Upregulated PD-1 signaling antagonizes glomerular health in aged kidneys and disease
Jeffrey W. Pippin, Natalya Kaverina, Yuliang Wang, Diana G. Eng, Yuting Zeng, Uyen Tran, Carol J. Loretz, Anthony Chang, Shreeram Akilesh, Chetan Poudel, Hannah S. Perry, Christopher O’Connor, Joshua C. Vaughan, Markus Bitzer, Oliver Wessely, Stuart J. Shankland
Jeffrey W. Pippin, Natalya Kaverina, Yuliang Wang, Diana G. Eng, Yuting Zeng, Uyen Tran, Carol J. Loretz, Anthony Chang, Shreeram Akilesh, Chetan Poudel, Hannah S. Perry, Christopher O’Connor, Joshua C. Vaughan, Markus Bitzer, Oliver Wessely, Stuart J. Shankland
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Research Article Aging

Upregulated PD-1 signaling antagonizes glomerular health in aged kidneys and disease

Abstract

With an aging population, kidney health becomes an important medical and socioeconomic factor. Kidney aging mechanisms are not well understood. We previously showed that podocytes isolated from aged mice exhibit increased expression of programmed cell death protein 1 (PD-1) surface receptor and its 2 ligands (PD-L1 and PD-L2). PDCD1 transcript increased with age in microdissected human glomeruli, which correlated with lower estimated glomerular filtration rate and higher segmental glomerulosclerosis and vascular arterial intima-to-lumen ratio. In vitro studies in podocytes demonstrated a critical role for PD-1 signaling in cell survival and in the induction of a senescence-associated secretory phenotype. To prove PD-1 signaling was critical to podocyte aging, aged mice were injected with anti–PD-1 antibody. Treatment significantly improved the aging phenotype in both kidney and liver. In the glomerulus, it increased the life span of podocytes, but not that of parietal epithelial, mesangial, or endothelial cells. Transcriptomic and immunohistochemistry studies demonstrated that anti–PD-1 antibody treatment improved the health span of podocytes. Administering the same anti–PD-1 antibody to young mice with experimental focal segmental glomerulosclerosis (FSGS) lowered proteinuria and improved podocyte number. These results suggest a critical contribution of increased PD-1 signaling toward both kidney and liver aging and in FSGS.

Authors

Jeffrey W. Pippin, Natalya Kaverina, Yuliang Wang, Diana G. Eng, Yuting Zeng, Uyen Tran, Carol J. Loretz, Anthony Chang, Shreeram Akilesh, Chetan Poudel, Hannah S. Perry, Christopher O’Connor, Joshua C. Vaughan, Markus Bitzer, Oliver Wessely, Stuart J. Shankland

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Figure 4

Podocyte density, scarring, stress, and ultrastructure.

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Podocyte density, scarring, stress, and ultrastructure. (A–E) Podocyte d...
(A–E) Podocyte density measured by p57 staining (dark blue, C–E) and summarized in A. Each circle represents an individual mouse. Density was lower in aged IgG2a-injected mice compared with young mice and was increased in aged aPD1ab-injected mice. Glomerular scarring was measured by glomerular collagen IV staining (brown, C–E) and is summarized in B. It was higher in IgG2a-injected aged mice compared with young mice and was lowered by aPD1ab. (F–H) The podocyte stress marker desmin (brown) was increased in aged IgG2a-injected mice compared with young and was lower in aged aPD1ab mice. (I–L) The filtration barrier ultrastructure was assessed by expansion microscopy of FLARE-labeled glomeruli, which demonstrated that glomerular basement membrane (GBM) thickness (pink) was significantly increased in aged IgG2a-injected mice (J) compared with young mice (I) and reduced in aged aPD1ab mice (K). Representative images are shown in I–K, and GBM thickness is quantified in L. N, nuclei; E, erythrocytes. (M–P) Podocyte ultrastructure was characterized by the podocyte exact morphology measurement procedure (PEMP). Representative images are shown in M–O, and filtration slit density (FSD) is quantified in P. This analysis shows a significant decrease in FSD in aged IgG2a-injected mice compared with young mice (M, N, and P). Elevation of FSD was observed in aged aPD1ab mice but did not reach significance (O and P). Scale bars: 5 μm (M–O), 10 μm (I–K), and 50 μm (C–H). Statistical analysis was performed by 1-way ANOVA.