HIV and HCV seroincidence, associated factors and drug use in people who inject drugs, SurvUDI network, eastern central Canada, 1995-2020.

BACKGROUND: The SurvUDI network is a biobehavioural survey among people who inject drugs (PWID) in Eastern Central Canada. OBJECTIVES: The objectives were to describe HIV and HCV seroincidence trends, associated factors and changes in drug use behaviours. METHODS: The network was initiated in 1995 and targets hard-to-reach, mostly out-of- treatment PWID. Participants were recruited mostly in harm reduction programs, completed an interviewer-administered questionnaire, provided a sample of gingival exudate for HIV and HCV antibody testing and were identified using an encrypted code allowing identification of multiple participations. Time trends were examined for HIV and HCV seroincidence, selected characteristics and behaviours. Cox proportional hazard regression was used to examine factors associated to HIV and HCV seroincidence. RESULTS: Between January 1995 and March 2020, 15,907 individuals have completed 31,051 questionnaires. HIV seroincidence decreased significantly from 5.0 per 100 person-years (p-y) in 1995 to 0.4 per 100 p-y in 2018. HCV seroincidence also decreased significantly between 1998 and 2011. The use of syringes already used by someone else decreased significantly, from 43.4 % in 1995 to 12.4 % in 2019, as well as the use of equipment other than syringe already used by someone else. Cocaine/crack injection decreased significantly while "opioids other than heroin" injection increased, concomitant to daily injection. Injection with syringes already used by someone else and cocaine as the most often injected drug were significantly associated with HIV seroincidence (1995-2020). Injected opioid other than heroin, injected cocaine/crack, injected 100 or more times in the past month, injected for less than 3 years, injected with syringes or equipment already used by someone else, injected with someone else and reported client sex partners were significantly associated with HCV seroincidence (2004-2020). CONCLUSION: HIV seroincidence and syringe/equipment sharing behaviour trends are encouraging, but HCV seroincidence remains high.

Ongoing Gaps in the Hepatitis C Care Cascade during the Direct-Acting Antiviral Era in a Large Retrospective Cohort in Canada: A Population-Based Study.

To achieve hepatitis C virus (HCV) elimination, high uptake along the care cascade steps for all will be necessary. We mapped engagement with the care cascade overall and among priority groups in the post-direct-acting antivirals (DAAs) period and assessed if this changed relative to pre-DAAs. We created a population-based cohort of all reported HCV diagnoses in Quebec (1990-2018) and constructed the care cascade [antibody diagnosed, RNA tested, RNA positive, genotyped, treated, sustained virologic response (SVR)] in 2013 and 2018. Characteristics associated with RNA testing and treatment initiation were investigated using marginal logistic models via generalized estimating equations. Of the 31,439 individuals HCV-diagnosed in Quebec since 1990 and alive as of 2018, there was significant progress in engagement with the care cascade post- vs. pre-DAAs; 86% vs. 77% were RNA-tested, and 64% vs. 40% initiated treatment. As of 2018, a higher risk of not being RNA-tested or treated was observed among individuals born <1945 vs. >1965 [hazard ratio (HR); 95% CI; 1.35 (1.16-1.57)], those with material and social deprivation [1.21 (1.06-1.38)], and those with alcohol use disorder [1.21 (1.08-1.360]. Overall, non-immigrants had lower rates of RNA testing [0.76 (0.67-0.85)] and treatment initiation [0.63 (0.57-0.70)] than immigrants. As of 2018, PWID had a lower risk of not being RNA tested [0.67 (0.61-0.85)] but a similar risk of not being treated, compared to non-PWID. Engagement in the HCV care cascade have improved in the post-DAA era, but inequities remain. Vulnerable subgroups, including certain older immigrants, were less likely to have received RNA testing or treatment as of 2018 and would benefit from focused interventions to strengthen these steps.

Correlates of Neisseria gonorrhoeae antimicrobial resistance: cross-sectional results from an open cohort sentinel surveillance network in Québec, Canada, 2016-2019.

OBJECTIVES: To examine correlates of Neisseria gonorrhoeae antimicrobial resistance (AMR) to first-line antimicrobials (azithromycin, cefixime and ceftriaxone). DESIGN AND SETTING: The sentinel surveillance network is an open cohort of gonococcal infection cases from Québec, Canada. Cross-sectional results are reported herein. PARTICIPANTS: Between 1 January 2016 and 31 December 2019, data from 886 individuals accounting for 941 gonorrhoea cases were included. METHODS: Epidemiological and clinical data were collected using an auto-administered questionnaire, direct case interviews and chart reviews. Antimicrobial susceptibility testing was performed using the agar dilution method. Generalised estimating equations were used for regression. RESULTS: The prevalence of azithromycin resistance with a minimal inhibitory concentration (MIC) of ≥2 mg/L was 21.3%. In 2016, men who have sex with men were more likely to be infected with an azithromycin-resistant N. gonorrhoeae isolate (adjusted prevalence ratio (aPR)=4.73, 95% CI 1.48 to 15.19) or with an isolate with increased third-generation cephalosporin (3GC) MIC (aPR=5.32, 95% CI 1.17 to 24.11 for cefixime (MIC≥0.06 mg/L) and aPR=4.38, 95% CI 1.53 to 12.54 for ceftriaxone (MIC≥0.03 mg/L)). However, these associations were not maintained between 2017 and 2019, with increased MIC observed in men who have sex exclusively with women and women. Overall, azithromycin resistance was significantly more likely in cases who self-reported HIV infection (aPR=1.65, 95% CI 1.00 to 2.71). Cefixime increased MIC were more likely in individuals 25-34 years old (aPR=2.23, 95% CI 1.18 to 4.21). Cefixime and ceftriaxone increased MIC were both more likely in cases who reported ≥5 sexual partners (cefixime: aPR=2.10, 95% CI 1.34 to 3.27 and ceftriaxone: aPR=1.62, 95% CI 1.14 to 2.30). CONCLUSION: Significant correlates of N. gonorrhoeae AMR to first-line antimicrobials were observed. Antimicrobial stewardship may be particularly important for 3GC. Active monitoring and interventions are critical for 3GC non-susceptible strains, especially considering the very low prevalence in Québec.

A population-based study of reported hepatitis C diagnoses from 1998 to 2018 in immigrants and nonimmigrants in Quebec, Canada.

Immigrants living in low hepatitis C (HCV) prevalence countries bear a disproportionate HCV burden, but there are limited HCV population-based studies focussed on this population. We estimated rates and trends of reported HCV diagnoses over a 20-year period in Quebec, Canada, to investigate subgroups with the highest rates and changes over time. A population-based cohort of all reported HCV diagnoses in Quebec (1998-2018) linked to health administrative and immigration databases. HCV rates, rate ratios (RR) and trends overall and stratified by immigrant status and country of birth were estimated using Poisson regression. Among 38,348 HCV diagnoses, 14% occurred in immigrants, a median of 7.5 years after arrival. The average annual HCV rate/100,000 decreased for immigrants and nonimmigrants, but the risk (RR) among immigrants increased over the study period [35.7 vs. 34.5 (RR = 1.03) and 18.4 vs. 12.7 (1.45) between 1998-2008 and 2009-2018]. Immigrants from middle-income Europe & Central Asia [55.8 (RR = 4.39)], sub-Saharan Africa [51.7 (RR = 4.06)] and South Asia [32.8 (RR = 2.58)] had the highest rates between 2009 and 2018. Annual HCV rates decreased more slowly among immigrants vs. nonimmigrants (-5.9% vs. -8.9%, p < 0.001), resulting in a 2.5-fold (9%-21%) increase in the proportion of HCV diagnoses among immigrants (1998-2018). The slower decline in HCV rates among immigrants over the study period highlights the need for targeted screening for this population, particularly those from sub-Saharan Africa, Asia and middle-income Europe. These data can inform micro-elimination efforts in Canada and other low-HCV-prevalence countries.

Occurrence and temporal trends of industrial antioxidants and UV absorbents in the endangered St. Lawrence Estuary beluga whale (Delphinapterus leucas).

Elevated contaminant exposure has been identified as a stressor that has negative impacts on the health and recovery of the endangered St. Lawrence Estuary (SLE) beluga (Delphinapterus leucas) population. However, the accumulation of many groups of contaminants of emerging concern is still unknown in the SLE beluga. The objective of this study was to investigate the occurrence and temporal trends (2000-2017) of synthetic phenolic antioxidants (SPAs), secondary aromatic amines (Ar-SAs), benzotriazole UV stabilizers (BZT-UVs), and organic UV filters (UVFs) in the blubber (n = 69) and liver (n = 80) of SLE beluga carcasses recovered in the SLE. The SPA 2,6-di-tert-butyl-1,4-benzoquinone (BHTQ) was the most prevalent contaminant in the blubber (detection frequency: 86 %; median: 71.1 ng/g wet weight (ww)) and liver (50 %; 12.2 ng/g ww) of SLE belugas. In the blubber, 2-hydroxy-4-methoxybenzophenone (BP3) (36 %; 3.15 ng/g ww) and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl butyl)phenol (UV329) (49 %; 6.84 ng/g ww) were the most frequently detected UVFs and BZT-UVs, respectively. Ar-SAs were not detected in most of the blubber and liver samples. Blubber accumulated higher levels of BHTQ and UV329 than liver, whereas the levels of BP3 were greater in the liver. Male SLE beluga accumulated greater concentrations of UV329 in blubber compared to females. These results indicated that the accumulation of BHTQ, UV329 and BP3 in SLE belugas is tissue- and sex-specific. BHTQ showed a decreasing trend in the blubber (2000-2017) of male SLE beluga, whereas no significant trend of this contaminant was found in females. UV329 showed no discernible temporal trend. This study established a baseline for the future monitoring of SPAs, Ar-SAs, BZT-UVs and UVFs in belugas and other marine mammals.

Repeated-Dose Toxicity, Biodistribution, and Shedding Assessments With a ChAd155 Respiratory Syncytial Virus Vaccine Candidate Evaluated in Rabbits and Rats.

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infections (LRTI) in infants, and toddlers and vaccines are not yet available. A pediatric RSV vaccine (ChAd155-RSV) is being developed to protect infants against RSV disease. The ChAd155-RSV vaccine consists of a recombinant replication-deficient chimpanzee-derived adenovirus (ChAd) group C vector engineered to express the RSV antigens F, N, and M2-1. The local and systemic effects of three bi-weekly intramuscular injections of the ChAd155-RSV vaccine was tested in a repeated-dose toxicity study in rabbits. After three intramuscular doses, the ChAd155-RSV vaccine was considered well-tolerated. Changes due to the vaccine-elicited inflammatory reaction/immune response were observed along with transient decreases in platelet count without physiological consequences, already reported for other adenovirus-based vaccines. In addition, the biodistribution and shedding of ChAd155-RSV were also characterized in two studies in rats. The distribution and persistence of the ChAd155-RSV vaccine candidate was consistent with other similar adenovector-based vaccines, with quantifiable levels of ChAd155-RSV observed at the injection site (muscle) and the draining lymph nodes up to 69 days post administration. The shedding results demonstrated that ChAd155-RSV was generally not detectable in any secretions or excreta samples. In conclusion, the ChAd155-RSV vaccine was well-tolerated locally and systemically.

Nonclinical safety assessment of repeated administration and biodistribution of a novel rabies self-amplifying mRNA vaccine in rats.

The novel self-amplifying mRNA (SAM) technology for vaccines consists of an engineered replication-deficient alphavirus genome encoding an RNA-dependent RNA polymerase and the gene of the target antigen. To validate the concept, the rabies glycoprotein G was chosen as antigen. The delivery system for this vaccine was a cationic nanoemulsion. To characterize the local tolerance, potential systemic toxicity and biodistribution of this vaccine, two nonclinical studies were performed. In the repeated dose toxicity study, the SAM vaccine was administered intramuscularly to rats on four occasions at two-week intervals followed by a four-week recovery period. SAM-related changes consisted of a transient increase in neutrophil count, alpha-2-macroglobulin and fibrinogen levels. Transient aspartate aminotransferase and alanine aminotransferase increases were also noted in females only. At necropsy, observations related to the elicited inflammatory reaction, such as enlargement of the draining lymph nodes were observed that were almost fully reversible by the end of the recovery period. In the biodistribution study, rats received a single intramuscular injection of SAM vaccine and then were followed until Day 60. Rabies RNA was found at the injection sites and in the draining lymph nodes one day after administration, then generally decreased in these tissues but remained detectable up to Day 60. Rabies RNA was also transiently found in blood, lungs, spleen and liver. No microscopic changes in the brain and spinal cord were recorded. In conclusion, these results showed that the rabies SAM vaccine was well-tolerated by the animals and supported the clinical development program.

Impact of sex work on risk behaviours and their association with HIV positivity among people who inject drugs in Eastern Central Canada: cross-sectional results from an open cohort study.

OBJECTIVES: The objectives of this study were: (1) to examine the correlates of HIV positivity among participants who injected drugs and engaged in sex work (PWID-SWs) in the SurvUDI network between 2004 and 2016, after stratification by sex, and (2) to compare these correlates with those of sexually active participants who did not engage in sex work (PWID non-SWs). DESIGN AND SETTING: This biobehavioural survey is an open cohort of services where participants who had injected in the past 6 months were recruited mainly through harm reduction programmes in Eastern Central Canada. PARTICIPANTS: Data from 5476 participants (9223 visits in total; 785 not included in multivariate analyses due to missing values) were included. METHODS: Participants completed an interviewer-administered questionnaire and provided saliva samples for anti-HIV antibody testing. Generalised estimating equations taking into account multiple participations were used. RESULTS: Baseline HIV prevalence was higher among SWs compared with non-SWs (women: 13.0% vs 7.7%; P<0.001, and men: 17.4% vs 10.8%; P<0.001). PWID-SWs were particularly susceptible to HIV infection as a result of higher levels of vulnerability factors and injection risk behaviours. They also presented different risk-taking patterns than their non-SWs counterparts, as shown by differences in correlates of HIV positivity. Additionally, the importance of sex work for HIV infection varies according to gender, as suggested by a large proportion of injection risk behaviours associated with HIV among women and, conversely, a stronger association between sexual behaviours and HIV positivity observed among men. CONCLUSION: These results suggest that sex work has an impact on the risk of HIV acquisition and that risk behaviours vary according to gender. Public health practitioners should take those specificities into account when designing HIV prevention interventions aimed at PWIDs.

Drug use practices among people who inject drugs in a context of drug market changes: Challenges for optimal coverage of harm reduction programs.

BACKGROUND: Until the early 2000s, people who inject drugs (PWID) in Québec had mainly been injecting powder cocaine and heroin. Since then, ethnographic studies have shown that the drug market has diversified, with crack and prescription opioids (PO) becoming increasingly available. This could have led to changes in drug use practices among PWID. The objectives of our study were to examine annual trends in injection of different drugs, crack smoking and frequent injection (FI), as well as relationships between injected drugs and FI. METHODS: PWID are participants in the ongoing Québec SurvUDI surveillance system. PWID (past 6 months) were recruited in 2 urban and 6 semi-urban/rural sites. Each visit included a structured interview addressing drug use behaviours. Analyses were carried out using GEE methods. For trend analyses (2003-2014) on drugs and FI (number of injections≥upper quartile, previous month), the first annual interview was selected for PWID with multiple participations per year. Analyses on associations between FI and types of injected drugs were based on all interviews (2004-2014). RESULTS: Crack/cocaine and heroin injection declined significantly, with prevalence ratios (PR) per year of 0.983 [95% confidence interval (CI): 0.980-0.986] and 0.979 (95% CI: 0.969-0.990), while PO injection [PR=1.052 (1.045-1.059)], crack smoking [PR=1.006 (1.001-1.012)], and FI (≥120 injections, previous month) significantly increased [PR=1.015 (1.004-1.026)]. Compared to PWID who injected crack/cocaine±other drugs, the proportion of PWID reporting FI was higher among those who injected PO+heroin/speedball, crack/cocaine or other drugs (adjusted PR 2.29; 95% CI: 2.07-2.53) or PO only (aPR 1.72; 95%CI: 1.47-2.01). CONCLUSIONS: Changes that have occurred in the drug market are reflected in PWID's practices. The high frequency of injection observed among PO injectors is of particular concern. Drug market variations are a challenge for health authorities responsible for harm reduction programs.

Sex Work as an Emerging Risk Factor for Human Immunodeficiency Virus Seroconversion Among People who Inject Drugs in the SurvUDI Network.

BACKGROUND: Recent analyses have shown an emerging positive association between sex work and human immunodeficiency virus (HIV) incidence among people who inject drugs (PWIDs) in the SurvUDI network. METHODS: Participants who had injected in the past 6 months were recruited across the Province of Quebec and in the city of Ottawa, mainly in harm reduction programs. They completed a questionnaire and provided gingival exudate for HIV antibody testing. The associations with HIV seroconversion were tested with a Cox proportional hazard model using time-dependent covariables including the main variable of interest, sexual activity (sex work; no sex work; sexually inactive). The final model included significant variables and confounders of the associations with sexual activity. RESULTS: Seventy-two HIV seroconversions were observed during 5239.2 person-years (py) of follow-up (incidence rates: total = 1.4/100 py; 95% confidence interval [CI], 1.1-1.7; sex work = 2.5/100 py; 95% CI, 1.5-3.6; no sex work = 0.8/100 py; 95% CI, 0.5-1.2; sexually inactive = 1.8/100 py; 95% CI, 1.1-2.5). In the final multivariate model, HIV incidence was significantly associated with sexual activity (sex work: adjusted hazard ratio [AHR], 2.19; 95% CI, 1.13-4.25; sexually inactive: AHR, 1.62; 95% CI, 0.92-2.88), and injection with a needle/syringe used by someone else (AHR, 2.84; 95% CI, 1.73-4.66). CONCLUSIONS: Sex work is independently associated with HIV incidence among PWIDs. At the other end of the spectrum of sexual activity, sexually inactive PWIDs have a higher HIV incidence rate, likely due to more profound dependence leading to increased vulnerabilities, which may include mental illness, poverty, and social exclusion. Further studies are needed to understand whether the association between sex work and HIV is related to sexual transmission or other vulnerability factors.

Prevalence and temporal trends of crack injection among injection drug users in eastern central Canada.

BACKGROUND: Little is known about crack injection and its temporal trends in North America. This article describes the extent of crack injection and examines temporal trends among injection drug users (IDUs) recruited from 2003 to 2010 in the SurvUDI network. METHODS: IDUs who injected recently (past 6 months) were recruited in harm reduction and health programs in eastern central Canada. Trend analyses were performed using generalized estimating equations. Some IDUs participated multiple times; first interview was retained for the descriptive analyses, while first interview per year was retained for the trend analyses. RESULTS: Of the 4088 IDUs recruited, 15.2% (621) reported crack injection; large variations across sites were noted (range: 0.3-39.5%). Trend analyses were limited to Ottawa (449 crack injectors) and Montréal (121). For Ottawa, a significant decline was observed, from 48.3% to 36.9%, with a prevalence ratio (PR) of 0.97 per year (95% CI: 0.94-0.99). For Montréal, a significant rise was observed, from 6.0% to 18.4%, with a PR of 1.29 per year (95% CI: 1.19-1.40). CONCLUSIONS: Strong variations in crack injection exist throughout the SurvUDI network, and reversed temporal trends have been observed in Ottawa and Montréal. These data will be useful to local harm reduction programs to evaluate the need to distribute items required by crack injectors and to develop prevention messages.

Glucocorticoid-induced androgen inactivation by aldo-keto reductase 1C2 promotes adipogenesis in human preadipocytes.

Adipogenesis and lipid storage in human adipose tissue are inhibited by androgens such as DHT. Inactivation of DHT to 3α-diol is stimulated by glucocorticoids in human preadipocytes. We sought to characterize glucocorticoid-induced androgen inactivation in human preadipocytes and to establish its role in the antiadipogenic action of DHT. Subcutaneous and omental primary preadipocyte cultures were established from fat samples obtained in subjects undergoing abdominal surgeries. Inactivation of DHT to 3α/ß-diol for 24 h was measured in dexamethasone- or vehicle-treated cells. Specific downregulation of aldo-keto reductase 1C (AKR1C) enzymes in human preadipocytes was achieved using RNA interference. In whole adipose tissue sample, cortisol production was positively correlated with androgen inactivation in both subcutaneous and omental adipose tissue (P < 0.05). Maximal dexamethasone (1 µM) stimulation of DHT inactivation was higher in omental compared with subcutaneous fat from men as well as subcutaneous and omental fat from women (P < 0.05). A significant positive correlation was observed between BMI and maximal dexamethasone-induced DHT inactivation rates in subcutaneous and omental adipose tissue of men and women (r = 0.24, n = 26, P < 0.01). siRNA-induced downregulation of AKR1C2, but not AKR1C1 or AKR1C3, significantly reduced basal and glucocorticoid-induced androgen inactivation rates (P < 0.05). The inhibitory action of DHT on preadipocyte differentiation was potentiated following AKR1C2 but not AKR1C1 or AKR1C3 downregulation. Specifically, lipid accumulation, G3PDH activity, and FABP4 mRNA expression in differentiated preadipocytes exposed to DHT were reduced further upon AKR1C2 siRNA transfection. We conclude that glucocorticoid-induced androgen inactivation is mediated by AKR1C2 and is particularly effective in omental preadipocytes of obese men. The interplay between glucocorticoids and AKR1C2-dependent androgen inactivation may locally modulate adipogenesis and lipid accumulation in a depot-specific manner.

Effects of androgens on adipocyte differentiation and adipose tissue explant metabolism in men and women.

OBJECTIVE: To examine the effects of aromatizable or nonaromatizable androgens on abdominal subcutaneous (SC) and omental (OM) adipose tissue lipid metabolism and adipogenesis in men and women. DESIGN AND SUBJECTS: Primary organ and preadipocyte cultures were established from surgical samples obtained in men (n = 22) and women undergoing biliopancreatic diversions (n = 12) or gynaecological surgeries (n = 8). Cultures were treated with testosterone, dihydrotestosterone (DHT) and methyltrienolone (R1881). MEASUREMENTS: Heparin-releasable lipoprotein lipase (HR-LPL) activity, glycerol release, adiponectin secretion, glycerol-3-phosphate dehydrogenase activity and lipid accumulation were measured. RESULTS: In organ cultures from men, DHT had a statistically significant inhibitory effect on HR-LPL activity in the OM compartment. Testosterone significantly inhibited HR-LPL activity in SC and OM cultures. In women, high DHT concentrations tended to inhibit HR-LPL activity in OM cultures. Minor androgenic effects were observed for basal and isoproterenol-stimulated lipolysis as well as adiponectin release in men. On the other hand, adipocyte differentiation was significantly and dose-dependently inhibited by DHT, testosterone and R1881 in SC and OM cultures from both sexes. These effects did not differ according to adipose tissue depot but appeared to be more pronounced in women than in men. CONCLUSIONS: Androgens slightly decreased HR-LPL activity in adipose tissue organ cultures, but markedly inhibited adipogenesis in SC and OM primary preadipocyte cultures in both sexes. Androgenic effects on adipose tissue in men vs. women may not differ in terms of direction but in the magnitude of their negative impact on adipogenesis and lipid synthesis.

Glucose transporter 4 and insulin receptor substrate-1 messenger RNA expression in omental and subcutaneous adipose tissue in women.

Insulin receptor substrate-1 (IRS-1) and glucose transporter 4 (GLUT4) expression may provide an indirect reflection of the capacity of adipocytes to respond to insulin stimulation. We examined messenger RNA (mRNA) expression of these genes in omental and subcutaneous adipose tissue of women. Paired omental and subcutaneous adipose tissue samples were obtained from 36 women (age, 47 +/- 5 years; body mass index, 28.0 +/- 5.4 kg/m(2)) undergoing gynecologic surgeries. Total adiposity and visceral adiposity were assessed by dual-energy x-ray absorptiometry and computed tomography. The GLUT4 and IRS-1 mRNA expression levels were both significantly higher in subcutaneous compared with omental adipose tissue. A negative correlation was observed between body fat percentage and subcutaneous adipose tissue GLUT4 (r = -0.39, P < .05) and IRS-1 (r = -0.30, P < .08) mRNA abundance. However, in omental fat, only GLUT4 mRNA was inversely associated with body fat percentage (r = -0.53, P < .001). Moreover, the homeostasis model assessment of insulin resistance index was associated with mRNA expression of subcutaneous GLUT4 (r = -0.56, P < .001), subcutaneous IRS-1 (r = -0.51, P < .01), and omental GLUT4 (r = -0.54, P < .001), but not omental IRS-1. Interestingly, plasma adiponectin was only associated with subcutaneous GLUT4 (r = 0.48, P < .01) and IRS-1 (r = 0.48, P < .05) mRNA expression. The GLUT4 protein, unlike mRNA expression, was higher in omental than in subcutaneous adipose tissue. However, abdominal obesity-related differences in protein or mRNA expression were similar. Omental IRS-1 expression was low and unaffected by visceral obesity. In contrast, omental and subcutaneous GLUT4 as well as subcutaneous IRS-1 were reduced in visceral obesity. This divergent pattern of expression may reflect a lower capacity of omental adipose tissue to respond to insulin stimulation at all adiposity levels.

Pathways of adipose tissue androgen metabolism in women: depot differences and modulation by adipogenesis.

The objective was to examine pathways of androgen metabolism in abdominal adipose tissue in women. Abdominal subcutaneous (SC) and omental (OM) adipose tissue samples were surgically obtained in women. Total RNA was isolated from whole adipose tissue samples and from primary preadipocyte cultures before and after induction of differentiation. Expression levels of several steroid-converting enzyme transcripts were examined by real-time RT-PCR. Androgen conversion rates were also measured. We found higher expression levels in SC compared with OM adipose tissue for type 1 3beta-hydroxysteroid dehydrogenase (3beta-HSD-1; P < 0.05), for aldo-keto reductase 1C3 (AKR1C3; P < 0.0001), for AKR1C2 (P < 0.0001), and for the androgen receptor (P < 0.0001). 17beta-HSD-2 mRNA levels were lower in SC adipose tissue (P < 0.05). Induction of adipocyte differentiation led to significantly increased expression levels in SC cultures for AKR1C3 (4.7-fold, P < 0.01), 11-cis-retinol dehydrogenase (6.9-fold, P < 0.02), AKR1C2 (5.6-fold, P < 0.004), P-450 aromatase (5.7-fold, P < 0.02), steroid sulfatase (3.1-fold, P < 0.02), estrogen receptor-beta (11.8-fold, P < 0.01), and the androgen receptor (4.0-fold, P < 0.0005). Generally similar but nonsignificant trends were obtained in OM cultures. DHT inactivation rates increased with differentiation, this effect being mediated by dexamethasone alone, through a glucocorticoid receptor-dependent mechanism. In conclusion, higher mRNA levels of enzymes synthesizing and inactivating androgens are found in differentiated adipocytes, consistent with higher androgen-processing rates in these cells. Glucocorticoid-induced androgen inactivation may locally modulate the exposure of adipose cells to active androgens.

Androgen metabolism in adipose tissue: recent advances.

Androgens modulate adipocyte function and affect the size of adipose tissue compartments in humans. Aldo-keto reductase 1C (AKR1C) enzymes, especially AKR1C2 and AKR1C3, through local synthesis and inactivation of androgens, may be involved in the fine regulation of androgen availability in adipose tissue. This review article summarizes recent findings on androgen metabolism in adipose tissue. Primary culture models and whole tissue specimens of human adipose tissue obtained from the abdominal subcutaneous and intra-abdominal (omental) fat compartments were used in our studies. The non-aromatizable androgen dihydrotestosterone (DHT) inhibits adipocyte differentiation in subcutaneous and omental adipocytes in humans. This inhibitory effect is partially reversed by anti-androgens. Activity and mRNA expression of AKR1C1, 2 and 3 were detected in SC and OM adipose tissue, in men and women, with higher levels in the SC depot than the omental depot of both sexes. The abundance of AKR1C enzyme mRNAs was particularly elevated compared to other steroid-converting enzymes. Significant positive associations were observed between AKR1C enzyme mRNA levels or DHT inactivation rates and visceral fat accumulation as well as OM adipocyte size in women and in men, at least in the normal weight to moderately obese range. Mature adipocytes had significantly higher DHT inactivation rates compared to preadipocytes. Accordingly, adipocyte differentiation significantly increased AKR1C enzyme expression and DHT inactivation rates. Treatment of preadipocytes with dexamethasone alone led to significant increases in the formation of 5alpha-androstan-3alpha,17beta-diol. This stimulation was completely abolished by RU486, suggesting that androgen inactivation is stimulated by a glucocorticoid receptor-dependent mechanism. In conclusion, higher AKR1C activity and expression in mature adipocytes may explain the associations between these enzymes and obesity. We speculate that glucocorticoid-induced androgen inactivation could locally decrease the exposure of adipose cells to active androgens and partially remove their inhibitory effect on adipogenesis. We hypothesize that body fat distribution patterns likely emerge from the local adipose tissue balance between active androgens and glucocorticoids in each fat compartment.

Impact of diet and adiposity on circulating levels of sex hormone-binding globulin and androgens.

This review summarizes studies on the effect of various diets on circulating androgen levels and sex hormone-binding globulin (SHBG). Reduced caloric intake leading to significant weight loss increases SHBG levels regardless of diet composition, particularly in women. Cross-sectional studies show that dietary composition is generally not associated with SHBG levels independent of obesity level. No clear conclusion can be reached regarding the effect of various eating habits or dietary composition on circulating androgens. The evidence indicates that dietary effects on circulating SHBG, and possibly androgens, can be expected if body weight or fatness and/or insulin homeostasis are modulated.

Androgens and body fat distribution.

An important sex difference in body fat distribution is generally observed. Men are usually characterized by the android type of obesity, with accumulation of fat in the abdominal region, whereas women often display the gynoid type of obesity, with a greater proportion of their body fat in the gluteal-femoral region. Accordingly, the amount of fat located inside the abdominal cavity (intra-abdominal or visceral adipose tissue) is twice as high in men compared to women. This sex difference has been shown to explain a major portion of the differing metabolic profiles and cardiovascular disease risk in men and women. Association studies have shown that circulating androgens are negatively associated with intra-abdominal fat accumulation in men, which explains an important portion of the link between low androgens and features of the metabolic syndrome. In women, the low circulating sex hormone-binding globulin (SHBG) levels found in abdominal obesity may indirectly indicate that elevated free androgens are related to increased visceral fat accumulation. However, data on non SHBG-bound and total androgens are not unanimous and difficult to interpret for total androgens. These studies focusing on plasma levels of sex hormones indirectly suggest that androgens may alter adipose tissue mass in a depot-specific manner. This could occur through site-specific modulation of preadipocyte proliferation and/or differentiation as well as lipid synthesis and/or lipolysis in mature adipocytes. Recent results on the effects of androgens in cultured adipocytes and adipose tissue have been inconsistent, but may indicate decreased adipogenesis and increased lipolysis upon androgen treatment. Finally, adipose tissue has been shown to express several steroidogenic and steroid-inactivating enzymes. Their mere presence in fat indirectly supports the notion of a highly complex enzymatic system modulating steroid action on a local basis. Recent data obtained in both men and women suggest that enzymes from the aldoketoreductase 1C family are very active and may be important modulators of androgen action in adipose tissue.

Adipogenesis in nonadherent and adherent bone marrow stem cells grown in fibrin gel and in the presence of adult plasma.

Bone marrow-derived mesenchymal stem cells (i.e., adherent cells) are known to differentiate into fat tissue in the presence of adipogenic supplements in cultures. Induction of adipogenesis has not been investigated within the nonadherent cell fraction that includes predominantly hematopoietic cells. In the present study, murine nonadherent bone marrow-derived stem cells (96% CD45+ cells) were seeded and then grown in fibrin gel to form cell clusters in which most cells were positive to DiI-acetylated low-density lipoprotein uptake. Amongst different culture media supplemented either in fetal bovine serum, horse serum, murine plasma, human plasma or adipogenic supplements, a subpopulation of nonadherent stem cells within clusters differentiated into adipocytes, specifically in the presence of adult syngeneic plasma. This was confirmed by the observation and quantification of oil red O-positive cells, the measurement of glycerol-3-phosphate dehydrogenase activity and peroxisome proliferator-activated receptor-gamma mRNA expression. Similarly, adipogenesis was also observed in the presence of murine plasma with adherent mesenchymal stem cells and 3T3-L1 preadipocytes which were grown either in monolayer plastic cultures or in fibrin gel. Thus, it is possible that nonadherent cells, once in a 3-dimensional environment, can further differentiate towards adipogenesis.

Effect of a six-week national cholesterol education program step 1 diet on plasma sex hormone-binding globulin levels in overweight premenopausal women.

BACKGROUND: Low circulating sex hormone-binding globulin (SHBG) concentrations have been associated with the presence of several features of the metabolic syndrome in both men and women. Nutritional factors including dietary lipids and fibers in particular have been suggested to modulate plasma SHBG levels. METHODS: The primary objective of the present study was to investigate the effect of an oat bran-rich supplement in conjunction with the National Cholesterol Education Program (NCEP) Step 1 diet (< 30% of total energy from fat, < 10% of energy from saturated fat, and < 300 mg cholesterol per day) on plasma SHBG levels in 35 overweight premenopausal women. Subjects (age 38.6 +/- 7.4 years) had normal menstrual cycles and were tested in the midluteal phase. Since no effect of the oat bran supplement was observed on plasma SHBG levels, data were analyzed according to the 6-week NCEP Step 1 diet. RESULTS: The NCEP Step 1 nutritional intervention caused a significant decrease in energy intake ( -11%, p < 0.05), percent fat intake (-10%, p < 0.005), as well as saturated (-20%, p < 0.005) and monounsaturated (-10%, p < 0.05) fatty acid intake. Body mass index (BMI) decreased slightly but significantly (from 29.2 +/- 4.5 to 28.8 +/- 4.3 kg/m(2), p < 0.005). Plasma SHBG levels increased significantly (from 70.6 +/- 17.7 to 79.9 +/- 15.3 pmol/L, p < 0.0005) following the 6-week NCEP Step 1 diet, whereas plasma insulin levels were not modified significantly. Significant correlations were observed between the change in plasma SHBG levels and baseline BMI (r = 0.36, p < 0.04), as well as baseline (r = -0.42, p < 0.05) and postintervention (r = -0.35, p < 0.05) HDL cholesterol levels. CONCLUSIONS: We observed that a 6-week NCEP Step 1 diet significantly increased plasma SHBG levels, despite the finding that fasting insulin was not modified. Further studies are needed to elucidate physiological mechanisms underlying a direct effect of dietary composition on SHBG production by the liver.