Semaphorin 3C exacerbates liver fibrosis

BACKGROUND AND AIMS

Chronic liver disease is a growing epidemic, leading to fibrosis and cirrhosis. TGF-β is the pivotal profibrogenic cytokine that activates HSC, yet other molecules can modulate TGF-β signaling during liver fibrosis. Expression of the axon guidance molecules semaphorins (SEMAs), which signal through plexins and neuropilins (NRPs), have been associated with liver fibrosis in HBV-induced chronic hepatitis. This study aims at determining their function in the regulation of HSCs.

APPROACH AND RESULTS

We analyzed publicly available patient databases and liver biopsies. We used transgenic mice, in which genes are deleted only in activated HSCs to perform ex vivo analysis and animal models. SEMA3C is the most enriched member of the semaphorin family in liver samples from patients with cirrhosis. Higher expression of SEMA3C in patients with NASH, alcoholic hepatitis, or HBV-induced hepatitis discriminates those with a more profibrotic transcriptomic profile. SEMA3C expression is also elevated in different mouse models of liver fibrosis and in isolated HSCs on activation. In keeping with this, deletion of SEMA3C in activated HSCs reduces myofibroblast marker expression. Conversely, SEMA3C overexpression exacerbates TGF-β-mediated myofibroblast activation, as shown by increased SMAD2 phosphorylation and target gene expression. Among SEMA3C receptors, only NRP2 expression is maintained on activation of isolated HSCs. Interestingly, lack of NRP2 in those cells reduces myofibroblast marker expression. Finally, deletion of either SEMA3C or NRP2, specifically in activated HSCs, reduces liver fibrosis in mice.

CONCLUSION

SEMA3C is a novel marker for activated HSCs that plays a fundamental role in the acquisition of the myofibroblastic phenotype and liver fibrosis.

Effects of realistic e-learning cases on students' learning motivation during COVID-19

Background

Keeping up motivation to learn when socially isolated during a pandemic can be challenging. In medical schools, the COVID-19 pandemic required a complete switch to e-learning without any direct patient contact despite early reports showing that medical students preferred face-to-face teaching in clinical setting. We designed close to real-life patient e-learning modules to transmit competency-based learning contents to medical students and evaluated their responses about their experience.

Methods

Weekly e-learning cases covering a 10-week leading symptom-based curriculum were designed by a team of medical students and physicians. The internal medicine curriculum (HeiCuMed) at the Heidelberg University Medical School is a mandatory part of clinical medical education in the 6^th or 7^th semester. Case-design was based on routine patient encounters and covered different clinical settings: preclinical emergency medicine, in-patient and out-patient care and follow-up. Individual cases were evaluated online immediately after finishing the respective case. The whole module was assessed at the end of the semester. Free-text answers were analyzed with MaxQDa following Mayring`s principles of qualitative content analyses.

Results

N = 198 students (57.6% female, 42.4% male) participated and 1252 individual case evaluations (between 49.5% and 82.5% per case) and 51 end-of-term evaluations (25.8% of students) were collected. Students highly appreciated the offer to apply their clinical knowledge in presented patient cases. Aspects of clinical context, interactivity, game-like interface and embedded learning opportunities of the cases motivated students to engage with the asynchronously presented learning materials and work through the cases.

Conclusions

Solving and interpreting e-learning cases close to real-life settings promoted students’ motivation during the COVID-19 pandemic and may partially have compensated for missing bedside teaching opportunities.

Isolation of Murine Primary Aortic Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) have been cultured for decades to study the role of these cells in cardiovascular disorders. The most common source of VSMCs is the rat aorta. Here we show the adaptation of this method to isolate and culture mouse aortic VSMCs. The advantage of this method is that there are many more transgenic mouse lines available compared to rats. The protocol consists of the isolation of the aorta, the liberation of vascular cells by the action of collagenase, culturing of VSCMs, and analyzing filamentous actin and alpha smooth muscle actin by fluorescence microscopy. VSCMs can be further used to study mechanisms underlying cardiovascular diseases. Graphic abstract: Figure 1.Working steps.