Immunotherapy strategies and prospects for acute lung injury: Focus on immune cells and cytokines

Exploring immune-related pathogenesis in lung injury: Providing new insights Into ALI/ARDS

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) represent a significant global burden of morbidity and mortality, with lung injury being the primary cause of death in affected patients. The pathogenesis of lung injury, however, remains a complex issue. In recent years, the role of the immune system in lung injury has attracted extensive attention worldwide. Despite advancements in our understanding of various lung injury subtypes, significant limitations persist in both prevention and treatment. This review investigates the immunopathogenesis of ALI/ARDS, aiming to elucidate the pathological processes of lung injury mediated by dendritic cells (DCs), natural killer (NK) cells, phagocytes, and neutrophils. Furthermore, the article expounds on the critical contributions of gut microbiota, inflammatory pathways, and cytokine storms in the development of ALI/ARDS.

Corilagin Inhibits Neutrophil Extracellular Trap Formation and Protects against Hydrochloric Acid/Lipopolysaccharide-Induced Acute Lung Injury in Mice by Suppressing the STAT3 and NOX2 Signaling Pathways

Acute lung injury (ALI) and its severe manifestation, acute respiratory distress syndrome (ARDS), are characterized by uncontrolled inflammatory responses, neutrophil activation and infiltration, damage to the alveolar capillary membrane, and diffuse alveolar injury. Neutrophil extracellular traps (NETs), formed by activated neutrophils, contribute significantly to various inflammatory disorders and can lead to tissue damage and organ dysfunction. Corilagin, a compound found in Phyllanthus urinaria, possesses antioxidative and anti-inflammatory properties. In this study, we investigated the protective effects and underlying mechanisms of corilagin in hydrochloric acid (HCl)/lipopolysaccharide (LPS)-induced lung injury. Mice received intraperitoneal administration of corilagin (2.5, 5, or 10 mg/kg) or an equal volume of saline 30 min after intratracheal HCl/LPS administration. After 20 h, lung tissues were collected for analysis. Corilagin treatment significantly mitigated lung injury, as evidenced by reduced inflammatory cell infiltration, decreased production of proinflammatory cytokines, and alleviated oxidative stress. Furthermore, corilagin treatment suppressed neutrophil elastase expression, reduced NET formation, and inhibited the expression of ERK, p38, AKT, STAT3, and NOX2. Our findings suggest that corilagin inhibits NET formation and protects against HCl/LPS-induced ALI in mice by modulating the STAT3 and NOX2 signaling pathways.

Upregulation of PGC-1α expression by pioglitazone mediates prevention of sepsis-induced acute lung injury

The imbalance between pro-inflammatory M1 and anti-inflammatory M2 macrophages plays a critical role in the pathogenesis of sepsis-induced acute lung injury (ALI). Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) may modulate macrophage polarization toward the M2 phenotype by altering mitochondrial activity. This study aimed to investigate the role of the PGC-1α agonist pioglitazone (PGZ) in modulating sepsis-induced ALI. A mouse model of sepsis-induced ALI was established using cecal ligation and puncture (CLP). An in vitro model was created by stimulating MH-S cells with lipopolysaccharide (LPS). qRT-PCR was used to measure mRNA levels of M1 markers iNOS and MHC-II and M2 markers Arg1 and CD206 to evaluate macrophage polarization. Western blotting detected expression of peroxisome proliferator-activated receptor gamma (PPARγ) PGC-1α, and mitochondrial biogenesis proteins NRF1, NRF2, and mtTFA. To assess mitochondrial content and function, reactive oxygen species levels were detected by dihydroethidium staining, and mitochondrial DNA copy number was measured by qRT-PCR. In the CLP-induced ALI mouse model, lung tissues exhibited reduced PGC-1α expression. PGZ treatment rescued PGC-1α expression and alleviated lung injury, as evidenced by decreased lung wet-to-dry weight ratio, pro-inflammatory cytokine secretion (tumor necrosis factor-α, interleukin-1β, interleukin-6), and enhanced M2 macrophage polarization. Mechanistic investigations revealed that PGZ activated the PPARγ/PGC-1α/mitochondrial protection pathway to prevent sepsis-induced ALI by inhibiting M1 macrophage polarization. These results may provide new insights and evidence for developing PGZ as a potential ALI therapy.

Salecan ameliorates LPS-induced acute lung injury through regulating Keap1-Nrf2/HO-1 pathway in mice

Acute lung injury (ALI) is a severe clinical condition with high mortality, characterized by rapid onset and limited treatment options. The pathogenesis of ALI involves inflammation and oxidative stress. The polysaccharide salecan, a water-soluble β-(1,3)-D-glucan, has been found to possess numerous pharmaceutical effects, including anti-inflammatory properties, inhibition of oxidative stress, and anti-fatigue effects. This study aims to investigate the protective effect and underlying mechanism of salecan against LPS-induced ALI in mice. Using an in vivo LPS-induced ALI mouse model and an in vitro RAW264.7 cell system, we investigated the role of salecan in ALI with various experimental approaches, including histological staining, quantitative real-time PCR, flow cytometry, western blot analysis, and other relevant assays. Pre-treatment with salecan effectively attenuated LPS-induced ALI in vivo, reducing the severity of pulmonary edema, inflammation, and oxidative stress. NMR-based metabolomic profiling analysis revealed that salecan attenuated LPS-induced metabolic imbalances associated with ALI. Furthermore, salecan downregulated Keap1 and upregulated Nrf2 and HO-1 protein levels, indicating its modulation of the Keap1-Nrf2/HO-1 signaling pathway as a potential mechanism underlying its protective effects against ALI. In vitro studies on RAW264.7 cells revealed that salecan exhibited binding affinity towards macrophages, thereby alleviating LPS-induced apoptosis and inflammation, which underpin its therapeutic potential against ALI. Our study suggests that salecan can alleviate LPS-induced ALI by modulating oxidative stress, inflammatory response, and apoptosis through the activation of the Keap1-Nrf2/HO-1 pathway. These findings provide novel insights into the potential therapeutic use of salecan for the treatment of ALI.

Adipose tissue-derived mesenchymal stromal cells attenuate acute lung injury induced by trauma and haemorrhagic shock

BACKGROUND

Mesenchymal stromal cells (MSCs) have shown promising therapeutic options for acute lung injury (ALI) caused by multiple factors. Here, we evaluated the therapeutic potential of adipose tissue-derived mesenchymal stromal cells (ADSCs) in trauma and hemorrhagic shock (THS)-induced ALI.

METHODS

ALI model induced by THS was constructed by fractures plus abdominal trauma plus acute hemorrhage plus fluid resuscitation. The ADSCs group rats were generated by injecting 2 × 106 ADSCs at 0 and 1 h after THS. The sham, ALI, and ADSCs group rats were sacrificed at 24 h after resuscitation. The changes in lung histopathology, total protein in bronchoalveolar lavage fluid (BALF), mRNA expression of pro-inflammatory/anti-inflammatory cytokines, antioxidant, and anti-apoptotic indicator, and the activity of Toll-like receptor 4 (TLR4) signaling in lung tissues were evaluated.

RESULTS

Administration of the ADSCs reversed ALI induced by THS, including lung histopathological changes/scores, and BALF total protein concentration. Additionally, ADSCs therapy also significantly down-regulated mRNA expression of pro-inflammatory TNF-α, IL-1β, and IL-6, up-regulated mRNA expression of anti-inflammatory IL-10, anti-apoptotic molecule Bcl-2, and anti-oxidative molecule HO-1 in THS rats. Furthermore, ADSCs suppressed the expression of TLR4 in lung tissue.

CONCLUSION

Our data show that ADSCs administration can exert therapeutic effects on THS-induced ALI in rats and may provide beneficial in preventative strategies for ALI.

Host PTX3 Protein and Bacterial Capsule Coordinately Regulate the Inflammatory Response during Streptococcus suis Infection

Streptococcus suis serotype 2 (SS2) is a noteworthy zoonotic pathogen that has been responsible for large economic losses in pig production and a great threat to human health. Pentraxin 3 (PTX3) is an essential regulator of the innate immune response to bacterial pathogens; however, its role during SS2 infection is not fully understood. In this study, we found that the SS2 strain HA9801 induced a significant inflammatory response in the mouse air pouch model; this response was amplified by the treatment of exogenous PTX3 simultaneously in terms of the results of inflammatory cell recruitment and proinflammatory cytokine IL-6 production. In addition, PTX3 facilitated the phagocytosis of macrophage Ana-1 against SS2 strain HA9801. The supplementation of exogenous PTX3 significantly reduced the bacterial loads in a dose-dependent manner in lungs, livers and bloods of SS2-infected mice compared to the samples with HA9801 infection alone; this finding indicated that PTX3 may facilitate the bacterial clearance through enhancing the host inflammatory response during SS2 infection. Both PTX3 and SS2 capsular polysaccharide (CPS2) were required for the robust inflammatory response, implying that the host PTX3 protein and SS2 surface CPS2 modulate the host innate immune response in concert. All of these results suggested that PTX3 is a potential novel biological agent for the SS2 infection; however, the recommended dose of PTX3 must be evaluated strictly to avoid inducing an excessive inflammatory response that can cause serious tissue injury and animal death.