EET Analogs and the Dual‐Inhibition of sEH/COX‐2 for the Treatment of Focal Segmental Glomerular Sclerosis
Authors: Barnett Scott D , Palygin Oleg , Khan Abdul Hye , Imig John D 
Published: June 2021

Focal segmental glomerulosclerosis (FSGS) is the single most common form of kidney disease. This devastating disorder can lead to end stage renal disease (ESRD), a terminal diagnosis in the absence of a kidney transplant. The progression of FSGS is defined by sclerotic damage to the glomerulus, the filtering unit of blood in the kidney. Epoxyeicosatrienoic acids (EETs) are a family of arachidonic acid metabolites important to glomerular function. EETs are metabolized by enzymes such as soluble epoxide hydrolase (sEH) and cyclooxygenase (COX), and we have developed a novel dual‐ligand drug (PTUPB) that inhibits both sEH and COX‐2. We hypothesize that EET analogs and the dual‐inhibition of sEH and COX‐2 will mitigate glomerular damage caused by FSGS. The long‐term goal of this research is to better understand the role of 8,9‐EET and its metabolites on glomerular function so that we can develop new therapies to treat FSGS and other nephropathies.

Methods

Glomerular Permeability Assay: Glomeruli were pre‐incubated in 5% albumin (50kDa dialyzed BSA), followed by a bath exchange to 1% albumin. Under normal conditions the glomeruli are non‐permeable to albumin, and as a result, when the 5% albumin bath is exchanged for 1% albumin, water is taken up into the intra‐glomerular space due to the rapid change in oncotic pressure. Glomerular permeability was tested using our non‐hydrolyzable 8,9‐EET analog (1μM), our non‐hydrolyzable 14,15‐EET analog (EET‐A, 1μM) or PTUPB (1μM) with isolated SD rat glomeruli in the presence or absence of angiotensin II (AngII, 10μM), a known glomerular permeabilizing agent. 3D‐Confocal imaging (72μm z‐depth, 27‐layer z‐stack) was utilized to measure the relative changes in glomerular volume.

Results

Glomerular permeability to albumin (Palb) is derived from the albumin reflection coefficient (σalb), where a value of 1 indicates high permeability to albumin, and 0 indicates low permeability (relative to control). A baseline response to a 5% to 1% albumin exchange resulted in very low albumin permeability (Palb = −0.21 ± 0.21, n=6). Conversely, the presence of AngII resulted high albumin permeability (Palb = 1.21 ± 0.12, n=15). Our 8,9‐EET analog, in the presence of AngII, mitigated the effects of AngII‐induced permeability (Palb = 0.13 ± 0.18, n=7), as did our dual sEH/COX2 inhibitor, PTUPB, under the same Ang‐II stimulation (Palb = 0.71% ± 0.35, n=7), but not the 14,15‐EET analog (Palb = 0.99% ± 0.21, n=4) . All values are mean ± SEM.

Conclusion

FSGS is complex multi‐model disease, and glomerular damage/dysfunction are at the core of this condition. The ability of our 8,9‐EET analog and PUTPB to decrease AngII‐associated glomerular permeability suggest and important role for EETs and their metabolism. Future work will investigate not only the effects of 8,9‐EET analogs and PTUPB on glomerular health, but also the consequences of EET metabolites and other EET‐analogs, on both glomerular and mesangial function using cell and animal models.

Support or Funding Information

R01 DK103616‐01 (John D. Imig). Dr. Ralph and Marian Falk Medical Research Trust ‐ Phase II (John D. Imig)

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.