Studies in animal models suggest that complement activation is crucial in the pathogenesis of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). Here we investigate the circulating complement activation profile of 66 patients with active stage AAV compared to that of 54 patients with AAV in remission. Plasma levels of C3a, C5a, soluble C5b-9, and Bb, all determined by enzyme-linked immunosorbent assay, were significantly higher in active stage than in remission of AAV, while plasma levels of properdin were significantly lower in the former than the latter disease stage. There was no significant difference in the plasma levels of C4d between active stage and remission. The plasma level of Bb in patients with active AAV significantly correlated with the proportion of total and cellular crescents in the renal biopsy, the erythrocyte sedimentation rate, and the Birmingham Vasculitis Activity Scores. Thus, systemic activation of complement by the alternative pathway takes place in human AAV. Circulating Bb might be a useful biomarker in assessing disease activity of AAV.

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SummaryBackground and objectives Previous study revealed that complement activation products of the alternative pathway could be detected in renal specimens of human ANCA-associated vasculitis. The current study aimed to investigate the clinical and pathologic significance of complement activation products in the urine and kidneys of patients with ANCA-associated vasculitis.Design, setting, participants, & measurements Renal biopsy specimens from 29 patients with ANCA-associated vasculitis diagnosed at Peking University First Hospital from January of 2008 to December of 2010 were randomly collected. Urine samples from 27 of 29 patients in active stage and 22 ANCA-associated vasculitis patients in complete remission who were independent of the above-mentioned 29 patients were collected. Urine samples from 28 patients with lupus nephritis and 25 healthy individuals were also collected. The renal deposition of Bb, C3d, and C5b-9 were detected by immunohistochemistry. The urinary levels of Bb, C3a, C5a, and soluble C5b-9 were determined by ELISA.Results The deposition, measured by the mean optical density of Bb, which is an alternative complement pathway marker, in glomeruli correlated with the proportion of total crescents (r=0.50, P=0.006), the extent of interstitial infiltrate (r=0.59, P=0.001), interstitial fibrosis (r=0.45, P=0.01), and tubular atrophy (r=0.55, P=0.002), whereas it correlated inversely with the proportion of normal glomeruli (r=20.49, P=0.008). The urinary levels of Bb, C3a, C5a, and soluble C5b-9 were all significantly higher in active compared with remission stage. The urinary levels of Bb in patients with active ANCA-associated vasculitis correlated with the serum creatinine (r=0.56, P=0.002) and correlated inversely with the proportion of normal glomeruli in renal specimens (r=20.49, P=0.009). ConclusionsThe present study provides additional evidence that complement activation through the alternative pathway occurred in the development of ANCA-associated vasculitis. The renal deposition of Bb and urinary Bb levels were associated with the severity of renal injury.

Testosterone (T) and vitamin D (VD) interact in androgen deficient men, however, this interaction and subsequent semen quality and bone mineral density (BMD) status is not clear in infertile men. Our objective was to investigate T, VD, semen quality, BMD and their relationships in Chinese infertile men. We conducted a cross-sectional study of 559 men aged 20-40 years, including 195 fertile men, 9 infertile men with known risk factors for osteoporosis (WR) and 355 infertile men without known risk factors for osteoporosis (WOR). WOR infertile men constituted 314 oligo-, astheno-, teratospermic or normospermic infertile men (OATN men) and 41 non-obstructive azoospermic men (NOA men). Differences of parameters were assessed, and the relationships were adjusted by multiple linear regression. WOR infertile men had significantly lower T, lumbar spine and total hip BMD than fertile men (all p < 0.05). Bioavailable T (Bio-T) and 25-hydroxyvitamin D [25(OH)D] were independent determinants of BMD in WOR infertile men (all p < 0.01) but not in fertile men. After stratifying Bio-T, WOR infertile men had lower BMD than fertile men (all p < 0.05) in low Bio-T subgroups (Bio-T ≤ 11.6 nmol/L), but not high Bio-T subgroups (Bio-T > 11.6 nmol/L). 25(OH)D was an independent determinant of sperm motility and morphology in WOR OATN men (all p < 0.05), with only borderline significance in fertile men(motility: p = 0.047; morphology: p = 0.056). T determined sperm concentration (square root) and morphology in WOR OATN men (all p < 0.001). No correlations between T and 25(OH)D were found in all groups. We suggest that infertile men have lower T and BMD than fertile men. 25(OH)D and T were associated with low BMD and poor semen quality in infertile men.

IntroductionThe complement system is crucial for the development of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). In particular, C5a plays a central role. In this study, plasma and urinary levels of C5a as well as renal C5a receptors (CD88 and C5L2) expression were investigated in patients with AAV.MethodsTwenty-four patients with AAV in the active phase, 19 patients with AAV in the remission phase, and 20 patients with lupus nephritis (LN) were included. Plasma and urinary levels of C5a were measured with enzyme-linked immunosorbent assay (ELISA). The staining of CD88 and C5L2 in renal specimens was detected with immunohistochemistry.ResultsThe level of plasma C5a was significantly higher in patients with AAV in the active phase than that in patients in remission, that in patients with LN, and that in normal controls. The urinary C5a level was significantly higher in patients with AAV in the active phase than that in patients in remission and that in normal controls, but not significantly different between patients with active AAV and patients with LN. The mean optical density of CD88 staining in the tubulointerstitium was significantly lower in AAV patients than that in normal controls (0.0052 ± 0.0011 versus 0.029 ± 0.0042; P = 0.005). The mean optical density of C5L2 in glomeruli was significantly higher in AAV patients than that in normal controls (0.013 ± 0.0027 versus 0.0032 ± 0.0006; P < 0.001). The mean optical density of CD88 staining closely correlated with the initial eGFR (r = 0.835; P < 0.001) in AAV patients. Double-labeling immunofluorescence assay suggested that CD88 did not express on neutrophils, monocytes, or macrophages, but C5L2 expressed on neutrophils (or monocytes) and macrophages.ConclusionThe elevated plasma and urinary C5a levels indicated complement activation in human AAV. The level of renal CD88 expression could reflect the disease severity of ANCA-associated glomerulonephritis. CD88 expression was downregulated, and C5L2 was upregulated in ANCA-associated glomerulonephritis.

Mitochondrial transfer plays a crucial role in the regulation of tissue homeostasis and resistance to cancer chemotherapy. Osteocytes have interconnecting dendritic networks and are a model to investigate its mechanism. We have demonstrated, in primary murine osteocytes with photoactivatable mitochondria (PhAM)floxed and in MLO-Y4 cells, mitochondrial transfer in the dendritic networks visualized by high-resolution confocal imaging. Normal osteocytes transferred mitochondria to adjacent metabolically stressed osteocytes and restored their metabolic function. The coordinated movement and transfer of mitochondria within the dendritic network rely on contact between the endoplasmic reticulum (ER) and mitochondria. Mitofusin 2 (Mfn2), a GTPase that tethers ER to mitochondria, predominantly mediates the transfer. A decline in Mfn2 expression with age occurs concomitantly with both impaired mitochondrial distribution and transfer in the osteocyte dendritic network. These data show a previously unknown function of ER-mitochondrial contact in mediating mitochondrial transfer and provide a mechanism to explain the homeostasis of osteocytes.

BackgroundAlthough a high incidence of cardiovascular disease (CVD) is observed among chronic kidney disease (CKD) patients in developed countries, limited information is available about CVD prevalence and risk factors in the Chinese CKD population. The Chinese Cohort of Chronic Kidney Disease (C-STRIDE) was established to investigate the prevalence and risk factors of CVD among Chinese CKD patients.MethodsParticipants with stage 1–4 CKD (18–74 years of age) were recruited at 39 clinical centers located in 28 cities from 22 provinces of China. At entry, the socio-demographic status, medical history, anthropometric measurements and lifestyle behaviors were documented, and blood and urine samples were collected. Estimated glomerular filtration rate (eGFR) was calculated by the CKD-EPI creatinine equation. CVD diagnosis was based on patient self-report and review of medical records by trained staff. A multivariable logistic regression model was used to estimate the association between risk factors and CVD.ResultsThree thousand four hundred fifty-nine Chinese patients with pre-stage 5 CKD were enrolled, and 3168 finished all required examinations and were included in the study. In total, 40.8% of the cohort was female, with a mean age of 48.21 ± 13.70 years. The prevalence of CVD was 9.8%, and in 69.1% of the CVD cases cerebrovascular disease was observed. Multivariable analysis showed that increasing age, lower eGFR, presence of hypertension, abdominal aorta calcification and diabetes were associated with comorbid CVD among CKD patients. The odds ratios and 95% confidence intervals for these risk factors were 3.78 (2.55–5.59) for age 45–64 years and 6.07 (3.89–9.47) for age ≥65 years compared with age <45 years; 2.07 (1.28–3.34) for CKD stage 3a, 1.66 (1.00–2.62) for stage 3b, and 2.74 (1.72–4.36) for stage 4 compared with stages 1 and 2; 2.57 (1.50–4.41) for hypertension, 1.82 (1.23–2.70) for abdominal aorta calcification, and 1.70 (1.30–2.23) for diabetes, respectively.ConclusionsWe reported the CVD prevalence among a CKD patient cohort and found age, hypertension, diabetes, abdominal aorta calcification and lower eGFR were independently associated with higher CVD prevalence. Prospective follow-up and longitudinal evaluations of CVD risk among CKD patients are warranted.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-017-0441-9) contains supplementary material, which is available to authorized users.

Inhibition of osteoclasts formation and bone resorption by estrogen is very important in the etiology of postmenopausal osteoporosis. The mechanisms of this process are still not fully understood. Recent studies implicated an important role of microRNAs in estrogen‐mediated responses in various cellular processes, including cell differentiation and proliferation. Thus, we hypothesized that these regulatory molecules might be implicated in the process of estrogen‐decreased osteoclasts formation and bone resorption. Western blot, quantitative real‐time polymerase chain reaction, tartrate‐resistant acid phosphatase staining, pit formation assay and luciferase assay were used to investigate the role of microRNAs in estrogen‐inhibited osteoclast differentiation and bone resorption. We found that estrogen could directly suppress receptor activator of nuclear factor B ligand/macrophage colony‐stimulating factor‐induced differentiation of bone marrow‐derived macrophages into osteoclasts in the absence of stromal cell. MicroRNA‐27a was significantly increased during the process of estrogen‐decreased osteoclast differentiation. Overexpressing of microRNA‐27a remarkably enhanced the inhibitory effect of estrogen on osteoclast differentiation and bone resorption, whereas which were alleviated by microRNA‐27a depletion. Mechanistic studies showed that microRNA‐27a inhibited peroxisome proliferator‐activated receptor gamma (PPARγ) and adenomatous polyposis coli (APC) expression in osteoclasts through a microRNA‐27a binding site within the 3′‐untranslational region of PPARγ and APC. PPARγ and APC respectively contributed to microRNA‐27a‐decreased osteoclast differentiation and bone resorption. Taken together, these results showed that microRNA‐27a may play a significant role in the process of estrogen‐inhibited osteoclast differentiation and function.