In Vitro Treatment Of Isolated Renal T Cells With Hmgb1-Neutralizing Antibody Decreases Activation In Hypertensive Males And Females

Background: Renal necrosis induces the release of pro-inflammatory danger associated molecular patterns (DAMPs), and HMGB1 is the best-characterized DAMP. Previous studies published by our lab found that male spontaneously hypertensive rats (SHR) have greater renal necrosis and more pro-inflammatory T cells than females. The current study tested the hypothesis that greater HMGB1 in male SHR will result in greater renal T cell activation compared to female SHR. Methods: Male and female SHR were euthanized at 13 weeks of age. One kidney was sectioned and the cortex homogenized for HMGB1 quantification by ELISA (n=5 per group). The remaining kidney was homogenized under sterile conditions and renal T cells isolated. T cells were cultured with total splenocytes from sex-matched WKY. Additional experiments were conducted in the presence of HMGB1-neutralizing antibody (n=6) or control IgG antibody (n=4). After 72 hours of culture, CD71 + cells were assessed by flow cytometric analysis as a measure of T cell activation and resulting data are expressed as a percentage of total T cells. Results: Renal HMGB1 levels were statistically comparable between male SHR and female SHR (1.61±0.1 vs. 1.3±0.1, respectively; p=0.12). Despite this, T cell activation was higher in male SHR than females (% CD71 + cells: 92±0.3 vs. 70±2; p<0.0001). IgG antibody treatment did not alter T cell activation in either sex (% CD71 + cells: 91±0.2 vs. 74±2), while treatment with HMGB1-neutralizing antibody decreased T cell activation in both sexes (% CD71 + cells: male SHR, 79±1; female SHR, 57±1.6; 2-way ANOVA: p sex <0.0001, p treatment <0.0001, p int =0.49). Conclusion: Although male SHR did not have higher levels of HMGB1 than female SHR, they had significantly greater T cell activation compared to females. Treatment with HMGB1-neutralizing antibody decreased T cell activation in both males and females, but sex differences in T cell activation were maintained, suggesting that HMGB1 contributes to T cell activation equally in both sexes. Further studies will be required to determine the physiological basis of sex differences in renal inflammation.