👤 T V Varga

Tirzepatide, a glucose-dependent insulinotropic polypeptide/glucagon-like peptide 1 receptor (GIPR/GLP-1R) agonist, has, in clinical trials, demonstrated greater reductions in glucose, body weight, and triglyceride levels compared with selective GLP-1R agonists in people with type 2 diabetes (T2D). However, cellular mechanisms by which GIPR agonism may contribute to these improved efficacy outcomes have not been fully defined. Using human adipocyte and mouse models, we investigated how long-acting GIPR agonists regulate fasted and fed adipocyte functions. In functional assays, GIPR agonism enhanced insulin signaling, augmented glucose uptake, and increased the conversion of glucose to glycerol in a cooperative manner with insulin; however, in the absence of insulin, GIPR agonists increased lipolysis. In diet-induced obese mice treated with a long-acting GIPR agonist, circulating triglyceride levels were reduced during oral lipid challenge, and lipoprotein-derived fatty acid uptake into adipose tissue was increased. Our findings support a model for long-acting GIPR agonists to modulate both fasted and fed adipose tissue function differentially by cooperating with insulin to augment glucose and lipid clearance in the fed state while enhancing lipid release when insulin levels are reduced in the fasted state. Show less

Systemic sclerosis is a fibrotic disease that initiates in the skin and progresses to internal organs, leading to a poor prognosis. Unraveling the etiology of a chronic, multifactorial disease such as systemic sclerosis has been aided by various animal models that recapitulate certain aspects of the human pathology. We found that the transcription factor SNAI1 is overexpressed in the epidermis of patients with systemic sclerosis, and a transgenic mouse recapitulating this expression pattern is sufficient to induce many clinical features of the human disease. Using this mouse model as a discovery platform, we have uncovered a critical role for the matricellular protein Mindin (SPON2) in fibrogenesis. Mindin is produced by SNAI1 transgenic skin keratinocytes and aids fibrogenesis by inducing early inflammatory cytokine production and collagen secretion in resident dermal fibroblasts. Given the dispensability of Mindin in normal tissue physiology, targeting this protein holds promise as an effective therapy for fibrosis. Show less

We aimed to determine the safety and efficacy of nintedanib, an oral anti-angiogenic tyrosine kinase inhibitor, in combination with pembrolizumab, an anti-PD1 immunotherapy, in patients with advanced solid tumors (PEMBIB trial; NCT02856425). In this monocentric phase Ib dose escalation cohort, we evaluated escalating doses of nintedanib (Dose level 1 (DL1) = 150 mg bid [bis in die, as twice a day]; DL2 = 200 mg bid, oral delivery) in combination with pembrolizumab (200 mg Q3W, IV). Patients received a 1-week lead-in dose of nintedanib monotherapy prior starting pembrolizumab. The primary objective was to establish the maximum tolerated dose (MTD) of the combination based on dose limiting toxicity (DLT) occurrence during the first 4 weeks. Secondary objectives were to assess the anti-tumor efficacy and to identify the associated immune and angiogenic parameters in order to establish the recommended nintedanib dose for expansion cohorts. Flow cytometry (FC), Immuno-Histo-Chemistry (IHC) and electrochemiluminescence multi-arrays were prospectively performed on baseline & on-treatment tumor and blood samples to identify immune correlates of efficacy. A total of 12/13 patients enrolled were evaluable for DLT (1 patient withdrew consent prior receiving pembrolizumab). Three patients at 200 mg bid experienced a DLT (grade 3 liver enzymes increase). Four patients developed grade 1-2 immune related adverse events (irAE). Eight patients died because of cancer progression. Median follow-up was 23.7 months (95%CI: 5.55-40.5). Three patients developed a partial response (PR) (ORR = 25%) and five patients (42%) had durable clinical benefit (DCB), defined as PR or stable disease (SD) ≥ 6 months. At baseline, patients with DCB had higher plasma levels of Tie2, CXCL10, CCL22 and circulating CD4 Nintedanib 150 mg bid is the recommended dose for combination with pembrolizumab and is currently investigated in multiple expansion cohorts. Early tumoral and circulating immune factors were associated with cancer outcome under nintedanib & pembrolizumab therapy. ClinicalTrials.gov, NCT02856425 . Registered August 4, 2016 - Prospectively registered. Show less

Recent analyses in Greenlandic Inuit identified six genetic polymorphisms (rs74771917, rs3168072, rs12577276, rs7115739, rs174602 and rs174570) in the fatty acid desaturase gene cluster (FADS1-FADS2-FADS3) that are associated with multiple metabolic and anthropometric traits. Our objectives were to systematically assess whether dietary polyunsaturated fatty acid (PUFA) intake modifies the associations between genetic variants in the FADS gene cluster and cardiometabolic traits, and to functionally annotate top-ranking candidates to estimate their regulatory potential. Data analyses consisted of the following: interaction analyses between the 6 candidate genetic variants and dietary PUFA intake; gene-centric joint analyses to detect interaction signals in the FADS region; haplotype-centric joint tests across 30 haplotype blocks in the FADS region to refine interaction signals; and functional annotation of top-ranking loci from the previous steps. These analyses were undertaken in Swedish adults from the GLACIER Study (N = 5,160); data on genetic variation and eight cardiometabolic traits were used. Interactions were observed between rs174570 and n-6 PUFA intake on fasting glucose (P The association between FADS variants and triglycerides may be modified by PUFA intake. The intronic FADS2 rs5792235 variant is a potential causal variant in the region, having the highest regulatory potential. However, our results suggest that multiple haplotypes may harbour functional variants in a region, rather than a single causal variant. Show less

Genome-wide association studies (GWAS) have identified >250 loci for body mass index (BMI), implicating pathways related to neuronal biology. Most GWAS loci represent clusters of common, noncoding variants from which pinpointing causal genes remains challenging. Here we combined data from 718,734 individuals to discover rare and low-frequency (minor allele frequency (MAF) < 5%) coding variants associated with BMI. We identified 14 coding variants in 13 genes, of which 8 variants were in genes (ZBTB7B, ACHE, RAPGEF3, RAB21, ZFHX3, ENTPD6, ZFR2 and ZNF169) newly implicated in human obesity, 2 variants were in genes (MC4R and KSR2) previously observed to be mutated in extreme obesity and 2 variants were in GIPR. The effect sizes of rare variants are ~10 times larger than those of common variants, with the largest effect observed in carriers of an MC4R mutation introducing a stop codon (p.Tyr35Ter, MAF = 0.01%), who weighed ~7 kg more than non-carriers. Pathway analyses based on the variants associated with BMI confirm enrichment of neuronal genes and provide new evidence for adipocyte and energy expenditure biology, widening the potential of genetically supported therapeutic targets in obesity. Show less

We screened variants on an exome-focused genotyping array in >300,000 participants (replication in >280,000 participants) and identified 444 independent variants in 250 loci significantly associated with total cholesterol (TC), high-density-lipoprotein cholesterol (HDL-C), low-density-lipoprotein cholesterol (LDL-C), and/or triglycerides (TG). At two loci (JAK2 and A1CF), experimental analysis in mice showed lipid changes consistent with the human data. We also found that: (i) beta-thalassemia trait carriers displayed lower TC and were protected from coronary artery disease (CAD); (ii) excluding the CETP locus, there was not a predictable relationship between plasma HDL-C and risk for age-related macular degeneration; (iii) only some mechanisms of lowering LDL-C appeared to increase risk for type 2 diabetes (T2D); and (iv) TG-lowering alleles involved in hepatic production of TG-rich lipoproteins (TM6SF2 and PNPLA3) tracked with higher liver fat, higher risk for T2D, and lower risk for CAD, whereas TG-lowering alleles involved in peripheral lipolysis (LPL and ANGPTL4) had no effect on liver fat but decreased risks for both T2D and CAD. Show less

Genome-wide association studies have so far identified 56 loci associated with risk of coronary artery disease (CAD). Many CAD loci show pleiotropy; that is, they are also associated with other diseases or traits. This study sought to systematically test if genetic variants identified for non-CAD diseases/traits also associate with CAD and to undertake a comprehensive analysis of the extent of pleiotropy of all CAD loci. In discovery analyses involving 42,335 CAD cases and 78,240 control subjects we tested the association of 29,383 common (minor allele frequency >5%) single nucleotide polymorphisms available on the exome array, which included a substantial proportion of known or suspected single nucleotide polymorphisms associated with common diseases or traits as of 2011. Suggestive association signals were replicated in an additional 30,533 cases and 42,530 control subjects. To evaluate pleiotropy, we tested CAD loci for association with cardiovascular risk factors (lipid traits, blood pressure phenotypes, body mass index, diabetes, and smoking behavior), as well as with other diseases/traits through interrogation of currently available genome-wide association study catalogs. We identified 6 new loci associated with CAD at genome-wide significance: on 2q37 (KCNJ13-GIGYF2), 6p21 (C2), 11p15 (MRVI1-CTR9), 12q13 (LRP1), 12q24 (SCARB1), and 16q13 (CETP). Risk allele frequencies ranged from 0.15 to 0.86, and odds ratio per copy of the risk allele ranged from 1.04 to 1.09. Of 62 new and known CAD loci, 24 (38.7%) showed statistical association with a traditional cardiovascular risk factor, with some showing multiple associations, and 29 (47%) showed associations at p < 1 × 10 We identified 6 loci associated with CAD at genome-wide significance. Several CAD loci show substantial pleiotropy, which may help us understand the mechanisms by which these loci affect CAD risk. Show less

Cross-sectional genome-wide association studies have identified hundreds of loci associated with blood lipids and related cardiovascular traits, but few genetic association studies have focused on long-term changes in blood lipids. Participants from the GLACIER Study (Nmax = 3492) were genotyped with the MetaboChip array, from which 29 387 SNPs (single nucleotide polymorphisms; replication, fine-mapping regions and wildcard SNPs for lipid traits) were extracted for association tests with 10-year change in total cholesterol (ΔTC) and triglycerides (ΔTG). Four additional prospective cohort studies (MDC, PIVUS, ULSAM, MRC Ely; Nmax = 8263 participants) were used for replication. We conducted an in silico look-up for association with coronary artery disease (CAD) in the Coronary ARtery DIsease Genome-wide Replication and Meta-analysis (CARDIoGRAMplusC4D) Consortium (N ∼ 190 000) and functional annotation for the top ranking variants. In total, 956 variants were associated (P < 0.01) with either ΔTC or ΔTG in GLACIER. In GLACIER, chr19:50121999 at APOE was associated with ΔTG and multiple SNPs in the APOA1/A4/C3/A5 region at genome-wide significance (P < 5 × 10-8), whereas variants in four loci, DOCK7, BRE, SYNE1 and KCNIP1, reached study-wide significance (P < 1.7 × 10-6). The rs7412 variant at APOE was associated with ΔTC in GLACIER (P < 1.7 × 10-6). In pooled analyses of all cohorts, 139 SNPs at six and five loci were associated with ΔTC and for ΔTG, respectively (P < 10-3). Of these, a variant at CAPN3 (P = 1.2 × 10-4), multiple variants at HPR (Pmin = 1.5 × 10-6) and a variant at SIX5 (P = 1.9 × 10-4) showed evidence for association with CAD. We identified seven novel genomic regions associated with long-term changes in blood lipids, of which three also raise CAD risk. Show less

Human complex metabolic traits are in part regulated by genetic determinants. Here we applied exome sequencing to identify novel associations of coding polymorphisms at minor allele frequencies (MAFs) >1% with common metabolic phenotypes. The study comprised three stages. We performed medium-depth (8×) whole exome sequencing in 1,000 cases with type 2 diabetes, BMI >27.5 kg/m(2) and hypertension and in 1,000 controls (stage 1). We selected 16,192 polymorphisms nominally associated (p < 0.05) with case-control status, from four selected annotation categories or from loci reported to associate with metabolic traits. These variants were genotyped in 15,989 Danes to search for association with 12 metabolic phenotypes (stage 2). In stage 3, polymorphisms showing potential associations were genotyped in a further 63,896 Europeans. Exome sequencing identified 70,182 polymorphisms with MAF >1%. In stage 2 we identified 51 potential associations with one or more of eight metabolic phenotypes covered by 45 unique polymorphisms. In meta-analyses of stage 2 and stage 3 results, we demonstrated robust associations for coding polymorphisms in CD300LG (fasting HDL-cholesterol: MAF 3.5%, p = 8.5 × 10(-14)), COBLL1 (type 2 diabetes: MAF 12.5%, OR 0.88, p = 1.2 × 10(-11)) and MACF1 (type 2 diabetes: MAF 23.4%, OR 1.10, p = 8.2 × 10(-10)). We applied exome sequencing as a basis for finding genetic determinants of metabolic traits and show the existence of low-frequency and common coding polymorphisms with impact on common metabolic traits. Based on our study, coding polymorphisms with MAF above 1% do not seem to have particularly high effect sizes on the measured metabolic traits. Show less

Numerous obesity loci have been identified using genome-wide association studies. A UK study indicated that physical activity may attenuate the cumulative effect of 12 of these loci, but replication studies are lacking. Therefore, we tested whether the aggregate effect of these loci is diminished in adults of European ancestry reporting high levels of physical activity. Twelve obesity-susceptibility loci were genotyped or imputed in 111,421 participants. A genetic risk score (GRS) was calculated by summing the BMI-associated alleles of each genetic variant. Physical activity was assessed using self-administered questionnaires. Multiplicative interactions between the GRS and physical activity on BMI were tested in linear and logistic regression models in each cohort, with adjustment for age, age(2), sex, study center (for multicenter studies), and the marginal terms for physical activity and the GRS. These results were combined using meta-analysis weighted by cohort sample size. The meta-analysis yielded a statistically significant GRS × physical activity interaction effect estimate (Pinteraction  = 0.015). However, a statistically significant interaction effect was only apparent in North American cohorts (n = 39,810, Pinteraction  = 0.014 vs. n = 71,611, Pinteraction  = 0.275 for Europeans). In secondary analyses, both the FTO rs1121980 (Pinteraction  = 0.003) and the SEC16B rs10913469 (Pinteraction  = 0.025) variants showed evidence of SNP × physical activity interactions. This meta-analysis of 111,421 individuals provides further support for an interaction between physical activity and a GRS in obesity disposition, although these findings hinge on the inclusion of cohorts from North America, indicating that these results are either population-specific or non-causal. Show less

There is no effective treatment for the loss of functional salivary tissue after irradiation for head and neck cancer or the autoimmune disease Sjögren's syndrome. One possible approach is the regeneration of salivary glands from stem cells. The present study aimed to investigate whether small pieces of human submandiblar gland tissue contain elements necessary for the reconstruction of salivary rudiments in vitro via acinar and ductal cell differentiation. Primary submandibular gland (primary total human salivary gland; PTHSG) cells were isolated from human tissue and cultured in vitro using a new method in which single cells form an expanding epithelial monolayer on plastic substrates. Differentiation, morphology, number, and organization of these cells were then followed on basement membrane extract (BME) using RNA quantitation (amylase, claudin-1 (CLN1), CLN3, kallikrein, vimentin), immunohistochemistry (amylase and occludin), viability assay, and videomicroscopy. On the surface of BME, PTHSG cells formed acinotubular structures within 24 h, did not proliferate, and stained for amylase. In cultures derived from half of the donors, the acinar markers amylase and CLN3 were upregulated. The PTHSG culture model suggests that human salivary gland may be capable of regeneration via reorganization and differentiation and that basement membrane components play a crucial role in the morphological and functional differentiation of salivary cells. Show less

The nuclear hormone receptors liver X receptor alpha (LXRalpha) and LXRbeta function as physiological receptors for oxidized cholesterol metabolites (oxysterols) and regulate several aspects of cholesterol and lipid metabolism. Seladin-1 was originally identified as a gene whose expression was down-regulated in regions of the brain associated with Alzheimer's disease. Seladin-1 has been demonstrated to be neuroprotective and was later characterized as 3beta-hydroxysterol-Delta24 reductase (DHCR24), a key enzyme in the cholesterologenic pathway. Seladin-1 has also been shown to regulate lipid raft formation. In a whole genome screen for direct LXRalpha target genes, we identified an LXRalpha occupancy site within the second intron of the Seladin-1/DHCR24 gene. We characterized a novel LXR response element within the second intron of this gene that is able to confer LXR-specific ligand responsiveness to reporter gene in both HepG2 and human embryonic kidney 293 cells. Furthermore, we found that Seladin-1/DHCR24 gene expression is significantly decreased in skin isolated from LXRbeta-null mice. Our data suggest that Seladin-1/DHCR24 is an LXR target gene and that LXR may regulate lipid raft formation. Show less

Cholesterol is required for normal cellular and physiological function, yet dysregulation of cholesterol metabolism is associated with diseases such as atherosclerosis. Cholesterol biosynthesis is regulated by end product negative feedback inhibition where the levels of sterols and oxysterols regulate the expression of cholesterologenic enzymes. Sterol regulatory element-binding protein-2 is responsive to both sterols and oxysterols and has been shown to mediate the transcriptional response of the cholesterologenic enzymes to these lipids. Here, we show that the nuclear hormone receptor for oxysterols, the liver X receptor alpha (LXRalpha), regulates cholesterol biosynthesis by directly silencing the expression of two key cholesterologenic enzymes (lanosterol 14alpha-demethylase (CYP51A1), and squalene synthase (farnesyl diphosphate farnesyl transferase 1)) via novel negative LXR DNA response elements (nLXREs) located in each of these genes. Examination of the CYP51A1 gene revealed that both the SRE and nLXRE are required for normal oxysterol-dependent repression of this gene. Thus, these data suggest that LXRalpha plays an important role in the regulation of cholesterol biosynthesis. Show less

Type I human hepatic 3alpha-hydroxysteroid dehydrogenase (AKR1C4) plays a significant role in bile acid biosynthesis, steroid hormone metabolism, and xenobiotic metabolism. Utilization of a hidden Markov model for predictive modeling of nuclear hormone receptor response elements coupled with chromatin immunoprecipitation/microarray technology revealed a putative binding site in the AKR1C4 promoter for the nuclear hormone receptor known as liver X receptor alpha, (LXRalpha [NR1H3]), which is the physiological receptor for oxidized cholesterol metabolites. The putative LXRalpha response element (LXRE), identified by chromatin immunoprecipitation, was approximately 1.5 kilobase pairs upstream of the transcription start site. LXRalpha was shown to bind specifically to this LXRE and mediate transcriptional activation of the AKR1C4 gene, leading to increased AKR1C4 protein expression. These data suggest that LXRalpha may modulate the bile acid biosynthetic pathway at a unique site downstream of CYP7A1 and may also modulate the metabolism of steroid hormones and certain xenobiotics. Show less