Characterization and role of intra-hepatic regulatory T cells in chronic hepatitis C pathogenesis.
OBJECTIVE
In chronic hepatitis C (CHC), HCV-specific T-cell responses are often dysfunctionnal. In vitro data point out that regulatory T cells (Treg) are able to suppress HCV-specific lymphocyte proliferation and cytokine secretion but their implication in this pathology is still debated.


METHODS
Three complementary approaches were performed to investigate phenotype, frequency or localization of intra-hepatic Treg in treatment naïve CHC patients. Double immunohistochemical analysis was performed in 20 formalin-fixed biopsies with CD8/FoxP3 and CD4/FoxP3 antibodies. Cellular markers and cytokines were investigated by quantitative RT-PCR in 27 additional frozen biopsies. Eight other fresh liver biopsies were selected for complementary analysis of immunophenotyping and frequency of intra-hepatic Treg.


RESULTS
Immunohistochemical analyses showed the presence of intra-hepatic CD4(+)FoxP3(+)T cells while CD8(+)FoxP3(+)T cells were very scarce. CD4(+)FoxP3(+)T cells were located in necro-inflammatory areas in contact with CD8(+)T cells, suggesting that Treg-mediated inhibition of CD8(+)T cell proliferation may occur by cell-cell contact. RT-PCR analyses showed strong correlations between CD8, FoxP3, and IL-10 with emergence of four distinct gene clusters, CD8-FoxP3, CD8-IL-10, TGF-beta-IL-10, and TNF-alpha-TGF-beta. No correlation was found between serum viral load and any immune markers. Interestingly, the FoxP3(+)/CD8(+) cells ratio significantly decreased in severe fibrosis (F>3) due to the dramatic decline of FoxP3 cells.


CONCLUSIONS
This study provides new insights into the histological localization of Treg within HCV-infected liver, with a special accumulation of CD4(+)FoxP3(+)Treg cells in necro-inflammatory areas, in contact with CD8(+)T cells. Our results suggest a link between Treg, CD8, and IL-10 which altogether could balance immune responses against the virus to avoid immunopathogenesis.
Sturm
Nathalie
N
INSERM, Unité 823, Grenoble, France.
Thélu
Marie-Ange
MA
Camous
Xavier
X
Dimitrov
Guéorgui
G
Ramzan
Muhammad
M
Dufeu-Duchesne
Tania
T
Bonorino
Paula
P
Guillermet
Christiane
C
Brambilla
Elisabeth
E
Arvers
Philippe
P
Pernollet
Martine
M
Leroy
Vincent
V
Zarski
Jean-Pierre
JP
Marche
Patrice N
PN
Jouvin-Marche
Evelyne
E
D000328:Adult; D000368:Aged; D001483:Base Sequence; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology; D016207:Cytokines / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D005260:Female; D051858:Forkhead Transcription Factors / Q000378:metabolism; D019698:Hepatitis C, Chronic / Q000209:etiology / Q000276:immunology* / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D016753:Interleukin-10 / Q000235:genetics; D008099:Liver / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000473:pathology*; D055815:Young Adult
D016207:Cytokines; D017931:DNA Primers; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; C508609:IL10 protein, human; D016753:Interleukin-10