Chang Ling Sia

Inflammation in Response to Glucose Ingestion Is Independent of Excess Abdominal Adiposity in Normal-Weight Women with Polycystic Ovary Syndrome

CONTEXT Inflammation and excess abdominal adiposity (AA) are often present in normal-weight women with polycystic ovary syndrome (PCOS). OBJECTIVE We determined the effects of hyperglycemia on nuclear factor-κB (NFκB) activation in mononuclear cells (MNC) of normal-weight women with PCOS with and without excess AA. DESIGN This was a prospective controlled study. SETTING The study was conducted at an academic medical center. PATIENTS Fifteen normal-weight, reproductive-age women with PCOS (seven normal AA, eight excess AA) and 16 body composition-matched controls (eight normal AA, eight excess AA) participated in the study. MAIN OUTCOME MEASURES Body composition was measured by dual-energy absorptiometry. Insulin sensitivity was derived from an oral glucose tolerance test (IS(OGTT)). Activated NFκB and the protein content of p65 and inhibitory-κB were quantified from MNC, and TNFα and C-reactive protein (CRP) were measured in plasma obtained from blood drawn while fasting and 2 h after glucose ingestion. RESULTS Compared with controls, both PCOS groups exhibited lower IS(OGTT), increases in activated NFκB and p65 protein, and decreases in inhibitory-κB protein. Compared with women with PCOS with excess AA, those with normal AA exhibited higher testosterone levels and lower TNFα and CRP levels. For the combined groups, the percent change in NFκB activation was negatively correlated with IS(OGTT) and positively correlated with androgens. TNFα and CRP were positively correlated with abdominal fat. CONCLUSION In normal-weight women with PCOS, the inflammatory response to glucose ingestion is independent of excess AA. Circulating MNC and excess AA are separate and unique sources of inflammation in this population.

Hyperglycemia-induced oxidative stress is independent of excess abdominal adiposity in normal-weight women with polycystic ovary syndrome

STUDY QUESTION What is the effect of glucose ingestion on leukocytic reactive oxygen species (ROS) generation in normal-weight women with polycystic ovary syndrome (PCOS) with and without excess abdominal adiposity (AA)? SUMMARY ANSWER Normal-weight women with PCOS exhibit an increase in leukocytic ROS generation in response to glucose ingestion, and this increase is independent of excess AA. WHAT IS KNOWN ALREADY Excess adipose tissue is a source of oxidative stress. Normal-weight women with PCOS exhibit oxidative stress and can have excess AA. STUDY DESIGN AND SIZE This is a cross-sectional study involving 30 reproductive-age women. PARTICIPANTS/MATERIALS, SETTING AND METHODS Fourteen normal-weight women with PCOS (6 normal AA, 8 excess AA) and 16 body composition-matched controls (8 normal AA, 8 excess AA) underwent body composition assessment by dual-energy absorptiometry and an oral glucose tolerance test (OGTT) at a university medical center. Insulin sensitivity was derived from the OGTT (IS(OGTT)). Blood was drawn while fasting and 2 h after glucose ingestion to measure leukocytic ROS generation and p47(phox) protein content and plasma thiobarbituric acid-reactive substances (TBARS) and C-reactive protein (CRP). MAIN RESULTS AND THE ROLE OF CHANCE Compared with controls, both PCOS groups exhibited lower IS(OGTT) (43-54%) and greater percentage change (% change) in ROS generation (96-140%), p47(phox) protein (18-28%) and TBARS (17-48%). Compared with women with PCOS with excess AA, those with normal AA exhibited higher testosterone levels (29%) and lower CRP levels (70%). For the combined groups, IS(OGTT) was negatively correlated with the % change in ROS generation and p47(phox) protein. CRP was positively correlated with abdominal fat. The % change in p47(phox) protein was positively correlated with CRP and androgens. LIMITATIONS, REASONS FOR CAUTION Although this study is adequately powered to assess differences in ROS generation between the women with PCOS and control participants, the modest sample size merits caution when interpreting the corroborative results of the additional measures of oxidative stress and inflammation. WIDER IMPLICATIONS OF THE FINDINGS This study highlights the unique pro-oxidant contribution of circulating leukocytes in the development of insulin resistance and hyperandrogenism in PCOS. STUDY FUNDING/COMPETING INTEREST(S) Supported by NIH grant HD-048535 to F.G. The authors have nothing to disclose.

Hyperandrogenism Induces a Proinflammatory TNFα Response to Glucose Ingestion in a Receptor-Dependent Fashion

CONTEXT Hyperandrogenism and inflammation are related in polycystic ovary syndrome (PCOS). Hyperandrogenemia can induce inflammation in reproductive-age women, but the mechanism for this phenomenon is unclear. OBJECTIVE We examined the in vivo and in vitro effects of hyperandrogenism on mononuclear cell (MNC)-derived androgen receptor (AR) status and TNFα release. DESIGN This study combined a randomized, controlled, double-blind protocol with laboratory-based cell culture experiments. SETTING This work was performed in an academic medical center. PARTICIPANTS Lean, healthy, reproductive-age women were treated with 130 mg of dehydroepiandrosterone (DHEA) or placebo (n = 8 subjects each) for 5 days and also provided untreated fasting blood samples (n = 12 subjects) for cell culture experiments. MAIN OUTCOME MEASURES AR mRNA content and TNFα release were measured before and after DHEA administration in the fasting state and 2 hours after glucose ingestion. TNFα release in the fasting state was also measured in cultured MNCs exposed to androgens with or without flutamide preincubation. RESULTS At baseline, subjects receiving DHEA or placebo exhibited no significant difference in androgens and TNFα release from MNCs before and after glucose ingestion. Compared with placebo, DHEA administration raised levels of T, androstenedione, and DHEA sulfate, and increased MNC-derived AR mRNA content and TNFα release in the fasting state and in response to glucose ingestion. Compared with MNC exposure to baseline concentrations of DHEA (175 ng/dL) or T (50 ng/dL), the absolute change in TNFα release increased after exposure to T concentrations of 125 and 250 ng/dL and a DHEA concentration of 1750 ng/dL. Preincubation with flutamide reduced the TNFα response by ≥ 60% across all T concentrations. CONCLUSION Androgen excess in vivo and in vitro comparable to what is present in PCOS increases TNFα release from MNCs of lean healthy reproductive-age women in a receptor-dependent fashion. Hyperandrogenemia activates and sensitizes MNCs to glucose in this population.

Pancreatic β-cell dysfunction in polycystic ovary syndrome: role of hyperglycemia-induced nuclear factor-κB activation and systemic inflammation

In polycystic ovary syndrome (PCOS), oxidative stress is implicated in the development of β-cell dysfunction. However, the role of mononuclear cell (MNC)-derived inflammation in this process is unclear. We determined the relationship between β-cell function and MNC-derived nuclear factor-κB (NF-κB) activation and tumor necrosis factor-α (TNF-α) secretion in response to a 2-h 75-g oral glucose tolerance test (OGTT) in normoglycemic women with PCOS (15 lean, 15 obese) and controls (16 lean, 14 obese). First- and second-phase β-cell function was calculated as glucose-stimulated insulin secretion (insulin/glucose area under the curve for 0-30 and 60-120 min, respectively) × insulin sensitivity (Matsuda Index derived from the OGTT). Glucose-stimulated NF-κB activation and TNF-α secretion from MNC, and fasting plasma thiobarbituric acid-reactive substances (TBARS) and high-sensitivity C-reactive protein (hs-CRP) were also assessed. In obese women with PCOS, first- and second-phase β-cell function was lower compared with lean and obese controls. Compared with lean controls, women with PCOS had greater change from baseline in NF-κB activation and TNF-α secretion, and higher plasma TBARS. β-Cell function was inversely related to NF-κB activation (1st and 2nd) and TNF-α secretion (1st), and plasma TBARS and hs-CRP (1st and 2nd). First- and second-phase β-cell function also remained independently linked to NF-κB activation after adjustment for body fat percentage and TBARS. In conclusion, β-cell dysfunction in PCOS is linked to hyperglycemia-induced NF-κB activation from MNC and systemic inflammation. These data suggest that in PCOS, inflammation may play a role in impairing insulin secretion before the development of overt hyperglycemia.

Glucose-Stimulated Oxidative Stress in Mononuclear Cells Is Related to Pancreatic β-Cell Dysfunction in Polycystic Ovary Syndrome

CONTEXT Oxidative stress induced by reactive oxygen species (ROS) is involved in the development of pancreatic β-cell dysfunction. OBJECTIVE We determined the relationship between mononuclear cell (MNC)-derived ROS generation and p47phox protein content in response to glucose ingestion and β-cell function in women with polycystic ovary syndrome (PCOS). DESIGN This was a cross-sectional study. SETTING This study was conducted at an academic medical center. PARTICIPANTS Twenty-nine normoglycemic women with PCOS (13 lean, 16 obese) and 25 ovulatory controls (16 lean, 9 obese) underwent a 3-h 75-g oral glucose tolerance test (OGTT). MAIN OUTCOME VARIABLES Pancreatic β-cell function was calculated as glucose-stimulated insulin secretion (insulin/glucose area under the curve0-30 min; GSIS)×Matsuda index-derived insulin sensitivity (ISOGTT). ROS generation was measured by chemiluminescence, and p47phox protein was quantified by Western blotting in MNC isolated from blood samples obtained at 0 and 2 hours of the OGTT. RESULTS Compared with controls, women with PCOS exhibited a higher percent change from baseline in ROS generation and p47phox protein in conjunction with greater GSIS and a tendency toward lower β-cell function. Lean women with PCOS exhibited a greater percent change from baseline in ROS generation and p47phox protein yet had similar GSIS responses compared with lean controls despite having lower ISOGTT. For the combined groups, β-cell function was inversely related to ROS generation and p47phox protein. GSIS was directly related to body mass index, central obesity, and circulating androgens. CONCLUSION In normoglycemic women, obesity plays a role in exaggerating GSIS. However, MNC-derived oxidative stress is independent of obesity and may contribute to the decline in β-cell function in women with PCOS.

The altered mononuclear cell-derived cytokine response to glucose ingestion is not regulated by excess adiposity in polycystic ovary syndrome.

CONTEXT Excess adipose tissue is a source of inflammation. Polycystic ovary syndrome (PCOS) is a proinflammatory state and is often associated with excess abdominal adiposity (AA) alone and/or frank obesity. OBJECTIVE To determine the effect of glucose ingestion on cytokine release from mononuclear cells (MNC) in women with PCOS with and without excess AA and/or obesity. DESIGN A cross-sectional study. SETTING Academic medical center. PATIENTS Twenty-three women with PCOS (seven normal weight with normal AA, eight normal weight with excess AA, eight obese) and 24 ovulatory controls (eight normal weight with normal AA, eight normal weight with excess AA, eight obese). INTERVENTION Three-hour 75-g oral glucose tolerance test (OGTT). MAIN OUTCOME MEASURES Body composition was measured by dual energy x-ray absorptiometry. Insulin sensitivity was derived from the OGTT (ISOGTT). TNFα, IL-6, and IL-1β release was measured in supernatants of cultured MNC isolated from blood samples drawn while fasting and 2 hours after glucose ingestion. RESULTS Insulin sensitivity was lower in obese subjects regardless of PCOS status and in normal-weight women with PCOS compared with normal-weight controls regardless of body composition status. In response to glucose ingestion, MNC-derived TNFα, IL-6, and IL-1β release decreased in both normal-weight control groups but failed to suppress in either normal-weight PCOS group and in obese women regardless of PCOS status. For the combined groups, the cytokine responses were negatively correlated with insulin sensitivity and positively correlated with abdominal fat and androgens. CONCLUSIONS Women with PCOS fail to suppress MNC-derived cytokine release in response to glucose ingestion, and this response is independent of excess adiposity. Nevertheless, a similar response is also a feature of obesity per se. Circulating MNC and excess adipose tissue are separate and distinct sources of inflammation in this population.