Decreased muscle mass is independently associated with knee pain in female patients with radiographically mild osteoarthritis: a nationwide cross-sectional study (KNHANES 2010-2011).

To evaluate the association between muscle mass and knee pain in relation to radiographic severity of knee osteoarthritis. We consulted nationwide health examination and survey records collected from 2010 to 2011 and extracted data regarding female patients aged > 50 years and diagnosed with knee osteoarthritis. Radiographic severity was assessed on plain radiographs using the Kellgren-Lawrence system, whereas appendicular skeletal mass was obtained from dual-energy X-ray absorptiometry data. We performed multivariate logistic regression to evaluate the association between knee pain and muscle mass index (appendicular skeletal muscle mass divided by body weight in percentile) in patient groups stratified by radiographic severity of knee osteoarthritis. Among 17,476 participants of the national survey, 2013 female knee osteoarthritis patients were identified and stratified by radiographic severity (grade ≤ 1, n = 1136; grade 2, n = 240; grade 3, n = 379; and grade 4, n = 258). For mild osteoarthritis (Kellgren-Lawrence grade 2), muscle mass index was significantly lower in patients with knee pain than in those without knee pain (24.9 ± 3.9 vs 26.5 ± 6.3%, P = 0.023), whereas no such difference was noted for severe osteoarthritis (Kellgren-Lawrence grade > 2). After adjusting for clinical variables by multivariate logistic regression, decreased muscle mass index remained significantly associated with knee pain in patients with mild osteoarthritis but not in those with severe osteoarthritis (regression coefficient 0.915, 95% confidence interval 0.854-0.981, P = 0.012). Lower muscle mass may be a risk factor for knee pain in patients with radiographically mild knee osteoarthritis but not in those with radiographically severe osteoarthritis.

Streptococcus pneumoniae pep27 mutant as a live vaccine for serotype-independent protection in mice.

Streptococcus pneumoniae (pneumococcus) is responsible for significant morbidity and mortality in worldwide. After introduction of current pneumococcal vaccines, a marked decrease in the incidence of pneumococcal disease was observed. Unfortunately, serotype shifts in carriage and disease, including capsular switch and presence of antimicrobial resistance, have been found. Here we report live attenuated vaccine strain which is avirulent and can protect from systemic and mucosal pneumococcal diseases. Pep27, an autolysis-inducing factor of S. pneumoniae is known to mediate LytA-dependent and -independent lysis and it was thus expected to effect virulence. The loss of Pep27 had a much larger than expected decrease in virulence and has made the Pep27 mutant strain sufficiently avirulent to be used as a live vaccine. The pep27 mutation unexpectedly had lower level of capsular polysaccharide than the wild type (type 2, D39) strain. Moreover, the pep27 mutant showed rapid clearance by 24 h post intranasal infection, and was not detected in lung and blood suggesting that mutant could not invade into the tissue. Even when 2×10(8)CFU were injected intravenously the mutant was not detected in the blood or brain after 4 h. Whereas 4 h after injection of 6×10(6) CFU of the wild type parent D39 strain, bacteremia was readily detected. Two dose intranasal immunizations with the live pep27 mutant in the absence of adjuvant elicited IgG antibody and serotype-independent protection against lethal intranasal challenge. Thus Pep27 was essential for virulence, and intranasal immunization with the pep27 mutant could provide protective immunity.