Secondary pneumonia

Associations of MMP9 polymorphism with the risk of severe pneumonia in a Southern Chinese children population

BACKGROUND

Severe pneumonia frequently causes irreversible sequelae and represents a major health burden for children under the age of 5. Matrix Metallopeptidase 9 (MMP9) is a zinc-dependent endopeptidase that is involved in various cellular processes. The correlation between MMP9 and the risk of severe childhood pneumonia remains unclear.

METHODS

Here we assemble a case-control cohort to study the association of genetic variants in MMP9 gene with severe childhood pneumonia susceptibility in a Southern Chinese population (1034 cases and 8426 controls).

RESULTS

Our results indicate that the allele G in rs3918262 SNP was significantly associated with an increased risk of severe pneumonia. Bioinformatic analyses by expression quantitative trait loci (eQTL), RegulomeDB and FORGEdb database analysis showed that rs3918262 SNP has potential regulatory effect on translational efficiency and protein level of MMP9 gene. Furthermore, MMP9 concentrations were significantly up-regulated in the bronchoalveolar lavages (BALs) of children with severe pneumonia.

CONCLUSION

In summary, our findings suggest that MMP9 is a novel predisposing gene for childhood pneumonia.

Pneumococcal infection and immunologic response to pneumococcal vaccine in chronic obstructive pulmonary disease. A pilot study

We assessed the importance of Streptococcus pneumoniae and immunologic response to 14-valent pneumococcal vaccine in a randomized (saline placebo or vaccine) double-blind pilot study involving 103 patients with chronic obstructive pulmonary disease (COPD). Antibody titers, the flora of the sputum, respiratory infections or pneumonias, and deaths were monitored. The patients' antibody titers before immunization were higher than healthy control subjects. Titers rose normally in those vaccinated but declined more rapidly. Differences between the group receiving placebo and vaccine were not significant at 12 and 24 months. The incidence of pneumonia was high before and after vaccine (47/1,000 vs 41/1,000 patient-years). Nonpneumococcal causes predominated (73 percent of pneumonias; 83.4 percent of lethal pneumonias). Isolates from sputum were predominantly nonvaccine types (50 to 62.5 percent). Twenty-seven patients died; pneumonia occurred in six (one pneumococcal in a vaccinated patient) as a terminal complication of other diseases. Thus, although pneumonia occurred frequently in these patients with COPD and contributed to mortality in 22 percent (six) of the 27 deaths, the predominance of nonpneumococcal causes and the data on antibodies and sputum suggest that pneumococcal vaccine may not be as beneficial for patients with COPD as was hoped. More observations are needed.