Daily Ards Research Analysis

Sepsis-induced acute lung injury (ALI), and its severe manifestation, acute respiratory distress syndrome (ARDS), are complex conditions associated with high global mortality. 17β-estradiol (E2), a sex hormone, is implicated in ARDS pathophysiology, but its mechanisms remain unclear. In this study, we explored the role of E2 in sepsis-induced ALI using ovariectomized female Sprague-Dawley rats and A549 cells. Endogenous E2 levels were assessed via the uterus-to-body weight ratio and serum E2 concentrations. Our findings demonstrate that E2 deficiency exacerbates LPS-induced mitochondrial damage, apoptosis, and lung injury, while exogenous E2 reverses these effects. Mechanistically, E2 promotes mitochondrial biogenesis through activation of the PGC-1β/Nrf2/TFAM signaling pathway. These results suggest that exogenous E2 may offer a promising therapeutic approach for ARDS by enhancing mitochondrial function and reducing apoptosis.

To date, murine sepsis models have failed to recapitulate human acute respiratory distress syndrome, one of the leading complications of human sepsis. We set out to determine if preexisting T cell memory, which is common in human adults and lacking in laboratory mice, could contribute to lung inflammation in the cecal ligation and puncture (CLP) model of sepsis. After administering an anti-CD3ε activating antibody to C57Bl/6 mice to induce a T cell memory repertoire, we compared the pulmonary immune response to CLP in these "Immune-Educated mice" to responses observed in Uneducated control animals. Compared to Uneducated mice, 24 hours after CLP, Immune-Educated mice had higher alveolar inflammatory cytokine and chemokine concentrations and more pulmonary interstitial macrophages. After 48 hours, the proportion of effector CD4 T cells that produced interferon-gamma was greater in Immune-Educated mice. After 72 hours, there were more alveolar macrophages in the lungs of Educated mice. Separately, we performed adoptive transfer of memory CD4 and CD8 T cells from immunized C57Bl/6J to B6.SJL mice and IFNγ blockade at the time of CLP. Interstitial macrophage recruitment 24 hours post-CLP was more pronounced in mice undergoing adoptive transfer of memory T cells compared to mice that did not undergo adoptive transfer. IFNγ blockade resulted in higher absolute numbers of T cells, memory T cells, and innate cells in the lungs of Educated mice 24 hours post-CLP suggesting that IFNγ is necessary for curbing an overactive immune response in these mice. In conclusion, the presence of memory T cells affects the course of CLP-induced lung inflammation and may provide a model that more closely resembles sepsis-associated lung injury.

Sepsis-induced acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe complications with high morbidity and mortality rates, characterized primarily by diffuse alveolar damage, endothelial dysfunction, and local inflammatory responses. Neutrophils and endothelial cells (ECs) play crucial roles in the pathogenesis and progression of these diseases. Neutrophils are important regulators of inflammation, while endothelial dysfunction exacerbates vascular permeability and the inflammatory cascade. The interaction between neutrophils and ECs is vital for the development of ALI/ARDS induced by sepsis, driving the pathological processes of inflammation and tissue damage. Despite advancements in treatment strategies such as protective mechanical ventilation and fluid management, effective methods for rapid lung tissue recovery or significant improvement in outcomes remain lacking. Therefore, we comprehensively summarize the current literature to gain deeper insights into the roles of neutrophils, ECs, and their interactions in sepsis-induced ALI/ARDS, hoping to provide critical insights into the mechanisms underlying sepsis-related ALI/ARDS and potential pathways for developing new therapeutic approaches.