Table 1.
Immune cell subsets | Impact on adipose tissue |
---|---|
T cells | Peripheral CD8+ T cells infiltrate inflamed AT (92, 93, 100, 136) |
Infiltrating T cells adopt a Th1 (interferon secreting) or a Th17 (IL-17-secreting) profile (93, 137-139) | |
Decreased antigen specificities recognized by infiltrating CD8+ T cells (100) | |
Resident CD4+ regulatory T cells maintain AT homeostasis through PPARγ. However, during obesity, the frequency of resident CD4+ regulatory T cells decreases (136, 140-143) | |
Macrophage | Infiltration into AT mediated by MCP-1 chemokine secreted by resident T cells (97, 136) |
Excessive nutrients induce activation of MΦ driven through HIF1α, NF-κB, and IL-1β (94, 95, 136, 144) | |
DC | Infiltration into AT mediated by CX3CL1 chemokine secreted by resident T cells (97, 145) |
In lean mice, DCs exhibit a CD11c+CD103+ phenotype that induces CD4+Foxp3+ Tregs to maintain AT homeostasis. In obese or db/db knockout mice, DC exhibit a CD11c+F4/80lo phenotype and induce Th17 cells (145, 146) | |
Other innate cells | In lean conditions, innate lymphoid cells type-2 induce anti-inflammatory responses and attenuate insulin resistance, but this is lost during obesity (147-149) |
Abbreviations: AT, adipose tissue; DC, dendritic cell; IL, interleukin; NF-κB, nuclear factor kappa B.