Morphological reseach on expression of inflammatory mediators in murine models of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) induced by T2 antigen

Abstract

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common clinical syndrome with unknown aetiology. In this study, we used the T2 peptide in C57BL/6 (B6) mice and Sprague Dawley (SD) rats model during different stages. We sought to understand the role of CD4+ T cells and macrophages in CP/CPPS. A total of 16 B6 mice and 18 SD rats were divided into five groups: B6-naïve (n = 6), B6 model (n = 10), SD-naïve (n = 6), SD-45-day model (n = 6) and SD-56-day model (n = 6). The B6 model group was subcutaneously injected with 0.2 ml of (225μg/ml) T2 peptide on 0 and 14th day and was finally sacrificed on 28th day. The SD-45- and SD-56-day model groups were subcutaneously injected with 1ml of (50 μg/ml) T2 peptide on 0 and 14th day and were finally sacrificed on 45th and 56th day respectively. An equivalent volume of normal saline (NS) solution was injected to the naïve groups and analysed the pain and voiding behaviour. We have calculated the prostate index, H&E staining and immunofluorescence of CD4+ T cells and macrophages (CD68) in each group. T2 peptide immunization in B6 mice and SD rats caused severe prostatitis and cell infiltration, mainly composed of CD4+ T cells and macrophages. The SD-56-day model group showed more severe inflammatory cells infiltration than SD-45-day model group. Moreover, inflammatory cells infiltration and red secretions in B6 model were less than SD model. Expression of CD4+ T cells and macrophages was also consistent with H&E results. These results indicated that different stages of CP/CPPS, inflammatory response, and the inflammation of the rat were stronger than the mouse. Our study suggests that CD4+ T cells and macrophages are key factors in the development of CP/CPPS.