Regulation of CD163 mRNA and soluble CD163 protein in human adipose tissue in vitro

Mitochondrial Dysfunction and Insulin Resistance in Pubertal Youth Living with Perinatally Acquired HIV

Mitochondrial dysfunction (MD) is linked to cardiometabolic complications, such as obesity and insulin resistance (IR), the frequencies of which are higher in adults living with HIV infection and receiving combination antiretroviral therapies (ARV). ARV-treated youth living with perinatally acquired HIV infection (YLPHIV) may be especially susceptible to IR due to long-term exposure to both factors. Medical histories, fasting blood chemistry panels, and mitochondrial function in banked peripheral blood mononuclear cells (PBMCs) were assessed in eligible YLPHIV from the Pediatric HIV/AIDS Cohort Study (PHACS)/Adolescent Master Protocol (AMP) Mitochondrial Determinants Component cohort, stratified by Homeostatic Model Assessment of IR (HOMA-IR) score: case (score ≥4, n = 39) or control (score <4, n = 105). PBMCs were sources for mitochondrial (mt) DNA copies/cell; mtRNA transcript levels of oxidative phosphorylation (OXPHOS) subunits NADH dehydrogenases 1 and 6, and cytochrome B; and enzymatic activities of OXPHOS Complexes I (CI) and IV (CIV). Logistic regression models were fit to estimate the odds of IR case diagnosis, adjusted for sex, race/ethnicity, body mass index (BMI) z-score, and Tanner stage. IR cases were similar to controls by age, sex, and race/ethnicity. Cases had higher median levels of peak HIV viral load, lactate, pyruvate, triglycerides, and BMI z-scores. OXPHOS CI enzymatic activity was lower in cases (log₁₀ 1.62 vs. 1.70) and inversely correlated with HOMA-IR score (r = -0.157, p = .061), but did not associate with IR in adjusted models. Fully adjusted models indicated associations of nadir CD4% [odds ratio (OR) = 0.95, 95% confidence intervals (CIs) = 0.90-1.00] or peak HIV load (OR = 3.48, 95% CIs = 1.70-10.79) with IR. IR in YLPHIV was strongly associated with morphometrics, but early virologic and immunologic factors may also influence MD.

Crosstalk between adipose tissue insulin resistance and liver macrophages in non-alcoholic fatty liver disease

BACKGROUND & AIMS

The pathogenesis of non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) is likely due to the interaction between a deranged metabolic milieu and local mediators of hepatic inflammation and fibrosis. We undertook this study to elucidate the interplay between macrophage activation, insulin resistance (IR) in target organs/tissues and hepatic damage.

METHODS

In 40 non-diabetic patients with biopsy-proven NAFLD we assessed: i) endogenous glucose production (EGP), glucose clearance and indexes of IR in the adipose tissue (Adipo-IR and Lipo-IR) and in the liver (Hep-IR) by tracer infusion ([6,6-2H2]glucose and [2H5]glycerol); ii) macrophage activity (by soluble sCD163) and iii) hepatic expression of CD163 (hCD163).

RESULTS

We found that sCD163 levels paralleled both the plasma free fatty acid (FFA) levels and lipolysis from adipose tissue. Consistently, sCD163 significantly correlated with adipose tissue IR (Adipo-IR: r = 0.32, p = 0.042; Lipo-IR: r = 0.39, p = 0.012). At multiple regression analysis, sCD163 levels were associated with FFA levels (r_p = 0.35, p = 0.026). In vitro exposure of human monocyte-derived macrophages to palmitate enhanced sCD163 secretion. Conversely, sCD163 did not correlate with EGP or with Hep-IR. In the liver, hCD163 positively correlated with sCD163 (r = 0.58, p = 0.007) and the degree of steatosis (r = 0.34, p = 0.048), but not with EGP or Hep-IR (r = -0.27 and r = 0.11, respectively, p >0.10, both).

CONCLUSIONS

Our findings suggest a link between deranged metabolism in the adipose tissue and activation of hepatic macrophages in patients with NAFLD, possibly in response to FFA overflow and independent of obesity and diabetes. Conversely, our findings do not support a link between activated hepatic macrophages and glucose metabolism (EGP or Hep-IR). The relationship between adipose tissue IR and hepatic macrophages should be considered to define therapeutic targets for NAFLD.

LAY SUMMARY

The pathogenesis of non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) is likely due to the interaction between a deranged metabolic milieu and local mediators of hepatic inflammation and fibrosis in the insulin resistant state. This study provides in vivo support for a possible link between deranged metabolism in the adipose tissue and activation of hepatic macrophages in patients with NAFLD, most likely in response to free fatty acid overflow and independent of obesity and diabetes.

Genome-Wide Association Study in Mexican Holstein Cattle Reveals Novel Quantitative Trait Loci Regions and Confirms Mapped Loci for Resistance to Bovine Tuberculosis

Simple Summary

Bovine tuberculosis is an infectious disease of cattle caused by Mycobacterium bovis characterized by the formation of tubercles in any organ or tissue. Bovine tuberculosis represents a significant veterinary and public health problem in many parts of the world. It is zoonotic, transmitted to humans through consumption of infected milk and other cattle products. Although many factors influence infection and progression of the disease, there must be an important host genetic component that explains why some animals get sick and others remain healty. We present evidence of genetic variants associated with resistance to tuberculosis in Mexican Holstein dairy cattle using a case-control approach with a selective DNA pooling. Here, we identified novel quantitative trait loci regions harboring genes involved in Mycobacterium spp. immune response. This is a first screening about resistance to tuberculosis infection on Mexican Holstein cattle based on a dense single nucleotide polymorphism chip. The identified genes belong to both, the already known, and the undisclosed quantitative trait loci regions.

Abstract

Bovine tuberculosis (bTB) is a disease of cattle that represents a risk to public health and causes severe economic losses to the livestock industry. Recently, genetic studies, like genome-wide association studies (GWAS) have greatly improved the investigation of complex diseases identifying thousands of disease-associated genomic variants. Here, we present evidence of genetic variants associated with resistance to TB in Mexican dairy cattle using a case-control approach with a selective DNA pooling experimental design. A total of 154 QTLRs (quantitative trait loci regions) at 10% PFP (proportion of false positives), 42 at 5% PFP and 5 at 1% PFP have been identified, which harbored 172 annotated genes. On BTA13, five new QTLRs were identified in the MACROD2 and KIF16B genes, supporting their involvement in resistance to bTB. Six QTLRs harbor seven annotated genes that have been previously reported as involved in immune response against Mycobacterium spp: BTA (Bos taurus autosome) 1 (CD80), BTA3 (CTSS), BTA 3 (FCGR1A), BTA 23 (HFE), BTA 25 (IL21R), and BTA 29 (ANO9 and SIGIRR). We identified novel QTLRs harboring genes involved in Mycobacterium spp. immune response. This is a first screening for resistance to TB infection on Mexican dairy cattle based on a dense SNP (Single Nucleotide Polymorphism) chip.

Soluble CD163-Associated Dietary Patterns and the Risk of Metabolic Syndrome

Elevated soluble cluster of differentiation 163 (sCD163) concentrations, a marker of macrophage activation, are associated with obesity. Weight reduction decreases circulating CD163 levels, and changes in sCD163 levels are associated with improved metabolic dysfunction. Currently, the relationship between sCD163 and diet remains unclear. This study investigated dietary patterns associated with sCD163 concentrations and its predictive effect on metabolic syndrome (MetS). Data on anthropometrics, blood biochemistry, and a food frequency questionnaire were collected from 166 Taiwanese adults. sCD163 levels independently predicted MetS (odds ratio (OR): 5.35; 95% confidence interval (CI): 2.13~13.44, p < 0.001), non-alcoholic fatty liver disease (OR: 2.19; 95% CI: 1.03~4.64, p < 0.001), and central obesity (OR: 3.90; 95% CI: 1.78~8.55, p < 0.001), after adjusting for age and sex. An adjusted linear regression analysis revealed strong correlations between levels of sCD163 and aspartate transaminase (AST) (β = 0.250 (0.023~0.477), p < 0.05) and red blood cell aggregation (β = 0.332 (0.035~0.628), p < 0.05). sCD163-associated dietary pattern scores (high frequencies of consuming noodles and desserts, and eating at home, and a low intake frequency of steamed/boiled/raw food, white/light-green-colored vegetables, orange/red/purple-colored vegetables, dairy products, seafood, dark-green leafy vegetables, and soy products) were positively correlated with MetS, liver injury biomarkers, and sCD163 levels (all p for trend < 0.05). Individuals with the highest dietary pattern scores (tertile 3) had a 2.37-fold [OR: 2.37; 95% CI: 1.04~5.37, p < 0.05] higher risk of MetS compared to those with the lowest scores (tertile 1). Overall, the study findings suggest the importance of a healthy dietary pattern in preventing elevated sCD163 levels and diet-related chronic disease such as MetS.

Characterization of immortalized human brown and white pre-adipocyte cell models from a single donor

Brown adipose tissue with its constituent brown adipocytes is a promising therapeutic target in metabolic disorders due to its ability to dissipate energy and improve systemic insulin sensitivity and glucose homeostasis. The molecular control of brown adipocyte differentiation and function has been extensively studied in mice, but relatively little is known about such regulatory mechanisms in humans, which in part is due to lack of human brown adipose tissue derived cell models. Here, we used retrovirus-mediated overexpression to stably integrate human telomerase reverse transcriptase (TERT) into stromal-vascular cell fractions from deep and superficial human neck adipose tissue biopsies from the same donor. The brown and white pre-adipocyte cell models (TERT-hBA and TERT-hWA, respectively) displayed a stable proliferation rate and differentiation until at least passage 20. Mature TERT-hBA adipocytes expressed higher levels of thermogenic marker genes and displayed a higher maximal respiratory capacity than mature TERT-hWA adipocytes. TERT-hBA adipocytes were UCP1-positive and responded to β-adrenergic stimulation by activating the PKA-MKK3/6-p38 MAPK signaling module and increasing thermogenic gene expression and oxygen consumption. Mature TERT-hWA adipocytes underwent efficient rosiglitazone-induced ‘browning’, as demonstrated by strongly increased expression of UCP1 and other brown adipocyte-enriched genes. In summary, the TERT-hBA and TERT-hWA cell models represent useful tools to obtain a better understanding of the molecular control of human brown and white adipocyte differentiation and function as well as of browning of human white adipocytes.

Insulin Resistance and Markers of Inflammation in HIV-infected Ugandan Children in the CHAPAS-3 Trial

BACKGROUND

Few studies have investigated metabolic complications in HIV-infected African children and their relation with inflammation.

METHODS

We compared baseline and changes in insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR)] and in markers of inflammation over 48 weeks, in a subset of antiretroviral therapy (ART)-naive Ugandan children from the Children with HIV in Africa-Pharmacokinetics and Adherence/Acceptability of Simple Antiretroviral Regimens trial randomized to zidovudine-, stavudine- or abacavir (ABC)-based regimen. Nonparametric methods were used to explore between-group and within-group differences, and multivariable analysis to assess associations of HOMA-IR.

RESULTS

One-hundred eighteen children were enrolled, and median age (interquartile range) was 2.8 years (1.7-4.3). Baseline median HOMA-IR (interquartile range) was 0.49 (0.38-1.07) and similar between the arms. At week 48, median relative changes in HOMA-IR were 14% (-29% to 97%) in the zidovudine arm, -1% (-30% to 69%) in the stavudine arm and 6% (-34% to 124%) in the ABC arm (P ≤ 0.03 for all the arms compared with baseline, but P = 0.90 for between-group differences). Several inflammation markers significantly decreased in all study arms; soluble CD14 increased on ABC and did not change in the other 2 arms. In multivariate analysis, only changes in soluble CD163 were positively associated with HOMA-IR changes.

CONCLUSIONS

In ART-naive Ugandan children, HOMA-IR changed significantly after 48 weeks of ART and correlated with monocyte activation.

High expression of organic cation transporter 3 in human BAT-like adipocytes. Implications for extraneuronal norepinephrine uptake

Brown adipose tissue (BAT) is activated by extracellular norepinephrine (NE) released by the sympathetic nervous system. The extracellular concentration of NE is additionally regulated by the disappearance/degradation of NE. Recent studies have introduced the organic cation transporter 3 (OCT3) as a possible contributor in the regulation of NE in adipose tissue. In the present study we set out to investigate the presence of OCT3 in human neck adipose tissue (AT), which is the primary localization of BAT in humans. Moreover, we wanted to assess the possible function and correlation of the transporter with known markers of thermogenic function, e.g. UCP1. When examining neck AT biopsies from 57 individuals we found that OCT3 was expressed at 2.5 ± 0.16 fold higher level in the deep-neck AT compared with subcutaneous AT. UCP1 was found extensively expressed in the deep-neck AT depot and the correlation between UCP1 and OCT3 within the deep-neck AT was found highly significant (r² = 0.4012, P-value < 0.0001). Lastly, we were able to reduce NE uptake in isolated brown adipocytes in an in vitro culture by adding corticosterone which is a known OCT3-blocker. In conclusion, we found that OCT3 may be a regulator of the concentration of NE in AT and by this mechanism a possible regulator of BAT function and a potential target for pharmacological intervention.

Changes in Insulin Resistance After Initiation of Raltegravir or Protease Inhibitors With Tenofovir-Emtricitabine: AIDS Clinical Trials Group A5260s

HIV-infected treatment-naive participants were randomized to tenofovir-emtricitabine (TDF/FTC) plus atazanavir-ritonavir (ATV/r), darunavir-ritonavir (DRV/r), or raltegravir (RAL) over 96 weeks. Insulin resistance increased rapidly and then plateaued and no differences were found with RAL when compared to ATV/r or DRV/r.

Background. Antiretroviral therapy (ART) can alter glucose metabolism, but little data exist on the association of raltegravir (RAL) with insulin resistance.

Methods. A5260s was a substudy of A5257, a prospective open-label randomized trial in which human immunodeficiency virus (HIV)-infected treatment-naive participants were randomized to tenofovir-emtricitabine (TDF/FTC) plus atazanavir-ritonavir (ATV/r), darunavir-ritonavir (DRV/r), or RAL over 96 weeks. Baseline and changes in insulin resistance as estimated by the homeostatic model assessment of insulin resistance (HOMA-IR) were assessed. Wilcoxon rank-sum tests were used to assess shifts in the distribution of fold increase from baseline between treatment arms, and Spearman correlation was used to assess associations between HOMA-IR and measures of inflammation and body composition.

Results. Three hundred twenty-eight participants were randomized; 90% were male, baseline median age was 36, HIV ribonucleic acid copies were 4.55 log₁₀ copies/mL, and CD4 cell count was 349/mm³. Overall, HOMA-IR increased significantly after 4 weeks (1.9-fold change; 95% confidence interval, 1.73–2.05) then plateaued over the remainder of the study. Changes in HOMA-IR were not different between the arms (P ≥ .23). Changes in HOMA-IR were associated with changes in body mass index at weeks 48 and 96 (r = 0.12–0.22; P ≤ .04). There was a trend with increases in HOMA-IR and increases in visceral abdominal fat at week 96 (r = 0.12; P = .06). At 48 and 96 weeks, HOMA-IR correlated with interleukin-6, high-sensitivity C-reactive protein, and soluble CD163 (r = 0.16–0.27; P ≤ .003).

Conclusions. Insulin resistance increased rapidly and then plateaued in treatment-naive participants initiating ART with TDF/FTC, and no differences were found with RAL when compared with ATV/r or DRV/r.

Plasma CXCL10, sCD163 and sCD14 Levels Have Distinct Associations with Antiretroviral Treatment and Cardiovascular Disease Risk Factors

We investigate the associations of three established plasma biomarkers in the context of HIV and treatment-related variables including a comprehensive cardiovascular disease risk assessment, within a large ambulatory HIV cohort. Patients were recruited in 2010 to form the Royal Perth Hospital HIV/CVD risk cohort. Plasma sCD14, sCD163 and CXCL10 levels were measured in 475 consecutive patients with documented CVD risk (age, ethnicity, gender, smoking, blood pressure, BMI, fasting metabolic profile) and HIV treatment history including immunological/virological outcomes. The biomarkers assessed showed distinct associations with virological response: CXCL10 strongly correlated with HIV-1 RNA (p<0.001), sCD163 was significantly reduced among 'aviraemic' patients only (p = 0.02), while sCD14 was unaffected by virological status under 10,000 copies/mL (p>0.2). Associations between higher sCD163 and protease inhibitor therapy (p = 0.05) and lower sCD14 with integrase inhibitor therapy (p = 0.02) were observed. Levels of sCD163 were also associated with CVD risk factors (age, ethnicity, HDL, BMI), with a favourable influence of Framingham score <10% (p = 0.04). Soluble CD14 levels were higher among smokers (p = 0.002), with no effect of other CVD risk factors, except age (p = 0.045). Our findings confirm CXCL10, sCD163 and sCD14 have distinct associations with different aspects of HIV infection and treatment. Levels of CXCL10 correlated with routinely monitored variables, sCD163 levels reflect a deeper level of virological suppression and influence of CVD risk factors, while sCD14 levels were not associated with routinely monitored variables, with evidence of specific effects of smoking and integrase inhibitor therapy warranting further investigation.

Increased asthma and adipose tissue inflammatory gene expression with obesity and Inuit migration to a western country

BACKGROUND

An overlap between obesity and asthma exists, and inflammatory cells in adipose tissue could drive the development of asthma. Comparison of adipose tissue gene expression among Inuit living in Greenland to those in Denmark provides an opportunity to assess how changes in adipose tissue inflammation can be modified by migration and diet.

OBJECTIVE

To examine mast cell and inflammatory markers in adipose tissue and the association with asthma.

METHODS

Two Inuit populations were recruited, one living in Greenland and another in Denmark. All underwent adipose subcutaneous biopsy, followed by clinical assessment of asthma, and measurement of AHR. Adipose tissue biopsies were homogenised, RNA extracted, and PCR was performed to determine the relative gene expression of mast cell (tryptase, chymase, CPA3) and inflammatory markers (IL-6, IL-1β, and CD163).

RESULTS

Of the 1059 Greenlandic Inuit participants, 556 were living in Greenland and 6.4% had asthma. Asthma was increased in Denmark (9%) compared to Greenland (3.6%, p < 0.0001) and associated with increased adipose tissue IL-6 gene expression and increased BMI. There was no association between asthma and adipose tissue mast cell gene expression. Pro-inflammatory gene expression (IL-6, IL-1β) was higher in those living in Denmark, and with increasing BMI and dietary changes. The anti-inflammatory (M2) macrophage marker, CD163, was higher in Greenland-dwelling Inuit (p < 0.01).

CONCLUSIONS

No association was found between gene expression of mast cell markers in adipose tissue and asthma. Among Greenlandic Inuit, adipose tissue inflammation is also increased in those who migrate to Denmark, possibly as a result of dietary changes.