Very early alloantigen-independent trafficking of lymphocytes during ischemic acute kidney injury

Comparison of ischemic and ischemic/reperfused kidney injury via clamping renal artery, vein, or pedicle in anesthetized rats

PURPOSE

We recently observed that 30 min of bilateral renal arterial, venous, or pedicle occlusion with 2-h reperfusion differentially induced acute kidney injury (AKI), which was suggested to be probably resulted from their directly exerting dissimilar impacts on kidney during the ischemic period. The present study was further designed to evaluate and prove this suggestion.

METHODS

Anesthetized male Sprague-Dawley rats were divided in two distinct supragroups with 30-min bilateral renal ischemia alone (BI) or followed by 30-min reperfusion (BIR), which each had four different groups (n = 8) of subjecting to renal artery, vein, or pedicle clamping and also sham operation.

RESULTS

In the BI groups, artery clamping caused lower renal tissue injury than pedicle clamping but vein occlusion caused the highest levels of kidney histological damages along with the widespread hemorrhagic congestion. In the BIR groups, renal vascular congestion, intratubular cast, and edema decreased, but tubular epithelial injury did not significantly change in comparison to their equivalents BI groups. However, the orders of total renal tissue damages in the BIR groups were still as clamping renal veins >  > pedicles > arteries and in association with their proportionally developed renal hemodynamic, excretory, and urine-concentrating dysfunctions.

CONCLUSION

The transmission of high arterial pressure into renal microvessels and rupturing of their walls during venous-clamping augment, but the retrograde blood flow from veins into kidney during artery clamping attenuates induction of renal tissue injury with respect to pedicle clamping not only at the ischemic period but also at the early reperfusion period and along with the proportional development of renal dysfunctions.

Integrative Analysis of Renal Ischemia/Reperfusion Injury and Remote Ischemic Preconditioning in Mice

Remote ischemic preconditioning (RIPC) is a strategy to induce resistance in a target organ against the oxidative stress and injury caused by ischemia and reperfusion (IR). RIPC harnesses the body's endogenous protective capabilities through brief episodes of IR applied in organs remote from the target. Few studies have analyzed this phenomenon in the kidney. Furthermore, the window of protection representing RIPC efficacy has not been fully elucidated. Here, we performed a multiomics study to specify those associated with protective effects of RIPC against the IR injury. A total of 30 mice were divided to four groups: sham, IR only, late RIPC + IR, and early RIPC + IR. We found that IR clearly led to tubular injury, whereas both preconditioning groups exhibited attenuated injury after the insult. In addition, renal IR injury produced changes of the metabolome in kidney, serum, and urine specimens. Furthermore, distinctive mRNA and associated protein expression changes supported potential mechanisms. Our findings revealed that RIPC effectively reduces renal damage after IR and that the potential mechanisms differed between the two time windows of protection. These results may potentially be extended to humans to allow non- or minimally invasive diagnosis of renal IR injury and RIPC efficacy.

Near-term anti-CD25 monoclonal antibody administration protects murine liver from ischemia-reperfusion injury due to reduced numbers of CD4+ T cells

Background

CD4⁺ T cell is acknowledged as a key factor in the initiation phase of liver ischemia reperfusion injury. The purpose of current study is to demonstrate the effect of antecedent near-term anti-CD25 monoclonal antibody treatment on IR-induced liver injury by modulation of CD4⁺ T cells.

Methods

70% liver warm IR was induced in male C57BL/6 mice after anti-CD25 mAb or non-specific IgG administration. Liver function, histological damage, invitro Proliferation, FACS, cytokine production, and immunofluorescence were assessed to evaluate the impact of antecedent near-term PC61 treatment on IR-induced liver injury.

Results

After 70% liver ischemia, mice preconditioned with PC61 displayed significantly preserved liver function as characterized by less histological damage and reduced serum enzymes level. Mechanistic studies revealed that the protection effect of anti-CD25 mAb was associated with ameliorated intrahepatic inflammatory milieu and reduced CD4⁺ T lymphocytes as manifested by the decrease of proinflammatory cytokine production (less expression of TNF-α, IFN-γ, IL-2, and IL-6) and the lower CD4/CD8 proportion.

Conclusions

Our results provide first line of evidence indicating that near-term treatment with anti-CD25 monoclonal antibody might provide protection for livers against IR-induced injury by reducing CD4⁺ T cells, but not influencing functional Treg population. Therefore, our results demonstrate a potential function of anti-CD25 monoclonal antibody which was neglected in the past, and may be helpful in various clinical conditions, particularly in liver and kidney transplantations.