Increased levels of matrix metalloproteinase-3 in the sera and synovial fluids of patients with pustulotic arthro-osteitis associated with palmoplantar pustulosis: report of 2 cases.

Pustulotic arthro-osteitis (PAO) is occasionally seen in patients with palmoplantar pustulosis (PPP); however, its pathogenesis is still obscure. Herein, two patients with PAO associated with PPP were described. Both patients developed hydrarthrosis on the knees, along with sternocostoclavicular pain. Detail examination revealed odontogenic infection in both cases. Matrix metalloproteinase-3 (MMP-3) is a useful marker reflecting the activity of rheumatoid arthritis. In this study, MMP-3 levels in the sera as well as joint fluids were examined. Serum MMP-3 levels were increased in both cases (274 ng/ml in Case 1 and 242 ng/ml in Case 2, normal; 17.3-59.7). Also, MMP-3 concentration in the joint fluids was markedly elevated (Case 1 > 80,000 ng/ml and 48,000 ng/ml in Case 2). Our studies suggest that MMP-3 may play a role in the pathogenesis of joint involvement of PPP.

Heme oxygenase-1 mediates protective effects on inflammatory, catabolic and senescence responses induced by interleukin-1ß in osteoarthritic osteoblasts.

Osteoarthritis (OA) is a chronic degenerative joint disease showing altered bone metabolism. Osteoblasts contribute to the regulation of cartilage metabolism and bone remodeling. We have shown previously that induction of heme oxygenase-1 (HO-1) protects OA cartilage against inflammatory and degradative responses. In this study, we investigated the effects of HO-1 induction on OA osteoblast metabolism. HO-1 was induced with cobalt protoporphyrin IX (CoPP) and by transduction with LV-HO-1. In osteoblasts stimulated with interleukin (IL)-1ß, CoPP enhanced mineralization, the expression of a number of markers of osteoblast differentiation such as Runx2, bone morphogenetic protein-2, osteocalcin, and collagen 1A1 and 1A2, as well as the ratio osteoprotegerin/receptor activator of nuclear factor-κB ligand. HO-1 induction significantly reduced the expression of matrix metalloproteinase (MMP)-1, MMP-2 and MMP-3, and the production of pro-inflammatory cytokines such as tumor necrosis factor-α and IL-6 whereas IL-10 levels increased. HO-1 also exerted inhibitory effects on prostaglandin (PG)E(2) production which could be dependent on cyclooxygenase-2 and microsomal PGE synthase-1 down-regulation. The activity of senescence-associated ß-galactosidase and the expression of the senescence marker caveolin-1 were significantly decreased after HO-1 induction. The inhibition of nuclear factor-κB activation induced by IL-1ß in OA osteoblasts may contribute to some HO-1 effects. Our results have shown that HO-1 decreases the production of relevant inflammatory and catabolic mediators that participate in OA pathophysiology thus eliciting protective effects in OA osteoblasts.

The role of cyclooxygenase-2 (COX-2) in inflammatory bone resorption.

Prostaglandin E2 (PGE(2)) is an important inflammatory mediator that plays an essential role in the development and progression of periradicular diseases. Cyclooxygenase-2 (COX-2) is the inducible enzyme responsible for increased PGE(2) levels during inflammation and other pathologic processes. The purpose of this study was to determine the role of COX-2-mediated PGE(2) synthesis in osteoclast formation in response to endodontic pathogens and materials. Primary osteoblast cultures and osteoclast cultures were prepared from COX-2 knockout (K/O) and wild-type (WT) littermates. These cultured cells were exposed to lipopolysaccharide (LPS) or root canal obturation materials including gutta-percha (GP), Resilon (RS), mineral trioxide aggregates (MTAs), and AH Plus (AH+). Osteoclast formation was evaluated using tartrate-resistant acid phosphatase (TRAP) staining. The expression of receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG) was determined by real-time polymerase chain reaction (PCR) analysis. It was found that in both WT and K/O cultures, treatment with LPS led to a marked increase in osteoclast formation. The number of osteoclasts formed was significantly lower in K/O cultures compared to WT cultures. Exposure to endodontic materials did not lead to any significant osteoclast formation. LPS and endodontic materials caused a decrease in both RANKL and OPG expression in WT cells. In K/O cells, the baseline levels of RANKL and OPG expression were dramatically decreased compared to the WT cells. In conclusion, COX-2-mediated PGE(2) expression is required for LPS-induced inflammatory bone resorption and maintaining the baseline level of RANKL and OPG expression. LPS-induced osteoclast formation may be independent of the RANKL pathway.

The etiology of chronic otitis media.

Various current theories regarding the aetiology of chronic otitis media are considered in detail. The concept that it originates from an acute middle ear infection no longer appears tenable. Recent experimental work has demonstrated the role of invading skin causing invasive osteitis. It is postulated that in some instances osteitis may follow erosion of the metal skin and proceed to widespread chronic disease of the temporal bone. The important difference between obstruction and inadequacy of the Eustachian tube and the significance of the latter in chronic middle ear disease is emphsized. The Eustachian mechanism of cholesteatoma formation may best be studied by observing the development of retraction pockets following tympanoplasty.