Melatonin Alleviates Renal Injury in Mouse Model of Sepsis

From Molecular Mechanisms to Clinical Therapy: Understanding Sepsis-Induced Multiple Organ Dysfunction

Sepsis-induced multiple organ dysfunction arises from the highly complex pathophysiology encompassing the interplay of inflammation, oxidative stress, endothelial dysfunction, mitochondrial damage, cellular energy failure, and dysbiosis. Over the past decades, numerous studies have been dedicated to elucidating the underlying molecular mechanisms of sepsis in order to develop effective treatments. Current research underscores liver and cardiac dysfunction, along with acute lung and kidney injuries, as predominant causes of mortality in sepsis patients. This understanding of sepsis-induced organ failure unveils potential therapeutic targets for sepsis treatment. Various novel therapeutics, including melatonin, metformin, palmitoylethanolamide (PEA), certain herbal extracts, and gut microbiota modulators, have demonstrated efficacy in different sepsis models. In recent years, the research focus has shifted from anti-inflammatory and antioxidative agents to exploring the modulation of energy metabolism and gut microbiota in sepsis. These approaches have shown a significant impact in preventing multiple organ damage and mortality in various animal sepsis models but require further clinical investigation. The accumulation of this knowledge enriches our understanding of sepsis and is anticipated to facilitate the development of effective therapeutic strategies in the future.

Detection of melatonin protective effects in sepsis via argyrophilic nucleolar regulatory region-associated protein synthesis and TLR4/NF-κB signaling pathway

In this study, the protective effect of melatonin was investigated in lipopolysaccharide induced sepsis model. Twenty-eight rats were randomly divided: Control, Melatonin, LPS and LPS + Melatonin. After LPS application, surgically remove kidney and liver tissues. The level of malondialdehyde (MDA) an oxidative stress marker and the immunoreactivity of Toll-like receptor-4 (TLR4), tumor necrosis factor-α (TNF-α), and transcription factor NF-κB were evaluated immunohistochemically. Expression levels for TLR4, TNF-α, NF-kB, IL-1β (interleukin 1 beta), and IL-6 (interleukin 6) were evaluated. Additionally, Argyrophilic NOR staining was performed in tissues. Vacuolization and inflammation were more intense in the kidney and liver sections in the LPS group compared to the other groups. It was observed that vacuolization and inflammation were decreased in LPS + Melatonin applied groups. It was determined that glomerular damage was increased in the LPS and LPS-melatonin groups, but the damage rate LPS-Melatonin group was decrease in the LPS group. It was determined that the MDA level in tissues of the LPS group was importantly increased compared to other groups. Additionally, TAA/NA ratio statistically significant differences were discovered between the groups. This study supports the potential protective effects of 10 mg/kg melatonin by modulating critical markers of local immune reaction in a model of LPS-induced sepsis.

Melatonin suppresses ferroptosis via activation of the Nrf2/HO-1 signaling pathway in the mouse model of sepsis-induced acute kidney injury

BACKGROUND

Ferroptosis is a regulated form of cell death. At present, the role of ferroptosis in sepsis-induced acute kidney injury (SAKI) has not been studied. Melatonin (MEL) has been reported to be an effective ferroptosis inhibitor, but it is unclear whether Melatonin can regulate ferroptosis in SAKI and whether its downstream mechanism correlates with the Nrf2/HO-1 pathway.

METHODS

The cecal ligation and puncture (CLP) method and LPS injection were used to induce SAKI in mouse model. Ferroptosis markers, including malondialdehyde (MDA) and glutathione peroxidase 4 (GPX4), were assessed. The ferroptosis inhibitor ferrostatin-1 (Fer-1) was used to explore the role of ferroptosis in SAKI. The GPX4 inhibitor RSL3, the HO-1 inhibitor zinc protoporphyrin(ZnPP), and the Nrf2 inhibitor ML385 were used to explore the specific mechanism of MEL in alleviation of SAKI.

RESULTS

The ferroptosis level was increased in the renal tissue of CLP- and LPS-induced septic mice. Both Fer-1 and MEL administration could suppress ferroptosis and attenuate kidney injury upon sepsis challenge. RSL3 partially blocked MEL's beneficial renal-protective effects. MEL up-regulated Nrf2 and HO-1 in CLP mice, and both ZnPP and ML385 blocked the MEL-mediated effects of ferroptosis inhibition and renal protection.

CONCLUSIONS

Ferroptosis aggravates SAKI. Melatonin treatment suppresses ferroptosis and alleviates kidney injury in the context of experimental sepsis by upregulating Nrf2/HO-1 pathway.

Berberine Ameliorates Inflammation in Acute Lung Injury via NF-κB/Nlrp3 Signaling Pathway

The inflammatory response is the key pathophysiological character of acute lung injury (ALI). Berberine (BBR), a natural quaternary ammonium alkaloid, plays a functional role in anti-inflammation both in vitro and in vivo. However, the underlying mechanism between BBR and ALI has not been expounded. Here, we found that BBR improved the permeability of pulmonary and repressed the inflammatory factors in the lipopolysaccharides (LPSs)-induced ALI model. We demonstrated that BBR could suppress the expression of phosphorylated nuclear factor-kappa B (NF-κB) and further restrain the downstream gene nucleotide-binding domain and leucine-rich repeat protein-3 (Nlrp3). Moreover, we also revealed that BBR could directly interact with Nlrp3 protein. After knocked down of Nlrp3 by using siRNA, the protective role of BBR was abrogated in vitro. The expression of IL-1β and IL-18 was downregulated by BBR via the two signaling pathways. Notably, in Nlrp3 deficient mice, the protective effect of BBR was abolished. These findings demonstrate that BBR has a depressant effect on inflammatory response caused by LPS via regulating NF-κB/Nlrp3 signaling pathway, providing a potential therapeutic strategy in ALI.

Indole-Based Small Molecules as Potential Therapeutic Agents for the Treatment of Fibrosis

Indole alkaloids are widely distributed in nature and have been particularly studied because of their diverse biological activities, such as anti-inflammatory, anti-tumor, anti-bacterial, and anti-oxidant activities. Many kinds of indole alkaloids have been applied to clinical practice, proving that indole alkaloids are beneficial scaffolds and occupy a crucial position in the development of novel agents. Fibrosis is an end-stage pathological condition of most chronic inflammatory diseases and is characterized by excessive deposition of fibrous connective tissue components, ultimately resulting in organ dysfunction and even failure with significant morbidity and mortality. Indole alkaloids and indole derivatives can alleviate pulmonary, myocardial, renal, liver, and islet fibrosis through the suppression of inflammatory response, oxidative stress, TGF-β/Smad pathway, and other signaling pathways. Natural indole alkaloids, such as isorhynchophylline, evodiamine, conophylline, indirubin, rutaecarpine, yohimbine, and vincristine, are reportedly effective in organ fibrosis treatment. In brief, indole alkaloids with a wide range of pharmacological bioactivities are important candidate drugs for organ fibrosis treatment. The present review discusses the potential of natural indole alkaloids, semi-synthetic indole alkaloids, synthetic indole derivatives, and indole-contained metabolites in organ fibrosis treatment.

Calcium dobesilate alleviates renal dysfunction and inflammation by targeting nuclear factor kappa B (NF-κB) signaling in sepsis-associated acute kidney injury

Acute kidney injury (AKI) is a serious complication of sepsis that increases mortality and the risk of progression to chronic kidney disease. Oxidative stress and apoptosis are reported to exert critical function in the pathogenesis of sepsis-associated AKI. Calcium dobesilate (CaD) was reported to play a protective role in renal diseases. Therefore, we explored the antioxidant effect and potential mechanism of CaD in lipopolysaccharide (LPS)-induced AKI in mice. We evaluated renal function (blood urea nitrogen (BUN) and serum creatinine (SCr)), histopathology, oxidative stress (superoxide dismutase (SOD) and malondialdehyde (MDA)), inflammation cytokines, and apoptosis in kidneys of mice. The effect of CaD on NF-κB signaling was evaluated by Western blot. Our findings showed that CaD alleviated renal dysfunction and kidney injury, and also reversed upregulated MDA concentration and reduced SOD enzyme activity in AKI mice. Moreover, LPS-induced inflammatory response was attenuated by CaD. CaD treatment also reduced the apoptosis evoked by LPS. Additionally, CaD downregulated phosphorylation of nuclear factor kappa B (NF-κB) signaling components in LPS mice. Conclusively, CaD alleviates renal dysfunction and inflammation by targeting NF-κB signaling in sepsis-associated AKI.