Complement receptor type 1 and 2 (CR1 and CR2) gene polymorphisms and plasma protein levels are associated with the Dengue disease severity

Abstract

The pathological outcome of dengue disease results from complex interactions between dengue virus (DENV) and host genetics and immune response. Complement receptor types 1 and 2 (CR1 and CR2) mediate complement activation through the alternative pathway. This study investigated the possible association of genetic polymorphisms and plasma levels of CR1 and CR2 with dengue disease. A total of 267 dengue patients and 133 healthy controls were recruited for this study. CR1 and CR2 gene polymorphisms were analyzed by Sanger sequencing, while plasma CR1 and CR2 levels were measured by ELISA. The frequency of the CR1 minor allele rs6691117G was lower in dengue patients and those with severe dengue compared to healthy controls. Plasma CR1 and CR2 levels were decreased in dengue patients compared to healthy controls (P < 0.0001) and were associated with platelet counts. CR1 levels were lower in dengue patients with warning signs (DWS) compared to those without DWS, while CR2 levels were decreased according to the severity of the disease and after 5 days (T1) and 8 days (T2) of follow-up. CR2 levels were decreased in dengue patients positive for anti-DENV IgG and IgM and patients with bleeding and could discriminate DWS and SD from dengue fever patients (AUC = 0.66). In conclusion, this study revealed a reduction in CR2 levels in dengue patients and that the CR1 SNP rs6691117A/G is associated with the dengue severity. The correlation of CR2 levels with platelet counts suggests that CR2 could be an additional biomarker for the prognosis of severe dengue disease.

Figure 1

CR1 and CR2 levels in dengue patients and healthy individuals. (A): CR1 levels in different groups of dengue patients and healthy controls. (B): CR1 levels in dengue patients with follow-up at the time of admission (T0), after 5 days of admission (T1), and after 8 days of admission (T2). (C): CR2 levels in different groups of dengue patients and healthy controls. (D): CR2 levels in dengue patients with follow-up at the time of admission (T0), after 5 days of admission (T1), and after 8 days of admission (T2). Box plots present medians with 25 and 75 percentiles with whiskers to 10 and 90 percentiles, the dots and asterisks are the outliners; HC: healthy control; DF: Dengue fever; DWS: dengue patients with warning signs. P values were calculated by the Mann–Whitney U test. (#): P < 0.0001 compared with DF, DWS and SD groups.

Figure 2

Correlation of CR1 and CR2 protein levels in healthy controls and dengue patients. (A) in healthy controls; (B): in all dengue patients; (C): in patients with dengue fever; (D) in patients with dengue fever with warning signs. rho (ρ) and P values were calculated by Spearman's correlation.

Figure 3

CR1 and CR2 levels in dengue patients according to dengue tests. (A): CR1 levels in dengue patients with negative and positive anti-DENV specific IgG. (B): CR1 levels in dengue patients with negative and positive anti-DENV specific IgM. (C): CR1 levels in dengue patients with negative and positive bleeding tests. (D): CR2 levels in dengue patients with negative and positive anti-DENV specific IgG. (E): CR2 levels in dengue patients with negative and positive anti-DENV specific IgM. (F): CR2 levels in dengue patients with negative and positive bleeding tests. Box plots present medians with 25 and 75 percentiles with whiskers to 10 and 90 percentiles, the dots and asterisks are the outliners; Neg: negative; Pos: positive; NS: not significant. P values were calculated by the Mann–Whitney U test.

Figure 4

Prognostic performance of the CR1 and CR2 proteins for dengue progression. (A and C): ROC curve of CR1 and CR2 protein levels, respectively, in differentiating dengue with warning signs from dengue fever. (B and D): ROC curve of CR1 and CR2 protein levels, respectively, in differentiating dengue with warning signs and severe dengue from dengue fever.

Figure 5

Distribution of CR1 and CR2 levels in healthy individuals with different CR1 genotypes, CR2 genotypes and haplotypes. (A): CR1 SNP rs6691117; (B): CR2 SNP rs1048971; (C): CR2 SNP rs17615; (D) CR2 SNP rs17616; (E): CR2 SNP rs4308977; (F): CR2 haplotype; Box-plots present medians with 25 and 75 percentiles with whiskers to 10 and 90 percentiles, the dots and asterisks are the outliners; Comparison was performed using Kruskal–Wallis test. NS: not significant.