Regulatory T Cells Improve Nephrocalcinosis but Not Dystrophic Cardiac Calcinosis in DBA/2 Mice

Abstract

Nephrocalcinosis is characterized by aberrant deposition of calcium in the kidneys and is seen in phosphate nephropathy, primary hyperparathyroidism, and distal renal tubular acidosis. To further evaluate the specific pathophysiologic role of T cells in ectopic calcification, we used DBA/2 mice that are prone to develop nephrocalcinosis and dystrophic cardiac calcinosis. Female DBA/2 mice were depleted of T cells (n = 10) or regulatory T cells (Tregs) (n = 15) using either an anti-CD3ɛ or an anti-CD25 monoclonal antibody and compared with isotype-treated controls (n = 9; n = 15), respectively. After this immunomodulation, the DBA/2 mice were given a high-phosphate diet for 9 days and the degree of calcification was assessed by microcomputed tomography. Successful depletion was confirmed by flow cytometry of splenocytes. In DBA/2 mice, the high-phosphate diet induced a phenotype of nephrocalcinosis and dystrophic cardiac calcinosis. T-cell depletion significantly increased renal calcification in microcomputed tomography (P = 0.022). Concordantly, Treg depletion significantly deteriorated acute phosphate nephropathy (P = 0.039) and was associated with a significantly increased mortality rate (P = 0.004). Immunomodulation had no impact on the amount of cardiac calcification. Semiquantitative histopathologic evaluations with Alizarin Red staining independently confirmed the respective radiologic measurements. In summary, our data suggest a pivotal role of T cells, particularly Tregs, in the progression of nephrocalcinosis and emphasize the fact that inflammation deteriorates the outcome in acute phosphate nephropathy.

A New Murine Model of Chronic Kidney Disease-Mineral and Bone Disorder

“…In our model, we do not need surgical interventions and the mortality of these mice is very low (5 to 10%; data not shown) since we stop HPD on day 4 or 7, respectively. As shown previously, mortality increases rapidly in our mice when fed with HPD for more than 10 days [ 19 ]. Of note, choosing the DBA/2 strain is of critical importance to induce CKD, since C57BL/6 mice do not develop critical calcification neither in the kidney nor in the cardiovascular system [ 20 ].…”

“…From our data, we cannot clearly tell, whether the mice also develop concentric left ventricular hypertrophy since we have low ( n ) numbers in echocardiography and heart weights did not differ between the groups. In HPD-induced acute kidney injury model due to phosphate nephropathy, we found the picture of dystrophic cardiac calcinosis resulting in the significantly increased mortality in the mice [ 19 ]. In the presented CKD model, the cardiac picture looked differently since we did not detect relevant calcifications in the myocardium (data not shown), but preliminary observations by echocardiography showed that the mice developed some extent of cardiac hypertrophy probably due to hypertension which more closely resembles the human CKD-MBD phenotype.…”

Genetic modulation of nephrocalcinosis in mouse models of ectopic mineralization: the Abcc6 and Enpp1 mutant mice

“…Nephrocalcinosis could be considered to be a passive phenomenon resulting from deposition of a supersaturated phosphate product associated with tissue remodeling and ultimately leading to the loss of functioning renal parenchyma. It has been demonstrated that acute phosphate nephropathy can be actively modulated by inflammatory repair mechanisms, suggesting a role for regulatory T cells (27). However, the mechanistic details in many of the pathological situations resulting in ectopic calcium deposition in kidney remain to be explored.…”

Autophagy Protects From Uremic Vascular Media Calcification

“…Within 5–14 days mice develop calcification within the Tunica media of the aorta, which is more pronounced in the abdominal part of the aorta mimicking the situation in ESRD patients ( 14 ). Whereas inflammation is of crucial importance in the development of renal calcification ( 13 ), vascular media calcification does not seem to be dependent on immune cells ( 14 ).…”