Limits...
Molecular mimicry of human cytochrome P450 by hepatitis C virus at the level of cytotoxic T cell recognition.

Kammer AR, van der Burg SH, Grabscheid B, Hunziker IP, Kwappenberg KM, Reichen J, Melief CJ, Cerny A - J. Exp. Med. (1999)

Bottom Line: We found that the naive CTL repertoire of both groups contains cross-reactive CTLs inducible by the HCV peptide recognizing both CYP2A6 and CYP2A7 peptides as well as endogenously processed CYP2A6 protein.Importantly, we failed to induce CTLs with the CYP-derived peptides that showed a lower capacity to form stable complexes with the HLA-A2 molecule.These findings demonstrate the potential of HCV to induce autoreactive CD8(+) CTLs by molecular mimicry, possibly contributing to virus-associated autoimmunity.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, University Hospital, Inselspital, 3010 Bern, Switzerland.

ABSTRACT
Hepatitis C virus (HCV) is thought to be involved in the pathogenesis of autoimmune hepatitis (AIH) type 2, which is defined by the presence of type I antiliver kidney microsome autoantibodies directed mainly against cytochrome P450 (CYP)2D6 and by autoreactive liver infiltrating T cells. Virus-specific CD8(+) cytotoxic T lymphocytes (CTLs) that recognize infected cells and contribute to viral clearance and tissue injury during HCV infection could be involved in the induction of AIH. To explore whether the antiviral cellular immunity may turn against self-antigens, we characterized the primary CTL response against an HLA-A*0201-restricted HCV-derived epitope, i.e., HCV core 178-187, which shows sequence homology with human CYP2A6 and CYP2A7 8-17. To determine the relevance of these homologies for the pathogenesis of HCV-associated AIH, we used synthetic peptides to induce primary CTL responses in peripheral blood mononuclear cells of healthy blood donors and patients with chronic HCV infection. We found that the naive CTL repertoire of both groups contains cross-reactive CTLs inducible by the HCV peptide recognizing both CYP2A6 and CYP2A7 peptides as well as endogenously processed CYP2A6 protein. Importantly, we failed to induce CTLs with the CYP-derived peptides that showed a lower capacity to form stable complexes with the HLA-A2 molecule. These findings demonstrate the potential of HCV to induce autoreactive CD8(+) CTLs by molecular mimicry, possibly contributing to virus-associated autoimmunity.

Show MeSH

Related in: MedlinePlus

Peptide-specific cytotoxicity induced in vitro with HCV core 178–187, CYP2A6 8–17, or CYP2A7 8–17 peptides. PBMCs from healthy HCV-seronegative blood donors were stimulated with HCV core 178–187 (a), CYP2A6 8–17 (b), or CYP2A7 8-18 (c) in four replicas 1234. After 5 wk of stimulation, peptide-specific lysis of each culture was determined on JY target cells pulsed with HCV core 178–187 (white bars), CYP2A6 8–17 (black bars), or CYP2A7 8–17 (gray bars). E/T cell ratios were fixed for each culture and ranged from 20:1 to 40:1 for the different cultures.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2195568&req=5

Figure 2: Peptide-specific cytotoxicity induced in vitro with HCV core 178–187, CYP2A6 8–17, or CYP2A7 8–17 peptides. PBMCs from healthy HCV-seronegative blood donors were stimulated with HCV core 178–187 (a), CYP2A6 8–17 (b), or CYP2A7 8-18 (c) in four replicas 1234. After 5 wk of stimulation, peptide-specific lysis of each culture was determined on JY target cells pulsed with HCV core 178–187 (white bars), CYP2A6 8–17 (black bars), or CYP2A7 8–17 (gray bars). E/T cell ratios were fixed for each culture and ranged from 20:1 to 40:1 for the different cultures.

Mentions: To determine the effect of the different HLA-A2 binding properties on T cell activation and antigen recognition by CTLs, we first analyzed the naive CTL repertoire in healthy blood donors. PBMCs from 12 healthy HCV-seronegative, HLA-A2–positive blood donors were stimulated with synthetic HCV core 178–187, CYP2A6 8–17, or CYP2A7 8–17 peptide in four replica cultures. After 5 wk, the cultures were tested for CTL activity against target cells presenting each of the three peptides. Long-term stimulation with the HCV core 178 peptide induced HCV core 178–specific CTLs in nine HCV-seronegative blood donors (Table ). In five individuals, the HCV core 178–specific CTLs not only recognized the inducing HCV peptide but also CYP2A6 and/or CYP2A7 self-peptides. A higher specific lysis of targets presenting CYP2A7 was observed in most cases. Two donors recognized all three peptides, three individuals recognized HCV core 178 and CYP2A7 8–17, four recognized HCV core 178 only, and three did not show a CTL response after stimulation with HCV core 178. Representative results of three donors are shown in Fig. 2 a. These results as well as data obtained from CTL lines derived from positive cultures (data not shown) indicate the presence of three phenotypes of HCV core 178–specific CTLs: CTLs recognizing HCV core 178 only, CTLs cross-reactive with HCV core 178 and CYP2A7, and CTLs specific for HCV core 178, CYP2A7, and CYP2A6. We did not find CTLs recognizing CYP2A6 without recognition of CYP2A7, nor cells recognizing one of the CYP peptides without recognition of HCV core 178. Importantly, no CTL response could be induced with the self-peptides CYP2A6 8–17 (Fig. 2 b) and CYP2A7 8–17 (Fig. 2 c) in any of the 12 donors tested. This fits with our observation of different MHC–peptide interactions, because peptide-induced MHC stability and immunogenicity of the peptide are strongly correlated 28.


Molecular mimicry of human cytochrome P450 by hepatitis C virus at the level of cytotoxic T cell recognition.

Kammer AR, van der Burg SH, Grabscheid B, Hunziker IP, Kwappenberg KM, Reichen J, Melief CJ, Cerny A - J. Exp. Med. (1999)

Peptide-specific cytotoxicity induced in vitro with HCV core 178–187, CYP2A6 8–17, or CYP2A7 8–17 peptides. PBMCs from healthy HCV-seronegative blood donors were stimulated with HCV core 178–187 (a), CYP2A6 8–17 (b), or CYP2A7 8-18 (c) in four replicas 1234. After 5 wk of stimulation, peptide-specific lysis of each culture was determined on JY target cells pulsed with HCV core 178–187 (white bars), CYP2A6 8–17 (black bars), or CYP2A7 8–17 (gray bars). E/T cell ratios were fixed for each culture and ranged from 20:1 to 40:1 for the different cultures.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2195568&req=5

Figure 2: Peptide-specific cytotoxicity induced in vitro with HCV core 178–187, CYP2A6 8–17, or CYP2A7 8–17 peptides. PBMCs from healthy HCV-seronegative blood donors were stimulated with HCV core 178–187 (a), CYP2A6 8–17 (b), or CYP2A7 8-18 (c) in four replicas 1234. After 5 wk of stimulation, peptide-specific lysis of each culture was determined on JY target cells pulsed with HCV core 178–187 (white bars), CYP2A6 8–17 (black bars), or CYP2A7 8–17 (gray bars). E/T cell ratios were fixed for each culture and ranged from 20:1 to 40:1 for the different cultures.
Mentions: To determine the effect of the different HLA-A2 binding properties on T cell activation and antigen recognition by CTLs, we first analyzed the naive CTL repertoire in healthy blood donors. PBMCs from 12 healthy HCV-seronegative, HLA-A2–positive blood donors were stimulated with synthetic HCV core 178–187, CYP2A6 8–17, or CYP2A7 8–17 peptide in four replica cultures. After 5 wk, the cultures were tested for CTL activity against target cells presenting each of the three peptides. Long-term stimulation with the HCV core 178 peptide induced HCV core 178–specific CTLs in nine HCV-seronegative blood donors (Table ). In five individuals, the HCV core 178–specific CTLs not only recognized the inducing HCV peptide but also CYP2A6 and/or CYP2A7 self-peptides. A higher specific lysis of targets presenting CYP2A7 was observed in most cases. Two donors recognized all three peptides, three individuals recognized HCV core 178 and CYP2A7 8–17, four recognized HCV core 178 only, and three did not show a CTL response after stimulation with HCV core 178. Representative results of three donors are shown in Fig. 2 a. These results as well as data obtained from CTL lines derived from positive cultures (data not shown) indicate the presence of three phenotypes of HCV core 178–specific CTLs: CTLs recognizing HCV core 178 only, CTLs cross-reactive with HCV core 178 and CYP2A7, and CTLs specific for HCV core 178, CYP2A7, and CYP2A6. We did not find CTLs recognizing CYP2A6 without recognition of CYP2A7, nor cells recognizing one of the CYP peptides without recognition of HCV core 178. Importantly, no CTL response could be induced with the self-peptides CYP2A6 8–17 (Fig. 2 b) and CYP2A7 8–17 (Fig. 2 c) in any of the 12 donors tested. This fits with our observation of different MHC–peptide interactions, because peptide-induced MHC stability and immunogenicity of the peptide are strongly correlated 28.

Bottom Line: We found that the naive CTL repertoire of both groups contains cross-reactive CTLs inducible by the HCV peptide recognizing both CYP2A6 and CYP2A7 peptides as well as endogenously processed CYP2A6 protein.Importantly, we failed to induce CTLs with the CYP-derived peptides that showed a lower capacity to form stable complexes with the HLA-A2 molecule.These findings demonstrate the potential of HCV to induce autoreactive CD8(+) CTLs by molecular mimicry, possibly contributing to virus-associated autoimmunity.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, University Hospital, Inselspital, 3010 Bern, Switzerland.

ABSTRACT
Hepatitis C virus (HCV) is thought to be involved in the pathogenesis of autoimmune hepatitis (AIH) type 2, which is defined by the presence of type I antiliver kidney microsome autoantibodies directed mainly against cytochrome P450 (CYP)2D6 and by autoreactive liver infiltrating T cells. Virus-specific CD8(+) cytotoxic T lymphocytes (CTLs) that recognize infected cells and contribute to viral clearance and tissue injury during HCV infection could be involved in the induction of AIH. To explore whether the antiviral cellular immunity may turn against self-antigens, we characterized the primary CTL response against an HLA-A*0201-restricted HCV-derived epitope, i.e., HCV core 178-187, which shows sequence homology with human CYP2A6 and CYP2A7 8-17. To determine the relevance of these homologies for the pathogenesis of HCV-associated AIH, we used synthetic peptides to induce primary CTL responses in peripheral blood mononuclear cells of healthy blood donors and patients with chronic HCV infection. We found that the naive CTL repertoire of both groups contains cross-reactive CTLs inducible by the HCV peptide recognizing both CYP2A6 and CYP2A7 peptides as well as endogenously processed CYP2A6 protein. Importantly, we failed to induce CTLs with the CYP-derived peptides that showed a lower capacity to form stable complexes with the HLA-A2 molecule. These findings demonstrate the potential of HCV to induce autoreactive CD8(+) CTLs by molecular mimicry, possibly contributing to virus-associated autoimmunity.

Show MeSH
Related in: MedlinePlus