scholarly journals Woodchuck Gamma Interferon Upregulates Major Histocompatibility Complex Class I Transcription but Is Unable To Deplete Woodchuck Hepatitis Virus Replication Intermediates and RNAs in Persistently Infected Woodchuck Primary Hepatocytes

2002 ◽  
Vol 76 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Mengji Lu ◽  
Beate Lohrengel ◽  
Gero Hilken ◽  
Thekla Kemper ◽  
Michael Roggendorf
Keyword(s):  
Gene Expression ◽  
Cellular Response ◽  
Hepatitis Virus ◽  
Woodchuck Hepatitis Virus ◽  
Complex Class ◽  
Mhc I ◽  
Histocompatibility Complex ◽  
Tnf Α ◽  
Ifn Γ ◽  
Replication Intermediates

ABSTRACT Gamma interferon (IFN-γ) is an important mediator with multiple functions in the host defense against viral infection. IFN-γ, in concert with tumor necrosis factor alpha (TNF-α), leads to a remarkable reduction of intrahepatic replication intermediates and specific mRNAs of hepatitis B virus (HBV) by a noncytolytic mechanism in the transgenic mouse model. Thus, it is rational to evaluate the potential value of IFN-γ for the treatment of chronic HBV infection. In the present study, we expressed recombinant woodchuck IFN-γ (wIFN-γ) in Escherichia coli and mammalian cells. wIFN-γ protected woodchuck cells against infection of murine encephalomyocarditis virus in a species-specific manner. It upregulated the mRNA level of the woodchuck major histocompatibility complex class I (MHC-I) heavy chain in permanent woodchuck WH12/6 cells and regulated differentially the gene expression. However, the level of the replication intermediates and specific RNAs of woodchuck hepatitis virus (WHV) in persistently WHV-infected primary woodchuck hepatocytes did not change despite a treatment with 1,000 U of wIFN-γ per ml or with a combination of wIFN-γ and woodchuck TNF-α. Rather, hepatocytes derived from chronic carriers had an elevated level of the MHC-I heavy-chain mRNAs, most probably due to the exposure to inflammatory cytokines in vivo. Treatment with high doses of wIFN-γ led to an abnormal cell morphology and loss of hepatocytes. Thus, wIFN-γ regulates the gene expression in woodchuck hepatocytes but could not deplete WHV replication intermediates and mRNAs in persistently infected hepatocytes. The cellular response to wIFN-γ may be changed in hepatocytes from chronically WHV-infected woodchucks. It should be clarified in the future whether the continuous exposure of hepatocytes to inflammatory cytokines or the presence of viral proteins leads to changes of the cellular response to wIFN-γ.

scholarly journals P03.22 Repolarization of tumor-associated macrophages for immunotherapy of tumors with diverse major histocompatibility complex class I expression

2020 ◽  
Vol 8 (Suppl 2) ◽  
pp. A31.1-A31
Author(s):  
A Piataková ◽  
I Poláková ◽  
M Šmahel
Keyword(s):  
Major Histocompatibility Complex ◽  
Cytotoxic Effect ◽  
Complex Class ◽  
Mhc I ◽  
Mhc Ii ◽  
Histocompatibility Complex ◽  
Tnf Α ◽  
Tumor Types ◽  
Combined Immunotherapy

BackgroundDepletion of tumor-associated macrophages (TAMs), which are regarded as M2, pro-tumor cells, is one of the strategies for cancer treatment. However, repolarization of TAMs to the M1 anti-tumor phenotype could constitute an immunotherapeutic alternative for tumors with defective major histocompatibility complex class I (MHC-I), where the anti-tumor effect of cytotoxic CD8+ T cells could be limited.Materials and MethodsIn this study, we characterized TAMs from mouse tumor models of human papillomavirus 16-associated tumors, characterized by either reversibly (TC-1/A9) or irreversibly (TC-1/dB2m) downregulated MHC-I expression. Tumors were treated with DNA immunization against the papillomaviral E7 oncoprotein combined with intraperitoneal injection of the synthetic oligodeoxynucleotide ODN1826, a Toll-like receptor 9 agonist. TAMs were characterized ex vivo by flow cytometry. In vitro, F4/80+ TAMs from naïve tumors were stimulated to M1 or M2 phenotype and co-cultures with TC-1/A9 or TC-1/dB2m cells were established. The cytotoxic effect of polarized TAMs was investigated, and the role of nitric oxide (NO) and tumor necrosis factor (TNF)-α was examined. Finally, interleukin (IL)-10, IL-12 and TNF-α concentrations were determined by ELISA in the culture media from polarized TAMs.ResultsWe demonstrated that TAMs infiltrated both tumor types and this effect was moderately enhanced after combined immunotherapy. Increase in MHC-II molecules, broadly regarded as an M1 marker, was observed solely in TAMs from treated TC-1/A9 tumors. In contrast, TAMs from TC-1/dB2m tumors expressed high MHC-II levels, regardless of the treatment. Therefore, the new CD38+/Egr2+ classification1 was applied and showed to be a better descriptive parameter for M1/M2 TAMs, respectively, because the number of Egr2+ TAMs decreased in both tumor types after combined immunotherapy. While CD38+ TAMs were significantly increased after treatment of TC-1/A9 tumors, they did not increase substantially in TC-1/dB2m tumors. In vitro, co-cultures with tumor cells resulted in increase of NO production by M1 TAMs. However, NO and TNF-α contributed to the cytotoxic effect only in TAMs from TC-1/A9 tumor. Finally, in vitro polarized M1 TAMs were able to produce TNF-α and IL-10 but not IL-12.ConclusionsOur results showed different effects of immunostimulation on cytotoxicity of TAMs from tumors with distinct MHC-I expression. While TAMs from TC-1/A9 tumors acquired M1 phenotype and became cytotoxic, TAMs from TC-1/dB2m tumors were more resistant to repolarization. This project was supported by grants GA19–00816S provided by the Czech Science Foundation and LQ1604 provided by the Ministry of Education, Youth and Sports of the Czech Republic.ReferenceJablonski KA, Amici SA, Webb LM, Ruiz-Rosado JdD, Popovich PG, Partida-Sanchez S, Arellano M. Novel Markers to Delineate Murine M1 and M2 Macrophages. PLoS ONE 2015; 10(12); 1–25.Disclosure InformationA. Piataková: None. I. Poláková: None. M. Šmahel: None.

scholarly journals Transmembrane Helices Are an Over-Presented and Evolutionarily Conserved Source of Major Histocompatibility Complex Class I and II Epitopes

2022 ◽  
Vol 12 ◽  
Author(s):  
Richèl J. C. Bilderbeek ◽  
Maksim V. Baranov ◽  
Geert van den Bogaart ◽  
Frans Bianchi
Keyword(s):  
T Cell ◽  
Membrane Proteins ◽  
T Cell Responses ◽  
Class I ◽  
Complex Class ◽  
Transmembrane Helices ◽  
Class I Mhc ◽  
Mhc I ◽  
Cell Responses ◽  
Histocompatibility Complex

Cytolytic T cell responses are predicted to be biased towards membrane proteins. The peptide-binding grooves of most alleles of histocompatibility complex class I (MHC-I) are relatively hydrophobic, therefore peptide fragments derived from human transmembrane helices (TMHs) are predicted to be presented more often as would be expected based on their abundance in the proteome. However, the physiological reason of why membrane proteins might be over-presented is unclear. In this study, we show that the predicted over-presentation of TMH-derived peptides is general, as it is predicted for bacteria and viruses and for both MHC-I and MHC-II, and confirmed by re-analysis of epitope databases. Moreover, we show that TMHs are evolutionarily more conserved, because single nucleotide polymorphisms (SNPs) are present relatively less frequently in TMH-coding chromosomal regions compared to regions coding for extracellular and cytoplasmic protein regions. Thus, our findings suggest that both cytolytic and helper T cells are more tuned to respond to membrane proteins, because these are evolutionary more conserved. We speculate that TMHs are less prone to mutations that enable pathogens to evade T cell responses.

scholarly journals TAPBPR mediates peptide dissociation from MHC class I using a leucine lever

2018 ◽  
Author(s):  
F. Tudor Ilca ◽  
Andreas Neerincx ◽  
Clemens Hermann ◽  
Ana Marcu ◽  
Stefan Stevanovic ◽  
...  
Keyword(s):  
Major Histocompatibility Complex ◽  
Major Histocompatibility Complex Class ◽  
Class I ◽  
Dependent Manner ◽  
Complex Class ◽  
Major Histocompatibility ◽  
Mhc I ◽  
Histocompatibility Complex ◽  
Peptide Dissociation ◽  
Peptide Exchange

AbstractTapasin and TAPBPR are known to perform peptide editing on major histocompatibility complex class I (MHC I) molecules, however, the precise molecular mechanism(s) involved in this process remain largely enigmatic. Here, using immunopeptidomics in combination with novel cell-based assays that assess TAPBPR-mediate peptide exchange, we reveal a critical role for the K22-D35 loop of TAPBPR in mediating peptide exchange on MHC I. We identify a specific leucine within this loop that enables TAPBPR to facilitate peptide dissociation from MHC I. Moreover, we delineate the molecular features of the MHC I F pocket required for TAPBPR to promote peptide dissociation in a loop-dependent manner. These data reveal that chaperone-mediated peptide editing of MHC I can occur by different mechanisms dependent on the C-terminal residue that the MHC I accommodates in its F pocket and provide novel insights that may inform the therapeutic potential of TAPBPR manipulation to increase tumour immunogenicity.Impact StatementThis work demonstrates for the first time that the K22-D35 loop of TAPBPR is the essential region for mediating peptide exchange and peptide selection on major histocompatibility complex class I molecules.

scholarly journals Transmembrane helices are an overlooked and evolutionarily conserved source of major histocompatibility complex class II epitopes

2021 ◽  
Author(s):  
Richel Bilderbeek ◽  
Maksim Baranov ◽  
Frans Bianchi ◽  
Geert van den Bogaart
Keyword(s):  
T Cell ◽  
Membrane Proteins ◽  
T Cell Responses ◽  
Nucleotide Polymorphisms ◽  
Complex Class ◽  
Transmembrane Helices ◽  
Class I Mhc ◽  
Mhc I ◽  
Cell Responses ◽  
Histocompatibility Complex

Cytolytic T cell responses are predicted to be biased towards membrane proteins. The peptide-binding grooves of most haplotypes of histocompatibility complex class I (MHC-I) are relatively hydrophobic, therefor peptide fragments derived from human transmembrane helices (TMHs) are predicted to be presented more often as would be expected based on their abundance in the proteome. However, the physiological reason of why membrane proteins might be over-presented is unclear. In this study, we show that the over-presentation of TMH-derived peptides is general, as it is predicted for bacteria and viruses and for both MHC-I and MHC-II. Moreover, we show that TMHs are evolutionarily more conserved, because single nucleotide polymorphisms (SNPs) are present relatively less frequently in TMH-coding chromosomal regions compared to regions coding for extracellular and cytoplasmic protein regions. Thus, our findings suggest that both cytolytic and helper T cells respond more to membrane proteins, because these are evolutionary more conserved. We speculate that TMHs therefor are less prone to escape mutations that enable pathogens to evade T cell responses.

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