Evaluation of the mannose-binding lection gene polymorphism on the severity of community acquired pneumonia in adults

Abstract

To evaluate the significance of the mannose-binding lection (MBL) gene polymorphism at code 54 of exon1 and MBL serum level and C-reactive protein (CRP) in the severity of community acquired pneumonia (CAP) in adults. A prospective observation was conducted. 104 adults Han patients with CAP hospitalized in Tianjin People's Hospital were enrolled. Frequencies of MBL54 alleles and genotypes were measured. The patients were evaluated by pneumonia severity index (PSI) score and were graded. Serum MBL was determined by enzyme linked immunosorbent assay (ELISA), and serum CRP was detected by immunoturbidimetry before and 4 days and 7 days after the treatment. 100 healthy control subjects with the same region, age, gender, nationality were enrolled as control group. Serum MBL and CRP levels were compared between CAP group and the control group or among different grades of PSI, and the correlation was analyzed. The variation of GGC->GGC in MBL54 was found in CAP patients and controls. Similar frequencies of genotypes (χ² = 0.018, P=0.893) and alleles (χ² = 0.019, P=0.903) of MBL54 with wild type and mutant type were found between two groups. The serum MBL level (mg/L) before and 4 days and 7 days after the treatment in CAP group was increased followed by the reduction and they were 3.75 ± 1.78, 4.53 ± 1.99 and 4.04 ± 1.91, respectively, which were significantly higher than those in control group (2.84 ± 1.41, all P<0.01). The serum CRP levels (mg/L) in CAP group were gradually declined, and they were 66.88 ± 40.47, 51.21 ± 37.54, 36.91 ± 36.02, respectively, which were significantly higher than those in control group (6.96 ± 2.19, all P<0.01). There were 12 cases with PSI grade I, 32 cases with grade II, 20 cases with grade III, 22 cases with grade IV and 18 cases with grade V in CAP patients. There was no significant difference in frequencies of MBL54 genotypes among different grades of PSI (χ² = 1.210, P=0.876) and between general ward and intensive care unit (χ² = 0.569, P=0.451). No differences in the serum MBL level before (F=1.313, P=0.279) and 4 days (F=1.705, P=0.165) and 7 days (F=1.684, P=0.170) after the treatment were found among different PSI grades. The serum MBL level 4 days after the treatment was significantly higher than that before treatment, then decreased to the level before treatment on the 7th day after treatment in CAP patients with grade II-IV. There was significant difference in serum CRP level before (F=23.179, P=0.000) and 4 days (F=26.601, P=0.000) and 7 days (F=10.358, P=0.000) after the treatment among different PSI grades in CAP patients. The serum levels of CRP in patients with different PSI grades were gradually decreased with time prolonged, the higher the PSI grade, the more obscure the serum CRP decrease. No correlation was found between PSI grade and serum MBL before and 4 days and 7 days after the treatment (before treatment: r=-0.205, P=0.145; 4 days after treatment: r=-0.062, P=0.662; 7 days after treatment: r=-0.063, P=0.656), and positive correlation between PSI grade and serum CRP was found(before treatment: r=0.809, P=0.000; 4 days after treatment: r=0.842, P=0.000; 7 days after treatment: r=0.702, P=0.000). The MBL54 codon genotypes had no effect on the susceptibility of CAP. The serum MBL was elevated and dynamic changes with increasing treatment time in CAP patients were shown. MBL can be used as a reaction of CAP in acute stage. But it cannot be used as an inflammatory marker for the severity of CAP.