Table 2.
An overview of included human studies (n = 11).
| Author and year | Experimental model | Intervention used | Role of T-cells/Findings |
|---|---|---|---|
| Kintscher et al., 2008 [22] | Individuals with T2D | None | Adipose tissue (AT) T-cell infiltration correlated with increased waist circumference in patients with type 2 diabetes mellitus (T2D). |
| Zeyda et al., 2011 [39] | Overweight and obese humans | None | Th1 and CD8+ T-cells were significantly upregulated in obese AT and correlated with AT inflammation. Surprisingly, Th2 and Tregs were also increased in visceral AT of individuals with obesity compared to lean counterparts |
| Deiuliis et al., 2011 [3] | Obese humans | None | Humans with obesity showed increased CD4+and CD8+ T-cells with a decreased Tregs in visceral AT. |
| Yang et al., 2010 [7] | Obese humans | None | There was increased infiltration of CD4+ and CD8+ T-cells in visceral AT of obese individuals compared to lean |
| Fabbrini et al., 2013 [68] | Obese humans with metabolically abnormal IR | None | The number of AT resident CD4+T-cells that produce interleukin (IL)-22 and IL-17 were 3–10 fold higher in obesity compared to lean subjects. |
| Deng et al., 2013 [25] | Obese women | None | Obesity enhanced major histocompatibility complex class II (MHC II) expression in adipocytes. Briefly, adipocytes activated AT resident CD4+ T-cells via MHC class II and leptin to induce AT inflammation |
| Zhong et al., 2014 [8] | Obese humans | None | Reduced B7 expression in obesity impaired regulatory T-cells (Treg) proliferation and function and led to exacerbated AT inflammation and IR |
| McLaughlin et al., 2014 [5] | Overweight and obese humans | None | CD4+ and CD8+ T-cells infiltrated AT with pro-inflammatory T-helper (Th)1, Th17 and CD8+ T-cells being significantly more frequent. Levels of Th2 in AT were inversely associated with systemic IR. |
| Fabrizi et al., 2014 [31] | Obese humans | None | IL-21 and IL-21R messenger RNA expression was upregulated in stromal vascular fraction from human obese subjects in parallel to macrophage and inflammatory markers. |
| Dalmas et al., 2014 [40] | Obese individuals with and without T2D | None | There was increased infiltration of IL-17 and IL-22-producing CD4+ T-cells in individuals with T2D. Moreover, CD4+ T-cell derived IL-22 amplified IL-1β driven inflammation in visceral AT and this was correlated with deterioration of glucose homeostasis. |
| Travers et al., 2015 [13] | Overweight and obese humans | None | Expression of CD4+ T-cells, macrophages and FOXP3 RNA transcripts were elevated in obesity. Furthermore, AT CD4+ and CD8+ T-cells expressed increased expression of CD69 and CD25 which was associated with increasing degree of obesity. In addition, increased T-cell activation correlated with increased expression and secretion of both pro and anti-inflammatory cytokines in AT. |
NB: All studies were observational studies.