Non-caveolar caveolin - 1 in retinal Müller glia promotes innate immune responses

Area of Science:

• Ocular biology
• Cellular biology
• Immunology

Background:

• Caveolae are specialized membrane structures involved in ocular diseases.
• Caveolin-1 (CAV1) typically functions in caveolae with CAVIN1/PTRF.
• The role of non-caveolar CAV1, especially in Müller glia, is largely unknown.

Purpose of the Study:

• To investigate the role of non-caveolar CAV1 in retinal Müller glia.
• To determine CAV1's function in inflammatory signaling within the retina.
• To explore therapeutic strategies targeting CAV1 in ocular inflammatory conditions.

Main Methods:

• Utilized Müller glial cell lines (MIO-M1) and human retinal endothelial cells (HRECs).
• Employed transmission electron microscopy to assess caveolae formation.
• Used CAV1 silencing and CAVIN1/PTRF overexpression to modulate CAV1 localization and function.
• Measured inflammatory markers like IL-6 and NF-κB activation in response to lipopolysaccharide (LPS).

Main Results:

• Müller glia predominantly express non-caveolar CAV1 due to minimal CAVIN1/PTRF and lack of caveolae.
• Non-caveolar CAV1 in Müller glia enhances Toll-like receptor-4 (TLR4) signaling and promotes LPS-induced IL-6 upregulation.
• CAV1 silencing or sequestration into caveolae significantly suppresses this pro-inflammatory response.
• In contrast, CAV1 in HRECs, which are caveolae-rich, shows different inflammatory regulation.

Conclusions:

• Non-caveolar CAV1 in Müller glia drives a pro-inflammatory phenotype in the retina.
• This inflammatory effect can be mitigated by reducing CAV1 levels or inducing caveolae formation.
• Cell-context-specific functions of CAV1 in inflammation suggest novel therapeutic avenues for ocular diseases.