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Cross Talk between P38MAPK and STAT3 Regulates Expression of Negative Costimulatory Molecules and Transcriptional Repressors in HIV-1 Primed T cells
Linköping University, Department of Clinical and Experimental Medicine, Molecular Virology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Molecular Virology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Molecular Virology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

HIV-1 infection enhances the expression of negative costimulatory molecules on T cellsleading to T cell impairment. The signaling pathway underlying the regulation ofinhibitory molecules and the subsequent onset of T cell impairment remains to beinvestigated. Herein, we showed that the T cells activated by HIV-pulsed dendritic cells(DCs) upregulated CTLA-4, TRAIL, LAG-3, TIM-3, and CD160 and suppressionassociated transcription factors BLIMP-1, DTX1, and FOXP3, leading to T cellsuppression. The induction of suppressor T cells was regulated by the signal transducerand activator of transcription 3 (STAT3) molecules as blockade of this pathwaysignificantly down regulates the expression of inhibitory molecules. The cytokines IL-6and IL-10 were not responsible for STAT3 activation as their neutralization could neitherrecover T cell proliferation nor decrease the expression of negative costimulatorymolecules. Contrarily, we demonstrated that the intracytoplasmic cross-talk of P38Mitogen-Activated Protein Kinase (MAPK) with STAT3 was responsible as blockade ofthe P38MAPK significantly impaired negative costimulatory molecular expression andthe subsequent recovery of T cell proliferation. Notably, the blockade of viral access toDC cytosol, via CD4 binding and fusion, significantly reduced the negative effects DCsimposed on the primed T cells. In conclusion, viral access to cytosol modulated theDCs- T cell priming to induce T cells with upreguled expression of negativecostimulatory molecules in a P38MAPK/STAT3 pathway dependent fashion

Keyword [en]
BLIMP-1; dendritic cells; HIV-1; LAG-3; P38MAPK, STAT3; T cells
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-71276OAI: oai:DiVA.org:liu-71276DiVA: diva2:446834
Available from: 2011-10-10 Created: 2011-10-10 Last updated: 2011-10-10Bibliographically approved
In thesis
1. Immunomodulatory Effects of Human ImmunodeficiencyVirus (HIV-1) on Dendritic Cell and T cell Responses: Studies of HIV-1 effects on Dendritic cell functionality reflected in primed T cells
Open this publication in new window or tab >>Immunomodulatory Effects of Human ImmunodeficiencyVirus (HIV-1) on Dendritic Cell and T cell Responses: Studies of HIV-1 effects on Dendritic cell functionality reflected in primed T cells
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The human immunodeficiency virus (HIV)-1 is the causative agent of acquired immune deficiency syndrome (AIDS) worldwide. Till date there are no vaccines or cure for this infection as the virus has adapted myriad ways to remain persistent in the host where it causes severe damage to the immune system. Both humoral and cellular immune responses are mounted against HIV-1 during the initial phase of infection but fail to control viral replication as these responses are severely depleted during disease progression. Of great importance in HIV-1 research today is the in depth understanding of the types of immune responses elicited, the mechanisms behind their decline and how these responses can be  maintained overtime.

The focus of this thesis was to examine the possibility of priming HIV-1 specific T cell responses in vitro from whole viral particles and in detail, scrutinize the type of T cell responses and epitope specificities generated. Next was to investigate in vitro the factors responsible for impaired immune responses in HIV-1 infected individuals. We were also interested in understanding the underlying mechanisms through which HIV-1 initiate suppression of T cell functionality.

Results showed that using HIV-1 pulsed monocyte derived dendritic cells (DCs), we were able to prime HIV-1 specific CD4+ and CD8+ T cells from naïve T cells in vitro. The epitopes primed in vitro were located within the HIV-1 envelope, gag, and pol proteins and were confirmed ex vivo to exist in acute and chronically infected individuals. We established that many of the novel CD4+ T cell epitopes primed in vitro also existed in vivo in HIV-1 infected individuals during acute infection. These responses declined/disappeared early on, which is in line with HIV-1 preferential infection of HIV-1 specific CD4+ T cells.

Besides declining HIV-1 specific T cell responses, many HIV-1 infected individuals also have impaired T cell functionality. We established that one reason behind the decline and impairment in immune responses was the increased expression of inhibitory molecules PD-1, CTLA-4, and TRAIL on HIV-1 primed T cells. These T cells had the capacity to suppress new responses in a cell-cell contact dependent manner. The ability of the HIV-1 primed T cells to proliferate was severely impaired and this condition was reversed after a combined blockade of PD-1, CTLA-4 and TRAIL. Furthermore, more inhibitory molecules TIM-3, LAG-3, CD160, BLIMP-1, and FOXP3 were also found increased at both gene and protein levels on HIV-1 primed T cells. Additionally, we showed decreased levels of functional cytokines IL-2, IFN-γ and TNF-α, and the cytolytic proteins perforin and granzyme in DC T cell priming cocultures containing HIV-1. This could be as a result of the decreased T cell activation or impaired production by T cells. The mechanisms responsible for the elevated levels of inhibitory molecules emanated mainly from the P38MAPK/STAT3 pathways. Blockade of these pathways in both allogeneic and autologous DC-T cell assays significantly suppressed expression of inhibitory molecules and subsequently rescued T cell proliferation.

In conclusion, HIV-1 pulsed DCs have the capacity to prime HIV-1 specific responses in vitro that do exist in HIV-1 infected individuals and we found evidence that many of these responses were eliminated rapidly in HIV-1 infected individuals. HIV-1 triggers through P38MAPK/STAT3 pathway the synthesis of inhibitory molecules, namely CTLA-4, PD-1, TRAIL, TIM-3, LAG-3, CD160, and suppression associated transcription factors FOXP3, BLIMP-1 and DTX1. This is followed by decreased T cell proliferation and functionality which are much needed to control viral replication.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. 67 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1256
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-71279 (URN)978-91-7393-093-2 (ISBN)
Public defence
2011-09-02, Eken, ingång 65, Campus US, Linköpings universitet, Linköping, 09:00 (English)
Opponent
Supervisors
Available from: 2011-10-10 Created: 2011-10-10 Last updated: 2011-11-28Bibliographically approved

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Che, Karlhans FruShankar, Esaki MSundaram, MuthuSigvardsson, MikaelHinkula, JormaLarsson, Marie

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Che, Karlhans FruShankar, Esaki MSundaram, MuthuSigvardsson, MikaelHinkula, JormaLarsson, Marie
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Molecular VirologyFaculty of Health SciencesDepartment of Clinical and Experimental MedicineExperimental Hematology
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