The response of testicular leukocytes to lipopolysaccharide-induced inflammation: further evidence for heterogeneity of the testicular macrophage population

Abstract

The majority of macrophages in the rat testis can be identified by the tissue-resident macrophage marker ED2. A smaller population of intratesticular macrophages do not express the ED2 antigen but are positive for the monocyte/macrophage marker ED1. Treatment of adult rats with the inflammatory stimulus lipopolysaccharide (LPS) had no effect on the number of testicular resident (ED2(+)) macrophages but caused a transient increase in ED1(+)ED2(-) monocyte-like macrophages (an average three-fold increase 12 h later). In both control and LPS-treated rat testes, a majority of macrophages that expressed ED1 and all Leydig cells were immuno-positive for the inducible isoform of nitric oxide synthase (iNOS). However, less than 6% of ED2(+) macrophages showed any iNOS expression, even after LPS treatment. This deficiency was confirmed by the finding that isolated ED2(+) testicular macrophages (>98% pure) stimulated with LPS did not produce NO in vitro. In contrast, resident macrophages from the peritoneum showed the expected NO response, and purified Leydig cells produced significant NO regardless of the presence or absence of LPS. Collectively, these data indicate the presence of at least two macrophage subsets in the adult rat testis: (1) the ED2(+) resident macrophages, which do not alter following LPS-treatment and mostly do not express iNOS or produce NO in response to an inflammatory stimulus, and (2) the ED1(+)ED2(-) monocyte-like macrophages, which increase in number after LPS-treatment and express iNOS even in the absence of exogenous inflammatory stimulation. It is highly probable that these different subsets have different functional roles within the testis.

Sertoli Cells Initiate Testicular Innate Immune Responses through TLR Activation

“…Moreover, higher MCP-1 levels detected in SCCM following treatment with MALP-2 correlate with a major number of cells transmigrated. Our results are in agreement with the data described in a previous paper showing an increase in the number of testicular macrophages stimulated by MCP-1 in an LPS inflammatory model (56).…”

Expression of Constitutive Endothelial, Neuronal and Inducible Nitric Oxide Synthase in the Testis and Epididymis of Horse

“…It is well known that macrophages express iNOS upon activation and release NO in cultured cell systems. In a previous study, a majority of the macrophages that expressed ED1 and all Leydig cells were immunopositive for iNOS in both control and LPStreated rat testes [9]. It is thus likely that the iNOS-immunoreactive cell populations detected in the interstitial tissue of horse testes in this study were comprised of Leydig cells and macrophages.…”

Donor Sertoli cells transplanted into irradiated rat testes stimulate partial recovery of endogenous spermatogenesis

“…The occasional observation of isolated spermatogonia in testicular biopsies at relatively long times after chemotherapy treatment (Kreuser et al 1989) and the spontaneous recovery of spermatogenesis in some men after several years of radiation or chemotherapy-induced azoospermia (Hahn et al 1982, Pryzant et al 1993, Gerdprasert et al 2002 indicate that there may indeed be a reversible block to differentiation in humans. Sertoli cell transplantation may still be useful for treatment of infertility induced by radiation or antineoplastic drugs to reverse this block and provide additional niches for co-transplanted stem cells.…”

“…LBNF 1 rats were chosen because they are an F 1 hybrid between two inbred strains, and therefore have hybrid vigor and can accept transplants from either parental strain, and are sensitive to the hormone-mediated block in spermatogonial differentiation induced by radiation and other cytotoxic agents (Parchuri et al 1993, Gerdprasert et al 2002, Meistrich & Shetty 2003. However, LBNF 1 is not unique as other inbred and outbred strains of rats, including Lewis, PVG, certain substrains of Wistar, Fischer 344, and Sprague-Dawley also have a high sensitivity to radiation and anticancer agents (Delic et al 1986a, 1986b, Ward et al 1990, Gerdprasert et al 2002, show this block in spermatogonial differentiation after exposure to toxicants (Allard et al 1996), and restore spermatogenic recovery from toxicant exposure upon suppression of hormones (Delic et al 1986a, 1986b, Gerdprasert et al 2002, Udagawa et al 2006. Donors were transgenic rats expressing GFP under the control of a CMV enhancer and ubiquitin-C promoter (Lois et al 2002).…”

“…The mouse monoclonal anti-human PCNA antibody (Dako, Glostrup, Denmark) was used to stain proliferating cells. Macrophages were stained with antibodies ED1 (1:100), which recognizes monocytes, dendritic cells, and circulating macrophages, or ED2 (1:50 dilution), which recognizes tissueresident macrophages (AbD Serotec, Raleigh, NC, USA; Gerdprasert et al 2002).…”