Notch Regulates Fibrocartilage Stem Cell Fate and Is Upregulated in Inflammatory TMJ Arthritis.

The Notch pathway is critical for the development of the extracellular matrix in cartilage by regulating both anabolic and catabolic cellular activities. Similarly, Notch signaling plays a biphasic role in adult cartilage health and osteoarthritis by maintaining homeostasis and contributing to degeneration, respectively. The temporomandibular joint (TMJ) is the synovial joint of the craniofacial complex and is subject to injury and osteoarthritis. While Notch has been studied in axial skeletal joints, little is known about the role of Notch in TMJ development and disease. We identified fibrocartilage stem cells (FCSCs) localized within the TMJ condyle superficial zone niche that regenerate cartilage and repair joint injury. Here we investigate the role of Notch in regulating TMJ development and FCSC fate. Using a Notch reporter mouse, we discovered FCSCs localized within the TMJ superficial niche exhibit Notch activity during TMJ morphogenesis. We further showed that constitutively activating Notch promotes FCSC differentiation toward both cartilage and bone lineages, but inhibits adipogenesis. Using a TNF-α-induced TMJ inflammatory arthritis mouse model, we found that the expression of Notch receptors and ligands are upregulated and coupled with cells undergoing cartilage to bone transdifferentiation, which may contribute to TMJ pathogenesis. We also discovered that global Notch inhibition reduces osteogenic and chondrogenic differentiation of FCSCs. Together, these findings suggest that Notch is critical for FCSC fate specification and TMJ homeostasis, and reveal that inhibition of the Notch pathway may be a new therapeutic target for treating TMJ osteoarthritis.

Fibrocartilage Stem Cells Engraft and Self-Organize into Vascularized Bone.

Angiogenesis is a complex, multicellular process that is critical for bone development and generation. Endochondral ossification depends on an avascular cartilage template that completely remodels into vascularized bone and involves a dynamic interplay among chondrocytes, osteoblasts, and endothelial cells. We have discovered fibrocartilage stem cells (FCSCs) derived from the temporomandibular joint (TMJ) mandibular condyle that generates cartilage anlagen, which is subsequently remodeled into vascularized bone using an ectopic transplantation model. Here we explore FCSC and endothelial cell interactions during vascularized bone formation. We found that a single FCSC colony formed transient cartilage and host endothelial cells may participate in bone angiogenesis upon subcutaneous transplantation in a nude mouse. FCSCs produced an abundance of the proangiogenic growth factor vascular endothelial growth factor A and promoted the proliferation of human umbilical vein endothelial cells (HUVECs). Using a fibrinogen gel bead angiogenesis assay experiment, FCSC cell feeder layer induced HUVECs to form significantly shorter and less sprouts than D551 fibroblast controls, suggesting that FCSCs may initially inhibit angiogenesis to allow for avascular cartilage formation. Conversely, direct FCSC-HUVEC contact significantly enhanced the osteogenic differentiation of FCSCs. To corroborate this idea, upon transplantation of FCSCs into a bone defect microenvironment, FCSCs engrafted and regenerated intramembranous bone. Taken together, we demonstrate that the interactions between FCSCs and endothelial cells are essential for FCSC-derived vascularized bone formation. A comprehensive understanding of the environmental cues that regulate FCSC fate decisions may contribute to deciphering the mechanisms underlying the role of FCSCs in regulating bone formation.

Peptidoglycan synthesis in Tannerella forsythia: Scavenging is the modus operandi.

Tannerella forsythia is a Gram-negative oral pathogen strongly associated with periodontitis. This bacterium has an absolute requirement for exogenous N-acetylmuramic acid (MurNAc), an amino sugar that forms the repeating disaccharide unit with amino sugar N-acetylglucosamine (GlcNAc) of the peptidoglycan backbone. In silico genome analysis indicates that T. forsythia lacks the key biosynthetic enzymes needed for the de novo synthesis of MurNAc, and so relies on alternative ways to meet its requirement for peptidoglycan biosynthesis. In the subgingival niche, the bacterium can acquire MurNAc and peptidoglycan fragments (muropeptides) released by the cohabiting bacteria during their cell wall breakdown associated with cell division. Tannerella forsythia is able to also use host sialic acid (Neu5Ac) in lieu of MurNAc or muropeptides for its survival during the biofilm growth. Evidence suggests that the bacterium might be able to shunt sialic acid into a metabolic pathway leading to peptidoglycan synthesis. In this review, we explore the mechanisms by which T. forsythia is able to scavenge MurNAc, muropeptide and sialic acid for its peptidoglycan synthesis, and the impact of these scavenging activities on pathogenesis.

Changes in opioid and other analgesic use 1995-2010: repeated cross-sectional analysis of dispensed prescribing for a large geographical population in Scotland.

BACKGROUND: Despite recent concerns about increasing rates of analgesic prescribing, detailed epidemiological studies are lacking. We identified and described changes in the pattern of community-dispensed prescriptions to the Tayside population, Scotland, between 31st March 1995 (n = 301,020) and 31st March 2010 (n = 311,881). METHODS: Repeated cross-sectional analysis of patient-level population data on dispensed analgesics, stratified by sociodemographic variables; logistic regression to identify factors associated with strong opioid dispensing in 2010. RESULTS: The proportion of people currently dispensed any analgesic increased in 2010 (17.9%) compared with 1995 (15.7%). This increase was not equal across drug classes, with paracetamol, opioids and gabapentin/pregabalin showing an increase, but others showing a decrease. Weak opioids were less commonly dispensed in 2010 (8.2% vs. 8.4%) but dispensing of strong opioids increased 18-fold (3.6% vs. 0.2%), including a five-fold increase of morphine, fentanyl or oxycodone (0.75% vs. 0.15%). People receiving more non-analgesic drugs (odds ratio 20.7 if dispensed >14 non-analgesic medications vs. those dispensed <4) and those living in more deprived areas (OR 1.63 most deprived vs. most affluent) were more likely to receive a strong opioid in 2010. CONCLUSIONS: Analgesic use rose modestly between 1995 and 2010, but with larger changes within individual classes, only partly reflecting evidence-based guidance. Dispensing of strong opioids increased dramatically, largely driven by tramadol, although other strong opioids tripled. Polypharmacy and socio-economic deprivation were strongly associated with strong opioid use. Research is needed to establish the causes, benefits and harms of the increase in analgesic, and especially strong opioid use.

[Cytomegalovirus-induced protein-losing gastropathy: a case report]. / Un raro caso di gastroenteropatia ipertrofica protido-disperdente da CMV.

Protein-losing gastropathy is an uncommon disease of uncertain etiology, known also as Menetrier's disease. In medical literature only 50 pediatric cases have been described. These childhood forms, in contrast to classic adult Menetrier's disease, have a typical benign and transient course, and require only supportive therapy. The role of Cytomegalovirus (CMV) in the pathogenesis has been demonstrated by gastric biopsy in one third of the cases. Also other infectious, allergic and immunological factors have been hypothesized. We describe a case of hypertrophic gastropathy with important protein-loss, admitted to our Pediatric Department for evaluation because of vomit, weight loss, abdominal pain and hypoalbuminemia. Gastric mucosal biopsy revealed a morphological evidence of CMV infection.

[Immunological development in asymptomatic HIV infected children]. / Follow-up immunologico di bambini con infezione asintomatica da HIV.

In HIV infected children, CD45+CD4+ T lymph. reconstitution has been related to efficient thymopoiesis. Because human thymus undergoes spontaneous involution at a relatively young age, institution of antiretroviral therapy early in the course of infection has been recommended. 12 HIV vertically infected children aged 4-8 years were investigated T-cell subsets for four years. 7 children were naive for therapy (group NT); 5 experienced nucleoside analogues only (group T). CD45RA+ and CD45RO+ CD4+ values were compared to predicted values of healthy children. The two groups showed similar clinical and immunological baseline characteristics (CDC class N-A). Mean VL at t0 was 4.26 log10 (SD 0.71) in gr. NT and 4.01 log10 (SD 0.57) in gr. T; median CD4 T lymph values were 27% in gr. NT and 23.5% in gr. T. Median CD45RA+ values were 62.8% in gr. NT and 71.3% in gr. T. No differences in VL, CD4+ T lymph., CD45RA+, CD45RO+ were found in between groups or within each group at each time evaluation. Median CD45RA+ values were not different from predicted values of healthy children. None of the children changed CDC class during the study period. Although the number of subjects was small, our study evidenced the possibility of a normal immunological development in HIV-1 vertically infected asymptomatic children naive for HAART during the first decade, even in the presence of significant viremia.