Background: Feline chronic kidney disease (CKD) is characterised by tubulointerstitial inflammation and fibrosis that positively correlates with disease progression. Beta thymosins are proteins with anti-inflammatory and anti-fibrotic properties. Thymosin beta 10 (TB10) kidney mRNA levels are increased in experimental kidney disease and spontaneous feline CKD. Hypothesis/
Objectives: To investigate TB10 protein expression in the kidneys of cats with progressive and stable CKD and controls, and to identify the cell types expressing TB10. Animals: Post-mortem tissue from client-owned cats with stable or progressive (> 25% increase in plasma [creatinine] in the year before death) CKD (n=13), and cats without clinical evidence of CKD (n=3).
Methods: Immunohistochemistry for TB10 (progressive n=4, stable n=3, control n=3), and immunofluorescent dual labelling of TB10 and the leucocyte marker, CD45, (progressive n=3, stable n=5, control n=2) was performed on formalin-fixed paraffin-embedded kidney sections.
Results: Blinded qualitative assessment identified more widespread TB10 labelling in CKD kidneys compared to controls, predominantly localised in interstitial infiltrates. TB10 was present in the glomerular tuft, Bowman’s capsule and tubular epithelium in CKD cases, but absent or scarce in these regions in controls. No differences were identified between progressive and stable cases. Immunofluorescence demonstrated CD45+TB10+, CD45+TB10- and CD45-TB10+ cells in all cats. Conclusions and Clinical Importance: TB10 protein is more widely expressed in CKD kidneys compared to controls. TB10 is expressed in a subset of interstitial leucocytes and also in a CD45- cell population. This information will aid hypothesis development regarding the action of TB10 in the healthy and diseased cat kidney.
