Histomorphometry indicates distinct contributions of myofibroblast activation and sinusoidal capillarization to portal hypertension

BACKGROUND AND AIMS: Portal hypertension (PH) is a severe consequence of cirrhosis and the primary driver of hepatic decompensation. We aimed to investigate the link between histological myofibroblast activation (alpha-smooth-muscle-actin: αSMA) and sinusoidal capillarization (CD34) markers to PH severity in patients with chronic liver disease (CLD). METHODS: Patients with CLD underwent hepatic venous pressure gradient (HVPG) measurement and liver biopsy. Liver samples were stained by picrosirius-red for collagen proportionate area (CPA) and for αSMA/CD34. Quantitative histomorphometry was performed on full-slide scans. RESULTS: 102 patients (63.7% male, median age 56.4 years, mainly steatotic liver disease: 58.8%) were included. The median HVPG was 13 [10-18] mmHg and severe PH (HVPG ≥ 16 mmHg, PH16) was found in 35.3%. Median liver-stiffness was 30.6 [19.1-57.6] kPa. In PH16 patients, fibrosis (CPA: 28.39 vs 17.72%), myofibroblast activation (αSMA: 10.84 vs 3.75%), and capillarization (CD34: 5.45 vs 2.67%) were significantly more pronounced (all p < 0.001 vs. no PH16). CD34 showed a higher correlation to HVPG (rho = 0.505) than CPA (rho = 0.472) and αSMA (rho = 0.347, all p < 0.001). CD34 expression was independently correlated with enhanced liver fibrosis (ELF) test and von Willebrand factor (VWF). When partially adjusting for fibrosis severity, patients with less severe fibrosis and high αSMA or CD34 had a trend for higher HVPG, whereas in intermediate fibrosis, only CD34-high patients trended higher HVPG. CONCLUSION: CPA, CD34 and αSMA expression all correlate with PH severity. CD34 represents a histologic sinusoidal capillarization marker that correlates with circulating VWF and ELF. αSMA and CD34 represent potential histologic markers of PH beyond the static component.