Effect of bile acids on fibroblast proliferation and viability

Negative pressure wound therapy with intermittent irrigation for treatment of post-traumatic giant abscess: A case report

Introduction

Negative pressure wound therapy (NPWT), also called vacuum-assisted closure, is an adjunctive therapy used to manage open wounds that apply subatmospheric pressure to the wound surface. The therapeutic effects of NPWT are exerted by stabilizing the wound environment, increasing blood flow, and macro-deformation of wounds that initiate granulation tissue formation.

Case presentation

We present a case of a 28-year-old Caucasian male who developed a giant non-resolving hepatic abscess secondary to a gunshot wound (GSW) to the upper right abdomen. The abscess was successfully treated with open debridement followed by NWPT with instillation therapy. Significant reduction in abscess diameter and cessation of trauma-induced bile leak was observed following 15 days of wound vac treatment.

Discussion

Wound vac treatment was essential in this patient due to the inherent erosive properties of bile that damage surrounding tissue and perpetuate opportunistic growth of pathogenic microbes. Prior to standard NPWT treatment, debridement of devitalized tissues and infection should be managed; however, instillation therapy has permitted NPWT to be used in the presence of infection or as an adjuvant to surgical infection management.

Conclusion

NPWT is indicated for a wide range of acute and chronic wounds; however, the utilization of NPWT to treat abscesses remains unclear.

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This case exhibits the novel use of NPWT to treat a hepatic abscess with bile leak.

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Instill wound VAC can reduce the bacterial wound burden and enhance wound healing.

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Hepatic abscess after trauma is a life-threatening condition with high morbidity.

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Operative management may be necessary for large non-resolving hepatic abscesses.

Sestrin2 protects against cholestatic liver injury by inhibiting endoplasmic reticulum stress and NLRP3 inflammasome-mediated pyroptosis

Chronic exposure to bile acid in the liver due to impaired bile flow induces cholestatic liver disease, resulting in hepatotoxicity and liver fibrosis. Sestrin2, a highly conserved, stress-inducible protein, has been implicated in cellular responses to multiple stress conditions and the maintenance of cellular homeostasis. However, its role in cholestatic liver injury is not fully understood. In this study, we investigated the role of hepatic Sestrin2 in cholestatic liver injury and its underlying mechanisms using in vivo and in vitro approaches. Hepatic Sestrin2 expression was upregulated by activating transcription factor 4 (ATF4) and CCAAT/enhancer-binding protein-β (C/EBP-β) after treatment with bile acids and correlated with endoplasmic reticulum (ER) stress responses. Bile-duct ligation (BDL)-induced hepatocellular apoptosis and liver fibrosis were exacerbated in Sestrin2-knockout (Sesn2^−/−) mice. Moreover, Sestrin2 deficiency enhanced cholestasis-induced hepatic ER stress, whereas Sestrin2 overexpression ameliorated bile acid-induced ER stress. Notably, the mammalian target of rapamycin (mTOR) inhibitor rapamycin and the AMP-activated protein kinase (AMPK) activator AICAR reversed bile acid-induced ER stress in Sestrin2-deficient cells. Furthermore, Sestrin2 deficiency promoted cholestasis-induced hepatic pyroptosis by activating NLRP3 inflammasomes. Thus, our study provides evidence for the biological significance of Sestrin2 and its relationship with cholestatic liver injury, suggesting the potential role of Sestrin2 in regulating ER stress and inflammasome activation during cholestatic liver injury.

A protein that manages the response to cellular stress can help prevent disruptions in bile flow from progressing to liver fibrosis or failure. Disrupted flow leads to the accumulation of bile acids, which triggers a state known as endoplasmic reticulum (ER) stress, fueling inflammation and eventual cell death. Researchers led by Hwan-Woo Park and Jongdae Shin at Konyang University, Daejon, South Korea, have demonstrated that the Sestrin2 protein plays a prominent role in managing this ER stress response to cytotoxic bile acids in cultured liver cells. They subsequently used a Sestrin2-deficient mouse model to demonstrate that the absence of this protein contributes to heightened ER stress and greatly increased liver damage following impaired bile flow. These results suggest that Sestrin2 modulators could offer effective treatments for liver disorders associated with bile flow obstruction.

Direct effect of chenodeoxycholic acid on differentiation of mouse embryonic stem cells cultured under feeder-free culture conditions

Chenodeoxycholic acid (CDCA), a farnesoid X receptor (FXR) ligand, is a member of the nuclear receptor family and is probably involved in regulating the cellular activities of embryonic stem (ES) cells. Recently, although it was reported that the FXR ligand can mediate differentiation, apoptosis, and/or growth arrest in several cell types, it is still not well known how CDCA mediates effects in ES cells. Therefore, we investigated the direct effect of CDCA on mES cells. Feeder-free mES cells were treated in a dose-dependent manner with CDCA (50, 100, and 200 μM) for 72 h, and then a 100 μM CDCA treatment was performed for an additional 72 h. We analyzed the morphology, cell growth, cell characteristics, immunocytochemistry, and RT-PCR. In CDCA-treated cells, we observed the disappearance of pluripotent stem cell markers including alkaline phosphatase, Oct4, and Nanog and a time- and dose-dependent increase in expression of nestin, PAX6, and α-smooth muscle actin, but not α-fetoprotein. The 100 μM CDCA-treated cells in their second passage continued this differentiation pattern similar to those in the controls. In conclusion, these results suggest that CDCA can guide mES cells by an FXR-independent pathway to differentiate into ectoderm and/or mesoderm, but not endoderm.