High fat diet and aging are associated with macrophage infiltration in mice ovaries

Leptin signalling regulates transcriptional differences in granulosa cells from genetically obese mice but not the activation of NLRP3 inflammasome

Obesity is associated with increased ovarian inflammation and the establishment of leptin resistance. We presently investigated the role of impaired leptin signalling on transcriptional regulation in granulosa cells (GCs) collected from genetically obese mice. Furthermore, we characterised the association between ovarian leptin signalling, the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome and macrophage infiltration in obese mice. After phenotype characterisation, ovaries were collected from distinct group of animals for protein and mRNA expression analysis: (i) mice subjected to a diet-induced obesity (DIO) protocol, where one group was fed a high-fat diet (HFD) and another a standard chow diet (CD) for durations of 4 or 16 weeks; (ii) mice genetically deficient in the long isoform of the leptin receptor (ObRb; db/db); (iii) mice genetically deficient in leptin (ob/ob); and (iv) mice rendered pharmacologically hyperleptinemic (LEPT). Next, GCs from antral follicles isolated from db/db and ob/ob mice were subjected to transcriptome analysis. Transcriptional analysis revealed opposing profiles in genes associated with steroidogenesis and prostaglandin action between the genetic models, despite the similarities in body weight. Furthermore, we observed no changes in the mRNA and protein levels of NLRP3 inflammasome components in the ovaries of db/db mice or in markers of M1 and M2 macrophage infiltration. This contrasted with the downregulation of NLRP3 inflammasome components and M1 markers in ob/ob and 16-wk HFD-fed mice. We concluded that leptin signalling regulates NLRP3 inflammasome activation and the expression of M1 markers in the ovaries of obese mice in an ObRb-dependent and ObRb-independent manner. Furthermore, we found no changes in the expression of leptin signalling and NLRP3 inflammasome genes in GCs from db/db and ob/ob mice, which was associated with no effects on macrophage infiltration genes, despite the dysregulation of genes associated with steroidogenesis in homozygous obese db/db. Our results suggest that: (i) the crosstalk between leptin signalling, NLRP3 inflammasome and macrophage infiltration takes place in ovarian components other than the GC compartment; and (ii) transcriptional changes in GCs from homozygous obese ob/ob mice suggest structural rearrangement and organisation, whereas in db/db mice the impairment in steroidogenesis and secretory activity.

Lipid-induced mononuclear cell cytokine secretion in the development of metabolic aberration and androgen excess in polycystic ovary syndrome

STUDY QUESTION

What is the effect of saturated fat ingestion on mononuclear cell (MNC) TNFα, IL-6 and IL-1β secretion and circulating IL-6 levels in women with polycystic ovary syndrome (PCOS)?

SUMMARY ANSWER

Women with PCOS exhibit increases in MNC-derived TNFα, IL-6 and IL-1β secretion and circulating IL-6 following saturated fat ingestion even in the absence of obesity, and these increases are linked to metabolic aberration and androgen excess.

WHAT IS KNOWN ALREADY

Cytokine excess and metabolic aberration is often present in PCOS.

STUDY DESIGN, SIZE, DURATION

A cross-sectional design was used in this study of 38 reproductive-age women.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Groups of 19 reproductive-age women with PCOS (10 lean, 9 obese) and 19 ovulatory controls (10 lean, 9 obese) participated in this study that was performed at a tertiary academic medical centre. TNFα, IL-6 and IL-1β secretion was measured from cultured MNC, and IL-6 was measured in plasma from blood sampling while fasting and 2, 3 and 5 h after saturated fat ingestion. Insulin sensitivity was determined using the Matsuda index following an oral glucose tolerance test. Androgen secretion was evaluated with blood sampling while fasting and 24, 48 and 72 h after an HCG injection.

MAIN RESULTS AND THE ROLE OF CHANCE

Lean and obese women with PCOS exhibited lipid-induced incremental AUC increases in MNC-derived TNFα (489-611%), IL-6 (333-398%) and IL-1β (560-695%) secretion and in plasma IL-6 levels (426-474%), in contrast with lean control subjects. In both PCOS groups, insulin sensitivity was lower (42-49%) and androgen secretion after HCG injection was greater (63-110%) compared with control subjects. The MNC-derived TNFα, IL-6 and IL-1β and circulating IL-6 responses were inversely associated with insulin sensitivity and directly associated with fasting lipids and androgen secretion after HCG injection.

LIMITATIONS, REASONS FOR CAUTION

The sample size of each of the four study groups was modest following group assignment of subjects by body mass.

WIDER IMPLICATIONS OF THE FINDINGS

This study showcases the unique pro-inflammatory contribution of circulating MNC in the development of metabolic aberration and androgen excess in PCOS.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by grant R01 DK107605 to F.G. from the National Institutes of Health, the Indiana Clinical and Translational Sciences Institute Clinical Research Center which is funded in part by grant UL1TR002529 from the National Institutes of Health, National Center for Advancing Translational Sciences, Clinical and Translational Sciences Award, and the Indiana University Center for Diabetes and Metabolic Diseases funded by grant P30 DK097512 from the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. No conflicts of interest, financial or otherwise, are declared by the authors.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT01489319.

Salicylate administration suppresses the inflammatory response to nutrients and improves ovarian function in polycystic ovary syndrome

Oxidative stress (OS) and inflammation are often present in polycystic ovary syndrome (PCOS). We examined the effects of salsalate treatment on nutrient-induced OS and inflammation, ovarian androgen secretion, ovulation, and insulin sensitivity in PCOS. Eight lean insulin-sensitive women with PCOS and eight age- and body composition-matched ovulatory controls for baseline comparison participated in the study. The women with PCOS underwent a 12-wk treatment of salsalate, a nonsteroidal anti-inflammatory drug, at a dose of 3 g daily. Markers of OS and inflammation were quantified in mononuclear cells (MNC) and plasma from blood drawn fasting and 2 h after saturated fat ingestion before and after treatment. Ovarian androgen secretion was assessed from blood drawn fasting and 24, 48, and 72 h after human chorionic gonadotropin (HCG) administration before and after treatment. Ovulation was documented based on biphasic basal body temperatures and luteal range progesterone elevations. A two-step pancreatic clamp was performed pre- and posttreatment to measure basal endogenous glucose production (EGP) and the steady-state glucose disposal rate (GDR) during the euglycemic phase and markers of OS and inflammation in MNC and plasma during the hyperglycemic phase. Salsalate administration suppressed lipid- and glucose-stimulated reactive oxygen species generation, activated nuclear factor-κB and circulating tumor necrosis factor-α, normalized basal androgen levels, and lowered HCG-stimulated androgen secretion without altering EGP or GDR. Four salsalate-treated subjects responded with two consecutive ovulations. We conclude that in PCOS, salsalate-induced suppression of OS and inflammation ameliorates ovarian androgen hypersecretion and may induce ovulation while maintaining insulin action.

Inflammation Triggered by Saturated Fat Ingestion Is Linked to Insulin Resistance and Hyperandrogenism in Polycystic Ovary Syndrome

CONTEXT

Inflammation and insulin resistance are often present in polycystic ovary syndrome (PCOS).

OBJECTIVE

We determined the effect of saturated fat ingestion on mononuclear cell (MNC) nuclear factor-κB (NFκB) activation; NFκB, inhibitory-κBα (IκBα), and tumor necrosis factor-α (TNFα) gene expression; and circulating C-reactive protein (CRP) in women with PCOS.

DESIGN

Cross-sectional study.

SETTING

Academic medical center.

PATIENTS

Twenty reproductive-age women with PCOS (10 lean, 10 with obesity) and 20 ovulatory controls (10 lean, 10 with obesity).

MAIN OUTCOME MEASURES

Activated NFκB, NFκB heterodimer subunits, IκBα and TNFα messenger ribonucleic acid content and NFκB p65 and IκBα protein content were quantified in mononuclear cells (MNC), and CRP was measured in plasma from blood drawn fasting and 2, 3, and 5 h after saturated fat ingestion. Insulin sensitivity was derived from oral glucose tolerance testing (ISOGTT). Androgen secretion was assessed from blood drawn fasting and 24, 48, and 72 h after human chorionic gonadotropin (HCG) administration.

RESULTS

In response to saturated fat ingestion, women with PCOS regardless of weight class exhibited lipid-induced increases in activated NFκB, NFκB, and TNFα gene expression and plasma CRP and decreases in IκBα protein compared with lean control subjects. Both PCOS groups exhibited lower ISOGTT and greater HCG-stimulated androgen secretion compared with control subjects. Lipid-stimulated NFκB activation was negatively correlated with ISOGTT, and positively correlated with HCG-stimulated androgen secretion.

CONCLUSION

In PCOS, increases in NFκB activation and circulating CRP and decreases in IκBα protein following saturated fat ingestion are independent of obesity. Circulating MNC and excess adipose tissue are separate and distinct contributors to inflammation in this disorder.

Preadipocyte secretory factors differentially modulate murine macrophage functions during aging which are reversed by the application of phytochemical EGCG

The present study aimed at evaluating the role of senescent cell microenvironment as an extrinsic causal factor for altered age-associated macrophage functions, and that whether such changes could be ameliorated by the application of tea catechin epigallocatechin gallate (EGCG). To ascertain this, we analyzed the impact of secretory metabolites of proliferating (P) and senescent (S) preadipocyte cells on the induction of phenotypic and functional characteristics associated with aging in macrophages isolated from young (YM) and old (OM) C57BL/6J mice. The role of EGCG as alleviator of preadipocyte media-induced senescence and inflamm-aging was evaluated in OM. Results revealed strong age-related dysregulation in macrophage functions as evident by decreased CD11b expression, enhanced expression of cytokines (IL-6/TNF-α/IL-1β/IL-10) and cell cycle inhibitors p53/p21^WAF1/p16^Ink4a, as well as augmentation of M2 phenotype (Arg1/Msr1/Mrc1) and SA-β-gal activity. Ex vivo exposure of macrophages (YM and OM) to secretory factors of preadipocytes induced differential effects, and treatment with S culture media largely showed an augmentation of senescent phenotype, particularly in the YM. Pretreatment with EGCG (10 µM) to OM caused a dramatic reversal of both age-associated and preadipocyte media-induced changes as evident from upregulation of CD11b and ROS levels, inhibition of inflammatory makers, attenuation of p53/p21^WAF1/p16^Ink4a expression and SA-β-gal activity. Our results indicate vital role of adipose tissue-mediated extrinsic factors in shaping macrophage phenotype and functions during aging. It is also apparent that EGCG is a promising candidate in developing preventive therapies aimed at alleviating macrophage inflamm-aging and senescence that may help curb incidences of inflammatory disorders in elderly.

Role of hormonal and inflammatory alterations in obesity-related reproductive dysfunction at the level of the hypothalamic-pituitary-ovarian axis

BACKGROUND

Besides being a risk factor for multiple metabolic disorders, obesity could affect female reproduction. While increased adiposity is associated with hormonal changes that could disrupt the function of the hypothalamus and the pituitary, compelling data suggest that obesity-related hormonal and inflammatory changes could directly impact ovarian function.

OBJECTIVE

To review the available data related to the mechanisms by which obesity, and its associated hormonal and inflammatory changes, could affect the female reproductive function with a focus on the hypothalamic-pituitary-ovarian (HPO) axis.

METHODS

PubMed database search for publications in English language until October 2017 pertaining to obesity and female reproductive function was performed.

RESULTS

The obesity-related changes in hormone levels, in particular leptin, adiponectin, ghrelin, neuropeptide Y and agouti-related protein, are associated with reproductive dysfunction at both the hypothalamic-pituitary and the ovarian levels. The pro-inflammatory molecules advanced glycation end products (AGEs) and monocyte chemotactic protein-1 (MCP-1) are emerging as relatively new players in the pathophysiology of obesity-related ovarian dysfunction.

CONCLUSION

There is an intricate crosstalk between the adipose tissue and the inflammatory system with the HPO axis function. Understanding the mechanisms behind this crosstalk could lead to potential therapies for the common obesity-related reproductive dysfunction.