IL (Interleukin)-33 Suppresses Abdominal Aortic Aneurysm by Enhancing Regulatory T-Cell Expansion and Activity.

Objective- Inflammation occurs during the progression of abdominal aortic aneurysm (AAA). IL (interleukin)-33 is a pleiotropic cytokine with multiple immunomodulatory effects, yet its role in AAA remains unknown. Approach and Results- Immunoblot, immunohistochemistry, and immunofluorescent staining revealed increased IL-33 expression in adventitia fibroblasts from mouse AAA lesions. Daily intraperitoneal administration of recombinant IL-33 or transgenic IL-33 expression ameliorated periaorta CaPO4 injury- and aortic elastase exposure-induced AAA in mice, as demonstrated by blunted aortic expansion, reduced aortic wall elastica fragmentation, enhanced AAA lesion collagen deposition, attenuated T-cell and macrophage infiltration, reduced inflammatory cytokine production, skewed M2 macrophage polarization, and reduced lesion MMP (matrix metalloproteinase) expression and cell apoptosis. Flow cytometry analysis, immunostaining, and immunoblot analysis showed that exogenous IL-33 increased CD4+Foxp3+ regulatory T cells in spleens, blood, and aortas in periaorta CaPO4-treated mice. Yet, ST2 deficiency muted these IL-33 activities. Regulatory T cells from IL-33-treated mice also showed significantly stronger activities in suppressing smooth muscle cell inflammatory cytokine and chemokine expression, macrophage MMP expression, and in increasing M2 macrophage polarization than those from vehicle-treated mice. In contrast, IL-33 failed to prevent AAA and lost its beneficial activities in CaPO4-treated mice after selective depletion of regulatory T cells. Conclusions- Together, this study established a role of IL-33 in protecting mice from AAA formation by enhancing ST2-dependent aortic and systemic regulatory T-cell expansion and their immunosuppressive activities.

Safety and efficacy of ethylenediaminetetraacetic acid for removing microcapsules.

BACKGROUND: Microencapsulated islets are used to prevent immune rejection associated with pancreatic islet transplantation, but cellular overgrowth affects transplantation success, necessitating removal of microcapsules prior to retransplantation. This study aimed to investigate the safety and efficacy of ethylendiaminetetraacetic acid (EDTA) for the removal of microcapsules surrounding islet cells. METHODS: Microcapsule dissolution was investigated after in vitro exposure to EDTA for 72 h. Dissolution, blood biochemical markers, and pathologic changes in abdominal organs were observed after intraperitoneal administration of different concentrations of EDTA to rats with abdominally transplanted empty microcapsules. The extent of overgrowth and time to adhesion development were recorded after implantation of microencapsulated islets into the abdominal cavity of diabetic rats. EDTA (0-240 mmol/L) was injected to observe the transplantation effect and ability to dissolve microcapsules. RESULTS: There was a positive correlation between the rate of microcapsule dissolution and EDTA concentration in vitro. Following administration of 60 mmol/L EDTA, the majority of microcapsules within the abdominal cavity were dissolved and the retrieval rate was 2.6%. No adverse effects, abnormal blood biochemical markers, or organ damage were observed in rats 1 mo following intraperitoneal injection with EDTA at doses up to 60 mmol/L. Microcapsule retrieval and blood glucose were significantly higher in cases of grade II cellular overgrowth than in cases of grade 0-I overgrowth. CONCLUSIONS: EDTA (60 mmol/L) dissolved microcapsules in vivo without affecting islet cell viability or secretion capacity, and without affecting blood biochemical markers. Optimal dissolution was achieved with grade 0-I overgrowth after implantation of microencapsulated islets.

Down-regulation of inducible co-stimulator (ICOS) by intravitreal injection of small interfering RNA (siRNA) plasmid suppresses ongoing experimental autoimmune uveoretinitis in rats.

BACKGROUND: RNA interference (RNAi) is now being exploited as a powerful tool for gene knockdown. Recently, we had shown that inducible co-stimulator (ICOS) was up-regulated in experimental autoimmune uveoretinitis (EAU). The aim of this study was to investigate whether intravitreal injection of small interfering RNA (siRNA) plasmid, targeting ICOS, suppresses the ongoing experimental autoimmune uveoretinitis (EAU) in rats. METHODS: Oligonucleotide targeting ICOS was cloned into linearized pRNAT-U6.1/Neo eukaryotic expression vector to construct the recombinant plasmid (pRNAT-U6.1/Neo-ICOS). After transfecting activated rat T cells with the recombinant plasmid, ICOS mRNA and protein expression levels were determined by real-time RT-PCR and Western blot analysis respectively. Rats were immunized with IRBP R16 peptide emulsified in complete Freund's adjuvant (CFA) and given an intravitreal injection of pRNAT-U6.1/Neo-ICOS on day 6 after immunization. After 13days of immunization, the ICOS protein expression and CD4(+) ICOS (+) T cells were identified in retinae through Western blot analysis and flow cytometry respectively. Intraocular inflammation was assessed by the scores of the clinical and histological appearances. Delayed-type hypersensitivity (DTH) and lymphocyte proliferation were detected to evaluate the systemic effect of intravitreal injection of pRNAT-U6.1/Neo-ICOS. RESULT: The recombinant plasmid (pRNAT-U6.1/Neo-ICOS) for the ICOS siRNA was successfully constructed. In vitro studies using the recombinant plasmid has showed the down-regulation of ICOS gene expression both at the mRNA and protein levels. Clinical and pathological scores showed that ocular inflammation of pRNAT-U6.1/Neo-ICOS-treated eyes was markedly less than that of vehicle-treated eyes. The expression of ICOS protein and the amount of CD4(+) ICOS(+) T cells in retinae significantly decreased by intravitreal injection of the recombinant plasmid, whereas delayed-type hypersensitivity response and lymphocyte proliferation were not impaired in rats treated with the recombinant plasmid. CONCLUSION: Intravitreal injection of siRNA plasmid targeting ICOS effectively down-regulated the expression of ICOS, and was highly effective in suppressing the ongoing process of EAU without any side-effects on systemic cellular immunity.