Colon Ascendens Stent Peritonitis (CASP) Induces Excessive Inflammation and Systemic Metabolic Dysfunction in a Septic Rat Model

The combination of high glucose and LPS induces autophagy in bovine kidney epithelial cells via the Notch3/mTOR signaling pathway

BACKGROUND

Aside respiratory diseases, beef cattle may also suffer from serious kidney diseases after transportation. Hyperglycemia and gram-negative bacterial infection may be the main reasons why bovine is prone to severe kidney disease during transportation stress, however, the precise mechanism is still unclear. The purpose of the current study is to explore whether the combined treatment of high glucose (HG) and lipopolysaccharide (LPS) could induce madin-darby bovine kidney (MDBK) cells injury and autophagy, as well as investigate the potential molecular mechanisms involved.

RESULTS

As we discovered, the combined effect of HG and LPS decreased MDBK cells viability. And, HG and LPS combination also induced autophagy in MDBK cells, which was characterized by increasing the expression of LC3-II/I and Beclin1 and decreasing p62 expression. LC3 fluorescence signal formation was also significantly increased by HG and LPS combination treatment. Furthermore, we measured whether the mammalian target of rapamycin (mTOR) and the Notch3 signaling pathways were involved in HG and LPS-induced autophagy. The results showed that the combination of HG and LPS significantly increased the protein expression of Notch3 and decreased protein expression of p-mTOR, indicating that Notch3 and mTOR signaling pathways were activated. However, co-treatment with the Notch3 inhibitor (DAPT) could reverse the induction of autophagy, and increased the protein expression of p-mTOR.

CONCLUSIONS

This study demonstrated that the combination effect of HG and LPS could induce autophagy in MDBK cells, and the Notch3/mTOR signaling pathway was involved in HG and LPS-induced autophagy.

Increased mortality and altered local immune response in secondary peritonitis after previous visceral operations in mice

Postoperative peritonitis is characterized by a more severe clinical course than other forms of secondary peritonitis. The pathophysiological mechanisms behind this phenomenon are incompletely understood. This study used an innovative model to investigate these mechanisms, combining the models of murine Colon Ascendens Stent Peritonitis (CASP) and Surgically induced Immune Dysfunction (SID). Moreover, the influence of the previously described anti-inflammatory reflex transmitted by the vagal nerve was characterized. SID alone, or 3 days before CASP were performed in female C57BL/6 N mice. Subdiaphragmatic vagotomy was performed six days before SID with following CASP. The immune status was assessed by FACS analysis and measurement of cytokines. Local intestinal inflammatory changes were characterized by immunohistochemistry. Mortality was increased in CASP animals previously subjected to SID. Subclinical bacteremia occurred after SID, and an immunosuppressive milieu occurred secondary to SID just before the induction of CASP. Previous SID modified the pattern of intestinal inflammation induced by CASP. Subdiaphragmatic vagotomy had no influence on sepsis mortality in our model of postoperative peritonitis. Our results indicate a surgery-induced inflammation of the small intestine and the peritoneal cavity with bacterial translocation, which led to immune dysfunction and consequently to a more severe peritonitis.

Essential Role of Visfatin in Lipopolysaccharide and Colon Ascendens Stent Peritonitis-Induced Acute Lung Injury

Acute lung injury (ALI) is a life-threatening syndrome characterized by acute and severe hypoxemic respiratory failure. Visfatin, which is known as an obesity-related cytokine with pro-inflammatory activities, plays a role in regulation of inflammatory cytokines. The mechanisms of ALI remain unclear in critically ill patients. Survival in ALI patients appear to be influenced by the stress generated by mechanical ventilation and by ALI-associated factors that initiate the inflammatory response. The objective for this study was to understand the mechanisms of how visfatin regulates inflammatory cytokines and promotes ALI. The expression of visfatin was evaluated in ALI patients and mouse sepsis models. Moreover, the underlying mechanisms were investigated using human bronchial epithelial cell lines, BEAS-2B and NL-20. An increase of serum visfatin was discovered in ALI patients compared to normal controls. Results from hematoxylin and eosin (H&E) and immunohistochemistry staining also showed that visfatin protein was upregulated in mouse sepsis models. Moreover, lipopolysaccharide (LPS) induced visfatin expression, activated the STAT3/NFκB pathway, and increased the expression of pro-inflammatory cytokines, including IL1-β, IL-6, and TNF-α in human bronchial epithelial cell lines NL-20 and BEAS-2B. Co-treatment of visfatin inhibitor FK866 reversed the activation of the STAT3/NFκB pathway and the increase of pro-inflammatory cytokines induced by LPS. Our study provides new evidence for the involvement of visfatin and down-stream events in acute lung injury. Further studies are required to confirm whether the anti-visfatin approaches can improve ALI patient survival by alleviating the pro-inflammatory process.

Urine metabolome in women with Chlamydia trachomatis infection

The aim of this study was to characterize the urine metabolome of women with Chlamydia trachomatis (CT) uro-genital infection (n = 21), comparing it with a group of CT-negative subjects (n = 98). By means of a proton-based nuclear magnetic resonance (¹H-NMR) spectroscopy, we detected and quantified the urine metabolites of a cohort of 119 pre-menopausal Caucasian women, attending a STI Outpatients Clinic in Italy. In case of a CT positive result, CT molecular genotyping was performed by omp1 gene semi-nested PCR followed by RFLP analysis. We were able to identify several metabolites whose concentrations were significantly higher in the urine samples of CT-positive subjects, including sucrose, mannitol, pyruvate and lactate. In contrast, higher urinary levels of acetone represented the main feature of CT-negative women.

These results were not influenced by the age of patients nor by the CT serovars (D, E, F, G, K) responsible of the urethral infections. Since the presence of sugars can increase the stability of chlamydial proteins, higher levels of sucrose and mannitol in the urethral lumen, related to a higher sugar consumption, could have favoured CT infection acquisition or could have been of aid for the bacterial viability. Peculiar dietary habits of the subjects enrolled, in term of type and amount of food consumed, could probably explain these findings. Lactate and pyruvate could result from CT-induced immunopathology, as a product of the inflammatory microenvironment. Further studies are needed to understand the potential role of these metabolites in the pathogenesis of CT infection, as well as their diagnostic/prognostic use.