Sepsis produces depression of testosterone and steroidogenic acute regulatory (StAR) protein

Exploring Clinically-Relevant Experimental Models of Neonatal Shock and Necrotizing Enterocolitis

Neonatal shock and necrotizing enterocolitis (NEC) are leading causes of morbidity and mortality in premature infants. NEC is a life-threatening gastrointestinal illness, the precise etiology of which is not well understood, but is characterized by an immaturity of the intestinal barrier, altered function of the adaptive immune system, and intestinal dysbiosis. The complexities of NEC and shock in the neonatal population necessitate relevant clinical modeling using newborn animals that mimic the disease in human neonates to better elucidate the pathogenesis and provide an opportunity for the discovery of potential therapeutics. A wide variety of animal species-including rats, mice, piglets, and primates-have been used in developing experimental models of neonatal diseases such as NEC and shock. This review aims to highlight the immunologic differences in neonates compared with adults and provide an assessment of the advantages and drawbacks of established animal models of both NEC and shock using enteral or intraperitoneal induction of bacterial pathogens. The selection of a model has benefits unique to each type of animal species and provides individual opportunities for the development of targeted therapies. This review discusses the clinical and physiologic relevance of animal models and the insight they contribute to the complexities of the specific neonatal diseases: NEC and shock.

Involvement of Cytokines and Hormones in the Development of Spermatogenesis In Vitro from Spermatogonial Cells of Cyclophosphamide-Treated Immature Mice

Aggressive chemotherapy treatment may lead to male infertility. Prepubertal boys do not produce sperm at this age, however, they have spermatogonial stem cells in their testes. Here, we examined the effect of intraperitoneal injection of cyclophosphamide (CP) on the capacity of immature mice (IM) to develop spermatogenesis in vivo and in vitro [using methylcellulose culture system (MCS)]. Our results show a significant decrease in testicular weight, total number of testicular cells, and the number of Sertoli, peritubular, premeiotic, and meiotic/post-meiotic cells, but an increase in the percentages of damaged seminiferous tubules in CP-treated IM compared to control. The functionality of Sertoli cells was significantly affected. The addition of testosterone to isolated cells from seminiferous tubules of CP-treated IM significantly increased the percentages of premeiotic (CD9-positive cells) and meiotic/post-meiotic cells (ACROSIN-positive cells) developed in MCS compared to control. The addition of FSH did not affect developed cells in MCS compared to control, but in combination with testosterone, it significantly decreased the percentages of CD9-positive cells and ACROSIN-positive cells. The addition of IL-1 did not affect developed cells in MCS compared to control, but in combination with testosterone, it significantly increased the percentages of VASA-positive cells and BOULE-positive cells compared to IL-1 or testosterone. Addition of TNF significantly increased only CD9-positive cells in MCS compared to control, but in combination with testosterone, it significantly decreased ACROSIN-positive cells compared to testosterone. Our results show a significant impairment of spermatogenesis in the testes of CP-treated IM, and that spermatogonial cells from these mice proliferate and differentiate to meiotic/post-meiotic cells under in vitro culture conditions.

Characterization of the male ApcMin/+ mouse as a hypogonadism model related to cancer cachexia

Cancer cachexia, the unintentional loss of lean body mass, is associated with decreased quality of life and poor patient survival. Hypogonadism, involving a reduction in circulating testosterone, is associated with the cachectic condition. At this time there is a very limited understanding of the role of hypogonadism in cancer cachexia progression. This gap in our knowledge is related to a lack of functional hypogonadal models associated with cancer cachexia. The Apc^Min/+ mouse is an established colorectal cancer model that develops an IL-6 dependent cachexia which is physiologically related to human disease due to the gradual progression of tumor development and cachexia. The purpose of this study was to assess the utility of the Apc^Min/+ mouse for the examination of hypogonadism during cancer cachexia and to investigate if IL-6 has a role in this process. We report that Apc^Min/+ mice that are weight stable have comparable testosterone levels and gonad size compared to wild type mice. Cachectic Apc^Min/+ mice exhibit a reduction in circulating testosterone and gonad size, which has a significant association with the degree of muscle mass and functional strength loss. Circulating testosterone levels were also significantly associated with the suppression of myofibrillar protein synthesis. Skeletal muscle and testes androgen receptor expression were decreased with severe cachexia. Although testes STAT3 phosphorylation increased with severe cachexia, systemic IL-6 over-expression for 2 weeks was not sufficient to reduce either testes weight or circulating testosterone. Inhibition of systemic IL-6 signaling by an IL-6 receptor antibody to Apc^Min/+ mice that had already initiated weight loss was sufficient to attenuate a reduction in testes size and circulating testosterone. In summary, the Apc^Min/+ mouse becomes hypogonadal with the progression of cachexia severity and elevated circulating IL-6 levels may have a role in the development of hypogonadism during cancer cachexia.

Influence of gender on the outcome of severe sepsis: a reappraisal

BACKGROUND

The influence of gender on survival of patients with severe sepsis is unclear. Earlier studies suggested better survival in women, possibly related to the sex-steroid profile.

METHODS

To investigate whether mortality from severe sepsis was higher in men than in women and whether the difference varied with menopausal status, we studied 1,692 patients with severe sepsis included in the OutcomeRea database over an 8-year period. We conducted a nested case-control study, accurately matching men and women on three criteria: a death propensity score, age, and center. Subgroup analyses were performed on individuals <or= 50 years old (men vs premenopausal women) and > 50 years old (men vs postmenopausal women).

RESULTS

We matched 1,000 men to 608 women with severe sepsis before and after adjustment for confounding factors (ie, chronic respiratory failure; metastatic cancer; immunocompromised status; emergency surgery, acute respiratory failure, and shock at admission; urinary tract infection; and type of microorganism). Overall hospital mortality was significantly lower in women (adjusted odds ratio [OR], 0.75; 95% confidence interval [CI], 0.57 to 0.97; p = 0.02). In the group > 50 years old (481 women, 778 men), hospital mortality was significantly lower in women (OR, 0.69; 95% CI, 0.52 to 0.93; p = 0.014). Hospital mortality was not significantly different between men and women in the younger group (127 women, 222 men) [OR, 1.01; 95% CI, 0.52 to 1.97; p = 0.98]. Level of care, as assessed using the nine equivalents of nursing manpower use score, was identical in men and women.

CONCLUSIONS

Among individuals > 50 years old with severe sepsis, women have a lower risk of hospital mortality than men.

Influence of Gender on Outcome of Severe Sepsis

Whether gender influences the outcome of severe sepsis remains a matter of debate. Because many confounding variables may affect observed associations between gender and mortality, high-quality statistical analyses are essential to carefully adjust the two groups of patients. About 55% to 65% of patients with sepsis have chronic co-morbidities associated with immune dysfunction (e.g., chronic renal failure, diabetes mellitus, human immunodeficiency virus [HIV] infection, and alcohol abuse), which increase the susceptibility to sepsis [1]. Genetic polymorphisms that affect the susceptibility to infection and/or the severity of the systemic response to infection [2] may lead to variability among individuals and between males and females [3]. Access to healthcare, another determinant of the incidence and outcome of sepsis, varies according to age, ethnic group, and gender, although a recent study conducted in the USA found only relatively small quality-of-care differences between males and females or across income groups compared to the gap for each subgroup between observed and desirable quality of health care [4]. Here, we review the data on the existence of, and reasons for, associations between gender and outcome of severe sepsis (Fig. 1).

Activation of a neural brain-testicular pathway rapidly lowers Leydig cell levels of the steroidogenic acute regulatory protein and the peripheral-type benzodiazepine receptor while increasing levels of neuronal nitric oxide synthase

Activation of a neural brain-testicular pathway by the intracerebroventricular injection of the beta-adrenergic agonist isoproterenol (ISO), the hypothalamic peptide corticotropin-releasing factor (CRF), or alcohol (EtOH) rapidly decreases the testosterone (T) response to human chorionic gonadotropin. To elucidate the intratesticular mechanisms responsible for this phenomenon, we investigated the influence of intracerebroventricular-injected ISO, CRF, or EtOH on levels of the steroidogenic acute regulatory (StAR) protein, the peripheral-type benzodiazepine receptor (PBR), and the cytochrome P450 side-chain cleavage enzyme in semipurified Leydig cells. ISO (10 microg), CRF (5 microg), or EtOH (5 microl of 200 proof, a dose that does not induce neuronal damage nor leaks to the periphery) rapidly decreased StAR and PBR but not cytochrome P450 side-chain cleavage enzyme protein levels. Levels of the variant of the neuronal nitric oxide synthase (nNOS) that is restricted to Leydig cells, TnNOS, significantly increased in response to ISO, CRF, and EtOH over the time course of altered StAR/PBR concentrations. However, pretreatment of the rats with N(w)nitro-arginine methylester, which blocked ISO-induced increases in TnNOS, neither restored the T response to human chorionic gonadotropin nor prevented the decreases in StAR and PBR. These results provide evidence of concomitant changes in Leydig cell StAR and PBR levels in live rats. They also indicate that activation of a neural brain-testicular pathway rapidly decreases concentrations of these steroidogenic proteins while up-regulating testicular NO production. However, additional studies are necessary to elucidate the functional role played by this gas in our model.

Bacterial endotoxin lipopolysaccharide and reactive oxygen species inhibit Leydig cell steroidogenesis via perturbation of mitochondria

Chronic inflammatory disease and acute infection are well known to inhibit gonadal steroidogenesis. Previous studies have demonstrated that immune activation in response to lipopolysaccharide (LPS) results in reductions in serum testosterone, and this is a direct effect on the Leydig cell. We hypothesize that during the early onset of LPS endotoxemia in vivo, testicular macrophages produce reactive oxygen species (ROS) leading to perturbation of Leydig cell mitochondria and an inhibition in steroidogenesis. To investigate the mechanism of LPS inhibition of Leydig cell steroidogenesis, alterations in mitochondria and markers of oxi-dative stress were assessed in vivo and in Leydig cell pri- mary culture. After a single injection of mice with LPS, serum testosterone was significantly decreased within 2 h. LPS injection of mice resulted in significant reductions in steroidogenic acute regulatory protein (StAR) and 3beta-hydroxysteroid dehydogenase-Delta4-Delta5 isomerase (3beta-HSD) proteins. LPS significantly increased lipid peroxidation of Leydig cell membranes, indicating that LPS results in oxidative damage in vivo. Mitochondria in Leydig cells isolated from LPS-injected mice were disrupted and showed a marked reduction in the mitochondrial membrane potential (DeltaPsim). Similar to the effects of LPS, treatment of Leydig cells with hydrogen peroxide acutely inhibited steroidogenesis, reduced StAR and 3beta-HSD protein levels, and disrupted DeltaPsim. These results suggest that LPS acutely inhibits Leydig cell function by ROS-mediated disruption of Leydig cell mitochondria. Taken together, these results demonstrate the necessity of having respiring mitochondria with an intact DeltaPsim to facilitate StAR function and Leydig cell steroidogenesis. The acute effects of LPS demonstrate how sensitive Leydig cell mitochondrial steroidogenesis is to inflammation-induced oxidative stress.

Peripubertal Immune Challenges Attenuate Reproductive Development in Male Siberian Hamsters (Phodopus sungorus)1

Differential allocation of energy to reproduction versus host defense is assumed to drive the seasonal antiphase relation between peak reproductive function and immunocompetence; however, evidence supporting this assumption is only correlational. These experiments tested whether photoperiod affects immune responses to antigens in peripubertal Siberian hamsters, whether such activation of the immune system exacts energetic and reproductive costs, and whether such costs vary seasonally. Male Siberian hamsters were raised from birth in long (LD) or short days (SD), which respectively initiate or inhibit the onset of puberty. To elicit a specific immune response, hamsters were injected with a novel antigen (keyhole limpet hemocyanin [KLH]) as juveniles. Reproductive development was attenuated and body temperature was elevated in LD hamsters relative to saline-injected control animals. In contrast, KLH treatments affected neither thermoregulation nor reproductive development in photoinhibited SD hamsters. In experiment 2, juvenile male hamsters were challenged with bacterial lipopolysaccharide (LPS) in order to elicit an innate immune response. Febrile and anorexic responses to LPS were greater in reproductively stimulated LD hamsters relative to reproductively inhibited SD hamsters. LPS treatments attenuated somatic and testicular development in LD hamsters, but did not significantly affect circulating testosterone concentrations. In contrast, LPS treatments were without effect on somatic and reproductive development in SD hamsters. These experiments indicate that photoperiod affects antigen-specific antibody production, febrile responses to LPS, and sickness behaviors in juvenile Siberian hamsters, and that peripubertal activation of the immune system exacts energetic and metabolic costs that can diminish the magnitude of somatic and reproductive maturation in LD. The data also underscore the importance of seasonally dependent life history factors in assessing physiological tradeoffs.

StAR protein and the regulation of steroid hormone biosynthesis

Steroid hormone biosynthesis is acutely regulated by pituitary trophic hormones and other steroidogenic stimuli. This regulation requires the synthesis of a protein whose function is to translocate cholesterol from the outer to the inner mitochondrial membrane in steroidogenic cells, the rate-limiting step in steroid hormone formation. The steroidogenic acute regulatory (StAR) protein is an indispensable component in this process and is the best candidate to fill the role of the putative regulator. StAR is expressed in steroidogenic tissues in response to agents that stimulate steroid production, and mutations in the StAR gene result in the disease congenital lipoid adrenal hyperplasia, in which steroid hormone biosynthesis is severely compromised. The StAR null mouse has a phenotype that is essentially identical to the human disease. The positive and negative expression of StAR is sensitive to agents that increase and inhibit steroid biosynthesis respectively. The mechanism by which StAR mediates cholesterol transfer in the mitochondria has not been fully characterized. However, the tertiary structure of the START domain of a StAR homolog has been solved, and identification of a cholesterol-binding hydrophobic tunnel within this domain raises the possibility that StAR acts as a cholesterol-shuttling protein.

Diametric effects of bacterial endotoxin lipopolysaccharide on adrenal and Leydig cell steroidogenic acute regulatory protein

Immune activation results in the activation of adrenal steroidogenesis and inhibition of gonadal steroidogenesis. Previous studies indicated that these effects were caused primarily by activation and suppression of the secretion of ACTH and LH, respectively. However, other evidence indicated a direct effect of the immune system on the gonads. In this study, serum testosterone, quantitated by RIA after lipopolysaccharide injection, showed a significant decrease within 2 h. Parallel measurement of serum LH showed no change. There were no differences in LH receptor or cAMP produced in Leydig cells between vehicle- and lipopolysaccharide-injected mice. The 30-kDa form of the steroidogenic acute regulatory (StAR) protein was quantitated, by Western blot, in Leydig cells and was found to decrease in a time-dependent manner. No change in StAR protein messenger RNA (mRNA) was detected by Northern analysis during this time, nor were any changes found in the levels of mRNA for the steroidogenic enzymes P450scc, 3beta-hydroxysteroid dehydrogenase delta4-delta5-isomerase, or P450c17. In the adrenal, StAR protein was increased, as was StAR protein mRNA. No changes were observed in the levels of mRNA for P450scc, 3beta-hydroxysteroid dehydrogenase delta4-delta5-isomerase, or P450c21. Thus, although the mechanisms of regulation differ, changes in the levels of StAR protein are a sensitive indicator of the steroidogenic capacity of these two tissues.

Influence of urogenital infection on sperm function

Male accessory sex gland infections are considered to be hazards to male fertility. Various pathophysiologic concepts have evolved from experimental and clinical studies that begin to explain the effects of bacteria and immunologic events on spermatozoa. Recent studies have identified and evaluated mediators that are responsible for specific molecular processes in infections that particularly affect the function of spermatozoa.