Clinical Histological Study Of “Subclinical” Primary Biliary Cholangitis

Backgrounds: Primary biliary cholangitis(PBC)is a chronic progressive cholestatic liver disease,characterized by interlobular bile duct destruction in histology.The factors leading to disease initiation are not well understood.Most patients are typically diagnosed by elevated serum alkaline phosphatase(AKP)and a positive antimitochondrial antibody(AMA)test.However,for the patients with positive AMA but normal AKP levels,it remains unclear whether the bile ducts will be damaged,whether they will progress to classic PBC,and whether early UDCA treatment is needed.Several histological features of PBC have been reported such as the loss of the canals of Hering(CoH),ductular reaction(DR),and cellular senescence.In the study,we mainly described the liver histological features of the patients with positive AMA but normal AKP levels.Part Ⅰ The clinical histological features of the patients with positive AMA but normal AKP levelsAims:To describe the clinical and histological features of patients with positive AMA but normal AKP levels,and to explore the appropriate timing for a liver biopsy so as to provide timely treatment and improve prognosis.Methods: We retrospectively analyzed 162 patients with positive AMA but normal AKP levels between January 2012 and January 2018,including 60 patients with a liver biopsy.Fourty-three classic PBC patients with a liver biopsy at baseline were enrolled for control.Results: The average age of 162 cases with positive AMA but normal AKP was 46 years,of which 87.0% were female.Normal serum immunoglobulin M(IgM)and whole biochemical liver tests(i.e.,bilirubin,AKP,gammaglutamyl transpeptidase(GGT),aminotransferase)were found in 86(53.1%)and 50(30.9%)of 162 cases,respectively.In the 60 patients who underwent a liver biopsy,49(81.7%)cases had varying degrees of cholangitis,37(38.3%)cases had varying degrees of hepatitis,and the stages 1,2,3,and 4 were distributed as 7/48/5/0(11.7%/80.0%/8.3%/0%).Of the 60 cases with a liver biopsy,49 cases were diagnosed as PBC by histology,termed as "subclinical" PBC,and the remaining 11 were not diagnosed as PBC,termed as "non-onset" patients.In multivariate analysis,serum AMA titer≥1:320 and AKP>0.475×upper limit of normal(ULN)were associated with "subclinical" PBC.During the mean follow-up of 27 months(3-77)and 20 months(4-53)for ‘‘subclinical” PBC and “non-onset” group,respectively,most(48/49)of ‘‘subclinical” PBC and and part(7/11)of “non-onset” group received UDCA or combined therapy of UDCA and prednisolone,and none of the 60 cases developed persistently raised serum AKP levels.There were no significant differences between ‘‘subclinical” PBC and classic PBC patients in chronic cholangitis activity(CA)grades(P=0.332),while hepatitic activity(HA)grades(P<0.001)and stages(P<0.001)were more serious in classic PBC cases.Conclusions: About 80%(49/60)of the patients with positive AMA but normal AKP levels can be diagnosed as "subclinical" PBC by liver histology.The severity of cholangitis in "subclinical" PBC patients was similar to that in classic PBC patients.Therefore,the timely liver biopsy for diagnosis may be helpful,especially AKP>0.475 upper limit normal(ULN)and serum AMA titer ≥1:320.Part Ⅱ: The morphological study of intrahepatic bile duct injury in "subclinical" PBCAims:To compare bile duct injury in liver histology between "subclinical" PBC,“non-onset” group,as well as classic PBC.Methods:The histological specimens of patients undergoing a liver biopsy in our hospital were selected for immunohistochemical staining for keratin 19(CK19),keratin 7(CK7),and p16INK4 a.The loss of CoH,ductular reaction(DR),and the cellular senescence of bile ductular cells were compared between each group.Results: CoH(0.52C/P)of "subclinical" PBC group was not statistically different from the “non-onset” group(0.61C/P,P = 0.775),nor was it statistically different from the classic PBC group(0.93C/P,P = 0.297).The degree of CK7+ DR in the "subclinical" PBC group(2.9%/0%/5.9%/41.2%/50.0%)was higher than that in the “non-onset” group(77.8%/ 22.2%/0%/0%/0%,p<0.001)and lower than that in the classic PBC group(0%/0%/7.1%/14.3%/78.6%,p = 0.032).The expression of P16INK4 a was less extensive in the "subclinical" PBC group than that in the classic PBC group(1+,14.7%;2+,85.3% vs.1+,76%;2+,24%,p<0.001).There was no statistically significant difference(1+,76%;2+,24% vs.1+,100%;2+,0%,p=0.309)between the "subclinical" PBC group and the “non-onset” group.However,the p16INK4a-negative portal area/total portal area was significantly reduced in "subclinical" PBC,compared to the “non-onset” group(range: 0.00-0.67,mean 0.21 vs.range 0.50-0.80,mean 0.69,p<0.001),but was significantly increased compared to the classic PBC group(range: 0.00-0.67,mean 0.21 vs.range 0.00-0.50,mean 0.07,p=0.004).Conclusions: Although milder than classic PBC patients,DR and the cellular senescence of bile ductular cells can be present in "subclinical" PBC patients,suggesting that the cholangiocytes in subclinical PBC patients were exactly damaged.