidence indicates that chemokines are involved in tumor growth. ITAC, a key member of chemokines, possesses the ability to recruit T cells and enhance immune responses. Therefore, ITAC might contribute to antitumor immunity. In this study, we evaluated the relationship between the expression of ITAC and human breast cancer advancement. We further investigated whether forced expression of ITAC in tumor sites could mediate enhanced antitumor immunity in a murine breast cancer model. Results showed that ITAC expression level was down-regulated in 31 breast cancer specimens compared to normal mammary tissues, and associated negatively with the stages of breast cancer. Contrarily, forced expression of ITAC in murine 4T1 tumor cells resulted in tumor regression after initial growth upon injection into naïve Balb/c mice. More lymphocytes were recruited to the site of tumor inoculated by 4T1-ITAC and more than 80% of these T cells expressed the ITAC receptor, CXCR3. ITAC-recruited TILs exhibited 4T1-specific proliferation and cytotoxicity, and an increased IFN-γ but decreased IL-4 production. Importantly, forced expression of ITAC in 4T1 tumor nodules inhibited tumor growth. These findings demonstrated that the decreased expression of ITAC is associated with the advancement of breast cancer in patients. Forced expression of ITAC in tumor site not only induces increased T cell-recruitment and elicits a specific antitumor immunity, but also mediates regression of established 4T1 tumors, indicating the potential application of ITAC-expressing tumor cells in cancer immunotherapy and vaccine designing.

Allogenic donor splenocytes pretreated with antisense peptide against B7 prolong cardiac allograft survival.

The interaction of T cell CD28/CTLA‐4 receptors with B7 on antigen‐presenting cells (APCs) represents an important co‐stimulatory pathway in T cell activation or anergy. Our previous study indicated that recipients immunized with allogenic donor immature dendritic cells (DCs) or resting B cells could induce specific immune tolerance and prolong allograft survival. A possible mechanism for this observation is that the expression of B7 molecules is either at a low level or lacking on these cells. The present study investigates whether blockade of B7 molecules on donor splenocytes with a B7 antisense peptide (B7AP), i.e. a peptide analogue of the CD28‐binding region, could induce specific immune tolerance and prolong allograft survival in the recipients. Both the lymphocyte proliferation reaction and the mice pinna cardiac allograft experiment were performed to evaluate the role of B7AP in inducing specific immune tolerance in recipients in vitro and in vivo. The results showed that 56·65% and 20·52% of C57BL/6 splenocytes expressed B7.1 and B7.2 molecules, respectively, on their cell surface. There were no significant changes of the B7 expression on such splenocytes after being treated by the B7AP (53·28% and 19·06%, respectively). B7AP inhibited the mixed lymphocyte reaction by up to 38·4% and a dose‐response correlation was observed for inhibition. The recipients (BALB/c) immunized with B7AP‐pretreated C57BL/6 splenocytes induced a specific immune hypo‐response (43%versus control) and notably prolonged survival of the C57BL/6 cardiac allograft by up to 20·3u2003days. In contrast to the normal saline group (average: 8·6 days) and FTD10 control peptide group (<4 days), the cardiac allograft survival of the test group was extended for an additional 11·7u2003days. These results strongly support the notion that immunization with donor splenocytes, which had been pretreated with B7AP, induced specific immune tolerance and prolonged allograft survival in the recipients.