Dhanireddy, Kiran

Abstract Background Acute kidney injury (AKI) frequently causes remote organ injury including hepatic steatosis, yet whether lipid accumulation reflects increased synthesis or impaired clearance has not been resolved. Methods We used a murine ischemia-reperfusion AKI model. Unbiased liver proteomics was performed at 24 hours after reperfusion, and dysregulated pathways were identified by Gene Set Enrichment Analysis. Results were validated by Western blotting, qPCR, and immunohistochemistry. These findings were complemented by retrospective analysis of two ICU databases (MIMIC-IV and eICU-CRD). Results AKI significantly increased serum ALT and AST and induced hepatic lipid accumulation. Proteomic analysis revealed that key lipogenic enzymes (Scd1, Fasn, Acly, Acaca) were uniformly suppressed rather than upregulated. Proteins essential for VLDL assembly (ApoB, MTTP, ApoE) were significantly downregulated. Plasma triglycerides were decreased while liver triglycerides were increased, consistent with impaired hepatic lipid export. As in renal tubular cells, AKI also disrupted ER protein folding homeostasis in the liver, triggering ER stress. This was evidenced by upregulated levels of the ER chaperone GRP78, increased XBP1 splicing indicative of UPR activation, and elevated expression of the ER stress-induced pro-apoptotic transcription factor CHOP, suggesting that prolonged ER stress may also promote hepatocyte cell death. TLR4/MyD88 signaling was activated, yet inflammatory cytokines were paradoxically reduced, accompanied by Kupffer cell depletion (decreased F4/80) and monocyte infiltration (increased CD68). In 6,996 propensity-matched ICU patients (MIMIC-IV), AKI independently increased the risk of clinically significant liver injury 4-fold (adjusted OR = 4.41). Analysis of 22,727 patients across 208 hospitals (eICU-CRD) identified a lipid dissociation pattern: elevated triglycerides alongside decreased total cholesterol, HDL, and LDL, with dose-dependent scaling across KDIGO stages. Conclusions These data support ER stress-mediated impairment of VLDL export as a primary driver of AKI-induced hepatic steatosis. Clinical validation across two independent ICU databases identifies a dual metabolic insult: enhanced peripheral lipid delivery compounds impaired hepatic export, amplifying hepatic lipid retention. ER stress and lipid export machinery represent potential therapeutic targets for AKI-associated liver injury.

Abstract Acute kidney injury (AKI) causes rapid loss of renal function with high morbidity and mortality. Our previous research showed that neuronal nitric oxide synthase (NOS1) mediates nitric oxide-dependent dilation of the afferent arteriole, inhibiting tubuloglomerular feedback (TGF), which critically regulates single nephron glomerular filtration rate (GFR). This mechanism could affect how vulnerable the organ is to ischemic injury, but this has not been directly tested. In the present study, we generated inducible macula densa (MD)-specific NOS1 knockout mice (NKCC2-Cre-NOS1 flox/flox) using a new inducible NKCC2-Cre line crossed with NOS1 flox mice. AKI was induced by 18-min bilateral renal pedicle clamping at 37°C, followed by 48-h reperfusion. Kidney injury was assessed by measuring GFR, plasma creatinine, histology, cytokines, apoptosis, fibrotic factors, and proteomics. Complete NOS1 deletion in MD cells was confirmed through NKCC2/NOS1 immunofluorescence. MD NOS1 deletion enhanced the TGF response, which was further amplified following AKI compared with control (Cre −/−). Following AKI, compared with controls (Cre −/−), NOS1 knockouts showed a significantly lower GFR (236 ± 66 to 24 ± 22 μl/min) and higher plasma creatinine levels, alongside more severe tubular damage evidenced by H&E staining. Cytokine array analysis showed chemokines such as MCP-1 and CXCL1 and macrophage marker CD68 were significantly increased; Western blot analysis showed cleaved caspase-3 levels were significantly increased, indicating enhanced apoptosis. Additionally, fibrosis markers TIMP-1, collagen-3, and α-SMA were significantly up-regulated at both mRNA and protein levels. We further observed increased hypoxia marker hypoxia-inducible factor-1α in MD-specific NOS1 knockout mice (Cre +/−). Global label-free proteomic profiling with targeted validation identified genotype-dependent responses involving haptoglobin, Tacstd2, and Cyp20a1, linking NOS1 deficiency to exaggerated inflammatory, fibrotic, and metabolic pathways. These findings highlight a novel role of MD NOS1 and TGF in AKI pathophysiology, suggesting NOS1 targeting as a therapeutic strategy. Haptoglobin was identified as a downstream plasma signal of NOS1-dependent AKI responses, indicating potential translational value.

Background. The availability of in situ normothermic regional perfusion (NRP) or ex situ normothermic machine perfusion (NMP) has revolutionized donation after circulatory death (DCD) liver transplant (LT). While some have suggested that NRP and NMP may represent competing technologies for DCD LT, there are many scenarios where these technologies can function in a complementary manner. Methods. Between January 2022 and March 2024, 83 DCD LTs were performed using NRP (62 NRP alone and 21 NRP + NMP) and were compared with 297 static cold storage (SCS) DCD LTs. NRP + NMP was used in scenarios with (1) long travel distances, (2) complicated transplant recipients, or (c) the need for additional liver graft recovery in “marginal” cases. Results. Ischemic cholangiopathy was lower in the NRP alone group (0%) and the NRP + NMP group (0%) compared with the SCS group (16.8; P < 0.001 and P = 0.04, respectively). In addition, early allograft dysfunction, number of packed red blood cells transfused, and acute kidney injury were lower in the NRP alone and NRP + NMP groups compared with the SCS group. Graft survival was higher in cases where NRP was used than in cases where SCS was used ( P = 0.016). In all the cases where lactate remained elevated at the end of NRP (mean 8.2 ± 2.0), it ultimately normalized at the end of NMP (0.92 ± 0.56). Conclusions. The present study demonstrates lower rates of ischemic cholangiopathy and improved graft survival with NRP alone or NRP + NMP compared with SCS when using liver grafts from DCD donors. It also demonstrates that excellent outcomes can be achieved with sequential NRP + NMP in cases with prolonged travel distances, complicated recipients, or when there is a need for additional liver recovery in “marginal” cases.