Deepthi P. Mallela

Background: Recent studies demonstrate gut-microbial trimethylamine N -oxide (TMAO) is clinically and mechanistically linked to chronic kidney disease (CKD) development. Prior studies showed selective targeting of gut-microbial TMAO production can prevent CKD initiation. A highly relevant clinical question is whether inhibiting TMAO generation can reverse established kidney dysfunction and fibrosis. Methods: CD1 mice were first randomized (Phase 1) to unilateral nephrectomy or sham surgery and fed a high-fat diet ± 1% choline supplementation to document CKD through measures of multiple indices of kidney function, tissue remodeling/fibrosis, and uremic toxins. Mice were then randomized (Phase 2) to continue the same diet ± fluoromethylcholine (FMC), a mechanism-based gut-microbial TMAO inhibitor, for 8 additional weeks, and the impact on CKD related phenotypes assessed. Results: After 12-weeks, choline-supplemented unilateral nephrectomized mice exhibited 15-fold higher circulating TMAO levels. In parallel, multiple kidney dysfunction indices progressed, including 48% reduction in measured glomerular filtration rate (mGFR), elevated Cystatin C and creatinine, 3.5-fold greater tubulointerstitial fibrosis, and upregulated profibrotic gene expression. Following Phase 2 (8 weeks ± FMC), choline-supplemented (high-TMAO) unilateral nephrectomized mice without FMC showed further elevation of circulating TMAO and multiple indices of progressive kidney function decline and fibrosis. Conversely, FMC-treated animals showed virtual elimination in circulating TMAO and significant improvements in all monitored CKD phenotypes including >50% higher mGFR, and improved (decreased) creatinine, Cystatin C, pseudouridine, urinary albumin/creatinine ratio, kidney fibrosis measures, and many uremic toxin levels (e.g. indoxyl sulfate and phenylacetylglycine). Beyond halting progression of kidney functional decline and fibrosis, there was frank regression in tubulointerstitial fibrosis (41% reduction) and significant improvement in mGFR (39% increase). Conclusions: Pharmacological targeting of gut-microbial TMAO production after CKD establishment halted disease progression and promoted regression of key CKD pathophysiological features.

Allosteric modulation is a central mechanism for metabolic regulation but has yet to be described for a gut microbiota-host interaction. Phenylacetylglutamine (PAGln), a gut microbiota-derived metabolite, has previously been clinically associated with and mechanistically linked to cardiovascular disease (CVD) and heart failure (HF). Here, using cells expressing β1- versus β2-adrenergic receptors (β1AR and β2AR), PAGln is shown to act as a negative allosteric modulator (NAM) of β2AR, but not β1AR. In functional studies, PAGln is further shown to promote NAM effects in both isolated male mouse cardiomyocytes and failing human heart left ventricle muscle (contracting trabeculae). Finally, using in silico docking studies coupled with site-directed mutagenesis and functional analyses, we identified sites on β2AR (residues E122 and V206) that when mutated still confer responsiveness to canonical β2AR agonists but no longer show PAGln-elicited NAM activity. The present studies reveal the gut microbiota-obligate metabolite PAGln as an endogenous NAM of a host GPCR.

Bile acids (BAs) are cholesterol-derived compounds that regulate glucose, lipid, and energy metabolism. Despite their significance in glucose homeostasis, the association between specific BA molecular species and their synthetic pathways with diabetes is unclear. Here, we used a recently validated, stable-isotope dilution, high-performance liquid chromatography with tandem mass spectrometry method to quantify a panel of BAs in fasting plasma from 2,145 study participants and explored structural and genetic determinants of BAs linked to diabetes, insulin resistance, and obesity. Multiple 12α-hydroxylated BAs were associated with diabetes (adjusted odds ratio [aOR] range, 1.3–1.9; P < 0.05 for all) and insulin resistance (aOR range, 1.3–2.2; P < 0.05 for all). Conversely, multiple 6α-hydroxylated BAs and isolithocholic acid (iso-LCA) were inversely associated with diabetes and obesity (aOR range, 0.3–0.9; P < 0.05 for all). Genome-wide association studies revealed multiple genome-wide significant loci linked with 9 of the 14 diabetes-associated BAs, including a locus for iso-LCA (rs11866815). Mendelian randomization analyses showed genetically elevated deoxycholic acid levels were causally associated with higher BMI, and iso-LCA levels were causally associated with reduced BMI and diabetes risk. In conclusion, comprehensive, large-scale, quantitative mass spectrometry and genetics analyses show circulating levels of multiple structurally specific BAs, especially DCA and iso-LCA, are clinically associated with and genetically linked to obesity and diabetes. Article Highlights:

Stroke is the second most common cause of cognitive impairment and dementia. Vascular dementia (VaD), a cognitive impairment following a stroke, is common and significantly impacts the quality of life. We recently demonstrated via gut microbe transplant studies that the gut microbe-dependent trimethylamine-N-oxide (TMAO) pathway impacts stroke severity, both infarct size and long-term cognitive outcomes. However, the molecular mechanisms that underly the role of the microbiome in VaD have not been explored in depth. To address this issue, we performed a comprehensive RNA-sequencing analysis to identify differentially expressed (DE) genes in the ischemic cerebral cortex of mouse brains at pre-stroke and post-stroke day 1 and day 3. A total of 4016, 3752 and 7861 DE genes were identified at pre-stroke and post-stroke day 1 and day 3, respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated pathways of neurodegeneration in multiple diseases, chemokine signaling, calcium signaling, and IL-17 signaling as the key enriched pathways. Inflammatory response genes interleukin-1 beta (Il-1β), chemokines (C–X–C motif chemokine ligand 10 (Cxcl10), chemokine ligand 2 (Ccl2)), and immune system genes (S100 calcium binding protein 8 (S100a8), lipocalin-2 (Lcn2)) were among the most significantly upregulated genes. Hypocretin neuropeptide precursor (Hcrt), a neuropeptide, and transcription factors such as neuronal PAS domain protein 4 (Npas4), GATA binding protein 3 (Gata3), and paired box 7 (Pax7) were among the most significantly downregulated genes. In conclusion, our results indicate that higher plasma TMAO levels induce differential mRNA expression profiles in the ischemic brain tissue in our pre-clinical stroke model, and the predicted pathways provide the molecular basis for regulating the TMAO-enhanced neuroinflammatory response in the brain.

Background: Given available effective biomedical and behavioral prevention and treatment interventions, HIV-related implementation research (IR) is expanding. The rapid generation and dissemination of IR to inform guidelines and practice has the potential to optimize the impact of the Ending the Epidemic Initiative and the HIV pandemic response more broadly. Methods: We leveraged a prior mapping review of NIH-funded awards in HIV and IR from January 2013 to March 2018 and identified all publications linked to those grants in NIH RePORTER through January 1, 2021 (n = 1509). Deduplication and screening of nonoriginal research reduced the count to 1032 articles, of which 952 were eligible and included in this review. Publication volume and timing were summarized; Kaplan–Meier plots estimated time to publication. Results: Among the 215 NIH-funded IR-related awards, 127 of 215 (59%) published original research directly related to the grant, averaging 2.0 articles (SD: 3.3) per award, largely in the early IR phases. Many articles (521 of 952, 55%) attributed to grants did not report grant-related data. Time from article submission to publication averaged 205 days (SD: 107). The median time-to-first publication from funding start was 4 years. Data dissemination velocity varied by award type, trending toward faster publication in recent years. Delays in data velocity included (1) time from funding to enrollment, (2) enrollment length, and (3) time from data collection completion to publication. Conclusion: Research publication was high overall, and time-to-publication is accelerating; however, over 40% of grants have yet to publish findings from grant-related data. Addressing bottlenecks in the production and dissemination of HIV-related IR would reinforce its programmatic and policy relevance in the HIV response.

BACKGROUND: Previous studies have documented that Black patients have worse outcomes after lower extremity revascularization procedures compared with White patients. However, the association of race on carotid endarterectomy (CEA) outcomes is not well described. The aim of this study was to compare perioperative outcomes of CEA for Black vs White patients with asymptomatic carotid artery stenosis. STUDY DESIGN: All patients who underwent CEA for asymptomatic carotid stenosis in the ACS-NSQIP targeted vascular database (2011-2019) were included. Perioperative (30-day) outcomes were compared for Black vs White patients using multivariable logistic regression adjusting for age/sex, comorbidities, and disease characteristics. RESULTS: Of 16,764 asymptomatic CEA patients, 95.2% (N = 15,960) were White and 4.8% (N = 804) were Black. Black patients were slightly younger (mean age 71.4 ± 0.1 vs 69.9 ± 0.3 years, P < 0.001) and more frequently had high-grade carotid artery stenosis compared to White patients (79.5% vs 74.0%, p = 0.001). Comorbidities including hypertension, diabetes, kidney disease, congestive heart failure, and coronary artery disease were all more prevalent among Black patients (p ≤ 0.01). Crude perioperative stroke (2.4% vs 1.3%, p = 0.007) and stroke/death (2.6% vs 1.4%, p = 0.003) were higher for Black patients, but myocardial infarction (1.7% vs 1.5%, p = 0.67) and death (0.4% vs 0.2%, p = 0.12) were similar. After adjusting for baseline differences between groups, the risk of perioperative stroke (odds ratio 1.66, 95% CI 1.01 to 2.73) and stroke/death (odds ratio 1.75, 95% CI 1.10 to 2.81) remained significantly higher for Black patients compared with White patients. CONCLUSIONS: Black patients undergoing CEA for asymptomatic carotid artery stenosis had more severe stenosis, more comorbidities, and worse perioperative outcomes compared to White patients. Overall, our data suggest substantial differences in the treatment and outcomes of asymptomatic carotid artery stenosis based on race. Export