IntroductionGenetic variability of the pulmonary surfactant proteins A and D may affect clearance of microorganisms and the extent of the inflammatory response. The genes of these collectins (SFTPA1, SFTPA2 and SFTPD) are located in a cluster at 10q21-24. The objective of this study was to evaluate the existence of linkage disequilibrium (LD) among these genes, and the association of variability at these genes with susceptibility and outcome of community-acquired pneumonia (CAP). We also studied the effect of genetic variability on SP-D serum levels.MethodsSeven non-synonymous polymorphisms of SFTPA1, SFTPA2 and SFTPD were analyzed. For susceptibility, 682 CAP patients and 769 controls were studied in a case-control study. Severity and outcome were evaluated in a prospective study. Haplotypes were inferred and LD was characterized. SP-D serum levels were measured in healthy controls.ResultsThe SFTPD aa11-C allele was significantly associated with lower SP-D serum levels, in a dose-dependent manner. We observed the existence of LD among the studied genes. Haplotypes SFTPA1 6A2 (P = 0.0009, odds ration (OR) = 0.78), SFTPA2 1A0 (P = 0.002, OR = 0.79), SFTPA1-SFTPA2 6A2-1A0 (P = 0.0005, OR = 0.77), and SFTPD-SFTPA1-SFTPA2 C-6A2-1A0 (P = 0.00001, OR = 0.62) were underrepresented in patients, whereas haplotypes SFTPA2 1A10 (P = 0.00007, OR = 6.58) and SFTPA1-SFTPA2 6A3-1A (P = 0.0007, OR = 3.92) were overrepresented. Similar results were observed in CAP due to pneumococcus, though no significant differences were now observed after Bonferroni corrections. 1A10 and 6A-1A were associated with higher 28-day and 90-day mortality, and with multi-organ dysfunction syndrome (MODS) and acute respiratory distress syndrome (ARDS) respectively. SFTPD aa11-C allele was associated with development of MODS and ARDS.ConclusionsOur study indicates that missense single nucleotide polymorphisms and haplotypes of SFTPA1, SFTPA2 and SFTPD are associated with susceptibility to CAP, and that several haplotypes also influence severity and outcome of CAP.

Mannose-binding lectin (MBL)-associated serine protease-2 (MASP-2) is an indispensable enzyme for the activation of the lectin pathway of complement. Its deficiency is classified as a primary immunodeficiency associated to pyogenic bacterial infections, inflammatory lung disease, and autoimmunity. In Europeans, MASP-2 deficiency, due to homozygosity for c.359A > G (p.D120G), occurs in 7 to 14/10,000 individuals. We analyzed the presence of the p.D120G mutation in adults (increasing the sample size of our previous studies) and children. Different groups of patients (1495 adults hospitalized with communityacquired pneumonia, 186 adults with systemic lupus erythematosus, 103 pediatric patients with invasive pneumococcal disease) and control individuals (1119 healthy adult volunteers, 520 adult patients without history of relevant infectious diseases, and a pediatric control group of 311 individuals) were studied. Besides our previously reported MASP-2-deficient healthy adults, we found a new p.D120G homozygous individual from the pediatric control group. We also reviewed p.D120G homozygous individuals reported so far: a total of eleven patients with a highly heterogeneous range of disorders and nine healthy controls (including our four MASP-2-deficient individuals) have been identified by chance in association studies. Individuals with complete deficiencies of several pattern recognition molecules of the lectin pathway (MBL, collectin-10 and collectin-11, and ficolin-3) as well as of MASP-1 and MASP-3 have also been reviewed. Cumulative evidence suggests that MASP-2, and even other components of the LP, are largely redundant in human defenses and that individuals with MASP-2 deficiency do not seem to be particularly prone to infectious or autoimmune diseases.

The purpose of this study was to examine whether several allelic variants in the polymorphic interleukin (IL)-10 promoter region were related with an increased risk of developing systemic lupus erythematosus (SLE) in Spanish patients from Canary Islands. Microsatellites (MS) at positions -4000 and -1200 (IL10R and IL10G, respectively) and single nucleotide polymorphisms (SNPs) (MS) at positions -1082G/A, -819C/T and -592C/A of the IL-10 promoter were analysed in patients with SLE and healthy controls from Canary Islands (Spain). We found that SNPs but not MS were associated with SLE. The GCC haplotype frequency was significantly higher in SLE patients (0.43) than in healthy donors (0.33) [P = 0.02; OR = 1.50 (95% CI = 1.06-2.14)], whereas the ACC haplotype was less represented in patients (0.28 vs. 0.37) [P = 0.02; OR = 0.64 (95% CI = 0.44-0.92)]. To assess the functional role of genotypes, serum IL-10 levels from patients and controls were quantified by ELISA. Also, the lipopolysaccharide-induced IL-10 secretion by monocytes from healthy controls was evaluated in vitro. Serum IL-10 levels were higher in patients [median (interquartile range) = 2.8 pg/mL (1.8-4.2)] than in controls [0.9 pg/mL (0-3.5)] (P = 0.02), but no association was observed between serum IL-10 levels or lipopolysaccharide-induced IL-10 secretion and the IL-10 promoter haplotypes. These data suggest that the IL-10 promoter haplotype that produces higher levels of cytokine is associated with SLE in patients from Canary Islands.