Negative Energy Balance Is Associated with Inflammatory and Oxidative Stress Conditions in Early Lactating Dairy Cows

Negative Energy Balance Is Associated with Inflammatory and Oxidative Stress Conditions in Early Lactating Dairy Cows

mtDNA and is integral to its transcription and replication. Using mice heterozygous for cardiomyocyte-specific Tfam deletion (Tfamwt/-) and WT control...

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mtDNA and is integral to its transcription and replication. Using mice heterozygous for cardiomyocyte-specific Tfam deletion (Tfamwt/-) and WT controls we induced sepsis by peritoneal implantation of a S. aureus (106CFU) impregnated clot to test whether loss of a single cardiac Tfam allele would exacerbate mitochondrial oxidative stress and reduce post sepsis organ recovery. Pre-sepsis, there were no appreciable differences in histology, ultrastructure or echocardiography between Tfam wt/-and WT hearts. Cardiac Tfam protein and mtDNA levels were also similar between strains. However, Tfam wt/-hearts did have increased basal mitochondrial oxidative stress demonstrated by increased protein carbonylation and 8-hydroxyguanosine colocalization with citrate synthase. Coincidentally, inflammasome activation was slightly increased in the Tfam wt/-heart. Post-sepsis, Tfam levels in WT mice increased concordantly with mtDNA, indicative of mitochondrial biogenesis. In contrast, Tfam levels fell after sepsis in Tfam wt/-hearts and mtDNA failed to increase. Electron microscopy revealed impressive mitochondrial damage in the Tfamwt/- strain characterized by organelle swelling and decreased cristae electron density. Tfam wt/-and WT hearts exhibited similar early (24 hr post-sepsis) myocardial leukocyte infiltration, histologic damage, and cell death by TUNEL assay. By 48 h post sepsis induction, the cell-death rate returned towards baseline in the WT heart, and histologic damage and inflammation were substantially mitigated. In contrast, more extensive histologic damage, inflammation, nuclear DNA oxidation and cell death tracked with increasing duration of sepsis in the Tfam wt/-heart. We conclude that loss of one Tfam allele results in basal oxidative stress and inflammasome activation and that robust Tfam upregulation is required for mitochondrial and organ recovery after sepsis.

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Jerome Lapointe1, Caroline Roy1, Marilou Lavoie1, Noemie Bergeron1, Daniele Beaudry1, Isabelle Blanchet1, Helene V Petit1, and Marie-France Palin1 1 Agriculture and Agri-Food Canada, Canada High-yielding dairy cows are susceptible to encounter severe metabolic stress conditions during transition and early lactation as feed intake is too low to meet energy requirements for maintenance and milk production. Hepatic and mammary gland tissues are particularly affected by such metabolic disorders, which are tightly associated with occurrence of infections and diseases. The development of innovative approaches thus appears essential to enhance health status of cows. However, better identification and characterization of well-defined markers of energetic status, oxidative stress and inflammation around calving is required. Ten (10) multiparous high-yielding Holstein cows were used to assess metabolic and oxidative status. Blood and urine samples were collected on week 4, 3, 2 and 1 prior to expected calving date and on week 1, 2, 3, 4, 5, 7, and 10 post-calving. Biopsies were taken on week 4 prior to calving (liver) as well as on week 1, 4 and 10 post-FDOYLQJ OLYHU DQG PDPPDU\ JODQG  3ODVPD OHYHOV RI ȕhydroxybutyrate, non-esterified fatty acids and glucose, and hepatic levels of ATP and AMPK indicated that cows were in negative energy balance from week 1 to 4 following calving. The early lactation period was also characterized by oxidative stress conditions as revealed by increased systemic oxidative damage to proteins (carbonyls) and DNA (8-OHdG). Analysis of enzymatic activity and/or mRNA expression of major cellular antioxidants

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(GPx, SOD, CAT and PRDx) at systemic, hepatic and mammary gland levels strongly suggested that antioxidant capacity was reduced during the same period. Plasma levels of acute phase proteins (SAA and HP), which are normally associated with inflammatory conditions, were also increased from week 1 to week 4 after calving. Altogether, these results clearly revealed that dairy cows were affected by energy deficiencies and oxidative stress conditions from weeks 1 to 4 following calving. This specific period should thus be targeted by future nutritional approaches aiming at alleviate metabolic and oxidative stress conditions and improve health of early lactating dairy cows.

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Tejasvi Matam1, Shataakshi Dube1, Jessica Yen 1, and Timothy A. Sutton1 1 Indiana University School of Medicine, USA Acute kidney injury (AKI) is a significant clinical problem associated with high morbidity and mortality. Oxidant stress during an episode of AKI is a key contributor to tubular epithelial cell injury that culminates in kidney dysfunction. In addition, there is a complex interplay between microvascular alterations and inflammation that can serve to amplify oxidant stress and extend tubular injury in AKI. Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that serves as an important modulator of the inflammatory response. We hypothesize that endothelial STAT3 (eSTAT3) signaling is a protective mechanism for limiting tubular epithelial cell injury and kidney dysfunction during AKI. We utilized eSTAT3-/- mice coupled with intravital multiphoton microscopy (MPM) to determine how deletion of eSTAT 3 modulates kidney injury, proximal tubule adaptive responses, and leukocyte trafficking in rodent models AKI. Following injury, the increase in serum creatinine was significantly greater in the eSTAT3 mice (3.0+0.2 mg/dL) as compared to background control mice (C57BL/6; 1.2+0.9 mg/dL) and was consistent with the pattern of injury observed on histopathology. Oxidant stress as measured by DCFDA and intravital MPM demonstrated a 25% increase in ROS generation following injury in eSTAT 3 mice vs. C57BL/6. Microvascular adhesion of leukocytes and macrophage infiltration were increased 90% and 38% respectively following injury in eSTAT 3 mice vs. C57BL/6. In addition, proximal tubule HO-1 levels, a key protective adaptation to oxidant stress, was diminished by approximately 40% following injury in eSTAT 3 mice vs. C57BL/6. In conclusion, eSTAT 3 signaling appears to modulate critical protective mechanism in models of AKI and may be an important therapeutic target for mitigating kidney dysfunction during an episode of AKI. doi: 10.1016/j.freeradbiomed.2015.10.112 doi: xxxxx

SFRBM 2015