Immunomodulatory role of recombinant human erythropoietin in acute kidney injury induced by crush syndrome via inhibition of the TLR4/NF-κB signaling pathway in macrophages.

Objective: The present study aimed to investigate whether recombinant human erythropoietin (rHuEPO) plays an immunomodulatory function by regulating the TLR4/NF-κB signaling pathway.Materials and methods: C57BL/6 mice were intraperitoneally injected with rHuEPO and, half an hour later, with 50% glycerol at the dose of 7.5 ml/kg to induce crush syndrome (CS)-acute kidney injury (AKI). The levels of TNF-α, IL-1ß, IL-6, serum creatinine (Scr), and creatine kinase (CK) were measured. The kidney tissues were analyzed by HE staining, and macrophage infiltration was detected by immunohistochemistry. Double immunofluorescence staining, RT-qPCR, and western blotting were conducted to analyze TLR4/NF-κB p65 expression. Ferrous myoglobin was co-cultured with RAW264.7 cells to mimic crush injury and the production of proinflammatory cytokines. The expression levels of TLR4 and NF-κB p65 were measured.Results: In vivo study results revealed that rHuEPO ameliorated renal function, tissue damage, production of proinflammatory cytokines, and macrophage infiltration in the kidneys. The protein and mRNA expression levels of genes involved in the TLR4/NF-κB signaling pathway in CS-induced AKI mice were upregulated (p < .05). Meanwhile, the expression levels of TLR4, NF-κB p65, and proinflammatory cytokines in RAW264.7 cells were downregulated in CS-AKI mice injected with rHuEPO (p < .05).Conclusions: Our results demonstrated the immunomodulatory capacity of rHuEPO and confirmed that rHuEPO exerts protective effects against CS-induced AKI by regulating the TLR4/NF-κB signaling pathway in macrophages. Therefore, our findings highlight the therapeutic potential of rHuEPO in improving the prognosis of CS-AKI patients.

Models of lower extremity damage in mice: time course of organ damage and immune response.

BACKGROUND: Post-traumatic inflammatory changes have been identified as major causes of altered organ function and failure. Both hemorrhage and soft tissue damage induce these inflammatory changes. Exposure to heterologous bone in animal models has recently been shown to mimic this inflammatory response in a stable and reproducible fashion. This follow-up study tests the hypothesis that inflammatory responses are comparable between a novel trauma model ("pseudofracture", PFx) and a bilateral femur fracture (BFF) model. MATERIALS AND METHODS: In C57BL/6 mice, markers for remote organ dysfunction and inflammatory responses were compared in four groups (control/sham/BFF/PFx) at the time points 2, 4, and 6 h. RESULTS: Hepatocellular damage in BFF and PFx was highly comparable in extent and evolution, as shown by similar levels of NFkappaB activation and plasma ALT. Pulmonary inflammatory responses were also comparably elevated in both trauma models as early as 2 h after trauma as measured by myeloperoxidase activity (MPO). Muscle damage was provoked in both BFF and PFx mice over the time course, although BFF induced significantly higher AST and CK levels. IL-6 levels were also similar with early and sustained increases over time in both trauma models. CONCLUSIONS: Both BFF and PFx create similar reproducible inflammatory and remote organ responses. PFx will be a useful model to study longer term inflammatory effects that cannot be studied using BFF.

[Endotoxemia in crush syndrome]. / Endotoksemiia pri sindrome dlitel'nogo razdavlivaniia.

The crush syndrome developing in casualties in mass catastrophes is the cause of their high mortality rates. We examined 18 children aged from 9 to 14 years with the crush syndrome who suffered during the earthquake in Armenia. Besides other laboratory studies, the test for the titer of antibodies (TA) to endotoxin was performed. Despite the applied complex therapy, the children's condition grew worse on day 8. The TA level reduced threefold. Six patients received a single infusion of plasma with naturally increased TA titer in a dose of 10 ml/kg. On the following day after TA infusion, the condition of children in the experimental group improved, the clinical picture of endotoxemia in the control group persisted for 10-12 days.

Macrophage activation decreases macrophage prostaglandin E2 release in experimental trauma.

Prostaglandin E2 (PGE2) derived from macrophages following trauma may contribute to trauma-induced immunosuppression. This study evaluated the effect of glucan, a macrophage-activating agent, on macrophage PGE2 release in a murine trauma model. ICR/HSD mice were administered D5W, glucan pre-trauma, or glucan post-trauma, and subjected to hindlimb crush and amputation injury. Splenic macrophages were isolated 24 hours following trauma, cultured (24 hrs), and macrophage PGE2 levels were determined. In-vitro marrow proliferation was assessed as a measure of immune function. Crush-amputation injury increased (184%) macrophage PGE2 release. In contrast, glucan administration (pre or post) reduced PGE2 levels in macrophage supernatants (71% and 85%, respectively). A 52% decrease in in-vitro bone marrow proliferation was observed following trauma. Glucan pre- or post-trauma eliminated the suppression of bone marrow proliferation. In conclusion, macrophage-activating immunomodulators may exert beneficial effects following trauma by: 1) reducing macrophage PGE2 synthesis and release; and 2) reducing traumatic suppression of bone marrow proliferation.