Leptin, ciliary neurotrophic factor, leukemia inhibitory factor and interleukin-6: class-I cytokines involved in the neuroendocrine regulation of the reproductive function

The Molecular Basis and Therapeutic Potential of Leukemia Inhibitory Factor in Cancer Cachexia

Simple Summary

The mechanism of cancer cachexia is linked to a variety of factors, and inflammatory factors are thought to play a key role. We summarize the main roles of LIF in the development of cancer cachexia, including promoting fat loss, inducing skeletal muscle atrophy and causing anorexia nervosa. The main aim of this review is to increase the understanding of the effects of LIF in cachexia and to provide new insights into the treatment of cancer cachexia.

Abstract

Cachexia is a chronic metabolic syndrome that is characterized by sustained weight and muscle mass loss and anorexia. Cachexia can be secondary to a variety of diseases and affects the prognosis of patients significantly. The increase in inflammatory cytokines in plasma is deeply related to the occurrence of cachexia. As a member of the IL-6 cytokine family, leukemia inhibitory factor (LIF) exerts multiple biological functions. LIF is over-expressed in the cancer cells and stromal cells of various tumors, promoting the malignant development of tumors via the autocrine and paracrine systems. Intriguingly, increasing studies have confirmed that LIF contributes to the progression of cachexia, especially in patients with metastatic tumors. This review combines all of the evidence to summarize the mechanism of LIF-induced cachexia from the following four aspects: (i) LIF and cancer-associated cachexia, (ii) LIF and alterations of adipose tissue in cachexia, (iii) LIF and anorexia nervosa in cachexia, and (iv) LIF and muscle atrophy in cachexia. Considering the complex mechanisms in cachexia, we also focus on the interactions between LIF and other key cytokines in cachexia and existing therapeutics targeting LIF.

Space Flight-Promoted Insulin Resistance as a Possible Disruptor of Wound Healing

During space flight, especially when prolonged, exposure to microgravity results in a number of pathophysiological changes such as bone loss, muscle atrophy, cardiovascular and metabolic changes and impaired wound healing, among others. Interestingly, chronic low-grade inflammation and insulin resistance appear to be pivotal events linking many of them. Interestingly, real and experimental microgravity is also associated to altered wound repair, a process that is becoming increasingly important in view of prolonged space flights. The association of insulin resistance and wound healing impairment may be hypothesized from some dysmetabolic conditions, like the metabolic syndrome, type 2 diabetes mellitus and abdominal/visceral obesity, where derangement of glucose and lipid metabolism, greater low-grade inflammation, altered adipokine secretion and adipocyte dysfunction converge to produce systemic effects that also negatively involve wound healing. Indeed, wound healing impairment after traumatic events and surgery in space remains a relevant concern for space agencies. Further studies are required to clarify the molecular connection between insulin resistance and wound healing during space flight, addressing the ability of physical, endocrine/metabolic, and pharmacological countermeasures, as well as nutritional strategies to prevent long-term detrimental effects on tissue repair linked to insulin resistance. Based on these considerations, this paper discusses the pathophysiological links between microgravity-associated insulin resistance and impaired wound healing.

LIF and bFGF enhanced chicken primordial follicle activation by Wnt/β-catenin pathway

The cytokines leukemia inhibitory factor (LIF) and basic fibroblast growth factor (bFGF) are closely related to the development of primordial follicles. In this study, the functions and correlation of LIF and bFGF in the development of chicken primordial follicles were examined, along with the signaling pathways including protein kinase B (AKT), extracellular regulated protein kinase (ERK) and Wnt/β-catenin signaling pathways. Ovarian tissues were collected from four-day-old chicks and incubated with LIF and bFGF alone or in combination for three days to observe the changes in follicular development. Results showed that there was a time-dependent correlation between the changes in expression of LIF/its receptor (LIFR) and the developmental process of primordial follicles. LIF and bFGF exerted a synergistic effect on the activation of primordial follicles. However, SC144 (an antagonist of LIFR) inhibited this stimulating action. The effect by LIF and bFGF were shown to operate at AKT and ERK signaling pathways to suppress cell apoptosis and promote proliferation (P < 0.05) via the Wnt/β-catenin signaling (P < 0.05). In conclusion, local cytokines LIF and bFGF functioned to enhance the activation of chicken primordial follicles by increasing cell proliferation and decreasing apoptosis in the ovary involving AKT, ERK and Wnt/β-catenin signaling.

The depot GnRH agonist protocol improves the live birth rate per fresh embryo transfer cycle, but not the cumulative live birth rate in normal responders: a randomized controlled trial and molecular mechanism study

STUDY QUESTION

Do cumulative live birth rates (CLBRs) after one complete ART cycle differ between the three commonly used controlled ovarian stimulation (COS) protocols (GnRH antagonist, depot GnRHa (GnRH agonist) and long GnRHa) in normal responders undergoing IVF/ICSI?

SUMMARY ANSWER

There were similar CLBRs between the GnRH antagonist, depot GnRHa and long GnRHa protocols.

WHAT IS KNOWN ALREADY

There is no consensus on which COS protocol is the most optimal in women with normal ovarian response. The CLBR provides the final success rate after one complete ART cycle, including the fresh and all subsequent frozen-thawed embryo transfer (ET) cycles. We suggest that the CLBR measure would allow for better comparisons between the different treatment protocols.

STUDY DESIGN, SIZE, DURATION

A prospective controlled, randomized, open label trial was performed between May 2016 and May 2017. A total of 819 patients were allocated to the GnRH antagonist, depot GnRHa or long GnRHa protocol in a 1:1:1 ratio. The minimum follow-up time from the first IVF cycle was 2 years. To further investigate the potential effect of COS with the GnRH antagonist, depot GnRHa or long GnRHa protocol on endometrial receptivity, the expression of homeobox A10 (HOXA10), myeloid ecotropic viral integration site 1 (MEIS1) and leukemia inhibitory factor (LIF) endometrial receptivity markers was evaluated in endometrial tissue from patients treated with the different COS protocols.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Infertile women with normal ovarian response (n = 819) undergoing IVF/ICSI treatment were randomized to the GnRH antagonist, depot GnRHa or long GnRHa protocol. Both IVF and ICSI cycles were included, and the sperm samples used were either fresh or frozen partner ejaculates or frozen donor ejaculates. The primary outcome was the live birth rate (LBR) per fresh ET cycle, and the CLBR after one complete ART cycle, until the birth of a first child (after 28 weeks) or until all frozen embryos were used, whichever occurred first. Pipelle endometrial biopsies from 34 female patients were obtained on Days 7-8 after oocyte retrieval or spontaneous ovulation in natural cycles, respectively, and HOXA10, MEIS1 and LIF mRNA and protein expression levels in the human endometrium was determined by quantitative real-time PCR and western blot, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

There were no significant differences in CLBRs between the GnRH antagonist, depot GnRHa or long GnRHa protocol (71.4 versus 75.5 versus 72.2%, respectively). However, there was a significantly higher LBR per fresh ET cycle in the depot GnRHa protocol than in the long GnRHa and GnRH antagonist protocols (62.6 versus 52.1% versus 45.6%, P < 0.05). Furthermore, HOXA10, MEIS1 and LIF mRNA and protein expression in endometrium all showed significantly higher in the depot GnRHa protocol than in the long GnRHa and GnRH antagonist protocols (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

A limitation of our study was that both our clinicians and patients were not blinded to the randomization for the randomized controlled trial (RCT). An inclusion criterion for the current retrospective cohort study was based on the 'actual ovarian response' during COS treatment, while the included population for the RCT was 'expected normal responders' based on maternal age and ovarian reserve test. In addition, the analysis was restricted to patients under 40 years of age undergoing their first IVF cycle. Furthermore, the endometrial tissue was collected from patients who cancelled the fresh ET, which may include some patients at risk for ovarian hyperstimulation syndrome, however only patients with 4-19 oocytes retrieved were included in the molecular study.

WIDER IMPLICATIONS OF THE FINDINGS

The depot GnRH agonist protocol improves the live birth rate per fresh ET cycle, but not the cumulative live birth rate in normal responders. A possible explanation for the improved LBR after fresh ET in the depot GnRHa protocol could be molecular signalling at the level of endometrial receptivity.

STUDY FUNDING/COMPETING INTEREST(S)

This project was funded by Grant 81571439 from the National Natural Sciences Foundation of China and Grant 2016YFC1000206-5 from the National Key Research & Development Program of China. The authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

The RCT trial was registered at the Chinese Clinical Trial Registry, Study Number: ChiCTR-INR-16008220.

TRIAL REGISTRATION DATE

5 April 2016.

DATE OF FIRST PATIENT’S ENROLLMENT

12 May 2016.

Mechanisms of Reciprocal Regulation of Gonadotropin-Releasing Hormone (GnRH)-Producing and Immune Systems: The Role of GnRH, Cytokines and Their Receptors in Early Ontogenesis in Normal and Pathological Conditions

Different aspects of the reciprocal regulatory influence on the development of gonadotropin-releasing hormone (GnRH)-producing- and immune systems in the perinatal ontogenesis and their functioning in adults in normal and pathological conditions are discussed. The influence of GnRH on the development of the immune system, on the one hand, and the influence of proinflammatory cytokines on the development of the hypothalamic-pituitary-gonadal system, on the other hand, and their functioning in adult offspring are analyzed. We have focused on the effects of GnRH on the formation and functional activity of the thymus, as the central organ of the immune system, in the perinatal period. The main mechanisms of reciprocal regulation of these systems are discussed. The reproductive health of an individual is programmed by the establishment and development of physiological systems during critical periods. Regulatory epigenetic mechanisms of development are not strictly genetically controlled. These processes are characterized by a high sensitivity to various regulatory factors, which provides possible corrections for disorders.

The role of non-neuronal cells in hypogonadotropic hypogonadism

The hypothalamic-pituitary-gonadal axis is controlled by gonadotropin-releasing hormone (GnRH) released by the hypothalamus. Disruption of this system leads to impaired reproductive maturation and function, a condition known as hypogonadotropic hypogonadism (HH). Most studies to date have focused on genetic causes of HH that impact neuronal development and function. However, variants may also impact the functioning of non-neuronal cells known as glia. Glial cells make up 50% of brain cells of humans, primates, and rodents. They include radial glial cells, microglia, astrocytes, tanycytes, oligodendrocytes, and oligodendrocyte precursor cells. Many of these cells influence the hypothalamic neuroendocrine system controlling fertility. Indeed, glia regulate GnRH neuronal activity and secretion, acting both at their cell bodies and their nerve endings. Recent work has also made clear that these interactions are an essential aspect of how the HPG axis integrates endocrine, metabolic, and environmental signals to control fertility. Recognition of the clinical importance of interactions between glia and the GnRH network may pave the way for the development of new treatment strategies for dysfunctions of puberty and adult fertility.

Obesity, Neuroinflammation, and Reproductive Function

The increasing occurrence of obesity has become a significant public health concern. Individuals with obesity have higher prevalence of heart disease, stroke, osteoarthritis, diabetes, and reproductive disorders. Reproductive problems include menstrual irregularities, pregnancy complications, and infertility due to anovulation, in women, and lower testosterone and diminished sperm count, in men. In particular, women with obesity have reduced levels of both gonadotropin hormones, and, in obese men, lower testosterone is accompanied by diminished LH. Taken together, these findings indicate central dysregulation of the hypothalamic-pituitary-gonadal axis, specifically at the level of the GnRH neuron function, which is the final brain output for the regulation of reproduction. Obesity is a state of hyperinsulinemia, hyperlipidemia, hyperleptinemia, and chronic inflammation. Herein, we review recent advances in our understanding of how these metabolic and immune changes affect hypothalamic function and regulation of GnRH neurons. In the latter part, we focus on neuroinflammation as a major consequence of obesity and discuss findings that reveal that GnRH neurons are uniquely positioned to respond to inflammatory changes.

Leukemia Inhibitory Factor Represses GnRH Gene Expression via cFOS during Inflammation in Male Mice

BACKGROUND

The mechanisms whereby neuroinflammation negatively affects neuronal function in the hypothalamus are not clear. Our previous study determined that obesity-mediated chronic inflammation elicits sex-specific impairment in reproductive function via reduction in spine density in gonadotropin-releasing hormone (GnRH) neurons. Neuroinflammation and subsequent decrease in GnRH neuron spine density was specific for male mice, while protection in females was independent of ovarian estrogens.

METHODS

To examine if neuroinflammation-induced cytokines can directly regulate GnRH gene expression, herein we examined signaling pathways and mechanisms in males in vivo and in GnRH-expressing cell line, GT1-7.

RESULTS

GnRH neurons express cytokine receptors, and chronic or acute neuroinflammation represses GnRH gene expression in vivo. Leukemia inhibitory factor (LIF) in particular represses GnRH expression in GT1-7 cells, while other cytokines do not. STAT3 and MAPK pathways are activated following LIF treatment, but only MAPK pathway, specifically p38α, is sufficient to repress the GnRH gene. LIF induces cFOS that represses the GnRH gene via the -1,793 site in the enhancer region. In vivo, following high-fat diet, cFOS is induced in GnRH neurons and neurons juxtaposed to the leaky blood brain barrier of the organum vasculosum of the lamina terminalis, but not in the neurons further away.

CONCLUSION

Our results indicate that the increase in LIF due to neuroinflammation induces cFOS and represses the GnRH gene. Therefore, in addition to synaptic changes in GnRH neurons, neuroinflammatory cytokines directly regulate gene expression and reproductive function, and the specificity for neuronal targets may stem from the proximity to the fenestrated capillaries.

Prenatal Programming of Neuroendocrine System Development by Lipopolysaccharide: Long-Term Effects

Various stress factors during critical periods of fetal development modulate the epigenetic mechanisms controlling specific genes, which can affect the structure and function of physiological systems. Maternal immune stress by bacterial infection simulated by lipopolysaccharide (LPS) in an experiment is considered to be a powerful programming factor of fetal development. Studies of the molecular mechanisms controlling the formation and functioning of physiological systems are in the pilot stage. LPSs are the most potent natural inflammation factors. LPS-induced increases in fetal levels of pro- and anti-inflammatory cytokines can affect brain development and have long-term effects on behavior and neuroendocrine functions. The degradation of serotonergic neurons induced by LPS in the fetus is attributed to the increased levels of interleukin (IL)-6 and tumor necrosis factor (TNFα) as well as to anxiety and depression in children. Dopamine deficiency causes dysthymia, learning disability, and Parkinson’s disease. According to our data, an LPS-induced increase in the levels of IL-6, leukemia inhibitory factor (LIF), and monocyte chemotactic protein (MCP-1) in maternal and fetal rats during early pregnancy disturbs the development and functioning of gonadotropin-releasing hormone production and reproductive systems. It is important to note the high responsiveness of epigenetic developmental mechanisms to many regulatory factors, which offers opportunities to correct the defects.

Diet-Induced Obesity Elicits Macrophage Infiltration and Reduction in Spine Density in the Hypothalami of Male but Not Female Mice

Increasing prevalence in obesity has become a significant public concern. C57BL/6J mice are prone to diet-induced obesity (DIO) when fed high-fat diet (HFD), and develop chronic inflammation and metabolic syndrome, making them a good model to analyze mechanisms whereby obesity elicits pathologies. DIO mice demonstrated profound sex differences in response to HFD with respect to inflammation and hypothalamic function. First, we determined that males are prone to DIO, while females are resistant. Ovariectomized females, on the other hand, are susceptible to DIO, implying protection by ovarian hormones. Males, but not females, exhibit changes in hypothalamic neuropeptide expression. Surprisingly, ovariectomized females remain resistant to neuroendocrine changes, showing that ovarian hormones are not necessary for protection. Second, obese mice exhibit sex differences in DIO-induced inflammation. Microglial activation and peripheral macrophage infiltration is seen in the hypothalami of males, while females are protected from the increase in inflammatory cytokines and do not exhibit microglia morphology changes nor monocyte-derived macrophage infiltration, regardless of the presence of ovarian hormones. Strikingly, the anti-inflammatory cytokine IL-10 is increased in the hypothalami of females but not males. Third, this study posits a potential mechanism of obesity-induced impairment of hypothalamic function whereby obese males exhibit reduced levels of synaptic proteins in the hypothalamus and fewer spines in GnRH neurons, located in the areas exhibiting macrophage infiltration. Our studies suggest that inflammation-induced synaptic remodeling is potentially responsible for hypothalamic impairment that may contribute to diminished levels of gonadotropin hormones, testosterone, and sperm numbers, which we observe and corresponds to the observations in obese humans. Taken together, our data implicate neuro-immune mechanisms underlying sex-specific differences in obesity-induced impairment of the hypothalamic function with potential consequences for reproduction and fertility.

Leukaemia inhibitory factor in serum and follicular fluid of women with polycystic ovary syndrome and its correlation with IVF outcome

Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism, ovarian dysfunction and polycystic ovarian morphology. Leukaemia inhibitory factor (LIF) affects many reproductive activities, including follicular development, embryo implantation and growth. The aim of this study was to evaluate LIF concentrations in serum and follicular fluid of women with PCOS and controls who underwent IVF with embryo transfer (IVF-ET). Serum and follicular fluid LIF concentrations were lower in women with PCOS compared with controls. Oestradiol concentrations in follicular fluid were higher in PCOS subjects compared with controls. LIF concentrations in serum (r = 0.6263, P < 0.05) and follicular fluid (r = 0.7093, P < 0.05) were negatively correlated with oestradiol concentration in the PCOS group. LIF concentrations in follicular fluid showed no difference between women who conceived and women who did not in both PCOS and control groups. However, LIF concentrations in embryo culture medium were higher in women who conceived following IVF compared with women who did not, in combined PCOS and control groups. The findings indicate that low LIF concentrations in serum and follicular fluid may contribute to disordered folliculogenesis in PCOS. LIF concentrations in embryo culture medium may predict the outcome of IVF treatment.

The potential role of leptin in tumor invasion and metastasis

The adipocyte-released hormone-like cytokine/adipokine leptin behaves differently in obesity compared to its functions in the normal healthy state. In obese individuals, elevated leptin levels act as a pro-inflammatory adipokine and are associated with certain types of cancers. Further, a growing body of evidence suggests that higher circulating leptin concentrations and/or elevated expression of leptin receptors (Ob-R) in tumors may be poor prognostic factors. Although the underlying pathological mechanisms of leptin's association with poor prognosis are not clear, leptin can impact the tumor microenvironment in several ways. For example, leptin is associated with a number of biological components that could lead to tumor cell invasion and distant metastasis. This includes interactions with carcinoma-associated fibroblasts, tumor promoting effects of infiltrating macrophages, activation of matrix metalloproteinases, transforming growth factor-β signaling, etc. Recent studies also have shown that leptin plays a role in the epithelial-mesenchymal transition, an important phenomenon for cancer cell migration and/or metastasis. Furthermore, leptin's potentiating effects on insulin-like growth factor-I, epidermal growth factor receptor and HER2/neu have been reported. Regarding unfavorable prognosis, leptin has been shown to influence both adenocarcinomas and squamous cell carcinomas. Features of poor prognosis such as tumor invasion, lymph node involvement and distant metastasis have been recorded in several cancer types with higher levels of leptin and/or Ob-R. This review will describe the current scenario in a precise manner. In general, obesity indicates poor prognosis in cancer patients.

Tumor-linked HER2 expression: association with obesity and lipid-related microenvironment

Obesity is associated with the risk of several health disorders including certain cancers. Among obesity-related cancers, postmenopausal breast carcinoma is a well-studied one. Apart from an increase in certain types of lipids in obesity, excess adipose tissue releases many hormone-like cytokines/adipokines, which are usually pro-inflammatory in nature. Leptin is one of such adipokines and significantly linked with the intracellular signaling pathways of other growth factors such as insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (HER2). In general, HER2 is overexpressed in roughly 30% of breast carcinomas; its presence indicates aggressive tumor behavior. Conversely, HER2 has certain effects in normal conditions such as differentiation of preadipocytes, cardiovascular health and vitamin D metabolism. HER2 has no known endogenous ligand, but it may form dimers with other three members of the epidermal growth factor receptor (EGFR) family and can activate downstream signaling pathways. Furthermore, HER2 is intimately connected with several enzymes, e.g. fatty acid synthase (FASN), phosphatidylinositol 3-kinase (PI3K), AKT and mechanistic target of rapamycin (mTOR), all of which play significant regulatory roles in lipogenic pathways or lipid metabolism. In obesity-related carcinogenesis, characteristics like insulin resistance and elevated IGF-1 are commonly observed. Both IGF-1 and leptin can modulate EGFR and HER2 signaling pathways. Although clinical studies have shown mixed results, the behavior of HER2+ tumor cells including HER2 levels can be altered by several factors such as obesity, leptin and fatty acids. A precise knowledge is useful in new therapeutic approaches against HER+ tumors.

Prediction and analysis of essential genes using the enrichments of gene ontology and KEGG pathways

Identifying essential genes in a given organism is important for research on their fundamental roles in organism survival. Furthermore, if possible, uncovering the links between core functions or pathways with these essential genes will further help us obtain deep insight into the key roles of these genes. In this study, we investigated the essential and non-essential genes reported in a previous study and extracted gene ontology (GO) terms and biological pathways that are important for the determination of essential genes. Through the enrichment theory of GO and KEGG pathways, we encoded each essential/non-essential gene into a vector in which each component represented the relationship between the gene and one GO term or KEGG pathway. To analyze these relationships, the maximum relevance minimum redundancy (mRMR) was adopted. Then, the incremental feature selection (IFS) and support vector machine (SVM) were employed to extract important GO terms and KEGG pathways. A prediction model was built simultaneously using the extracted GO terms and KEGG pathways, which yielded nearly perfect performance, with a Matthews correlation coefficient of 0.951, for distinguishing essential and non-essential genes. To fully investigate the key factors influencing the fundamental roles of essential genes, the 21 most important GO terms and three KEGG pathways were analyzed in detail. In addition, several genes was provided in this study, which were predicted to be essential genes by our prediction model. We suggest that this study provides more functional and pathway information on the essential genes and provides a new way to investigate related problems.

Translating the biology of adipokines in atherosclerosis and cardiovascular diseases: Gaps and open questions

AIM

Critically discuss the available data, to identify the current gaps and to provide key concepts that will help clinicians in translating the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

DATA SYNTHESIS

Adipose tissue is nowadays recognized as an active endocrine organ, a function related to the ability to secrete adipokines (such as leptin and adiponectin) and pro-inflammatory cytokines (tumor necrosis factor alpha and resistin). Studies in vitro and in animal models have observed that obesity status presents a chronic low-grade inflammation as the consequence of the immune cells infiltrating the adipose tissue as well as adipocytes. This inflammatory signature is often related to the presence of cardiovascular diseases, including atherosclerosis and thrombosis. These links are less clear in humans, where the role of adipokines as prognostic marker and/or player in cardiovascular diseases is not as clear as that observed in experimental models. Moreover, plasma adipokine levels might reflect a condition of adipokine-resistance in which adipokine redundancy occurs. The investigation of the cardio-metabolic phenotype of carriers of single nucleotide polymorphisms affecting the levels or function of a specific adipokine might help determine their relevance in humans. Thus, the aim of the present review is to critically discuss the available data, identify the current gaps and provide key concepts that will help clinicians translate the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

Disruptions in the hypothalamic-pituitary-gonadal axis in rat offspring following prenatal maternal exposure to lipopolysaccharide

Postnatal treatment with bacterial endotoxin lipopolysaccharide (LPS) changes the activity of the hypothalamic-pituitary-gonadal (HPG) axis and the gonadotropin-releasing hormone (GnRH) surge in rats. Exposure to an immune challenge in the critical periods of development has profound and long-lasting effects on the stress response, immune, metabolic, and reproductive functions. Prenatal LPS treatment delays the migration of GnRH neurons associated with increased cytokine release in maternal and fetal compartments. We investigated the effects of a single maternal exposure to LPS (18 μg/kg, i.p.) on day 12 (embryonic day (E)12) of pregnancy on reproductive parameters in rat offspring. Hypothalamic GnRH content, plasma luteinizing hormone (LH), testosterone, and estradiol concentrations were measured in both male and female offsprings at different stages of postnatal development by RIA and ELISA (n = 10 each per group). Body weight and in females day of vaginal opening (VO) were recorded. In offspring exposed to LPS prenatally, compared with controls, body weight was decreased in both sexes at P5 and P30; in females, VO was delayed; hypothalamic GnRH content was decreased at postnatal days 30-60 (P30-P60) in both sexes; plasma LH concentration was decreased at P14-P60 in females; plasma concentrations of testosterone/estradiol were increased at P14 in females, and plasma estradiol was increased at P14 in males. Hence activation of the maternal immune system by LPS treatment at a prenatal critical period leads to decreased GnRH and LH levels in pre- and postpubertal life and sex steroid imbalance in the prepubertal period, and delayed sexual maturation of female offspring.

Lipopolysaccharide-induced maternal inflammation affects the gonadotropin-releasing hormone neuron development in fetal mice

Recent studies provide evidence that prenatal immunological stress may affect the programming of reproductive health and sexual behavior in adult animals. The aim of this study was to investigate the influence of maternal inflammation, induced by an intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 45 µg/kg) on embryonic day 11.5 (E 11.5), on the development of the gonadotropin-releasing hormone (GnRH) system in mouse fetuses as well as on the proinflammatory cytokine level in pregnant mice and their fetuses. In the fetuses, the GnRH neuron migration from the olfactory pit to the forebrain was estimated on embryonic days 14.5 and 18.5. The levels of the proinflammatory cytokines interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, tumor necrosis factor (TNF)-α and leukemia inhibitory factor (LIF) were measured with the cytometric bead and ELISA array method in the maternal and fetal blood, amniotic fluid and fetal cerebrospinal fluid (CSF). According to our data, activation of the immune system by LPS treatment on embryonic day 11.5 leads to an increased quantity of neurons in the nasal and olfactory bulb areas and a decreased quantity in the forebrain area on embryonic day 14.5. There was a slight decrease in the total number of neurons in the forebrain area on embryonic day 18.5. The levels of proinflammatory cytokines were significantly increased within 3 h after LPS treatment in the maternal and fetal blood, amniotic fluid and fetal CSF. IL-6-receptor immunoreactivity was detected on olfactory/vomeronasal axons. Thus, prenatal immunological stress delays the GnRH neuron migration in the nasal compartment of mouse fetuses, which may be mediated by the regulation of IL-6, MCP-1 and LIF secretion in the maternal-fetal system.

From heart beats to health recipes: The role of fractal physiology in the Ancestral Health movement

The human body-an amazing biological system that scales up fractally from its cellular building blocks-exhibits an incredible ability to self heal. Why then, are chronic diseases and degeneration on the rise in the population? Why are we sicker, more obese, and more depressed and stressed than ever before in human history? Why can't we heal? The answers to these questions may lie in our ancestry, and modern departure from the human ecological niche. The ability to heal requires proper spatio-temporal inputs-nutrition, sleep, stress, activity, and socialization-in order for cellular signaling to occur properly across semi-permeable cell membranes. We first review key steps in the evolutionary history of multicellular life, focusing on the fundamental role of cell-cell interactions. Next, we present this as an important framework by which to understand how the entrainment of physiological signals in homeostatic mechanisms reveals new insights into the processes of disease. Examples are drawn from the evolution of metabolism, nutrition, and respiration in multicellular life. We argue that disease processes result from a mismatch between the physiological inputs an individual receives and their optimal amount and fractal distribution as determined by an individual's ancestry. A comparative analysis is a useful tool by which to illuminate deep homologies that reveal a mechanistic account for disease processes. This cell-molecular approach provides a useful contrast to the traditional reductionist approach to disease exemplified by the human genome project. As an example, we describe how cell-cell communication drives the ontogeny and phylogeny of physiology, producing the tissues, organs, and organ systems that hierarchically serve human physiology on various levels. Modern society, with its disconnected and stress-riddled lifestyle, is increasingly failing to provide the proper inputs for healthy gene expression and physiological function. Thus, the answers to our modern health woes-physical, mental, and social-may lie in acknowledging the powerful roles that our past has played in shaping our bodies. Finding ways to provide the proper inputs of the human ecological niche in the modern day may lead to significant, perhaps staggering improvements in our health and wellness. The fractal mathematics underpinning these dynamics also serves as a metaphor for the Ancestral Health Movement, which is currently arising as a multi-cultural, multi-national grass-roots pluralistic phenomenon.

Signaling of cytokines is important in regulation of GnRH neurons

Cytokines encompass a broad class of peptides that mediate signals in a broad range of physiological situations including inflammation, infection, and obesity. The cytokine receptor-associated tyrosine kinase, Jak2, is one of the most important proteins mediating cytokine signaling pathway activation. Recently, our group has demonstrated that Jak2 signaling in the gonadotropin-releasing hormone (GnRH) neuron plays a critical role in fertility in males and females, implicating cytokine activation of the neuron in GnRH neuronal development and function. To date, the specific cytokine(s) essential for activating Jak2 during neuroendocrine development are not known. In this article, we review the evidence for the role of several class 1 cytokines in regulating GnRH neuronal development, GnRH secretion, and GnRH expression.

Chronic immune stimulation as a contributing cause of chronic disease in opiate addiction including multi-system ageing

Evidence of immune stimulation has been noted in opiate dependent patients for many decades. Documented changes have included lymphadenopathy, round cell infiltration of the hepatic portal triads, diffuse peri-bronchitis, hyperglobulinaemia, lymphocytosis, monocytosis, systemic cytokine stimulation, and cytokine and chemokine activation within the neuraxis. A parallel literature describes an elevated list of chronic degenerative disease as common in such patients including neurodegenerative conditions, atherosclerosis, nephrosclerosis, hepatic fibrosis and cirrhosis, chronic obstructive and fibrotic lung disease, osteoporosis, chronic periodontitis, various cancers, hair greying, and stem cell suppression. All of these disorders are now known to have an important immunological role in their pathogenic pathways. The multisystem nature of these myriad changes strongly suggest that the ageing process itself is stimulated in these patients. The link between the immunostimulation on the one hand and the elevated and temporally advanced nature of the chronic degenerative diseases on the other appears not to have been made in the literature. Moreover as immunostimulation is also believed to be an important, potent and principal contributor to the ageing process it appears that experimental and studies of this putative link are warranted. Verification of such an hypothesis would also carry management implications for dose and duration of chronic pain and addiction treatment, pharmacotherapeutic selection, and novel treatments such as long term naltrexone implant therapy and heroin trials.

Update on the role of leukemia inhibitory factor in assisted reproduction

PURPOSE OF REVIEW

To review the recent literature on the involvement and importance of leukemia inhibitory factor (LIF) in the human implantation process, and the attempts using LIF-based interventions to improve assisted reproductive technologies (ARTs) outcome in women with recurrent implantation failure.

RECENT FINDINGS

High LIF expression is an indicator of receptive endometrium in fertile women. However, in infertile individuals, the data on endometrial LIF expression and secretion are controversial. Even after ruling out other causes of infertility, such as tubal, endocrine, male factor, and endometriosis, LIF-only detection is not sufficient for assessment of implantation potential in women with unexplained infertility. This is obviously in contrast to evidence of the crucial role of LIF in mouse endometrial physiology. In a large multicenter study, recombinant human LIF failed to improve the outcome of IVF treatment in women with recurrent implantation failure.

SUMMARY

A better comprehension of the mechanisms underlying endometrial receptivity and implantation should guide clinicians through proper management and treatment of infertility and implantation failure, and may eventually enable widespread adherence to single embryo transfer practices.