Louisiana Research Day Program Book 2025

Biomedical Research: Section 1

Biomedical Research: Section 1

Ryan Vergara, OMS-II; Hunter Santogrossi, OMS-III, Keith Jackson, PhD (ULM, College of Pharmacy); Dinesh Aryal, PhD (VCOM) 1 VCOM-Louisiana, 2 ULM-Louisiana 18 CHRONIC METABOLIC ACIDOSIS PROMOTES RENAL HEME OXYGENASE OVEREXPRESSION ALTERING TUBULAR SODIUM TRANSPORT IN EXPERIMENTAL RATS

Sahana Padumane, OMS-II; Sarah Voth, PhD 1 VCOM-Louisiana, Department of Cell Biology and Physiology 19 IN-VITRO EVALUATION OF TAU ACCUMULATION LEVELS IN HYPERGLYCEMIC VS NORMOGLYCEMIC CONDITIONS

Context: Heme oxygenase (HO) is an enzyme that catalyzes the degradation of heme to produce biliverdin, iron, and carbon monoxide. HO-1 isoform produced in kidney plays a key role in a cellular homeostasis, and its aberrant expression or activity is implicated in pathophysiology of a wide spectrum of metabolic disorders. Chronic metabolic acidosis (CMA) is one of these disorders whose consequence has been previously linked with pathogenesis of hypertension. However, there lacks direct evidence on HO-1 mediated effect of CMA on pressure natriuresis. This study aims to evaluate the extent of renal HO-1 expression during chronic metabolic acidotic state and its role in tubular sodium transport. Objectives: (i) To evaluate renal HO-1 levels during chronic metabolic acidosis, (ii) To investigate the sodium tubular transport mediated by HO-1 during the chronic acidotic conditions. Method: Male Sprague Dawley rats weighing 150-320g were grouped into 5 groups (n=5). (I. Control, II. CMA, III. CMA+DALA, IV. CMA+Fasudil, V. CMA+ZnPP.) 0.28M ammonium

chloride induced chronic acidosis model is implemented for the latter 4 groups along with respective inducer/inhibitor treatments (once a week), for the period of 8 weeks. At the end of experiment, microdialysis samples of renal interstitial fluid were taken, blood and urine samples were collected, from all 5 groups. Acidemia were measured on latter 4 groups using pH meter to confirm chronic acidosis. ELISA was performed to evaluate renal HO-1 levels from the dialysates. Sodium levels were measured in blood and urine samples collected using flame photometry. Mean arterial pressure (MAP) were taken of all animals using pressure transducer connected with catheterized carotid arteries prior to sacrifice. All animals used in this work were approved by IACUC at University of Louisiana at Monroe (Protocol # 23 SEPT DA_KEJ 01). Anticipated Results: Animals in group II – V were chronically acidotic at the end of experiment. ELISA confirmed the renal HO-1 levels & MAP in CMA group were significantly increased compared to control group. Increase in MAP in CMA group is consistent with our previous result. The CMA+DALA (HO-1 inducer)

group showed no significant increase in renal HO-1 levels compared to CMA group. Moreover, renal HO-1 levels in CMA+ZnPP (HO-1 inhibitor) group were not reduced significantly. This implied the systemic administration of HO-1 inducer/inhibitor had minimum to no effect on renal HO-1 levels. Similarly, no significant changes in MAP were observed in Groups III & V. However, Fasudil (ROCK inhibitor) treatment (Group IV), produced a significant decline in MAP but the renal HO-1 remains unchanged. Serum sodium levels were increased, but urine sodium was significantly reduced in the CMA group compared to the control, suggesting reduced pressure natriuresis. Conclusion: Our results demonstrated that the renal HO-1 expression is increased during chronic acidotic conditions. The Rho kinase (ROCK) has no effect on the renal HO-1 levels. Induction of HO-1 in kidneys are independent to the circulating HO-1. Furthermore, HO-1 mediated effect of the observed increase in MAP in CMA group might be due to sodium reabsorption, thereby increasing blood volume and vascular resistance.

Rationale: Nosocomial pneumonia is a frequent complication in the critical care setting. Lung infection promotes increased morbidity and mortality despite resolution of the active infection. Survivors often suffer poor outcomes including chronic impairment post-discharge. Hyperglycemia, considered a modifiable risk factor for this acute-to chronic disease transition known as post intensive care syndrome (PICS), is particularly exacerbated during infection. Some hospital acquired pathogens, including Pseudomonas aeruginosa, contribute to chronic impairment by seeding the blood with prion-like tau cytotoxins that promote end-organ damage. P. aeruginosa utilizes a cyclase toxin, exoenzyme Y (ExoY), to promote aberrant cNMP signaling in the air blood barrier of the lung to induce permeability and toxic tau release. ExoY is homologous to the CyaA toxin of Bordetella pertussis and Edema factor of Bacillus anthracis. However, whether hyperglycemia during infection contributes to the poor outcomes associated with PICS via increased tau prion release has not been determined. We hypothesize that hyperglycemia during infection will promote barrier disruption and tau prion release.

Methods: Wildtype and tau knockout pulmonary microvascular endothelial cells (PMVECs) were serum starved and infected with isogenic strains of P. aeruginosa at an MOI of 20:1 in HBSS with glucose concentrations of 100 mg/dL, 150 mg/dL, and 200 mg/dL. P. aeruginosa strains ExoYK81M (control strain; does not make cNMPs) and ExoY+ (virulent; generates cNMPs in host cells) were used for infections. Supernatants were filter-sterilized, boiled, and iced to denature non-amyloid proteins. Samples were probed for prion-like tau and amyloid burden was assessed via thioflavin T. Cytotoxicity of the supernatant was ascertained through transferring heat-inactivated supernatant to naïve cells and imaging over time and measuring cell health with resazurin. Prion like self-replicating capacity was determined via passaging assays.

Results: TBD

Conclusion: TBD

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2025 Research Recognition Day