Plasma Monocyte Chemoattractant Protein-1 Level as a Predictor of the Severity of Community-Acquired Pneumonia

Abstract

Monocyte chemoattractant protein (MCP)-1 increases in the serum of immunocompetent patients with community-acquired pneumonia (CAP). However, the correlation between the circulating level of MCP-1 and severity of CAP remains unclear. This study investigated differential changes in the plasma MCP-1 levels of patients with CAP before and after an antibiotic treatment and further analyzes the association between the CAP severity and MCP-1 levels. We measured the plasma MCP-1 levels of 137 patients with CAP and 74 healthy controls by using a commercial enzyme-linked immunosorbent assay. Upon initial hospitalization, Acute Physiology and Chronic Health Evaluation II (APACHE II); confusion, urea level, respiratory rate, blood pressure, and age of >64 years (CURB-65); and pneumonia severity index (PSI) scores were determined for assessing the CAP severity in these patients. The antibiotic treatment reduced the number of white blood cells (WBCs) and neutrophils as well as the level of C-reactive protein (CRP) and MCP-1. The plasma MCP-1 level, but not the CRP level or WBC count, correlated with the CAP severity according to the PSI (r = 0.509, p < 0.001), CURB-65 (r = 0.468, p < 0.001), and APACHE II (r = 0.360, p < 0.001) scores. We concluded that MCP-1 levels act in the development of CAP and are involved in the severity of CAP.

Keywords: biochemical marker; community-acquired pneumonia; monocyte chemoattractant protein-1; pneumonia severity index.

Figure 1

Levels of plasma monocyte chemoattractant protein (MCP)-1 in healthy controls and in patients with community-acquired pneumonia (CAP) before and after antibiotic treatment. The plasma MCP-1 level was significantly elevated in patients with CAP before they received treatment compared with the controls (p < 0.001) and significantly decreased in patients with CAP after treatment (p < 0.001).

Figure 2

Correlations of plasma monocyte chemoattractant protein (MCP)-1 with white blood cells (WBCs), neutrophils, and C-reactive protein (CRP) in 137 patients with community-acquired pneumonia (CAP). (A) No significant correlation was observed between the pretreatment plasma MCP-1 levels and WBC counts (Spearman’s correlation coefficients: r = 0.008, p = 0.921, n = 137); (B) no significant correlation was observed between the pretreatment plasma MCP-1 levels and neutrophil counts (Spearman’s correlation coefficients: r = 0.059, p = 0.495, n = 137); and (C) no significant correlation was observed between the pretreatment plasma MCP-1 levels and CRP levels (Spearman’s correlation coefficients: r = 0.075, p = 0.385, n = 137).

Figure 3

Correlations of plasma monocyte chemoattractant protein (MCP)-1 with the pneumonia severity index (PSI), confusion, urea level, respiratory rate, blood pressure, and age of >64 years (CURB-65), and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores in 137 patients with community-acquired pneumonia (CAP). (A) A significantly positive correlation was observed between plasma MCP-1 levels and PSI scores (Spearman’s correlation coefficients: r = 0.509, p < 0.001); (B) A significantly positive correlation was observed between plasma MCP-1 levels and CURB-65 scores (Spearman’s correlation coefficients: r = 0.468, p < 0.001); (C) A positive correlation was observed between plasma MCP-1 levels and APACHE II scores (Spearman’s correlation coefficients: r = 0.360, p < 0.001).