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Integrate Imaging Flow Cytometry and Transcriptomic Profiling to Evaluate Altered Endocytic CD1d Trafficking
Published on: October 29, 2018
Bcl-xL regulates CD1d-mediated antigen presentation to NKT cells by altering CD1d trafficking through the endocytic
Priyanka B Subrahmanyam1, Gregory B Carey1, Tonya J Webb2
1Department of Microbiology and Immunology, University of Maryland School of Medicine and the Marlene and Stewart Greenebaum Cancer Center, Baltimore, MD 21201.
Abstract:
NKT cells are a unique subset of T cells that recognize glycolipid Ags presented in the context of CD1d molecules. NKT cells mount strong antitumor responses and are a major focus in developing effective cancer immunotherapy. It is known that CD1d molecules are constantly internalized from the cell surface, recycled through the endocytic compartments, and re-expressed on the cell surface. However, little is known about the regulation of CD1d-mediated Ag processing and presentation in B cell lymphoma. Prosurvival factors of the Bcl-2 family, such as Bcl-xL, are often upregulated in B cell lymphomas and are intimately linked to sphingolipid metabolism, as well as the endocytic compartments. We hypothesized that Bcl-xL can regulate CD1d-mediated Ag presentation to NKT cells. We found that overexpression or induction of Bcl-xL led to increased Ag presentation to NKT cells. Conversely, the inhibition or knockdown of Bcl-xL led to decreased NKT cell activation. Furthermore, knockdown of Bcl-xL resulted in the loss of CD1d trafficking to lysosome-associated membrane protein 1(+) compartments. Rab7, a late endosomal protein, was upregulated and CD1d molecules accumulated in the Rab7(+) late endosomal compartment. These results demonstrate that Bcl-xL regulates CD1d-mediated Ag processing and presentation to NKT cells by altering the late endosomal compartment and changing the intracellular localization of CD1d.
Insights
Bcl-xL protein regulates how Natural Killer T (NKT) cells recognize cancer cells by controlling the presentation of antigens. This finding offers new insights into developing targeted cancer immunotherapies.
Area of Science:
- Immunology
- Cell Biology
- Cancer Research
Background:
- Natural Killer T (NKT) cells are crucial for anti-tumor immunity, recognizing glycolipid antigens via CD1d molecules.
- CD1d molecules cycle through cellular compartments, but their antigen processing regulation in B cell lymphoma is unclear.
- Bcl-xL, a prosurvival factor often upregulated in lymphomas, impacts sphingolipid metabolism and endocytic pathways.
Purpose of the Study:
- To investigate the role of Bcl-xL in regulating CD1d-mediated antigen presentation to NKT cells in B cell lymphoma.
- To determine if Bcl-xL influences the intracellular trafficking and processing of CD1d molecules.
Main Methods:
- Overexpression and knockdown of Bcl-xL in relevant cellular models.
- Assessment of NKT cell activation in response to antigen presentation.
- Analysis of CD1d molecule localization within endocytic compartments using markers like LAMP1 and Rab7.
Main Results:
- Overexpression of Bcl-xL enhanced CD1d-mediated antigen presentation and NKT cell activation.
- Inhibition or knockdown of Bcl-xL reduced NKT cell activation.
- Bcl-xL knockdown disrupted CD1d trafficking to late endosomes (Rab7+ compartments), leading to CD1d accumulation.
Conclusions:
- Bcl-xL plays a critical role in regulating CD1d-mediated antigen presentation to NKT cells.
- Bcl-xL influences antigen presentation by modulating the late endosomal pathway and CD1d intracellular localization.
- Targeting Bcl-xL could be a strategy to enhance NKT cell-based cancer immunotherapy.
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