Kidney Week

Abstract: SA-PO928

Kidney Localization of Cardiac Protein in Acute Cardiorenal Syndrome

Session Information

• Pathology and Lab Medicine - 2
  October 26, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pathology and Lab Medicine

• 1800 Pathology and Lab Medicine

Authors

• Aomura, Daiki, Oregon Health & Science University, Portland, Oregon, United States

Daiki Aomura, MD, PhD

• Funahashi, Yoshio, Oregon Health & Science University, Portland, Oregon, United States

Yoshio Funahashi, MD, PhD

• Munhall, Adam C., Oregon Health & Science University, Portland, Oregon, United States

Adam C. Munhall

• Groat, Tahnee, Oregon Health & Science University, Portland, Oregon, United States

Tahnee Groat, MPH

• Hutchens, Michael, Oregon Health & Science University, Portland, Oregon, United States

Michael Hutchens, MD, MA

Background

In a translational acute cardiorenal syndrome (CRS) model, mouse cardiac arrest and cardiopulmonary resuscitation (CA/CPR), heart-specific cardiac LIM protein (CSRP3) filters into the proximal tubule (PT), and mediates renal fibrosis. In the heart, CSRP3 undergoes stress-induced nuclear translocation and participates in fibrosis signaling. However, how endocrine CSRP3 acts in PT is unknown. Therefore, we characterized CSRP3 appearance in PT after CA/CPR using immunohistochemistry (IHC).

Methods

CA/CPR was performed on wild-type C57/B6J mice. CA was induced with potassium chloride; CPR, started after 8 minutes CA, included chest compressions and epinephrine. Mice were sacrificed on day (d) 1, 3, 7, or 49 after CA/CPR or sham (n=3/group). Kidneys were stained for CSRP3 with IHC. The volume of CSRP3 positivity with respect to kidney (V_CSRP3/V_Kidney, by Cavalieri method) was quantified using unbiased stereology on whole kidney sections to reduce IHC bias. Kidney compartments were independently segmented on 5 random high-power sections per mouse using machine learning (ilastik) to test localization of CSRP3. Segmentation was manually validated. Plasma CSRP3 was quantified by ELISA. Group differences were assessed with ANOVA and post-hoc tests.

Results

CSRP3 was heterogeneously stained at low level in sham. After CA/CPR (d1-7), CSRP3 was abundant in PT, concentrated at the apical brush border and in intratubular cell punctae. V_CSRP3/V_Kidney increased after CA/CPR (0.14±0.00 in sham vs 0.16±0.02 on d1 and 0.16±0.00 on d49, p=0.01). PT and nuclear segmentation was adequate (F=0.88). PT-associated CSRP3 increased after CA/CPR (p<0.001) and correlated with V_CSRP3/V_Kidney (r=0.58, p=0.02). Apical-basal distribution of CSRP3 within PT did not vary much with time, however, perinuclear CSRP3 localization within PT was persistently increased after CA/CPR (0.47±0.09 in sham and 0.58±0.10 on d49, p<0.001). Plasma of CSRP3 peaked on d1 and declined to baseline by d3 (sham 1.4±0.2, d1 20±4.2 p=0.003 vs sham, d3 3.7±4.0 p=0.9 vs sham, ng/mL).

Conclusion

CSRP3 is present at the renal brush border and in tubular punctae at baseline. PT CSRP3 increases after CA/CPR. Perinuclear distribution of CSRP3 increased immediately after CA/CPR, persisting for weeks. Therefore, CSRP3 is taken up by PT after CA/CPR in a manner suggesting intracellular trafficking.

Funding

• Veterans Affairs Support