Objective The aim of this study was to evaluate demographic, clinical, laboratory, imaging, histopathology characteristics, and treatment responses of children with Chronic nonbacterial osteomyelitis (CNO). Methods Retrospective multi-center case series study of pediatric patients diagnosed with CNO treated at five tertiary centers in south China. Results Totally there were 18 patients diagnosed as CNO between 2014 and 2020. The median age of onset was 9.2 years (range 3.7–13.1) and 55.6% were female. Median delay in diagnosis was 10.9 months (range 1.0–72.0). The most frequent presenting symptoms were bone pain (100%) and fever (44.4%). Most patients had more than one lesion (median of 5, range 1–7). Most frequently affected bones were tibiofibula (88.9%) and femur (77.8%). The MRI characteristics mainly presented as bone edema and hyperintensity in bone marrow. Bone biopsy was conducted in 11 patients (61.1%) with inflammatory cells infiltration manifested as chronic osteomyelitis, and none showed bacterial infection or tumor. In treatment, non-steroid anti-inflamatory drugs (NSAIDs) is used as the first-line drug followed by steriods, methotexate (MTX), salazosulfadimidine (SASP), Bisphosphonates and TNF-α inhibitor. Two refractory cases received combination therapy with Bisphosphonates and TNF-α inhibitor, and achieved good therapeutic effect. Conclusions The present study described a multicenter series of CNO from south China and highlighted the clinical features, laboratory tests, imaging characteristics and treatment outcomes. Increasing awareness of this disease is important to decrease time to diagnosis, improve access to treatment, and reduce complications.

Background: Chronic kidney disease (CKD) eventually manifests as renal interstitial fibrosis, and loss of peritubular capillaries in the fibrotic area is the main marker of disease progression. Tie2, as the main functional receptor of angiopoietin, is characteristically expressed in vascular endothelial cells. This study aimed to evaluate the effect and mechanism of an agonistic Tie2 monoclonal antibody on folic acid (FA)-induced renal fibrosis (FAN) in mice.Methods: Mice were randomly divided into wild-type mice, FAN model mice, and FAN model mice treated with the agonistic Tie2 antibody. Human umbilical vein endothelial cells with lipopolysaccharide-induced injury were treated with the agonistic Tie2 antibody in vitro.Results: FA-induced renal tubulointerstitial lesions could be prevented with the agonistic Tie2 antibody. The extent of renal fibrosis induced by FA was suppressed by treatment with the agonistic Tie2 antibody. The level of fibroblast-specific protein 1 was reduced in mice that were administered the agonistic Tie2 antibody. Further, the agonistic Tie2 antibody inhibited FA‐induced vascular inflammation by downregulating vascular cell adhesion molecule-1. In addition, peritubular capillary density was upregulated by agonistic Tie2 antibody treatment, as evidenced by an increase in the level of cluster of differentiation 31. These findings were verified by the in vivo results, which showed that the levels of VCAM-1, Bax, and α-smooth muscle actin were downregulated after treatment with the agonistic Tie2 antibody.Conclusions: Based on all these findings, it appears that the agonistic Tie2 antibody attenuated renal interstitial fibrosis in FAN model mice by promoting peritubular capillary regeneration, inhibiting inflammation, and improving peritubular capillary lesions, and therefore, it may have promise for the treatment of CKD.