TY - JOUR
T1 - Phenotypic and functional heterogeneity of the testicular macrophage population: A new regulatory model
AU - Winnall, Wendy Rachael
AU - Hedger, Mark Peter
PY - 2013
Y1 - 2013
N2 - Testicular macrophages (TMs) are important contributors to the response of the testis to infection, as well as the regulation of spermatogenesis, steroidogenesis and other homeostatic functions of the testis. The TMs are the largest population of immune cells in a region of tight immunoregulation, where both innate and acquired immune responses are effectively suppressed, and these cells are predicted to be responsible for regulating this immunosuppression. In the rat, TMs have been broadly classified into two main populations, designated newly arrived and resident , the latter being characterised by expression of the scavenger receptor, CD163. Systemic inflammation in response to lipopolysaccharide leads to an influx of CD163(-) monocyte-like ( infiltrating ) macrophages into the rodent testis, which have a pro-inflammatory phenotype and express interleukin-1beta, tumour necrosis factor-alpha, inducible nitric oxide synthase and other inflammatory factors. The resident CD163(+) TMs, on the other hand, constitutively produce IL-10 and are poor stimulators of T-cell proliferation in vitro, indicating that they contribute to testicular immunosuppression. However, our recent studies have demonstrated that the newly-arrived CD163(-) TMs present in the rat testis under normal homeostatic conditions show very little response to LPS stimulation in vitro. We here propose a modified model of TM heterogeneity whereby the CD163(-) TMs of the normal rat testis are derived from a monocyte subset that continuously repopulates the testis, and is distinct from the monocyte-like infiltrating subset from which pro-inflammatory CD163(-) TMs may be derived during systemic inflammation.
AB - Testicular macrophages (TMs) are important contributors to the response of the testis to infection, as well as the regulation of spermatogenesis, steroidogenesis and other homeostatic functions of the testis. The TMs are the largest population of immune cells in a region of tight immunoregulation, where both innate and acquired immune responses are effectively suppressed, and these cells are predicted to be responsible for regulating this immunosuppression. In the rat, TMs have been broadly classified into two main populations, designated newly arrived and resident , the latter being characterised by expression of the scavenger receptor, CD163. Systemic inflammation in response to lipopolysaccharide leads to an influx of CD163(-) monocyte-like ( infiltrating ) macrophages into the rodent testis, which have a pro-inflammatory phenotype and express interleukin-1beta, tumour necrosis factor-alpha, inducible nitric oxide synthase and other inflammatory factors. The resident CD163(+) TMs, on the other hand, constitutively produce IL-10 and are poor stimulators of T-cell proliferation in vitro, indicating that they contribute to testicular immunosuppression. However, our recent studies have demonstrated that the newly-arrived CD163(-) TMs present in the rat testis under normal homeostatic conditions show very little response to LPS stimulation in vitro. We here propose a modified model of TM heterogeneity whereby the CD163(-) TMs of the normal rat testis are derived from a monocyte subset that continuously repopulates the testis, and is distinct from the monocyte-like infiltrating subset from which pro-inflammatory CD163(-) TMs may be derived during systemic inflammation.
UR - http://www.ncbi.nlm.nih.gov/pubmed/23415010
U2 - 10.1016/j.jri.2013.01.001
DO - 10.1016/j.jri.2013.01.001
M3 - Article
VL - 97
SP - 147
EP - 158
JO - Journal of Reproductive Immunology
JF - Journal of Reproductive Immunology
SN - 0165-0378
IS - 2
ER -