An antibody to IL-1 receptor 7 protects mice from LPS-induced tissue and systemic inflammation.

Introduction: Interleukin-18 (IL-18), a pro-inflammatory cytokine belonging to the IL-1 Family, is a key mediator ofautoinflammatory diseases associated with the development of macrophage activation syndrome (MAS).High levels of IL-18 correlate with MAS and COVID-19 severity and mortality, particularly in COVID-19patients with MAS. As an inflammation inducer, IL-18 binds its receptor IL-1 Receptor 5 (IL-1R5), leadingto the recruitment of the co-receptor, IL-1 Receptor 7 (IL-1R7). This heterotrimeric complex subsequentlyinitiates downstream signaling, resulting in local and systemic inflammation. Methods: We reported earlier the development of a novel humanized monoclonal anti-human IL-1R7 antibody whichspecifically blocks the activity of human IL-18 and its inflammatory signaling in human cell and wholeblood cultures. In the current study, we further explored the strategy of blocking IL-1R7 inhyperinflammation in vivo using animal models. Results: We first identified an anti-mouse IL-1R7 antibody that significantly suppressed mouse IL-18 andlipopolysaccharide (LPS)-induced IFNg production in mouse splenocyte and peritoneal cell cultures. Whenapplied in vivo, the antibody reduced Propionibacterium acnes and LPS-induced liver injury and protectedmice from tissue and systemic hyperinflammation. Importantly, anti-IL-1R7 significantly inhibited plasma,liver cell and spleen cell IFNg production. Also, anti-IL-1R7 downregulated plasma TNFa, IL-6, IL-1b,MIP-2 production and the production of the liver enzyme ALT. In parallel, anti-IL-1R7 suppressed LPSinducedinflammatory cell infiltration in lungs and inhibited the subsequent IFNg production andinflammation in mice when assessed using an acute lung injury model. Discussion: Altogether, our data suggest that blocking IL-1R7 represents a potential therapeutic strategy to specificallymodulate IL-18-mediated hyperinflammation, warranting further investigation of its clinical application intreating IL-18-mediated diseases, including MAS and COVID-19.

Dysregulation of hepatic one-carbon metabolism in classical homocystinuria: Implications of redox-sensitive DHFR repression and tetrahydrofolate depletion for pathogenesis and treatment.

Cystathionine beta-synthase-deficient homocystinuria (HCU) is a life-threatening disorder of sulfur metabolism. HCU can be treated by using betaine to lower tissue and plasma levels of homocysteine (Hcy). Here, we show that mice with severely elevated Hcy and potentially deficient in the folate species tetrahydrofolate (THF) exhibit a very limited response to betaine indicating that THF plays a critical role in treatment efficacy. Analysis of a mouse model of HCU revealed a 10-fold increase in hepatic levels of 5-methyl -THF and a 30-fold accumulation of formiminoglutamic acid, consistent with a paucity of THF. Neither of these metabolite accumulations were reversed or ameliorated by betaine treatment. Hepatic expression of the THF-generating enzyme dihydrofolate reductase (DHFR) was significantly repressed in HCU mice and expression was not increased by betaine treatment but appears to be sensitive to cellular redox status. Expression of the DHFR reaction partner thymidylate synthase was also repressed and metabolomic analysis detected widespread alteration of hepatic histidine and glutamine metabolism. Many individuals with HCU exhibit endothelial dysfunction. DHFR plays a key role in nitric oxide (NO) generation due to its role in regenerating oxidized tetrahydrobiopterin, and we observed a significant decrease in plasma NOx (NO2 + NO3) levels in HCU mice. Additional impairment of NO generation may also come from the HCU-mediated induction of the 20-hydroxyeicosatetraenoic acid generating cytochrome CYP4A. Collectively, our data shows that HCU induces dysfunctional one-carbon metabolism with the potential to both impair betaine treatment and contribute to multiple aspects of pathogenesis in this disease.

Activation of AMPD2 drives metabolic dysregulation and liver disease in mice with hereditary fructose intolerance.

Hereditary fructose intolerance (HFI) is a painful and potentially lethal genetic disease caused by a mutation in aldolase B resulting in accumulation of fructose-1-phosphate (F1P). No cure exists for HFI and treatment is limited to avoid exposure to fructose and sugar. Using aldolase B deficient mice, here we identify a yet unrecognized metabolic event activated in HFI and associated with the progression of the disease. Besides the accumulation of F1P, here we show that the activation of the purine degradation pathway is a common feature in aldolase B deficient mice exposed to fructose. The purine degradation pathway is a metabolic route initiated by adenosine monophosphate deaminase 2 (AMPD2) that regulates overall energy balance. We demonstrate that very low amounts of fructose are sufficient to activate AMPD2 in these mice via a phosphate trap. While blocking AMPD2 do not impact F1P accumulation and the risk of hypoglycemia, its deletion in hepatocytes markedly improves the metabolic dysregulation induced by fructose and corrects fat and glycogen storage while significantly increasing the voluntary tolerance of these mice to fructose. In summary, we provide evidence for a critical pathway activated in HFI that could be targeted to improve the metabolic consequences associated with fructose consumption.

Quantifying Protein Acetylation in Diabetic Nephropathy from Formalin-Fixed Paraffin-Embedded Tissue.

PURPOSE: Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus and a leading cause of chronic kidney disease and end-stage renal disease. One potential mechanism underlying cellular dysfunction contributing to kidney disease is aberrant protein post-translational modifications. Lysine acetylation is associated with cellular metabolic flux and is thought to be altered in patients with diabetes and dysfunctional renal metabolism. EXPERIMENTAL DESIGN: A novel extraction and LC-MS/MS approach was adapted to quantify sites of lysine acetylation from formalin-fixed paraffin-embedded (FFPE) kidney tissue and from patients with DKD and non-diabetic donors (n = 5 and n = 7, respectively). RESULTS: Analysis of FFPE tissues identified 840 total proteins, with 225 of those significantly changing in patients with DKD. Acetylomic analysis quantified 289 acetylated peptides, with 69 of those significantly changing. Pathways impacted in DKD patients revealed numerous metabolic pathways, specifically mitochondrial function, oxidative phosphorylation, and sirtuin signaling. Differential protein acetylation in DKD patients impacted sirtuin signaling, valine, leucine, and isoleucine degradation, lactate metabolism, oxidative phosphorylation, and ketogenesis. CONCLUSIONS AND CLINICAL RELEVANCE: A quantitative acetylomics platform was developed for protein biomarker discovery in formalin-fixed and paraffin-embedded biopsies of kidney transplant patients suffering from DKD.

Disruption in glutathione metabolism and altered energy production in the liver and kidney after ischemic acute kidney injury in mice.

Acute kidney injury (AKI) is a systemic disease that affects energy metabolism in various remote organs in murine models of ischemic AKI. However, AKI-mediated effects in the liver have not been comprehensively assessed. After inducing ischemic AKI in 8-10-week-old, male C57BL/6 mice, mass spectrometry metabolomics revealed that the liver had the most distinct phenotype 24 h after AKI versus 4 h and 7 days. Follow up studies with in vivo [13C6]-glucose tracing on liver and kidney 24 h after AKI revealed 4 major findings: (1) increased flux through glycolysis and the tricarboxylic (TCA) cycle in both kidney and liver; (2) depleted hepatic glutathione levels and its intermediates despite unchanged level of reactive oxygen species, suggesting glutathione consumption exceeds production due to systemic oxidative stress after AKI; (3) hepatic ATP depletion despite unchanged rate of mitochondrial respiration, suggesting increased ATP consumption relative to production; (4) increased hepatic and renal urea cycle intermediates suggesting hypercatabolism and upregulation of the urea cycle independent of impaired renal clearance of nitrogenous waste. Taken together, this is the first study to describe the hepatic metabolome after ischemic AKI in a murine model and demonstrates that there is significant liver-kidney crosstalk after AKI.

Inflammatory Cells in Control and Prolapsed Uterosacral Ligament Tissue.

Pelvic organ prolapse (POP), a downward descent of the vagina and/or uterus through the vaginal canal, is a prevalent condition affecting up to 40% of women. Several risk factors of POP have been identified, including childbirth, connective tissue defects, and chronic intra-abdominal pressure; however, the underlying etiologies of POP development are not fully understood, leading to a high burden on patients and the healthcare systems. The uterosacral ligaments are key support structures of the uterus and upper vagina. Our previous work describes observed histopathological changes in uterosacral ligament (USL) tissue and demonstrates the presence of neutrophils in a subgroup of POP individuals. This presence of neutrophils prompted an examination for the presence of a broader spectrum of inflammatory cell types in the USL. Immunohistochemical staining was performed to identify neutrophils, lymphocytes, macrophages, and mast cells outside of the vasculature. All 4 inflammatory cell types were increased in the POP-HQ system-defined POP-Inflammatory (POP-I) phenotype USL tissue relative to the USL tissues of control or other POP-HQ phenotypes. Focal T-lymphocyte and macrophage co-accumulations were observed in the arterial walls from some patients of the POP-vascular (POP-V) phenotype suggesting previous arterial injury. In addition, 1 control and 2 POP-V subjects' USLs contained arterial wall foamy macrophages, evidence of atherosclerosis. These findings further support a complex etiology for POP and indicate that personalized approaches to preventing and treating the condition may be warranted.

Prophage terminase with tRNase activity sensitizes Salmonella enterica to oxidative stress.

Phage viruses shape the evolution and virulence of their bacterial hosts. The Salmonella enterica genome encodes several stress-inducible prophages. The Gifsy-1 prophage terminase protein, whose canonical function is to process phage DNA for packaging in the virus head, unexpectedly acts as a transfer ribonuclease (tRNase) under oxidative stress, cleaving the anticodon loop of tRNALeu. The ensuing RNA fragmentation compromises bacterial translation, intracellular survival, and recovery from oxidative stress in the vertebrate host. S. enterica adapts to this transfer RNA (tRNA) fragmentation by transcribing the RNA repair Rtc system. The counterintuitive translational arrest provided by tRNA cleavage may subvert prophage mobilization and give the host an opportunity for repair as a way of maintaining bacterial genome integrity and ultimately survival in animals.

Antigen-driven CD8 + T cell clonal expansion is a prominent feature of MASH in humans and mice.

Background and Aims: Chronic liver disease due to metabolic dysfunction-associated steatohepatitis (MASH) is a rapidly increasing global epidemic. MASH progression is a consequence of the complex interplay between inflammatory insults and dysregulated hepatic immune responses. T lymphocytes have been shown to accumulate in the liver during MASH, but the cause and consequence of T cell accumulation in the liver remain unclear. Our study aimed to define the phenotype and T cell receptor diversity of T cells from human cirrhotic livers and an animal model of MASH to begin resolving their function in disease. Approach and Results: In these studies, we evaluated differences in T cell phenotype in the context of liver disease we isolated liver resident T cell populations from individuals with cirrhosis and a murine model of MASH. Using both 5' single cell sequencing and flow cytometry we defined the phenotype and T cell receptor repertoire of liver resident T cells during health and disease. Conclusions: MASH-induced cirrhosis and diet-induced MASH in mice resulted in the accumulation of activated and clonally expanded T cells in the liver. The clonally expanded T cells in the liver expressed markers of chronic antigenic stimulation, including PD1 , TIGIT and TOX . Overall, this study establishes for the first time that T cells undergo antigen-dependent clonal expansion and functional differentiation during the progression of MASH. These studies could lead to the identification of potential antigenic targets that drive T cell activation, clonal expansion, and recruitment to the liver during MASH.

Myeloid Cells and Sphingosine-1-Phosphate Are Required for TCRαß Intraepithelial Lymphocyte Recruitment to the Colon Epithelium.

Intraepithelial lymphocytes (IELs) are T cells important for the maintenance of barrier integrity in the intestine. Colon IELs are significantly reduced in both MyD88-deficient mice and those lacking an intact microbiota, suggesting that MyD88-mediated detection of bacterial products is important for the recruitment and/or retention of these cells. Here, using conditionally deficient MyD88 mice, we show that myeloid cells are the key mediators of TCRαß+ IEL recruitment to the colon. Upon exposure to luminal bacteria, myeloid cells produce sphingosine-1-phosphate (S1P) in a MyD88-dependent fashion. TCRαß+ IEL recruitment may be blocked using the S1P receptor antagonist FTY720, confirming the importance of S1P in the recruitment of TCRαß+ IELs to the colon epithelium. Finally, using the TNFΔARE/+ model of Crohn's-like bowel inflammation, we show that disruption of colon IEL recruitment through myeloid-specific MyD88 deficiency results in reduced pathology. Our results illustrate one mechanism for recruitment of a subset of IELs to the colon.

Epithelial heme oxygenase-1 enhances colonic tumorigenesis by inhibiting ferroptosis.

Colorectal cancer has been linked to chronic colitis and red meat consumption, which can increase colonic iron and heme. Heme oxygenase-1 ( Hmox1 ) metabolizes heme and releases ferrous iron, but its role in colonic tumorigenesis is not well-described. Recent studies suggest that ferroptosis, the iron-dependent form of cell death, protects against colonic tumorigenesis. Ferroptosis culminates in excessive lipid peroxidation that is constrained by the antioxidative glutathione pathway. We observed increased mucosal markers of ferroptosis and glutathione metabolism in the setting of murine and human colitis, as well as murine colonic neoplasia. We obtained similar results in murine and human colonic epithelial organoids exposed to heme and the ferroptosis activator erastin, especially induction of Hmox1 . RNA sequencing of colonic organoids from mice with deletion of intestinal epithelial Hmox1 (Hmox1 ΔIEC ) revealed increased ferroptosis and activated glutathione metabolism after heme exposure. In a colitis-associated cancer model we observed significantly fewer and smaller tumors in Hmox1 ΔIEC mice compared to littermate controls. Transcriptional profiling of Hmox1 ΔIEC tumors and tumor organoids revealed increased ferroptosis and oxidative stress markers in tumor epithelial cells. In total, our findings reveal ferroptosis as an important colitis-associated cancer signature pathway, and Hmox1 as a key regulator in the tumor microenvironment.

Anaerobic respiration of host-derived methionine sulfoxide protects intracellular Salmonella from the phagocyte NADPH oxidase.

Intracellular Salmonella experiencing oxidative stress downregulates aerobic respiration. To maintain cellular energetics during periods of oxidative stress, intracellular Salmonella must utilize terminal electron acceptors of lower energetic value than molecular oxygen. We show here that intracellular Salmonella undergoes anaerobic respiration during adaptation to the respiratory burst of the phagocyte NADPH oxidase in macrophages and in mice. Reactive oxygen species generated by phagocytes oxidize methionine, generating methionine sulfoxide. Anaerobic Salmonella uses the molybdenum cofactor-containing DmsABC enzymatic complex to reduce methionine sulfoxide. The enzymatic activity of the methionine sulfoxide reductase DmsABC helps Salmonella maintain an alkaline cytoplasm that supports the synthesis of the antioxidant hydrogen sulfide via cysteine desulfuration while providing a source of methionine and fostering redox balancing by associated dehydrogenases. Our investigations demonstrate that nontyphoidal Salmonella responding to oxidative stress exploits the anaerobic metabolism associated with dmsABC gene products, a pathway that has accrued inactivating mutations in human-adapted typhoidal serovars.

Implications of neonatal absence of innate immune mediated NFκB/AP1 signaling in the murine liver.

BACKGROUND: The developmental immaturity of the innate immune system helps explains the increased risk of infection in the neonatal period. Importantly, innate immune signaling pathways such as p65/NFκB and c-Jun/AP1 are responsible for the prevention of hepatocyte apoptosis in adult animals, yet whether developmental immaturity of these pathways increases the risk of hepatic injury in the neonatal period is unknown. METHODS: Using a murine model of endotoxemia (LPS 5 mg/kg IP x 1) in neonatal (P3) and adult mice, we evaluated histologic evidence of hepatic injury and apoptosis, presence of p65/NFκB and c-Jun/AP1 activation and associated transcriptional regulation of apoptotic genes. RESULTS: We demonstrate that in contrast to adults, endotoxemic neonatal (P3) mice exhibit a significant increase in hepatic apoptosis. This is associated with absent hepatic p65/NFκB signaling and impaired expression of anti-apoptotic target genes. Hepatic c-Jun/AP1 activity was attenuated in endotoxemic P3 mice, with resulting upregulation of pro-apoptotic factors. CONCLUSIONS: These results demonstrate that developmental absence of innate immune p65/NFκB and c-Jun/AP1 signaling, and target gene expression is associated with apoptotic injury in neonatal mice. More work is needed to determine if this contributes to long-term hepatic dysfunction, and whether immunomodulatory approaches can prevent this injury. IMPACT: Various aspects of developmental immaturity of the innate immune system may help explain the increased risk of infection in the neonatal period. In adult models of inflammation and infection, innate immune signaling pathways such as p65/NFκB and c-Jun/AP1 are responsible for a protective, pro-inflammatory transcriptome and regulation of apoptosis. We demonstrate that in contrast to adults, endotoxemic neonatal (P3) mice exhibit a significant increase in hepatic apoptosis associated with absent hepatic p65/NFκB signaling and c-Jun/AP1 activity. We believe that these results may explain in part hepatic dysfunction with neonatal sepsis, and that there may be unrecognized developmental and long-term hepatic implications of early life exposure to systemic inflammatory stress.

MAIT cells drive chronic inflammation in a genetically diverse murine model of spontaneous colitis.

Background & aims: Lymphocytes that produce IL-17 can confer protective immunity during infections by pathogens, yet their involvement in inflammatory diseases is a subject of debate. Although these cells may perpetuate inflammation, resulting in tissue damage, they are also capable of contributing directly or indirectly to tissue repair, thus necessitating more detailed investigation. Mucosal-Associated-Invariant-T (MAIT) cells are innate-like T cells, acquiring a type III phenotype in the thymus. Here, we dissected the role of MAIT cells in vivo using a spontaneous colitis model in a genetically diverse mouse strain. Methods: Multiparameter spectral flow cytometry and scRNAseq were used to characterize MAIT and immune cell dynamics and transcriptomic signatures respectively, in the collaborative-cross strain, CC011/Unc and CC011/Unc- Traj33 -/- . Results: In contrast to many conventional mouse laboratory strains, the CC011 strain harbors a high baseline population of MAIT cells. We observed an age-related increase in colonic MAIT cells, Th17 cells, regulatory T cells, and neutrophils, which paralleled the development of spontaneous colitis. This progression manifested histological traits reminiscent of human IBD. The transcriptomic analysis of colonic MAIT cells from CC011 revealed an activation profile consistent with an inflammatory milieu, marked by an enhanced type-III response. Notably, IL-17A was abundantly secreted by MAIT cells in the colons of afflicted mice. Conversely, in the MAIT cell-deficient CC011-Traj33-/- mice, there was a notable absence of significant colonic histopathology. Furthermore, myeloperoxidase staining indicated a substantial decrease in colonic neutrophils. Conclusions: Our findings suggest that MAIT cells play a pivotal role in modulating the severity of intestinal pathology, potentially orchestrating the inflammatory process by driving the accumulation of neutrophils within the colonic environment.

Disrupting Poly(ADP-ribosyl)ating Pathway Creates Premalignant Conditions in Mammalian Liver.

Hepatocellular carcinoma (HCC) is a major global health concern, representing one of the leading causes of cancer-related deaths. Despite various treatment options, the prognosis for HCC patients remains poor, emphasizing the need for a deeper understanding of the factors contributing to HCC development. This study investigates the role of poly(ADP-ribosyl)ation in hepatocyte maturation and its impact on hepatobiliary carcinogenesis. A conditional Parg knockout mouse model was employed, utilizing Cre recombinase under the albumin promoter to target Parg depletion specifically in hepatocytes. The disruption of the poly(ADP-ribosyl)ating pathway in hepatocytes affects the early postnatal liver development. The inability of hepatocytes to finish the late maturation step that occurs early after birth causes intensive apoptosis and acute inflammation, resulting in hypertrophic liver tissue with enlarged hepatocytes. Regeneration nodes with proliferative hepatocytes eventually replace the liver tissue and successfully fulfill the liver function. However, early developmental changes predispose these types of liver to develop pathologies, including with a malignant nature, later in life. In a chemically induced liver cancer model, Parg-depleted livers displayed a higher tendency for hepatocellular carcinoma development. This study underscores the critical role of the poly(ADP-ribosyl)ating pathway in hepatocyte maturation and highlights its involvement in liver pathologies and hepatobiliary carcinogenesis. Understanding these processes may provide valuable insights into liver biology and liver-related diseases, including cancer.

Endogenous Fructose Production and Metabolism Drive Metabolic Dysregulation and Liver Disease in Mice with Hereditary Fructose Intolerance.

Excessive intake of sugar, and particularly fructose, is closely associated with the development and progression of metabolic syndrome in humans and animal models. However, genetic disorders in fructose metabolism have very different consequences. While the deficiency of fructokinase, the first enzyme involved in fructose metabolism, is benign and somewhat desirable, missense mutations in the second enzyme, aldolase B, causes a very dramatic and sometimes lethal condition known as hereditary fructose intolerance (HFI). To date, there is no cure for HFI, and treatment is limited to avoiding fructose and sugar. Because of this, for subjects with HFI, glucose is their sole source of carbohydrates in the diet. However, clinical symptoms still occur, suggesting that either low amounts of fructose are still being consumed or, alternatively, fructose is being produced endogenously in the body. Here, we demonstrate that as a consequence of consuming high glycemic foods, the polyol pathway, a metabolic route in which fructose is produced from glucose, is activated, triggering a deleterious mechanism whereby glucose, sorbitol and alcohol induce severe liver disease and growth retardation in aldolase B knockout mice. We show that generically and pharmacologically blocking this pathway significantly improves metabolic dysfunction and thriving and increases the tolerance of aldolase B knockout mice to dietary triggers of endogenous fructose production.

Expression of circadian regulatory genes is dysregulated by increased cytokine production in mice subjected to concomitant intestinal injury and parenteral nutrition.

BACKGROUND: We have developed a mouse model of Parenteral Nutrition Associated Cholestasis (PNAC) in which combining intestinal inflammation and PN infusion results in cholestasis, hepatic macrophage activation, and transcriptional suppression of bile acid and sterol signaling and transport. In the liver, the master circadian gene regulators Bmal/Arntl and Clock drive circadian modulation of hepatic functions, including bile acid synthesis. Once activated, Bmal and Clock are downregulated by several transcription factors including Reverbα (Nr1d1), Dbp (Dbp), Dec1/2 (Bhlhe40/41), Cry1/2 (Cry1/2) and Per1/2 (Per1/2). The aim of this study was to examine the effects of PN on expression of hepatic circadian rhythm (CR) regulatory genes in mice. METHODS: WT, IL1KO or TNFRKO mice were exposed to dextran sulfate sodium (DSS) for 4 days followed by soy-oil lipid emulsion-based PN infusion through a central venous catheter for 14 days (DSS-PN) and the expression of key CR regulatory transcription factors evaluated. Animals were NPO on a 14 hr light-dark cycle and were administered PN continuously over 24 hrs. Mice were sacrificed, and hepatic tissue obtained at 9-10AM (Zeitgeber Z+3/Z+4 hrs). PNAC was defined by increased serum aspartate aminotransferase, alanine aminotransferase, total bile acids, and total bilirubin and the effect of i.p. injection of recombinant IL-1ß (200ng/mouse) or TNFα (200ng/mouse) on CR expression was examined after 4 hrs. RESULTS: In the PNAC model, DSS-PN increased serum biomarkers of hepatic injury (ALT, AST, serum bile acids) which was suppressed in both DSS-PN IL1KO and DSS-PN TNFRKO mice. In WT DSS-PN, mRNA expression of Arntl and Dec1 was suppressed corresponding to increased Nr1d1, Per2, Dbp and Dec2. These effects were ameliorated in both DSS-PN IL1KO and DSS-PN TNFRKO groups. Western analysis of the circadian transcription factor network revealed in WT mice DSS-PN significantly suppressed Reverbα, Bmal, Dbp, Per2 and Mtnr1b. With the exception of Dbp, DSS-PN mediated suppression was ameliorated by both IL1KO and TNFRKO. Intraperitoneal injection of IL-1ß or TNFα into WT mice increased serum AST and ALT and suppressed mRNA expression of Nr1d1, Arntl and Clock and increased Dbp and Per2. CONCLUSIONS: Altered expression of CR-dependent regulatory genes during PNAC accompanies cholestasis and is, in part, due to increased cytokine (IL-1ß and TNFα) production. Evaluation of the effects of modulating CR in PNAC thus deserves further investigation.

REMOTE BURN INJURY IN AGED MICE INDUCES COLONIC LYMPHOID AGGREGATE EXPANSION AND DYSBIOSIS OF THE FECAL MICROBIOME WHICH CORRELATES WITH NEUROINFLAMMATION.

ABSTRACT: The Earth's population is aging, and by 2050, one of six people will be 65 years or older. Therefore, proper treatment of injuries that disproportionately impact people of advanced age will be more important. Clinical studies reveal people 65 years or older account for 16.5% of all burn injuries and experience higher morbidity, including neurocognitive decline, and mortality that we and others believe are mediated, in part, by heightened intestinal permeability. Herein, we used our clinically relevant model of scald burn injury in young and aged mice to determine whether age and burn injury cooperate to induce heightened colonic damage, alterations to the fecal microbiome, and whether resultant changes in the microbiome correlate with neuroinflammation. We found that aged, burn-injured mice have an increase in colonic lymphoid aggregates, inflammation, and proinflammatory chemokine expression when compared with young groups and sham-injured aged mice. We then performed fecal microbiota sequencing and found a striking reduction in gut protective bacterial taxa, including Akkermansia , in the aged burn group compared with all other groups. This reduction correlated with an increase in serum fluorescein isothiocyanate-Dextran administered by gavage, indicating heightened intestinal permeability. Furthermore, loss of Akkermansia was highly correlated with increased messenger RNA expression of neuroinflammatory markers in the brain, including chemokine ligand 2, TNF-α, CXC motif ligand 1, and S100 calcium-binding protein A8. Finally, we discovered that postburn alterations in the microbiome correlated with measures of strength in all treatment groups, and those that performed better on the rotarod and hanging wire tests had higher abundance of Akkermansia than those that performed worse. Taken together, these findings indicate that loss of protective bacteria after burn injury in aged mice contributes to alterations in the colon, gut leakiness, neuroinflammation, and strength. Therefore, supplementation of protective bacteria, such as Akkermansia , after burn injury in aged patients may have therapeutic benefit.

Ethanol exacerbates pulmonary complications after burn injury in mice, regardless of frequency of ethanol exposures.

Burn injuries are associated with significant morbidity and mortality, and lungs are the most common organ to fail. Interestingly, patients with alcohol intoxication at the time of burn have worse clinical outcomes, including pulmonary complications. Using a clinically relevant murine model, we have previously reported that episodic ethanol exposure before burn exacerbated lung inflammation. Specifically, intoxicated burned mice had worsened pulmonary responses, including increased leukocyte infiltration and heightened levels of CXCL1 and IL-6. Herein, we examined whether a single binge ethanol exposure before scald burn injury yields similar pulmonary responses. C57BL/6 male mice were given ethanol (1.2 g/kg) 30 min before a 15 % total body surface area burn. These mice were compared to a second cohort given episodic ethanol binge for a total of 6 days (3 days ethanol, 4 days rest, 3 days ethanol) prior to burn injury. 24 h after burn, histopathological examination of lungs were performed. In addition, survival, and levels of infiltrating leukocytes, CXCL1, and IL-6 were quantified. Episodic and single ethanol exposure before burn decreased survival compared to burn only mice and sham vehicle mice, respectively (p < 0.05). However, no difference in survival was observed between burned mice with single and episodic ethanol binge. Examination of H&E-stained lung sections revealed that regardless of ethanol binge frequency, intoxication prior to burn worsened pulmonary inflammation, evidenced by elevated granulocyte accumulation and congestion, relative to burned mice without any ethanol exposure. Levels of infiltrating granulocyte in the lungs were significantly higher in burned mice with both episodic and single ethanol intoxication, compared to burn injury only (p < 0.05). In addition, there was no difference in the granulocyte count between single and ethanol binge mice with burn injury. Neutrophil chemoattractant CXCL1 levels in the lung were similarly increased following single and episodic ethanol exposure prior to burn compared to burn alone (22-fold and 26-fold respectively, p < 0.05). Lastly, we assessed pulmonary IL-6, which revealed that irrespective of frequency, ethanol exposure combined with burn injury raised pro-inflammatory cytokine IL-6 in the lungs relative to burn mice. Again, we did not find any difference in the amount of IL-6 in lungs of burned mice with single and episodic ethanol intoxication. Taken altogether, these data demonstrate that both single and episodic exposure to ethanol prior to burn injury similarly worsens pulmonary inflammation. These results suggest that ethanol-induced exacerbation of the pulmonary responses to burn injury is due to presence of ethanol at the time of injury rather than longer-term effects of ethanol exposure.

Endocrine pancreas-specific Gclc gene deletion causes a severe diabetes phenotype.

Reduced glutathione (GSH) is an abundant antioxidant that regulates intracellular redox homeostasis by scavenging reactive oxygen species (ROS). Glutamate-cysteine ligase catalytic (GCLC) subunit is the rate-limiting step in GSH biosynthesis. Using the Pax6-Cre driver mouse line, we deleted expression of the Gclc gene in all pancreatic endocrine progenitor cells. Intriguingly, Gclc knockout (KO) mice, following weaning, exhibited an age-related, progressive diabetes phenotype, manifested as strikingly increased blood glucose and decreased plasma insulin levels. This severe diabetes trait is preceded by pathologic changes in islet of weanling mice. Gclc KO weanlings showed progressive abnormalities in pancreatic morphology including: islet-specific cellular vacuolization, decreased islet-cell mass, and alterations in islet hormone expression. Islets from newly-weaned mice displayed impaired glucose-stimulated insulin secretion, decreased insulin hormone gene expression, oxidative stress, and increased markers of cellular senescence. Our results suggest that GSH biosynthesis is essential for normal development of the mouse pancreatic islet, and that protection from oxidative stress-induced cellular senescence might prevent abnormal islet-cell damage during embryogenesis.