The effect of restricted nutrition on uterine macrophage populations in mice

The abundant macrophage populations present in the endometrium are implicat ed in the tissue remodelling events and immunological changes necessary for pregnancy. Using two regimens of restricted nutrition (95 and 88% of ad li bitum intake for 19 days), we have shown that moderately reduced food consu mption can dramatically alter the number of endometrial macrophages and the ir immunoaccessory function in mice. Restricted nutrition also interfered w ith the estrous cycle, but the effects on endometrial macrophages were more extensive and qualitatively different than could be explained by diminishe d ovarian steroid hormone activity. Significantly less F4/80 + and Ia + cel ls were found in the endometrium of food restricted mice than in ad libitum mice at the same estrous cycle stage. In the more severely restricted mice the losses were even greater than those seen after ovariectomy. In ad libi tum fed animals, uterine but not peritoneal macrophages showed an ovarian h ormone-dependent inhibitory phenotype in a splenocyte mitogenesis assay. Ma crophages derived from both locations exhibited greater immunostimulatory a ctivity following restricted nutrition. We conclude that endometrial macrop hage populations are influenced by nutritional status and this may be media ted through both steroid hormone-dependent and -independent mechanisms. Nut ritionally induced aberrations in the number or behaviour of endometrial ma crophages during the estrous cycle or in early pregnancy could have importa nt implications for the quality of the pre- and peri-implantation environme nt and the maternal immune response to pregnancy. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.