Membrane Attack Complex in Biliary Atresia: New Insight for Etiopathogenesis

Purpose Biliary atresia (BA) is the most common cause of neonatal cholestasis (NC); nevertheless, there is a lack of an established etiology. Understanding etiopathogenesis opens the way to adjuvant medical therapy. Membrane attack complex (MAC) is the terminal step in the complement cascade and was found to share in the pathogenesis in some hepatic diseases. So, we aimed to study the MAC immunostaining in liver sections of BA. Methods In this retrospective case-control study, 165 NC cases that underwent liver biopsy from January 2017 to December 2019 in our Institute were checked. Their liver biopsy paraffin blocks were retrieved. Those with insufficient tissue and those without sufficient data within the patients' files were excluded. Finally, 66 cases were included (35 cases of BA and 31 cases of non-BA cholestasis). Clinical, laboratory, and radiological data were registered from the patients' files. All liver sections were examined for MAC by immunostaining using anti-human C5b-9 monoclonal antibody. Results No significant difference was found between the studied groups regarding age (p = 0.452) and sex (p = 0.56). Portal MAC immunostaining was significantly (p = 0.004) associated with BA (54%) than non-BA cholestasis (19%). On the other hand, hepatocellular MAC immunostaining was higher in the non-BA group (p = 0.039). MAC-positive BA cases had significantly higher (p = 0.04) gamma-glutamyl transferase (GGT) than MAC-negative BA. Conclusion MAC is significantly expressed in the portal structures of BA. MAC is a proposed pathophysiologic mechanism for developing the fibro-obliterative process of the biliary tree in BA. Assessment of targeting MAC-mediated pathophysiological process in MAC-positive BA cases is warranted.