miR-146a targeted to splenic macrophages prevents sepsis-induced multiple organ injury.

Development of a novel agent against life-threatening sepsis requires the in-depth understanding of the relevant pathophysiology and therapeutic targets. Given the function of microRNAs (miRNAs) as potent oligonucleotide therapeutics, here we investigated the pathophysiological role of exogenously applied miRNA in sepsis-induced multiple organ injury. In vitro, miR-16, miR-126, miR-146a, and miR-200b suppressed the production of pro-inflammatory cytokines in RAW264.7 macrophage cells after lipopolysaccharide (LPS) stimulation. Of these, miR-146a displayed the most highly suppressive effect, wherein the transcriptional activity of nuclear factor kappa B (NF-κB) was decreased via targeting of interleukin 1 receptor-associated kinase 1 and tumor necrosis receptor-associated factor 6. Sepsis was induced in mice via cecal ligation and puncture (CLP) and an intravenous injection of a complex of miR-146a-expressing plasmid and polyethyleneimine. Treatment with this complex significantly decreased the level of serum inflammatory cytokines, attenuated organ injury including kidney injury, and led to increased survival from polymicrobial sepsis induced by CLP. miR-146a-expressing plasmid was abundantly distributed in splenic macrophages, but not in renal parenchymal cells. CLP mice treated with miR-146a displayed significantly decreased NF-κB activation and splenocyte apoptosis. Splenectomy diminished the anti-inflammatory effects of miR-146a. The collective results support the conclusion that the induction of miR-146a expression in splenic macrophages prevents excessive inflammation and sepsis-induced multiple organ injury. This study establishes a novel and critical pathophysiological role for splenic macrophage interference in sepsis-related organ injury.

Plasma cell-rich acute rejection after renal transplantation in a patient with pyoderma gangrenosum: a case report.

A 40-yr-old female received a living-related renal transplantation on January 29, 2008. She had type I diabetes mellitus and pyoderma gangrenosum (PG). Induction immunosuppressive therapy consisted of tacrolimus, mycophenolate mofetil, basiliximab, and prednisolone. Intravenous methylprednisolone pulse therapy was administered to prevent ulceration at the surgical site. The postoperative outcome was almost uneventful, and renal graft function was well preserved for 11 months. Her graft function deteriorated on December 24, 2008 and thus an episode biopsy was performed. The histopathological findings were consistent with plasma cell-rich acute rejection (PCAR). During hospitalization, it was noted that the patient was non-compliant. We then performed steroid pulse therapy, and her graft function and histological findings improved. This is the first report of PCAR in a patient with PG who received a renal allograft. It was thought that PCAR was triggered because of her non-compliance. Thus, we should recognize the importance of enhancing compliance in transplant recipients.