Cytokine mRNA expression in the liver of patients with primary biliary cirrhosis (PBC) and chronic hepatitis B (CHB).
The expression of cytokine mRNA species was determined in liver biopsies from six normal subjects, 18 patients with PBC and 14 patients with hepatitis B e antigen (HBeAg)-positive CHB using a reverse transcriptase-polymerase chain reaction (RT-PCR) technique. cDNA, obtained by reverse transcription using oligo d(T) primers, was amplified by PCR using primers specific for the coding region of seven different cytokines (IL-1, IL-2, IL-4, IL-5, IL-6, interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha)). The abundance of some cytokines (IL-2, IL-4, IL-5 and IFN-gamma) was also estimated by semiquantitative RT-PCR, using as standards dilutions of synthetic cytokine mRNA transcripts, that could be distinguished electrophoretically from respective native cytokine mRNAs. Hepatic inflammation was assessed by a semiquantitative histologic score and by amplification of mRNA for T cell receptor (TCR)-alpha. mRNAs for IL-1 and IL-6 were detected in only one control liver. In CHB, mRNAs for IL-1, IL-2, IL-4, IL-5 and IFN-gamma were detected in 43%, 60%, 80%, 20%, and 54% of biopsies, respectively. mRNA for IFN-gamma and IL-4, but not IL-1, tended to be associated with severe inflammation. In five biopsies semiquantitative analyses revealed increased levels of mRNA for TCR-alpha and, when transcripts were detectable, high levels of mRNA for IFN-gamma and IL-4. In PBC, mRNA for IFN-gamma was detected in 60% of biopsies, but no mRNAs for IL-1, IL-2, IL-4, IL-5, or IL-6, or for TNF-alpha, were detected. Semiquantitative analyses revealed that absolute levels of mRNA for IFN-gamma tended to correlate with the severity of hepatic inflammation. The results suggest that: (i) there may be fundamental differences in the roles that cytokines play in the hepatic inflammatory processes of PBC and CHB; and (ii) while hepatic IFN-gamma mRNA expression is not specific for PBC, IFN-gamma may play a prominent role in the immunopathogenesis of PBC.
Shindo
M
M
Liver Diseases Section, NIDDK, National Institutes of Health, Bethesda, MD, USA.
Mullin
G E
GE
Braun-Elwert
L
L
Bergasa
N V
NV
Jones
E A
EA
James
S P
SP
D000328:Adult; D001483:Base Sequence; D002908:Chronic Disease; D016207:Cytokines / Q000235:genetics*; D006509:Hepatitis B / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics; D008099:Liver / Q000378:metabolism*; D008105:Liver Cirrhosis, Biliary / Q000276:immunology*; D008875:Middle Aged; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics
D016207:Cytokines; D012333:RNA, Messenger; D016693:Receptors, Antigen, T-Cell, alpha-beta; D007371:Interferon-gamma