# Calhm6 Governs Macrophage Polarization Through Chp1‐Camk4‐Creb1 Axis and Ectosomal Delivery in Inflammatory Responses

## TL;DR

The ion channel Calhm6 helps control inflammation by influencing macrophage behavior through a specific signaling pathway and by being delivered via ectosomes.

## Contribution

The study identifies Calhm6 as a novel regulator of macrophage polarization and inflammation via the Chp1-Camk4-Creb1 axis and ectosomal delivery.

## Key findings

- Calhm6-bearing ectosomes promote M2-like macrophage polarization and anti-inflammatory responses.
- Calhm6 deficiency increases M1-like polarization and pro-inflammatory cytokine secretion.
- LPS/IFNγ upregulate Calhm6 via Irf1, while IL-4/Stat6 suppresses it, balancing immune outcomes.

## Abstract

Macrophage plasticity, critical for immune response, is often dysregulated in various infectious and inflammatory diseases. While ion channels have been implicated in immune cell modulation, how they influence macrophage polarization remains poorly understood. Here, it is demonstrated that ectosomes carrying the ion channel Calhm6 effectively suppress severe inflammation triggered by LPS. These Calhm6‐bearing ectosomes, secreted by macrophages, facilitate M2‐like polarization, elicit an anti‐inflammatory response, and foster immune tolerance. Conversely, Calhm6 deficiency leads to suppressed Creb1 activity, which in turn augments M1‐like macrophage polarization, enhancing bactericidal activity and the secretion of pro‐inflammatory cytokines. Mechanistically, Chp1 serves as a scaffold protein and undergoes phosphorylation by CaMK4. This phosphorylation enhances the localization of the Calhm6‐Chp1‐CaMK4 complex to the cell membrane, promoting Creb1 activation and M2‐like macrophage polarization calcium‐dependently. Moreover, the M1‐like polarization inducers LPS and IFNγ enhance the binding of Irf1 to the Calhm6 promoter, upregulating its expression and stimulating ectosome formation. Conversely, Stat6, activated by IL‐4, competes with Irf1 for binding to the Calhm6 promoter, thereby suppressing its expression. In summary, our findings unravel the intricate interplay between ion channels, ectosomes, and macrophage polarization, revealing that ectosomal‐Calhm6 can serve as a novel therapeutic agent to modulate inflammatory responses and facilitate tissue repair.

Calhm6 drives M2 macrophage polarization via the Chp1‐Camk4‐Creb1 axis, suppressing inflammation through calcium‐dependent ectosomal delivery. Calhm6 deficiency enhances M1 responses, boosting bactericidal activity but exacerbating tissue damage. LPS/IFNγ upregulate Calhm6 via Irf1, while IL‐4/Stat6 inhibits it, balancing immune outcomes. Ectosomal Calhm6 emerges as a therapeutic candidate for inflammatory diseases and tissue regeneration.