Influence of the immune system on reproductive function

Leukocytes: essential cells in ovarian function and ovulation

The disciplines of reproduction and immunology, once quite discrete, are now closely associated, with compelling evidence to suggest that immune mechanisms play important roles in the cervix, uterus, fallopian tubes and ovary. Cells and mediators classically described as part of the immune system are found throughout the reproductive tract. Disorders of reproduction, including pre-eclampsia, unexplained infertility, endometriosis, recurrent miscarriage and disturbed fetal growth almost certainly have some of their origins in the dysfunction of immune regulation. There appears to be some evidence that immune disorders, such as rheumatoid arthritis and scleroderma, can manifest as infertility, before clinical disease becomes apparent.

Developing Ovarian Follicles Inhibit the Endotoxin-Induced Glomerular Inflammatory Reaction in Pseudopregnant Rats

PROBLEM

We tested the hypothesis that developing ovarian follicles produce factors inhibiting the endotoxin induced inflammatory response.

METHOD OF STUDY

Pseudopregnant rats were treated with FSH to induced follicular development (FSH-rats). For control we used untreated pseudopregnant rats (PSP-rats) and rats in the follicular phase of the ovarian cycle (C-rats). All rats were infused with either saline or endotoxin. Three days after the infusion rats were sacrificed and kidney specimens were snapfrozen. Cryostat kidney sections were stained for the presence of monocytes, granulocytes, CD11a- and CD11b-positive cells and for ICAM-1 expression.

RESULTS

The results show that induction of follicular development in pseudopregnant rats inhibited glomerular infiltration of monocytes and CD11b(+) cells, while it did not affect the other parameters, i.e. glomerular granulocyte number, CD11a(+) cells and glomerular ICAM-1 expression.

CONCLUSION

Developing ovarian follicles produce factors inhibiting monocyte responses to endotoxin.

Suppression by developing ovarian follicles of the low-dose endotoxin-induced glomerular inflammatory reaction in the pregnant rat

OBJECTIVE

In the current study the role of developing ovarian follicles in the control of the endotoxin-induced pregnancy-specific inflammatory reaction was evaluated.

STUDY DESIGN

Follicular development was induced in pregnant rats (n = 20) by means of daily intraperitoneal injections of follicle-stimulating hormone from day 11 of pregnancy until the end of the experiment. Control pregnant rats (n = 20) received daily sodium chloride injections. All pregnant rats were infused for 1 hour with either 2 mL endotoxin solution (1.0 microg/kg body weight) or 2 mL sodium chloride solution on day 14 and killed 4 hours or 3 days later. At death, the left kidneys were snap-frozen and immunohistologically stained for the presence of polymorphonuclear leukocytes and monocytes.

RESULTS

The results show that in control pregnant rats endotoxin significantly increased glomerular polymorphonuclear leukocyte and monocyte numbers at both 4 hours and 3 days after endotoxin infusion. Induction of follicular development did not affect glomerular polymorphonuclear leukocyte number after endotoxin infusion but significantly decreased the number of monocytes in the glomeruli at both 4 hours and 3 days after endotoxin infusion.

CONCLUSION

We conclude that follicles stimulated with follicle-stimulating hormone produce a follicular factor or factors that are able to prevent the endotoxin-induced influx of monocytes into the glomeruli of pregnant rats. It is suggested that these factors play a role in the control of inflammatory processes associated with reproduction, including the disease of pregnancy, preeclampsia.

The equine endometrial cup reaction: a review

The function of eCG in equine pregnancy is far from clear but it has become evident that eCG has little or no FSH activity in the horse and is therefore probably not responsible for the secondary ovulations. eCG does have luteotrophic activity and it could play a role in the resurgence of the primary corpus luteum (1,7,44). Some evidence exists that the receptor population on the equine gonads is heterogenous in a way that makes it possible to distinguish eCG from eLH, resulting in different post-receptor effects (7). There is also evidence that eCG itself is heterogenous, both in glycosylation and in primary structure, not only between different individual animals but also within one animal during different stages of gestation. The differences could simply reflect the difference between stored and secreted hormone, but on the other hand the release of different eCG forms could be under endocrine control, allowing the mare to produce forms appropriate to specific biological needs (74). Thus some forms of eCG could play a role in immunological events taking place at the foeto-maternal interface. The role of cytotoxic antibodies in the equine pregnancy is not understood. The fact that they are not harmful to the pregnancy can be explained by the fact that their target, the paternal MHC molecules, are withdrawn from the endometrial cup tissue by the time the antibodies start appearing in the circulation. This unique way of regulation of MHC expression is also poorly understood.(ABSTRACT TRUNCATED AT 250 WORDS)

In utero infections responsible for abortion, stillbirth, and birth of weak calves in beef cows

A multitude of in utero infections may cause abortion, stillbirths, or the birth of weak calves (see Table 1). Because the diagnostic success for determining the cause of abortions may be low (25%-40%), it is important that more knowledge about the causes and differential diagnoses is gained, and proper samples are collected and submitted. Use of an abortion diagnosis kit enables multiple samples to be analyzed and increases the likelihood of making a diagnosis. The immune response is suppressed during pregnancy. In part, this can be controlled by proper nutrition and appropriately timed vaccination programs.