Bcl-2 as a Therapeutic Target in Human Tubulointerstitial Inflammation.

OBJECTIVE: In lupus nephritis, tubulointerstitial inflammation (TII) is associated with in situ adaptive immune cell networks that amplify local tissue damage. Since conventional therapy appears ineffective for severe TII, and these patients often progress to renal failure, understanding in situ mechanisms might reveal new therapeutic targets. This study was undertaken to assess whether dysregulated apoptotic regulators maintain local adaptive immunity and drive inflammation in TII. METHODS: This study utilized novel computational approaches that, when applied to multicolor confocal images, quantified apoptotic regulator protein expression in selected lymphocyte subsets. This approach was validated using laser-capture microdissection (LCM) coupled to quantitative polymerase chain reaction (qPCR). Furthermore, the consequences of dysregulated apoptotic mediator expression were explored in a murine model of lupus nephritis. RESULTS: Analyses of renal biopsy tissue from patients with lupus nephritis and those with mixed cellular renal allograft rejection revealed that the B cell lymphoma 2 protein (Bcl-2) was frequently expressed in infiltrating lymphocytes, whereas expression of myeloid cell leukemia 1 was low. In contrast, the reciprocal pattern of expression was observed in tonsil germinal centers. These results were consistent with RNA expression data obtained using LCM and qPCR. Bcl-2 was also highly expressed in tubulointerstitial infiltrates in (NZB × NZW)F1 (NZB/NZW) mice. Furthermore, treatment of NZB/NZW mice with ABT-199, a selective oral inhibitor of Bcl-2, prolonged survival and prevented proteinuria and development of TII in a lupus prevention model. Interestingly, glomerular immune complexes were partially ameliorated by ABT-199 treatment, and serum anti-double-stranded DNA antibody titers were unaffected. CONCLUSION: These data demonstrate that Bcl-2 is an attractive therapeutic target in patients with lupus nephritis who manifest TII.

Cell distance mapping identifies functional T follicular helper cells in inflamed human renal tissue.

T follicular helper (TFH) cells are critical for B cell activation in germinal centers and are often observed in human inflamed tissue. However, it is difficult to know if they contribute in situ to inflammation. Expressed markers define TFH subsets associated with distinct functions in vitro. However, such markers may not reflect in situ function. The delivery of T cell help to B cells requires direct cognate recognition. We hypothesized that by visualizing and quantifying such interactions, we could directly assess TFH cell competency in situ. Therefore, we developed computational tools to quantify spatial relationships between different cell subtypes in tissue [cell distance mapping (CDM)]. Analysis of inflamed human tissues indicated that measurement of internuclear distances between TFH and B cells could be used to discriminate between apparent cognate and noncognate interactions. Furthermore, only cognate-competent TFH cell populations expressed high levels of Bcl-6 and interleukin-21. These data suggest that CDM can be used to identify adaptive immune cell networks driving in situ inflammation. Such knowledge should help identify diseases, and disease subsets, that may benefit from therapeutic targeting of specific T cell-antigen-presenting cell interactions.