1,2-Bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic Acid Acetoxymethyl Ester Loaded Reactive Oxygen Species Responsive Hyaluronic Acid-Bilirubin Nanoparticles for Acute Kidney Injury Therapy via Alleviating Calcium Overload Mediated Endoplasmic Reticulum Stress

Calcium overload is one of the early determinants of the core cellular events that contribute to the pathogenesis of acute kidney injury (AKI), which include oxidative stress, ATP depletion, calcium overload, and inflammatory response with self-amplifying and interactive feedback loops that ultimately lead to cellular injury and renal failure. Excluding adjuvant therapy, there are currently no approved pharmacotherapies for the treatment of AKI. Using an adipic dihydride linker, we modified the hyaluronic acid polymer chain with a potent antioxidant, bilirubin, to produce an amphiphilic conjugate. Subsequently, we developed a kidney-targeted and reactive oxygen species (ROS)-responsive drug delivery system based on the flash nanocomplexation method to deliver a well-known intracellular calcium chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N ',N '-tetraacetic acid acetoxymethyl ester (BAPTA-AM, BA), with the goal of rescuing renal cell damage via rapidly scavenging of intracellularly overloaded Ca2+. In the ischemia-reperfusion (I/R) induced AKI rat model, a single dose of as-prepared formulation (BA 100 mu gmiddotkg-1) 6 h post-reperfusion significantly reduced renal function indicators by more than 60% within 12 h, significantly alleviated tissular pathological changes, ameliorated tissular oxidative damage, significantly inhibited apoptosis of renal tubular cells and the expression of renal tubular marker kidney injury molecule 1, etc., thus greatly reducing the risk of kidney failure. Mechanistically, the treatment with BA-loaded NPs significantly inhibited the activation of the ER stress cascade response (IRE1-TRAF2-JNK, ATF4-CHOP, and ATF6 axis) and regulated the downstream apoptosisrelated pathway while also reducing the inflammatory response. The BA-loaded NPs hold great promise as a potential therapy for I/R injury-related diseases.

Automated summary

Calcium overload is a key factor in the development of acute kidney injury (AKI), but no approved pharmacotherapies for AKI exist. Researchers have developed a drug delivery system that targets the kidneys and responds to reactive oxygen species (ROS). In animal models, this system effectively reduced renal damage and improved kidney function by scavenging excess calcium and inhibiting apoptosis and inflammatory response.