Analysis and validation of diagnostic biomarkers and immune cell infiltration characteristics in pediatric sepsis by integrating bioinformatics and machine learning

BACKGROUND

Pediatric sepsis is a complicated condition characterized by life-threatening organ failure resulting from a dysregulated host response to infection in children. It is associated with high rates of morbidity and mortality, and rapid detection and administration of antimicrobials have been emphasized. The objective of this study was to evaluate the diagnostic biomarkers of pediatric sepsis and the function of immune cell infiltration in the development of this illness.

METHODS

Three gene expression datasets were available from the Gene Expression Omnibus collection. First, the differentially expressed genes (DEGs) were found with the use of the R program, and then gene set enrichment analysis was carried out. Subsequently, the DEGs were combined with the major module genes chosen using the weighted gene co-expression network. The hub genes were identified by the use of three machine-learning algorithms: random forest, support vector machine-recursive feature elimination, and least absolute shrinkage and selection operator. The receiver operating characteristic curve and nomogram model were used to verify the discrimination and efficacy of the hub genes. In addition, the inflammatory and immune status of pediatric sepsis was assessed using cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT). The relationship between the diagnostic markers and infiltrating immune cells was further studied.

RESULTS

Overall, after overlapping key module genes and DEGs, we detected 402 overlapping genes. As pediatric sepsis diagnostic indicators, CYSTM1 (AUC = 0.988), MMP8 (AUC = 0.973), and CD177 (AUC = 0.986) were investigated and demonstrated statistically significant differences (P < 0.05) and diagnostic efficacy in the validation set. As indicated by the immune cell infiltration analysis, multiple immune cells may be involved in the development of pediatric sepsis. Additionally, all diagnostic characteristics may correlate with immune cells to varying degrees.

CONCLUSIONS

The candidate hub genes (CD177, CYSTM1, and MMP8) were identified, and the nomogram was constructed for pediatric sepsis diagnosis. Our study could provide potential peripheral blood diagnostic candidate genes for pediatric sepsis patients.

Expression pattern of hepcidin in E.coli challenged obese mice (IRM9P.600)

Background:Hepcidin is a master regulator of iron metabolism and plays important roles in the pathophysiology of sepsis. Obesity leads to host immune changes and is associated with the pathogenesis of sepsis. Increased hepcidin expression has been observed in adipose tissue. However, the expression pattern of hepcidin in obese mice after sepsis challenge remains unknown. Methods:Mice were fed with high-fat-diet (HFD) containing 60% energy from fat for 12 weeks. The control mice were supplied with a diet with 10% energy from fat. Sepsis was induced by intraperitoneal injection of E. coli. Hepcidin mRNA expression was studied in peripheral blood mononuclear cell (PBMC), liver, spleen, adipose tissue and peritoneal macrophage. Results:HFD-fed mice showed higher weight and increased total cholesterol and triglyceride levels in serum than controls. Obese mice, as compared with controls, exhibited increased mortality following E.coli administration. Bacterial load and IL-6 levels in blood and peritoneal lavage fluid in the HFD group were higher than controls. The hepcidin mRNA levels were increased both in HFD and LFD groups. Especially, in septic obese mice, the hepcidin mRNA levels in PBMC, spleen and peritoneal macrophage, but no in liver and adipose tissue, were higher than those in controls. Conclusions:The different expression pattern of hepcidin after E.coli challenge suggests that tissue specific hepcidin may take a diverse role in the pathogenesis of sepsis in obese mice.

Hepcidin protects sepsis through regulating iron homeostasis to inhibit immunocyte apoptosis in mice (P4435)

Background: Hepcidin is a key regulator of iron metabolism and may have a critical role in modulating LPS-induced acute inflammatory responses. The role of hepcidin in cecal ligation and puncture (CLP) induced sepsis model was not clear. Methods: Adenovirus-mediated shRNA to inhibit the expression of hepcidin and a relative negative control were constructed and were administrated to mice through hydrodynamic injection via tail vein. Thirteen days later, the mice were subjected to CLP. Bacterial colony counts in blood and organs, reactive oxygen species (ROS) production in liver and immunocyte apoptosis in spleen were analyzed. Survival rate was estimated after 7 days. Results: The survival rate of hepcidin-knock down (KD) mice in CLP-induced sepsis was significantly decreased. Hepcidin-KD mice exposed to CLP showed more severe lung injury and increased inflammation cytokines. The serum iron concentration in hepcidin-KD mice after CLP was significantly higher, which resulted in more ROS production in liver and increased bacterial counts in blood and organs. In the spleen, there were significantly more apoptotic immunocytes in hepcidin-KD mice than those in controls. However, no significant differences in SOCS3 and phosphorylation of STAT3 level between the two groups were observed. Conclusions: Hepcidin may have a protective role in sepsis through regulating iron balance to inhibit bacterial infection and oxidative stress, which then protected immunocyte from apoptosis.

Salvianolic acid A inhibits platelet activation and arterial thrombosis via inhibition of phosphoinositide 3-kinase

BACKGROUND AND OBJECTIVE

Salvianolic acid A (SAA) is a water-soluble component from the root of Salvia miltiorrhiza Bunge, a herb that is widely used for atherothrombotic disease treatment in Asian medicine. As platelets play pivotal roles in atherothrombogenesis, we studied the effect of SAA on platelet activation and its underlying mechanisms.

METHODS AND RESULTS

SAA dose-dependently inhibited platelet aggregation induced by ADP, thrombin, collagen and U46619. It reduced ADP-enhanced platelet P-selectin expression and fibrinogen binding, which consequently hampered ADP-induced platelet-leukocyte aggregation. SAA also inhibited platelet spreading on fibrinogen, a process mediated by outside-in signaling. Under an arterial shear rate of 1000 s(-1), SAA decreased platelet adhesion on collagen surfaces by approximately 40%. Western blot analysis showed that SAA, like the phosphoinositide 3-kinase (PI3K) inhibitors LY294002 and TGX-221, potently inhibited PI3K, as shown by reduced Akt phosphorylation. The in vitro findings were further evaluated in the mouse model of arterial thrombosis, in which SAA prolonged the mesenteric arterial occlusion time in wild-type mice (35 + or - 2 min without SAA and 56 + or - 4 min with SAA; P < 0.01). Interestingly, SAA could even counteract the shortened arterial occlusion time in Ldlr(tm1Her) mutant mice (21 + or - 2 min without SAA and 45 + or - 4 min with SAA; P < 0.01).

CONCLUSIONS

SAA inhibits platelet activation via the inhibition of PI3K, and attenuates arterial thrombus formation in vivo. Our data suggest that SAA may be developed as a novel therapeutic agent for the prevention of thrombotic disorders.

Resveratrol reduces endothelial progenitor cells senescence through augmentation of telomerase activity by Akt-dependent mechanisms

BACKGROUND AND PURPOSE

Recent studies have shown that resveratrol increased endothelial progenitor cells (EPCs) numbers and functional activity. However, the mechanisms remain to be determined. Previous studies have demonstrated that increased EPC numbers and activity were associated with the inhibition of EPC senescence, which involves activation of telomerase. Therefore, we investigated whether resveratrol inhibits the onset of EPC senescence through telomerase activation, leading to potentiation of cellular activity.

EXPERIMENTAL APPROACH

After prolonged in vitro cultivation, EPCs were incubated with or without resveratrol. The senescence of EPCs were determined by acidic beta-galactosidase staining. The bromo-deoxyuridine incorporation assay or a modified Boyden chamber assay were employed to assess proliferative or migratory capacity, respectively. To further examine the underlying mechanisms of these effects, we measured telomerase activity and the phosphorylation of Akt by western blotting.

KEY RESULTS

Resveratrol dose dependently prevented the onset of EPCs senescence and increased the proliferation and migration of EPCs. The effect of resveratrol on senescence could not be abolished by eNOS inhibitor or by an oestrogenic receptor antagonist. Resveratrol significantly increased telomerase activity and Akt phosphorylation. Pre-treatment with the PI3K inhibitor, LY294002, significantly attenuated resveratrol-induced telomerase activity.

CONCLUSIONS AND IMPLICATIONS

Resveratrol delayed the onset of EPC senescence and this effect was accompanied by activation of telomerase through the PI3K-Akt signalling pathway. The inhibition of EPCs senescence by resveratrol might protect EPCs against dysfunction induced by pathological factors in vivo and improve EPC functional activities in a way that may be important for cell therapy.

Structures of two new diterpenoid dimers from bulbs of Fritillaria ebeiensis

Two new ent-kauranoid diterpenoid dimers, fritillebin C (1) and fritillebin D (2), were isolated from the bulbs of Fritillaria ebeiensis G.D. Yu and G.Q. Ji. Their structures were determined to be ent-16beta-hydroxy-kauran-17-yl ent-16beta3-kauran-17-oate (1); ent-16alpha-hydroxy-kauran-17-yl ent-16beta-kauran-17-oate (2) by means of spectral analysis and chemical evidence.

Acute adrenal insufficiency in association with pancreatic carcinoma

Addison's disease secondary to metastatic cancer to the adrenal gland is underdiagnosed. Prompt diagnosis and treatment is essential and could enhance the quality of life. Cases of adrenal insufficiency produced by metastatic carcinoma are unusual, despite the frequency of carcinomatous metastases to the adrenal glands. The clinical features of adrenal insufficiency are relatively nonspecific and can be easily overlooked in a patient with a malignant neoplasm. We report herein the case of a middle-aged man who presented with adrenal insufficiency in association with pancreatic carcinoma. To our knowledge, this is the first reported case of adrenal insufficiency occurring with adenocarcinoma of the pancreas.