The transmembrane protein 43 (TMEM43/LUMA) p.S358L mutation causes arrhythmogenic cardiomyopathy named as ARVC5, a fully penetrant disease with high risk of ventricular arrhythmias, sudden death, and heart failure. Male gender and vigorous exercise independently predicted deleterious outcome. Our systems genetics analysis revealed the importance of
Circadian rhythms are ubiquitous in nature, driving many bodily processes and behaviors, including sleep-wake cycles and feeding patterns over 24 hours. We and others revealed gut microbes and their functional outputs also exhibit diurnal rhythms that are responsive to how much, what, and when food is consumed. These microbial cues are integrated into host circadian networks, serving as key regulators of metabolism. High fat (HF) diet disrupts diurnal microbial oscillations, impacting diet-induced obesity (DIO). Apart from feeding, host factors that drive microbial oscillations, specifically in the small intestine, are complex and remain poorly understood. We hypothesized that HF diet disrupts coordination of diurnal rhythms between host-derived antimicrobial peptides, particularly the host C-type lectin Regenerating islet-derived 3 gamma(Reg3γ), and gut microbial community membership, contributing to DIO and metabolic dysfunction.Distal ileal tissue and luminal contents were collected every 4 hours over a 12:12 LD cycle from regular chow (RC) vs. HF-fed germ-free (GF) and conventionally raised (CONV) C57Bl/6 age and sex-matched mice. Ileal tissue gene expression analysis reveals diurnal Reg3γ expression is only observed in RC-fed, but not HF-fed, CONV mice. Illumina MiSeq 16S rRNA gene amplicon sequencing of ileal luminal contents indicates that HF diet significantly shifts microbial community membership with a corresponding reduction in oscillations relative to RC. Specific Lactobacillaceae bacteria selected by RC oscillate and exhibit positive correlation with Reg3γ expression, while HF promotes expansion of Clostridiales bacteria that negatively correlate with Reg3γ. Using both in vitro intestinal organoid and in vivomonoassociation of GF mice, we identified that exposure to bacterial strains representative of those selected by RC or HF diet elicit a bi-directional interaction with Reg3γ; only RC-driven Lactobacillus rhamnosus GG (LGG) induces diurnal Reg3γ expression, suggesting a bacteria-specific effect. While dietary composition remains the primary driver of microbial oscillators, host factors such as Reg3γ provide secondary cues to drive abundance and oscillation of key gut microbes that are essential for host metabolic homeostasis.Together, these results demonstrate transkingdom co-evolved biological rhythms that are primarily influenced by diet, and reciprocal sensor-effector signals between host and microbial components. The diurnal dynamics of host innate immune factors and specific diet-induced ileal gut microbes are key for the maintenance of regional intestinal host-microbe interactions and metabolic homeostasis.
Objectives: Total Parenteral Nutrition (TPN) is a lifesaving therapy providing intravenous nutrition when enteral use is contraindicated. Prolonged TPN can induce hepatic complications (i.e., PN associated liver dysfunction [PNALD]) affecting 40% of patients. TPN is often infused at a steady rate which contributes to PNALD. Restricting TPN infusion to the evening can delay the condition, raising the possibility that specific infusion patterns may prevent PNALD. We hypothesized that, compared to steady-rate infusions, a sinusoidal infusion schedule matched to diurnal consumption patterns in mice, would attenuate PNALD. Methods: 17 male C57B/6 mice aged 9-11 weeks were randomly assigned to 3 groups: chow (n=5), steady rate (n=6), and sinusoidal (n=6). The jugular vein was cannulated with 0.12 mm diameter silicon catheter attached to TPN syringe on a programmable pump. Mice were housed in a metabolic chamber (Promethion Core, Sable Systems International, Las Vegas NV) at 30°C and infused with 5.5 mL/d of TPN formula (21.5% dextrose, 5.6% amino acids, 2% Intralipid-20) at a steady or sinusoidal rate for 5 days. Mice were euthanized and tissues were weighed, processed, and snap frozen. Average daily respiratory exchange rate (RER) was extracted for analysis and qPCR was conducted on hepatic metabolic targets. Results: Two-way ANOVA revealed significant group and time effects on RER (F = 1.19, r2 = 0.14, p = 0.004) with a mean difference of 0.063 (95% CI = 0.058 – 0.068, p < 0.001) between steady (mean = 0.96, min = 0.88, max = 1.11) and sinusoidal groups (mean = 0.90, min = 0.78, max = 0.96). PCR revealed trending differential expression of Srebp1 (F = 2.053, p = 0.18) and Acaca (F = 2.041, p = 0.18) driven by relatively higher expression under steady rate infusion. There were no significant differences in metabolic tissue weights or intestine length between groups. Conclusions: Sinusoidal infusions, matched to ad-libitum consumption patterns, are tolerated and do not induce complications in murine TPN. This novel approach may improve lipid utilization and match with circadian rhythm of metabolism. Further investigations are underway to establish this mouse model of human PNALD. Funding Sources: Metabolism and Nutrition Training Program T32 (DK 007665)Wisconsin Dairy Innovation Hub Start-up Funding.
Parenteral nutrition (PN) provides nutritional support intravenously to individuals who have gastrointestinal (GI) failure or contraindication to enteral feeding. Since the initial development of PN, researchers have developed specialized formulas with complete macronutrients, micronutrients, vitamins, minerals, and electrolytes to support patients’ metabolic needs. These formulas prevent malnutrition and optimize patient health, especially under long-term feeding circumstances. Although PN is commonly used and essential in preterm and malnourished patients, complications associated with PN feeding include gastrointestinal defects, infection, and other metabolic abnormalities such as liver injury and brain related disorders. In this chapter, we highlight an overview of PN and its association with abnormalities of microbiome composition as well as with gastrointestinal (GI), immune, hepatic, and neuronal disfunction. Within the gut, PN influences the number and composition of gut-associated lymphoid tissue (GALT) cells, altering adaptive immune responses. PN also modulates intestinal epithelium cell turnover, secretions, and gut barrier function, as well as the composition of the intestinal microbiome leading to changes in gut permeability. Collectively, these changes result in increased susceptibility to infection and injury. Here, we highlight animal models used to examine parenteral nutrition, changes that occur to the major organ systems, and recent advancement in using enteric nervous system (ENS) neuropeptides or microbially derived products during PN, which may improve GI, immune cell, hepatic, and neuronal function.
Parenteral nutrition (PN) prevents starvation and supports metabolic requirements intravenously when patients are unable to be fed enterally. Clinically, infants are frequently provided PN in intensive care settings along with exposure to antibiotics (ABX) to minimize infection during care. Unfortunately, neonates experience extremely high rates of hepatic complications. Adult rodent and piglet models of PN are well-established but neonatal models capable of leveraging the considerable transgenic potential of the mouse remain underdeveloped. Utilizing our newly established neonatal murine PN mouse model, we administered ABX or controlled drinking water to timed pregnant dams to disrupt the maternal microbiome. We randomized mouse pups to PN or sham surgery controls +/- ABX exposure. ABX or short-term PN decreased liver and brain organ weights, intestinal length, and mucosal architecture (vs. controls). PN significantly elevated evidence of hepatic proinflammatory markers, neutrophils and macrophage counts, bacterial colony-forming units, and evidence of cholestasis risk, which was blocked by ABX. However, ABX uniquely elevated metabolic regulatory genes resulting in accumulation of hepatocyte lipids, triglycerides, and elevated tauro-chenoxycholic acid (TCDCA) in serum. Within the gut, PN elevated the relative abundance of
Background: Outbred mice exhibit increased airway and intestinal immunoglobulin A (IgA) following injury when fed normal chow, consistent with humans. Parenteral nutrition (PN) eliminates IgA increases at both sites. Inbred mice are needed for detailed immunological studies; however, specific strains have not been evaluated for this purpose. BALB/c and C57BL/6 are common inbred mouse strains but demonstrate divergent immune responses to analogous stress. This study addressed which inbred mouse strain best replicates the outbred mouse and human immune response to injury. Methods: Intravenously cannulated mice received chow or PN for 5 days and then underwent sacrifice at 0 or 8 hours following controlled surgical injury (BALB/c: n = 16–21/group; C57BL/6: n = 12–15/group). Bronchoalveolar lavage (BAL) was analyzed by enzyme‐linked immunosorbent assay for IgA, tumor necrosis factor–α (TNF‐α), interleukin (IL)–1β, and IL‐6, while small intestinal wash fluid (SIWF) was analyzed for IgA. Results: No significant increase in BAL IgA occurred following injury in chow‐ or PN‐fed BALB/c mice (chow: P = .1; PN: P = .7) despite significant increases in BAL TNF‐α and SIWF IgA (chow: 264 ± 28 vs 548 ± 37, P < .0001; PN: 150 ± 12 vs 301 ± 17, P < .0001). Injury significantly increased mucosal IgA in chow‐fed C57BL/6 mice (BAL: 149 ± 33 vs 342 ± 87, P = .01; SIWF: 236 ± 28 vs 335 ± 32, P = .006) and BAL cytokines. After injury, PN‐fed C57BL/6 mice exhibited no difference in BAL IgA ( P = .9), BAL cytokines, or SIWF IgA ( P = .1). Conclusions: C57BL/6 mice exhibit similar airway responses to injury as outbred mice and humans, providing an appropriate model for studying mucosal responses to injury. The BALB/c mucosal immune system responds differently to injury and does not replicate the human injury response.
Pneumonia is the leading cause of infectious related death costing 12 billion dollars annually in the United States alone. Despite improvements in clinical care, total mortality remains around 4%, with inpatient mortality reaching 5-10%. For unknown reasons, mortality risk remains high even after hospital discharge and there is a need to identify those patients most at risk. Also of importance, clinical symptoms alone do not distinguish viral from bacterial infection which may delay appropriate treatment and may contribute to short-term and long-term mortality. Biomarkers have the potential to provide point of care diagnosis, identify high-risk patients, and increase our understanding of the biology of disease. However, there have been mixed results on the diagnostic performance of many of the analytes tested to date. Urine represents a largely untapped source for biomarker discovery and is highly accessible. To test this hypothesis, we collected urine from hospitalized patients with community-acquired pneumonia (CAP) and performed a comprehensive screen for urinary tract microbiota signatures, metabolite, and cytokine profiles. CAP patients were diagnosed with influenza or bacterial (Streptococcus pneumoniae and Staphylococcus aureus) etiologies and compared with healthy volunteers. Microbiome signatures showed marked shifts in taxonomic levels in patients with bacterial etiology versus influenza and CAP versus normal. Predictive modeling of 291 microbial and metabolite values achieved a + 90% accuracy with LASSO in predicting specific pneumonia etiology. This study demonstrates that urine from patients hospitalized with pneumonia may serve as a reliable and accessible sample to evaluate biomarkers that may diagnose etiology and predict clinical outcomes.
Immune checkpoint blockade (ICB) has improved outcomes in some cancers. A major limitation of ICB is that most patients fail to respond, which is partly attributable to immunosuppression. Obesity appears to improve immune checkpoint therapies in some cancers, but impacts on breast cancer (BC) remain unknown. In lean and obese mice, tumor progression and immune reprogramming were quantified in BC tumors treated with anti-programmed death-1 (PD-1) or control. Obesity augments tumor incidence and progression. Anti-PD-1 induces regression in lean mice and potently abrogates progression in obese mice. BC primes systemic immunity to be highly responsive to obesity, leading to greater immunosuppression, which may explain greater anti-PD-1 efficacy. Anti-PD-1 significantly reinvigorates antitumor immunity despite persistent obesity. Laminin subunit beta-2 (Lamb2), downregulated by anti-PD-1, significantly predicts patient survival. Lastly, a microbial signature associated with anti-PD-1 efficacy is identified. Thus, anti-PD-1 is highly efficacious in obese mice by reinvigorating durable antitumor immunity.Video abstracthttps://www.cell.com/cms/asset/411585c2-4b9b-4c33-989f-3bd379b0504f/mmc4.mp4Loading ...(mp4, 8.42 MB) Download video
