RNA-seq analysis of LPS-induced transcriptional changes and its possible implications for the adrenal gland dysregulation during sepsis

Molecular cloning, characterization and expression analysis of the Chinese soft-shelled turtle (Pelodiscus sinensis) chemokine CXCL11

Chemokines are small, secreted proteins with chemoattractive properties, which play an important role in the recruitment and activation of immune cells. CXCL11 is a CXC chemokine specific for the CXCR3 receptors, which has been shown to mediate the generation of Th1-type immune responses and have bactericidal effects similar to defensins. Herein, we cloned the full-length cDNA of Chinese soft-shelled turtle (Pelodiscus sinensis) CXCL11, designated as PsCXCL11, which consist of an open reading frame (ORF) of 282 bp encoding 93 amino acids, with estimated molecular weight of 10.055 kDa and isoelectric point of 10.37. The deduced PsCXCL11 sequence had a signal peptide, a highly conserved family-specific small cytokine (SCY) domain, one putative N-glycosylation site and ten potential phosphorylation sites. Phylogenetic analysis showed a close relationship between P. sinensis and Chelydra Serpentina CXCL11. P. sinensis CXCL11 basal expression levels were higher in heart, kidney and spleen than in other organs of health turtles. Infections of Aeromonas hydrophila and Staphylococcus aureus led to significant upregulation of P. sinensis CXCL11 in the blood, while significant upregulation of PsCXCL11 were observed in liver and spleen after infection of A. hydrophila, but not S. aureus. PsCXCL11 recombinant protein with His-tag was successfully expressed by an auto-inducible expression system, and purified by Ni-NTA affinity chromatography. These findings laid a solid foundation for further research towards development of the Chinese soft-shelled turtle as a model for the role of CXCL11 in regulating inflammatory responses to stimulation by invading pathogens.

Increased R-spondin 3 contributes to aerobic exercise-induced protection against renal vascular endothelial hyperpermeability and acute kidney injury

AIM

Exercise training exerts protective effects against sepsis-associated multiple organ dysfunction. This study aimed to investigate whether aerobic exercise protected against sepsis-associated acute kidney injury (AKI) via modulating R-spondin 3 (RSPO3) expression.

METHODS

To investigate the effects of aerobic exercise on lipopolysaccharide (LPS)-induced AKI, LPS (20 mg/kg) was intraperitoneally injected after six weeks of treadmill training. To investigate the role of RSPO3 in LPS-induced AKI, wild-type (WT) or inducible endothelial cell-specific RSPO3 knockout (RSPO3EC-/- ) mice were intraperitoneally injected with 12 mg/kg LPS. RSPO3 was intraperitoneally injected 30 min before LPS treatment.

RESULTS

Aerobic exercise-trained mice were more resistant to LPS-induced body weight loss and hypothermia and had a significant higher survival rate than sedentary mice exposed to LPS. Exercise training restored the LPS-induced decreases in serum and renal RSPO3 levels. Exercise or RSPO3 attenuated, whereas inducible endothelial cell-specific RSPO3 knockout exacerbated LPS-induced renal glycocalyx loss, endothelial hyperpermeability, inflammation, and AKI. Bioinformatics analysis results revealed significant increases in the expression of matrix metalloproteinases (MMPs) in kidney tissues of mice exposed to sepsis or endotoxaemia, which was validated in renal tissue from LPS-exposed mice and LPS-treated human microvascular endothelial cells (HMVECs). Both RSPO3 and MMPs inhibitor restored LPS-induced downregulation of tight junction protein, adherens junction protein, and glycocalyx components, thus ameliorating LPS-induced endothelial leakage. Exercise or RSPO3 reversed LPS-induced upregulation of MMPs in renal tissues.

CONCLUSION

Increased renal expression of RSPO3 contributes to aerobic exercise-induced protection against LPS-induced renal endothelial hyperpermeability and AKI by suppressing MMPs-mediated disruption of glycocalyx and tight and adherens junctions.

FAM3 family genes are associated with prognostic value of human cancer: a pan-cancer analysis

Family with sequence similarity three member (FAM3) plays a crucial role in the malignant development of various cancers of human. However, there remains doubtful what specific role of FAM3 family genes in pan-cancer. Our study aimed to investigate the role of FAM3 family genes in prognosis, immune subtype, tumor immune microenvironment, stemness score, and anticancer drug sensitivity of pan-cancer. We obtained data from UCSC Xena GDC and CellMiner databases, and used them to study the correlation of the expression, survival, immune subtype, tumor microenvironment, stemness score, and anticancer drug sensitivity between FAM3 family genes with pan-cancer. Furthermore, we investigated the tumor cellular functions and clinical prognostic value FAMC3 in pancreatic cancer (PAAD) using cellular experiments and tissue microarray. Cell Counting Kit-8 (CCK-8), transwell invasion, wound-healing and apoptosis assays were performed to study the effect of FAM3C on SW1990 cells' proliferation, migration, invasion and apoptosis. Immunohistochemical staining was used to study the relationship between FAM3C expression and clinical characteristics of pancreatic cancer patients. The results revealed that FAM3 family genes are significantly differential expression in tumor and adjacent normal tissues in 7 cancers (CHOL, HNSC, KICH, LUAD, LUSC, READ, and STAD). The expression of FAM3 family genes were negatively related with the RNAss, and robust correlated with immune type, tumor immune microenvironment and drug sensitivity. The expression of FAM3 family genes in pan-cancers were significantly different in immune type C1 (wound healing), C2 (IFN-gamma dominant), C3 (inflammatory), C4 (lymphocyte depleted), C5 (immunologically quiet), and C6 (TGF-beta dominant). Meanwhile, overexpression FAM3C promoted SW1990 cells proliferation, migration, invasion and suppressed SW1990 cells apoptosis. While knockdown of FAM3C triggered opposite results. High FAM3C expression was associated with duodenal invasion, differentiation and liver metastasis. In summary, this study provided a new perspective on the potential therapeutic role of FAM3 family genes in pan-cancer. In particular, FAM3C may play an important role in the occurrence and progression of PAAD.

Nlrp3 Deficiency Alleviates Lipopolysaccharide-Induced Acute Kidney Injury via Suppressing Renal Inflammation and Ferroptosis in Mice

The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is a vital component of many inflammatory responses. Here, we intended to investigate the involvement of NLRP3 in lipopolysaccharide (LPS)-induced sepsis-associated acute kidney injury (S-AKI) and explore its mechanisms. For the first time, we validated elevated NLRP3 expression in the renal tissues of S-AKI patients by immunohistochemistry analysis. Through LPS injection in both wild-type and Nlrp3-/- mice, a S-AKI model was developed. It was found that LPS-induced kidney injury, including an abnormal morphology in a histological examination, abnormal renal function in a laboratory examination, and an increase in the expression of AKI biomarkers, was dramatically reversed in Nlrp3-deficient mice. Nlrp3 deletion alleviated renal inflammation, as evidenced by the suppression of the expression of pro-inflammatory cytokines and chemokines. A combinative analysis of RNA sequencing and the FerrDb V2 database showed that Nlrp3 knockout regulated multiple metabolism pathways and ferroptosis in LPS-induced S-AKI. Further qPCR coupled with Prussian blue staining demonstrated that Nlrp3 knockout inhibited murine renal ferroptosis, indicating a novel mechanism involving S-AKI pathogenesis by NLRP3. Altogether, the aforementioned findings suggest that Nlrp3 deficiency alleviates LPS-induced S-AKI by reducing renal inflammation and ferroptosis. Our data highlight that NLRP3 is a potential therapeutic target for S-AKI.

Succinate mediates inflammation-induced adrenocortical dysfunction

The hypothalamus-pituitary-adrenal (HPA) axis is activated in response to inflammation leading to increased production of anti-inflammatory glucocorticoids by the adrenal cortex, thereby representing an endogenous feedback loop. However, severe inflammation reduces the responsiveness of the adrenal gland to adrenocorticotropic hormone (ACTH), although the underlying mechanisms are poorly understood. Here, we show by transcriptomic, proteomic, and metabolomic analyses that LPS-induced systemic inflammation triggers profound metabolic changes in steroidogenic adrenocortical cells, including downregulation of the TCA cycle and oxidative phosphorylation, in mice. Inflammation disrupts the TCA cycle at the level of succinate dehydrogenase (SDH), leading to succinate accumulation and disturbed steroidogenesis. Mechanistically, IL-1β reduces SDHB expression through upregulation of DNA methyltransferase 1 (DNMT1) and methylation of the SDHB promoter. Consequently, increased succinate levels impair oxidative phosphorylation and ATP synthesis and enhance ROS production, leading to reduced steroidogenesis. Together, we demonstrate that the IL-1β-DNMT1-SDHB-succinate axis disrupts steroidogenesis. Our findings not only provide a mechanistic explanation for adrenal dysfunction in severe inflammation, but also offer a potential target for therapeutic intervention.

Single-cell atlas of murine adrenal glands reveals immune-adrenal crosstalk during systemic <i>Candida albicans</i> infection

Fungal sepsis remains a major health threat with high mortality, where the adrenal gland stress response has been rarely reported. <i>Candida albicans</i> (<i>C.albicans</i>) is the most common opportunistic fungal pathogen of life-threatening disseminated candidiasis and fungal sepsis. In the present study, we performed single-cell RNA sequencing (scRNA-Seq) using the 10x Genomics platform to analyze the changes in murine adrenal transcriptome following systemic <i>C.albicans</i> infection. A total of 16 021 cells were categorized into 18 transcriptionally distinct clusters, representing adrenocortical cells, endothelial cells, various immune cells, mesenchymal cells, smooth muscle cells, adrenal capsule, chromaffin cells, neurons and glials. As the main cell component in the adrenal gland responsible for steroidogenesis, the adrenocortical cells dramatically diminished and were further grouped into 10 subclusters, which differently distributed in the infected and uninfected samples. Pseudo-time analysis revealed transitions of the adrenocortical cells from the initial normal states to active or dysfunctional states following systemic <i>C.albicans</i> infection <i>via</i> two trajectory paths. Endothelial cells in the highly vascularized organ of adrenal gland further proliferated following infection, with the upregulation of genes positively regulating angiogenesis and downregulation of protective genes of endothelial cells. Immune cells were also excessively infiltrated in adrenal glands of <i>C.albicans</i>-infected mice. Macrophages dominated the immune microenvironments in murine adrenal glands both before and after <i>C.albicans</i> infection, mediating the crosstalk among the steroid-producing cells, endothelial cells and immune cells within the adrenal gland. NLR family, pyrin domain containing 3 (NLRP3, encoded by <i>Nlrp3</i>) and complement receptor 3 (CR3, encoded by <i>Itgam</i>) were found to be significantly upregulated on the adrenal macrophages upon systemic <i>C.albicans</i> infection and might play critical roles in mediating the myeloid response. Meanwhile, the number and strength of the interactions between the infiltrating immune cells and adrenal resident cells were unveiled by cell-cell communication analysis to be dramatically increased after systemic <i>C.albicans</i> infection, indicating that the immune-adrenal crosstalk might contribute to the compromised functions of adrenal cells. Overall, our comprehensive picture of the murine adrenal gland microenvironment in systemic <i>C.albicans</i> infection provides deeper insights into the immune-adrenal cell communications during fungal sepsis.

Results of Structural and Bacteriological Analysis of the Mouse Adrenal Glands in a Sepsis Model

The article presents the results of histological and bacteriological analysis of the adrenal glands in two models of sepsis caused by intraperitoneal administration of Pseudomonas aeruginosa strains 1623 and 5266 to sexually mature male C57BL/6 mice. In both models, histological changes in the adrenal glands in the dynamics of sepsis consist in cell destruction and decrease in the absolute areas of the zona glomerulosa, columnar part of the zona fasciculata, and medulla, the development of venous congestion in the absence of pronounced signs of leukocytic infiltration. Most adrenocortical cells of the zona glomerulosa and chromaffin cells of the medulla show signs of destruction. The columnar part of the zona fasciculata loses normal architectonics, the cells undergo degeneration and apoptosis, a significant part of cells in the deep layers of the zona fasciculata remain intact, but do not show tinctorial and ultrastructural signs of steroidogenesis. The active growth of P. aeruginosa colonies from adrenal homogenates in both models already in the first hours after infection of animals makes it possible to associate the revealed structural changes in the adrenal glands with the direct negative effect of P. aeruginosa, and high levels of mRNA of proinflammatory cytokines in the adrenal tissues raise the question of the possible synthesis of these modulators of inflammation in the adrenal parenchyma of septic animals.

Multi-Organ Transcriptome Dynamics in a Mouse Model of Cecal Ligation and Puncture-Induced Polymicrobial Sepsis

PURPOSE

During sepsis, an excessive inflammatory immune reaction contributes to multi-organ dysfunction syndrome (MODS), a critical condition associated with high morbidity and mortality; however, the molecular mechanisms driving MODS remain elusive.

METHODS

We used RNA sequencing to characterize transcriptional changes in the early phase of sepsis, at 6, 12, 24 hour time points in lung, kidney, liver, and heart tissues, in a cecal ligation and puncture (CLP)-induced polymicrobial sepsis murine model.

RESULTS

The CLP surgery induced significant changes (adj. p-value<0.05) in expression of hundreds of transcripts in the four organs tested, with the highest number exceeding 2,000 differentially expressed genes (DEGs) in all organs at 12 hours post-CLP. Over-representation analysis by functional annotations of DEGs to the Reactome database revealed the immune system, hemostasis, lipid metabolism, signal transduction, and extracellular matrix remodeling biological processes as significantly altered in at least two organs, while metabolism of proteins and RNA were revelaed as being liver tissue specific in the early phase of sepsis.

CONCLUSION

RNA sequencing across organs and time-points in the CLP murine model allowed us to study the trajectories of transcriptome changes demonstrating alterations common across multiple organs as well as biological pathways altered in an organ-specific manner. These findings could pave new directions in the research of sepsis-induced MODS and indicate new sepsis treatment strategies.

H2S counteracts proinflammatory effects of LPS through modulation of multiple pathways in human cells

BACKGROUND

Hydrogen sulfide donors reduce inflammatory signaling in vitro and in vivo. The biological effect mediated by H₂S donors depends on the kinetics of the gas release from the donor molecule. However, the molecular mechanisms of H₂S-induced immunomodulation were poorly addressed. Here, we studied the effect of two different hydrogen sulfide (H₂S)-producing agents on the generation of the LPS-induced inflammatory mediators. Importantly, we investigated the transcriptomic changes that take place in human cells after the LPS challenge, combined with the pretreatment with a slow-releasing H₂S donor-GYY4137.

METHODS

We investigated the effects of GYY4137 and sodium hydrosulfide on the release of proinflammatory molecules such as ROS, NO and TNF-α from LPS-treated human SH-SY5Y neuroblastoma and the THP-1 promonocytic cell lines. Transcriptomic and RT-qPCR studies using THP-1 cells were performed to monitor the effects of the GYY4137 on multiple signaling pathways, including various immune-related and proinflammatory genes after combined action of LPS and GYY4137.

RESULTS

The GYY4137 and sodium hydrosulfide differed in the ability to reduce the production of the LPS-evoked proinflammatory mediators. The pre-treatment with GYY4137 resulted in a drastic down-regulation of many TNF-α effectors that are induced by LPS treatment in THP-1 cells. Furthermore, GYY4137 pretreatment of LPS-exposed cells ameliorates the LPS-mediated induction of multiple pro-inflammatory genes and decreases expression of immunoproteasome genes. Besides, in these experiments we detected the up-regulation of several important pathways that are inhibited by LPS.

CONCLUSION

Based on the obtained results we believe that our transcriptomic analysis significantly contributes to the understanding of the molecular mechanisms of anti-inflammatory and cytoprotective activity of hydrogen sulfide donors, and highlights their potential against LPS challenges and other forms of inflammation.

Transcriptional Analysis of Sepsis-Induced Activation and Damage of the Adrenal Endothelial Microvascular Cells

Bacterial sepsis is a serious threat to the body homeostasis and is often associated with high mortality in non-coronary intensive stations. In order to survive sepsis, rapid activation of the hypothalamus-pituitary-adrenal gland axis and sympathomedullary system is necessary. In many patients with sepsis, the function of those two arms of the stress system is dysregulated with underlying mechanisms remaining unknown. In our previous experimental studies, we have demonstrated that LPS-induced systemic inflammation and CLP-induced peritonitis can result in adrenal gland damage. Histological and transcriptomic analysis revealed a potential involvement of the adrenal microvascular endothelium in this process. However, our knowledge about the function of adrenal microvascular cells during sepsis is scarce. In the present study, we have characterized transcriptomic alterations in isolated mouse adrenal microvascular endothelial cells induced by systemic administration of bacterial LPS. Our results revealed that LPS induced a distinct transcriptomic profile in the adrenal microvascular cells, including multiple genes regulating inflammation, activation of the coagulation cascade and vascular permeability. Activation of those genes may be potentially involved in the damage to the microvascular endothelium and altogether contribute to the sepsis-mediated adrenal dysregulation.