Biology subjects

Baek, O.

Publications and source records attributed to Baek, O..

5 recordsLinked to original sources

bioRxiv2025

Ketone and glycolytic metabolism are key modulators of inflammation during neonatal sepsis

Neonatal sepsis is a life-threatening condition in preterm infants, primarily due to a dysregulated immunometabolic response to infection. Sepsis and infection mortality are associated with excessive glycolysis-induced inflammation, impaired mitochondrial oxidative phosphorylation (OXPHOS) and loss of disease tolerance. Reduced glucose intake can reverse these dysregulations, but it is unclear how the mechanistic control of glycolysis-OXPHOS balance drives defense strategies and infection outcomes. Here, in a preterm piglet model of neonatal sepsis, glycolysis inhibition with 2-deoxyglucose (2-DG) completely prevents acute infection mortality, reduces systemic inflammation and markers of liver injury, accompanied by enhanced mitochondrial metabolism and disease tolerance. Strikingly, this protection by 2-DG is conferred despite elevated blood glucose levels and higher bacterial burdens than the infected controls. Alternatively, partial replacement of glucose intake with the ketone beta-hydroxybutyrate (BHB) abolishes sepsis-related mortality via improving disease tolerance and clinical parameters. This intervention also shifts the hepatic transcriptome away from inflammatory signaling and towards mitochondrial metabolism. In macrophages in vitro, BHB also exerts anti-inflammatory effects independently of metabolic modulation via the HCAR2 receptor. Finally, data from a cohort of 700 infants confirm an association of plasma BHB levels and anti-inflammatory state. These findings demonstrate that metabolic reprogramming through glycolysis inhibition or ketone supplementation is a promising therapeutic strategy to enhance disease tolerance and improve sepsis outcomes in neonates.

immunology↗

bioRxiv2025

Harnessing systemic glycolysis-TCA cycle axis to boost the host defense against newborn infection

Energy metabolism and immune response are tightly connected, but it is poorly understood how this interplay is regulated in early life to dictate host defense strategy, infection risks and severity. This interplay is particularly relevant for preterm, low birthweight or otherwise immunocompromised infants, who have poor metabolic control and increased risks of sepsis. Here, we utilized data from the COPSAC2010 cohort with 700 mother-child pairs and showed that plasma levels of TCA cycle metabolites in early life were associated with reduced childhood risk of bacterial infection and an attenuated systemic inflammatory response. Next, we explored how two distinct nutritional strategies, which were aimed at boosting TCA cycle activity instead of glycolysis, impacted neonatal host defense against a serious bloodstream infection in preterm piglets. Substituting galactose for glucose in parenteral nutrition enhanced disease tolerance in early phase of infection and overall glucose homeostasis, improving survival. Further, combining glucose restriction with supplementation of glucogenic amino acids conferred glycemic control and completely prevented sepsis and abnormal changes of organ injury markers. Mechanistically, this intervention enhanced both disease resistance and tolerance, accompanied by metabolic rewiring from glycolysis towards gluconeogenesis, TCA cycle activity and oxidative phosphorylation. Thus, optimized nutritional strategies controlling the interplay of energy metabolism and host defense may be lifesaving for infected infants. In briefNewborns rely on two distinct defense strategies to combat infections in early life. Disease resistance, fueled by aerobic glycolysis, seeks to actively eliminate microorganisms while disease tolerance, fueled by mitochondrial oxidative phosphorylation, seeks to reduce collateral tissue damage during infections. We found that in healthy human newborns, increased plasma levels of metabolites from the tricarboxylic acid (TCA) cycle were associated with lower burden of childhood infections and reduced pro-inflammatory status. In a newborn animal model of bloodstream infection, nutritional strategies boosting systemic TCA cycle activity, while reducing aerobic glycolysis, enhanced both host disease tolerance and resistance, thereby improving survival. These findings could pave a path for improved infection management in human newborns. HighlightsO_LIIn healthy children, higher plasma levels of TCA cycle metabolites are associated with lower infection risks and systemic inflammation. C_LIO_LIIn a neonatal infection model, the supply of galactose, instead of glucose, improves host glucose homeostasis and TCA cycle activity, improving disease tolerance and survival. C_LIO_LIA combination of glucose restriction and glucogenic amino acid supply also improves TCA cycle activity, enhancing both disease resistance and tolerance and completely preventing lethal sepsis. C_LI

immunology↗

bioRxiv2024

Reduced glucose supply during neonatal infection attenuates neurological and renal pathology via modulation of innate and Th1 immunity

BackgroundPremature infants are highly susceptible to infections that can lead to sepsis with life-threatening organ dysfunctions. The clinical practice of high parenteral glucose supply in preterm infants can exacerbate infection outcomes through excessive glycolysis-induced inflammatory response. This in turn can affect the health of vital preterm organs, including the brain and kidneys. We hypothesized that reducing glucose supply in infected preterm newborns may help protect against pathology in these two key organs. MethodsCaesarean-delivered preterm pigs were nourished with high or low parenteral glucose levels, infected with Staphylococcus epidermidis or saline, and cared for until 22h. Blood, brain, and kidney samples were collected at the end of the study for analyses. ResultsInfection led to multiple pathological changes, increased inflammation and tissue injury and dysfunction in both brain and kidneys of preterm piglets. Reduced glucose supply in infected animals alleviated neurological degradation, hyperemia and enhanced M2 microglial phenotype in the brain. This intervention also reduced plasma creatinine, renal edema, tubular vacuolization and dilatation. Multiple genes related to innate and Th1 immunity in both organs were highly correlated and dampened by reduced glucose supply, but there were clear signs that renal inflammation was closely connected to systemic inflammation while neuroinflammation was likely driven by immune response to the bacteria translocated into the brain. ConclusionReduced glucose supply can protect brain and kidney health in infected preterm neonates.

immunology↗

bioRxiv2024

Regulation of defense strategies and host metabolism to survive neonatal infection

Two distinct defense strategies, resistance and tolerance, enable a host to survive infectious diseases. Newborns, constrained by limited energy reserves, predominantly rely on tolerance to cope with infection. However, this approach may fail as pathogen levels surpass a critical threshold, prompting a shift to resistance that can lead to dysregulated immune responses and sepsis. The mechanisms governing the interplay between tolerance and resistance in newborns remain poorly understood. Here, we compare metabolic traits and defense strategies between survivors and non- survivors in Staphylococcus epidermidis (S. epidermidis)-infected preterm piglets, mimicking infection in preterm infants. Relative to non-survivors, survivors displayed elevated resistance during the early phase of infection, followed by stronger tolerance in later stages. Conversely, animals succumbing to sepsis showed clear signs of respiratory and metabolic acidosis, together with exaggerated inflammation and organ dysfunctions. Hepatic transcriptomics revealed a strong association between the tolerance phenotype and heightened oxidative phosphorylation in survivors, coupled with suppressed glycolysis and immune signaling. Plasma metabolomics supported the finding of enhanced mitochondrial metabolism in survivors. Our findings suggest a link between mitochondrial metabolism, disease tolerance, and ultimately improved survival during infections in newborns. Metabolic regulations related to tolerance may be exploited to discover novel therapeutics for neonatal infection. Conflict-of-interest statementThe authors have declared that no conflict of interest exists.

immunology↗

bioRxiv2023

Altered hepatic metabolism mediates sepsis preventive effects of reduced glucose supply in infected preterm newborns

Preterm infants are susceptible to neonatal sepsis, a syndrome of pro-inflammatory activity, organ damage and altered metabolism following infection. Given the unique metabolic challenges and poor glucose regulatory capacity of preterm infants, their glucose intake during infection may have a high impact on the degree metabolism dysregulation and organ damage. Using a preterm pig model of neonatal sepsis, we previously showed that a drastic restriction in glucose supply during infection protects against sepsis via suppression of glycolysis-induced inflammation, but results in severe hypoglycemia. Now we explored clinically relevant options of reducing glucose intake to decrease sepsis risk, without causing hypoglycemia and further explore the involvement of the liver in these protective effects. We found that a reduced glucose regime during infection increased survival via reduced pro-inflammatory response, while maintaining normoglycemia. Mechanistically, this intervention enhanced hepatic oxidative phosphorylation and possibly gluconeogenesis, and dampened both circulating and hepatic inflammation. However, switching from a high to a reduced glucose supply after debut of clinical symptoms did not prevent sepsis, suggesting metabolic conditions at the start of infection are key in driving the outcome. Finally, an early therapy with purified human inter-alpha inhibitor protein, a liver derived anti-inflammatory protein, partially reversed the effects of low parenteral glucose provision, likely by inhibiting neutrophil functions that mediate pathogen clearance. Our findings suggest a clinically relevant regime of reduced glucose supply for infected preterm infants could prevent or delay the development of sepsis in vulnerable neonates.

immunology↗