Macrophage-derived exosomes mediate glomerular endothelial cell dysfunction in sepsis-associated acute kidney injury

Aquaporin 1 is renoprotective in septic acute kidney injury by attenuating inflammation, apoptosis and fibrosis through inhibition of P53 expression

Sepsis associated Acute kidney injury (AKI) is a common clinical syndrome characterized by suddenly decreased in renal function and urinary volume. This study was designed to investigate the role of Aquaporin 1 (AQP1) and P53 in the development of sepsis-induced AKI and their potential regulatory mechanisms. Firstly, transcriptome sequencing analysis of mice kidney showed AQP1 expression was reduced and P53 expression was elevated in Cecal ligation and puncture (CLP)-induced AKI compared with controls. Bioinformatics confirmed that AQP1 expression was remarkably decreased and P53 expression was obviously elevated in renal tissues or peripheral blood of septic AKI patients. Moreover, we found in vivo experiments that AQP1 mRNA levels were dramatically decreased and P53 mRNA significantly increased following the increased expression of inflammation, apoptosis, fibrosis, NGAL and KIM-1 at various periods in septic AKI. Meanwhile, AQP1 and P53 protein levels increased significantly first and then decreased gradually in kidney tissue and serum of rats in different stages of septic AKI. Most importantly, in vivo and vitro experiments demonstrated that silencing of AQP1 greatly exacerbates renal or cellular injury by up-regulating P53 expression promoting inflammatory response, apoptosis and fibrosis. Overexpression of AQP1 prevented the elevation of inflammation, apoptosis and fibrosis by down-regulating P53 expression in Lipopolysaccharide (LPS)-induced AKI or HK-2 cells. Therefore, our results suggested that AQP1 plays a protective role in modulating AKI and can attenuate inflammatory response, apoptosis and fibrosis via downregulating P53 in septic AKI or LPS-induced HK-2cells. The pharmacological targeting of AQP1 mediated P53 expression might be identified as potential targets for the early treatment of septic AKI.

Endothelial Cell Dysfunction Due to Molecules Secreted by Macrophages in Sepsis

Sepsis is recognized as a syndrome of systemic inflammatory reaction induced by dysregulation of the body's immunity against infection. The multiple organ dysfunction associated with sepsis is a serious threat to the patient's life. Endothelial cell dysfunction has been extensively studied in sepsis. However, the role of macrophages in sepsis is not well understood and the intrinsic link between the two cells has not been elucidated. Macrophages are first-line cells of the immune response, whereas endothelial cells are a class of cells that are highly altered in function and morphology. In sepsis, various cytokines secreted by macrophages and endothelial cell dysfunction are inextricably linked. Therefore, investigating how macrophages affect endothelial cells could offer a theoretical foundation for the treatment of sepsis. This review links molecules (TNF-α, CCL2, ROS, VEGF, MMP-9, and NO) secreted by macrophages under inflammatory conditions to endothelial cell dysfunction (adhesion, permeability, and coagulability), refining the pathophysiologic mechanisms of sepsis. At the same time, multiple approaches (a variety of miRNA and medicines) regulating macrophage polarization are also summarized, providing new insights into reversing endothelial cell dysfunction and improving the outcome of sepsis treatment.

Exosome-Derived microRNA: Potential Target for Diagnosis and Treatment of Sepsis

Exosome-derived microRNAs (miRNAs) are emerging as pivotal players in the pathophysiology of sepsis, representing a new frontier in both the diagnosis and treatment of this complex condition. Sepsis, a severe systemic response to infection, involves intricate immune and nonimmune mechanisms, where exosome-mediated communication can significantly influence disease progression and outcomes. During the progress of sepsis, the miRNA profile of exosomes undergoes notable alterations, is reflecting, and may affect the progression of the disease. This review comprehensively explores the biology of exosome-derived miRNAs, which originate from both immune cells (such as macrophages and dendritic cells) and nonimmune cells (such as endothelial and epithelial cells) and play a dynamic role in modulating pathways that affect the course of sepsis, including those related to inflammation, immune response, cell survival, and apoptosis. Taking into account these dynamic changes, we further discuss the potential of exosome-derived miRNAs as biomarkers for the early detection and prognosis of sepsis and advantages over traditional biomarkers due to their stability and specificity. Furthermore, this review evaluates exosome-based therapeutic miRNA delivery systems in sepsis, which may pave the way for targeted modulation of the septic response and personalized treatment options.

Endothelial cell dysfunction and targeted therapeutic drugs in sepsis

Sepsis is a life-threatening organ dysfunction caused by an abnormal host response to microbial infections. During its pathogenesis, vascular endothelial cells (ECs) play a pivotal role as essential components in maintaining microcirculatory homeostasis. This article aims to comprehensively review the multifaceted physiological functions of vascular ECs, elucidate the alterations in their functionality throughout the course of sepsis, and explore recent advancements in research concerning sepsis-related therapeutic drugs targeting ECs.

The science of exosomes: Understanding their formation, capture, and role in cellular communication

Extracellular vesicles (EVs) serve as a crucial method for transferring information among cells, which is vital in multicellular organisms. Among these vesicles, exosomes are notable for their small size, ranging from 20 to 150 nm, and their role in cell-to-cell communication. They carry lipids, proteins, and nucleic acids between cells. The creation of exosomes begins with the inward budding of the cell membrane, which then encapsulates various macromolecules as cargo. Once filled, exosomes are released into the extracellular space and taken up by target cells via endocytosis and similar processes. The composition of exosomal cargo varies, encompassing diverse macromolecules with specific functions. Because of their significant roles, exosomes have been isolated from various cell types, including cancer cells, endothelial cells, macrophages, and mesenchymal cells, with the aim of harnessing them for therapeutic applications. Exosomes influence cellular metabolism, and regulate lipid, glucose, and glutamine pathways. Their role in pathogenesis is determined by their cargo, which can manipulate processes such as apoptosis, proliferation, inflammation, migration, and other molecular pathways in recipient cells. Non-coding RNA transcripts, a common type of cargo, play a pivotal role in regulating disease progression. Exosomes are implicated in numerous biological and pathological processes, including inflammation, cancer, cardiovascular diseases, diabetes, wound healing, and ischemic-reperfusion injury. As a result, they hold significant potential in the treatment of both cancerous and non-cancerous conditions.

Exosomes on the development and progression of renal fibrosis

Renal fibrosis is a prevalent pathological alteration that occurs throughout the progression of primary and secondary renal disorders towards end-stage renal disease. As a complex and irreversible pathophysiological phenomenon, it includes a sequence of intricate regulatory processes at the molecular and cellular levels. Exosomes are a distinct category of extracellular vesicles that play a crucial role in facilitating intercellular communication. Multiple pathways are regulated by exosomes produced by various cell types, including tubular epithelial cells and mesenchymal stem cells, in the context of renal fibrosis. Furthermore, research has shown that exosomes present in bodily fluids, including urine and blood, may be indicators of renal fibrosis. However, the regulatory mechanism of exosomes in renal fibrosis has not been fully elucidated. This article reviewed and analysed the various mechanisms by which exosomes regulate renal fibrosis, which may provide new ideas for further study of the pathophysiological process of renal fibrosis and targeted treatment of renal fibrosis with exosomes.

Unveiling the Role of Exosomes in the Pathophysiology of Sepsis: Insights into Organ Dysfunction and Potential Biomarkers

Extracellular vesicles (EVs) are tools for intercellular communication, mediating molecular transport processes. Emerging studies have revealed that EVs are significantly involved in immune processes, including sepsis. Sepsis, a dysregulated immune response to infection, triggers systemic inflammation and multi-organ dysfunction, posing a life-threatening condition. Although extensive research has been conducted on animals, the complex inflammatory mechanisms that cause sepsis-induced organ failure in humans are still not fully understood. Recent studies have focused on secreted exosomes, which are small extracellular vesicles from various body cells, and have shed light on their involvement in the pathophysiology of sepsis. During sepsis, exosomes undergo changes in content, concentration, and function, which significantly affect the metabolism of endothelia, cardiovascular functions, and coagulation. Investigating the role of exosome content in the pathogenesis of sepsis shows promise for understanding the molecular basis of human sepsis. This review explores the contributions of activated immune cells and diverse body cells' secreted exosomes to vital organ dysfunction in sepsis, providing insights into potential molecular biomarkers for predicting organ failure in septic shock.

Fibroblastic reticular cell-derived exosomes are a promising therapeutic approach for septic acute kidney injury

Sepsis-induced acute kidney injury (S-AKI) is highly lethal, and effective drugs for treatment are scarce. Previously, we reported the robust therapeutic efficacy of fibroblastic reticular cells (FRCs) in sepsis. Here, we demonstrate the ability of FRC-derived exosomes (FRC-Exos) to improve C57BL/6 mouse kidney function following cecal ligation and puncture-induced sepsis. In vivo imaging confirmed that FRC-Exos homed to injured kidneys. RNA-Seq analysis of FRC-Exo-treated primary kidney tubular cells (PKTCs) revealed that FRC-Exos influenced PKTC fate in the presence of lipopolysaccharide (LPS). FRC-Exos promoted kinase PINK1-dependent mitophagy and inhibited NLRP3 inflammasome activation in LPS-stimulated PKTCs. To dissect the mechanism underlying the protective role of Exos in S-AKI, we examined the proteins within Exos by mass spectrometry and found that CD5L was the most upregulated protein in FRC-Exos compared to macrophage-derived Exos. Recombinant CD5L treatment in vitro attenuated kidney cell swelling and surface bubble formation after LPS stimulation. FRCs were infected with a CD5L lentivirus to increase CD5L levels in FRC-Exos, which were then modified in vitro with the kidney tubular cell targeting peptide LTH, a peptide that binds to the biomarker protein kidney injury molecule-1 expressed on injured tubule cells, to enhance binding specificity. Compared with an equivalent dose of recombinant CD5L, the modified CD5L-enriched FRC-Exos selectively bound PKTCs, promoted kinase PINK-ubiquitin ligase Parkin-mediated mitophagy, inhibiting pyroptosis and improved kidney function by hindering NLRP3 inflammasome activation, thereby improving the sepsis survival rate. Thus, strategies to modify FRC-Exos could be a new avenue in developing therapeutics against kidney injury.

An overview of the mechanisms and potential roles of extracellular vesicles in septic shock

Septic shock, a subset of sepsis, is a fatal condition associated with high morbidity and mortality. However, the pathophysiology of septic shock is not fully understood. Moreover, the diagnostic markers employed for identifying septic shock lack optimal sensitivity and specificity. Current treatment protocols for septic shock have not been effective in lowering the mortality rate of patients. Most cells exhibit the capability to release extracellular vesicles (EVs), nanoscale vesicles that play a vital role in intercellular communication. In recent years, researchers have investigated the potential role of EVs in the pathogenesis, diagnosis, and treatment of different diseases, such as oncological, neurological, and cardiovascular diseases, as well as diabetes and septic shock. In this article, we present an overview of the inhibitory and facilitative roles that EVs play in the process of septic shock, the potential role of EVs in the diagnosis of septic shock, and the potential therapeutic applications of both native and engineered EVs in the management of septic shock.

Exosomes Highlight Future Directions in the Treatment of Acute Kidney Injury

Acute kidney injury (AKI) is a severe health problem associated with high morbidity and mortality rates. It currently lacks specific therapeutic strategies. This review focuses on the mechanisms underlying the actions of exosomes derived from different cell sources, including red blood cells, macrophages, monocytes, mesenchymal stem cells, and renal tubular cells, in AKI. We also investigate the effects of various exosome contents (such as miRNA, lncRNA, circRNA, mRNA, and proteins) in promoting renal tubular cell regeneration and angiogenesis, regulating autophagy, suppressing inflammatory responses and oxidative stress, and preventing fibrosis to facilitate AKI repair. Moreover, we highlight the interactions between macrophages and renal tubular cells through exosomes, which contribute to the progression of AKI. Additionally, exosomes and their contents show promise as potential biomarkers for diagnosing AKI. The engineering of exosomes has improved their clinical potential by enhancing isolation and enrichment, target delivery to injured renal tissues, and incorporating small molecular modifications for clinical use. However, further research is needed to better understand the specific mechanisms underlying exosome actions, their delivery pathways to renal tubular cells, and the application of multi-omics research in studying AKI.