IntroductionWe examined the impact of autoantibodies on the erythropoietin receptor (EPOR) in type 2 diabetic patients with chronic kidney disease (CKD).MethodsA total of 112 Japanese patients with type 2 diabetes who had CKD were enrolled in this study and followed for a mean of 45 months. Sera from these patients were screened for anti-EPOR antibodies using enzyme-linked immunosorbent assays.ResultsAnti-EPOR antibodies were detected in 26 patients (23%). Anti-EPOR antibodies were associated with low hemoglobin concentrations and decreased renal function. In patients with biopsy-proven diabetic nephropathy, anti-EPOR antibodies were associated with increased levels of interstitial inflammation. A decrease in renal function was observed more frequently in patients with antibodies than in those without antibodies, and the presence of the antibodies together with well-known clinical parameters, including proteinuria and low glomerular filtration rate, was a significant risk factor for end-stage renal disease. In human tubular epithelial HK-2 cells, IgG fractions containing anti-EPOR antibodies upregulated the expression of monocyte chemoattractant protein-1 mRNA under a high concentration of glucose.ConclusionAnti-EPOR antibodies might be involved in the progression of renal lesions and in the impaired erythropoiesis in type 2 diabetic patients with CKD. Furthermore, the presence of anti-EPOR antibodies may be an additional predictor for end-stage renal disease in type 2 diabetes.

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Daptomycin (DAP) is widely used in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection. The emergence of DAP non-susceptible MRSA strains during therapy is a major concern in clinical settings. Recent studies revealed that MRSA spontaneously reverts to a subsequent methicillin-susceptible S. aureus (MSSA) strain. However, it is not clear whether DAP non-susceptible MRSA has the ability to revert to a susceptible strain. We obtained an MRSA strain pair, DAP non-susceptible strain and subsequent DAP susceptible strain, from a patient. To understand the underlying mechanism by which DAP non-susceptible MRSA reverts to a susceptible strain, we performed genetic and phenotypic analysis in the strain pair. Although whole-genome analysis revealed four missense mutations, including L826F in mprF, in both strains, the net cell-surface charge was similar between the DAP non-susceptible and susceptible strains. However, the thickness of the cell wall was higher in the DAP non-susceptible strain, which was decreased to the same level as the control after reversion to the DAP susceptible strain. Moreover, the non-susceptible strain showed higher mRNA expression of the two-component system (TCS), such as VraSR, yycG and GraS, with the up-regulated transcription levels of cell-wall biosynthesis-related genes. The expression levels of those genes were decreased after reversion to the susceptible strain. These results indicated that DAP non-susceptibility due to up-regulation of the TCS and cell-wall biosynthesis-related genes may be reversible by the discontinuation of DAP, leading to reversion to the DAP susceptible phenotype.

The present study suggests that anti-EPOR antibodies might be involved in overall disease activity and active renal lesions, as well as in the impaired erythropoiesis in patients with SLE with LN. Further, the levels of anti-EPOR antibodies may be an additional predictor for renal injury.

Diabetic nephropathy (DN) is a major cause of end stage kidney disease and a strong risk factor for cardiovascular diseases. Growing data show chronic inflammation plays an important role for the progression of DN. As for the immune cells, anti-inflammatory leukocytes as well as pro-inflammatory leukocytes play an important role in DN. In addition to leukocytes, renal resident cells contribute to the inflammatory process of DN. However, precise functions, phenotypes and immune balance of renal resident cells remain to be explored. Therefore, we hypothesized that the aberrant immune balance of renal resident cells contributes to the pathogenesis of DN. To explore this possibility, we performed genome-wide transcriptome profiling in mesangial cells and tubular epithelial cells (TECs), which were stimulated by high glucose (HG) and detected the expression of inflammation associated genes. HG increased the mRNA expression of oxidative stress, inflammasome and mammalian target of rapamycin (mTOR) related genes in mesangial cells. Pro-inflammatory/Th1 gene expression was upregulated, but Th2 related gene expression was downregulated in mesangial cells. In TECs, HG stimulation increased pro-inflammatory/Th1/Th2 gene expression. Phosphorylation of signaling proteins shifted towards pro-inflammatory phenotype with suppressed phosphorylation of Th2 related signaling in TECs. The data taken together indicate that HG shifts the immune balance toward pro-inflammatory/Th1 phenotype in mesangial cells and TECs, which might initiate and/or prolong inflammation, thereby resulting in diabetic nephropathy.