Chemokine Therapy in Cats With Experimental Renal Fibrosis and in a Kidney Disease Pilot Study

Abstract

Background: Chronic tubulointerstitial fibrosis is a common final pathway leading to end stage kidney disease in cats and has no effective treatment. The use of cell-based molecules to treat kidney fibrosis may be a promising approach. The objectives were to test the effects of intra-renal chemokine CXCL12 injection in a pre-clinical cat model of unilateral ischemia/reperfusion (I/R)-induced kidney fibrosis and then, within a clinical pilot study, test the safety/feasibility of CXCL12 injection in cats that might have early chronic kidney disease (CKD).Methods:Pre-clinical: Thirty cats received intra-renal injection of 100, 200, or 400 ng of recombinant human CXCL12, or sterile saline, into the I/R kidney 70 days post-injury, or were non-injured, non-injected controls (n = 6/group). Kidney collagen content was quantified 4 months post-treatment using Masson's Trichrome and Picrosirius Red (PSR) stained tissues. In a separate study (n = 2) exploring short-term effects of CXCL12, 200 ng CXCL12 was injected into I/R kidneys and then harvested either 30 min (n = 1) or 1 month (n = 1) post-injection. Kidney concentrations of CXCL12, matrix metalloproteinase 1 (MMP-1), and lysyl oxidase-like enzyme 2 (LOXL-2) were quantified via ELISA. Clinical Pilot: 14 client-owned cats with potential early kidney disease received a single-treatment, bilateral intra-renal injection of 200 ng CXCL12 (n = 7), or received no injection (n = 7). Blood/urine samples were collected monthly for 9 months to assess renal function and CKD staging.Results:Pre-clinical: I/R increased the affected kidney collagen content, which both mid and high doses of CXCL12 restored to normal (ps < 0.05 vs. untreated). I/R increased collagen fiber width, which both mid and high doses of CXCL12 restored to normal (p < 0.001 vs. untreated). Early changes in kidney MMP-1, associated with collagen breakdown, and subsequent decreases in LOXL-2, associated with collagen cross-linking, in response to CXCL12 treatment may contribute to these findings. Clinical Pilot: Bilateral intra-renal injection of CXCL12 using ultrasound guidance in cats with CKD was feasible and safe in a general practice clinical setting with no obvious side effects noted during the 9-month follow-up period.Conclusions: Intra-renal injection of CXCL12 may prove to be an effective treatment for kidney fibrosis in cats with CKD. Additional mechanistic and clinical evaluations are needed.

Effects of Age and Multiple Vaginal Births on Lower Urinary Tract Structure and Function in Nonhuman Primates

“…Remaining harvested tissues (ovaries, uterus, pelvic support muscles [levator ani and coccygeus]) were removed, immersed in 10% neutral buffered formalin for 48 hours, and then transferred to 70% ethanol prior to paraffin embedding. Paraffinized tissue was sectioned into 5-μm slices using a microtome, and histology slides were stained with Masson’s trichrome stain (#HT15, Sigma-Aldrich Inc., St. Louis, MO, USA) and Picrosirius red (PSR) (#24901, PolySciences, Warrington, PA, USA) for collagen content analyses [ 10 , 11 ].…”

“…For tissues stained with PSR under polarized light, collagen fiber quantification for length, width, and straightness was performed using the segmentation software CT-FIRE (Laboratory for Optical and Computation Instrumentation, University of Wisconsin). The results of 10 images were averaged for each monkey [ 11 ].…”