FcγRIIa and FcγRIIIb polymorphisms and associations with clinical manifestations in systemic lupus erythematosus patients.

In this study, we aimed to investigate whether the distribution of the FcγRIIa and FcγRIIIb polymorphisms determines susceptibility to systemic lupus erythematosus (SLE) and acts as predictors of SLE clinical manifestations in the Brazilian patients. A total of 157 patients that fulfilled the American College of Rheumatology classification criteria for SLE and 160 healthy volunteers were included in this study. FCGR2A and FCGR3B genotypes were determined by polymerase chain reaction-based allotyping methods with allele-specific primers; the clinical features were obtained from the patients' official medical records. In the case of FcγRIIa polymorphism, it was observed association of the allele FCGR2A-R-131 (p = 0.02, odds ratio (OR)=1.44) and genotype RR-131 (p = 0.03, OR = 2.09) with SLE. These associations were higher with allele (p < 0.01, OR = 1.67) as well genotype (p = 0.01, OR = 2.85) when lupus nephritis was considered. In contrast, the allele FCGR2A-H-131 was associated with susceptibility to arthritis and anti-DNA antibodies (p = 0.05 for both). As for FcγRIIIb polymorphism, skewing did not differ significantly between patients and controls, however the genotype FCGR3B*02*02 was associated with susceptibility to arthritis (p = 0.02) and malar rash (p = 0.03), but no association with nephritis was found. The results demonstrate that FcγRIIa polymorphism is associated with susceptibility to SLE in Brazilian patients, whereas for FcγRIIIb polymorphism no association was found. However, notably, both polymorphisms present allelic variants that influence the clinical manifestations and may contribute to the pathogenesis of the disease. In addition, to our knowledge, this is the first study considering the frequency of FcγRIIIb polymorphism in Brazilian SLE patients.

The variant of CD11b, rs1143679 within ITGAM, is associated with systemic lupus erythematosus and clinical manifestations in Brazilian patients.

BACKGROUND/AIMS: Immune responses mediated by complement receptors (CR) are impaired in patients with systemic lupus erythematosus (SLE). Regarding CR3 (CD11b/CD18), the CD11b subunit is encoded by the ITGAM gene and a single nucleotide polymorphism (G230A; rs1143679) in ITGAM changes an arginine to a histidine at position 77 (R77H). We assessed whether the variant R77H, rs1143679 within ITGAM, is associated with the risk to developing SLE and the clinical manifestations of Brazilian SLE patients. METHODS: The rs1143679 was genotyped by SSP-PCR in 157 patients with SLE and 147 healthy individuals. Clinical and laboratorial manifestations were obtained from the official medical records according the criteria of the American College of Rheumatology. RESULTS: The 77H variant was associated with susceptibility to SLE (OR=1.8); the frequencies of the minor allele A were 0.25 (SLE) and 0.15 (healthy) (p<0.01). In addition, the minor allele A was associated with lupus nephritis (p=0.02) and antiphospholipid antibodies (p=0.04). CONCLUSION: These results showed that the rs1143679 variant is also associated with the risk to SLE in our population and with the risk to specific clinical manifestations, as nephritis and presence of antiphospholipid antibodies. These results may have implications for discussing the association of this polymorphism with the IC deposition in SLE.

Mannose binding lectin gene (MBL2) functional polymorphisms are associated with systemic lupus erythematosus in southern Brazilians.

Susceptibility to systemic lupus erythematosus (SLE) has been associated with immunologic, environmental, and genetic factors. To uncover a possible association between MBL2 gene polymorphisms and SLE, we analyzed functional polymorphisms in the promoter and first exon of the MBL2 gene in 134 Brazilian SLE patients and 101 healthy controls. Genotype and allele frequencies of MBL2 A/O polymorphism were significantly different between patients and controls, and the O allele was associated with an increased risk of SLE. An association between low mannose binding lectin (MBL) producer combined genotypes and increased risk for SLE was also reported. Furthermore, when stratifying SLE patients according to clinical and laboratory data, an association between the A/O genotype and nephritic disorders and between the X/Y genotype and antiphospholipid syndrome was evident. Combined genotypes responsible for low MBL production were more frequently observed in SLE patients with nephritis. Our results indicate MBL2 polymorphisms as possible risk factors for SLE development and disease-related clinical manifestations.

Human leukocyte antigen (HLA) and single nucleotide polymorphisms (SNPs) tumor necrosis factor (TNF)-alpha -238 and -308 as genetic markers of susceptibility to psoriasis and severity of the disease in a long-term follow-up Brazilian study.

BACKGROUND: The strongest genetic marker for psoriasis is Cw*06. Polymorphisms in the tumor necrosis factor (TNF)-alpha promoter region, especially replacement of guanine with adenine in positions -238 and -308 are related to higher TNF-alpha production and higher risk for psoriasis in Caucasoid populations, not found in Asians. We performed a case-control study of 69 patients with psoriasis type I and 70 controls, characterized clinical progression along 10-years of follow-up in mild or severe disease and determined HLA class I, II, and TNF single nucleotide polymorphisms (SNPs) -238 and -308 polymorphisms to demonstrate whether these polymorphisms may be genetic risk for susceptibility to psoriasis or severity of the disease in Brazilians. METHODS: Polymorphisms were identified using PCR/SSP. Alleles, genotypes, and haplotypes frequencies were compared using Fisher's test. RESULTS: More severe disease was found in male patients. It may be suggested that alleles B*37, Cw*06, Cw*12, and DRB1*07 were associated with severe disease course, while B*57 with mild disease. No statistical difference was found between the patients and controls regarding polymorphisms frequencies in TNF SNPs. This study pointed to a higher TNF-238 G/G genotype frequency (OR: 3.21; CI: 1.06­9.71; P = 0.04) in the group with severe disease. CONCLUSIONS: Polymorphisms in the TNF-alpha SNPs do not seem to be a more important genetic risk factor for psoriasis than the already known Cw*06 in Brazilian patients, but these markers may be related to clinical manifestations.

Autonomic dysfunction in experimental sepsis induced by cecal ligation and puncture.

A systemic inflammatory response to infection characterizes sepsis which associated to refractory hypotension, turns into severe sepsis. Our aim was to evaluate hormonal and cardiovascular alterations after experimental sepsis induced by cecal ligation and puncture (CLP). Male Wistar rats (200-250 g) were submitted to CLP or sham operation. The animals were decapitated at 0, 2, 4, 6 and 8 h after surgery for collection of blood samples for plasma osmolality, sodium and vasopressin (AVP) measurements. The mean arterial pressure (MAP) and heart rate (HR) were recorded 1 h before and to each 1 h during 5hs after surgery. The spontaneous baroreflex sensitivity and spectral analysis of HR and MAP variability were analyzed after recording. The plasma osmolality and sodium did not show any alterations compared to the sham group. MAP decreased from 3 h (85 vs.103 mm Hg, P<0.05) to 5 h in the CLP group (76 vs.106 mm Hg, P<0.05). This was accompanied by an increase in HR. The AVP plasma level was elevated at 4 h (6.0+/-1.1 vs. 1.1+/-0.2 pg/mL, P<0.05) and returned to basal levels at 8 h after CLP (2.3+/-0.5 vs. 1.9+/-0.2 pg/mL, P>0.05). A reduction in baroreflex sensitivity occurred 1 h after injury. The CLP group showed a reduction in overall variability, low-frequency power, and low/high-frequency ratio of HR and low-frequency power of MAP. The data suggest an impairment of autonomic control of the heart and vessels during polymicrobial sepsis. This reduction in autonomic nervous system activity causes the impairment of baroreflex that in turn may contribute to the reduction of vasopressin plasma levels in the late phase of severe sepsis.

Participation of iNOS-derived NO in hypothalamic activation and vasopressin release during polymicrobial sepsis.

Clinical and experimental studies with LPS injection have shown an increase in vasopressin (AVP) secretion in the early phase of severe sepsis, which is subsequently reduced despite persistent hypotension. The aim of this study was to evaluate the role of inducible nitric oxide synthase (iNOS)-derived NO in hypothalamic activation and in AVP release during severe sepsis induced by cecal ligation and puncture (CLP). Male Wistar rats received i.p. injections of aminoguanidine, an iNOS inhibitor, or saline 30 min before CLP or sham surgeries (controls). CLP led to increased plasma nitrate levels, protein leakage and hypotension and caused mortality of 80% by 24 h. Expression of c-fos in paraventricular (PVN), supraoptic (SON) and organum vasculosum of lamina terminalis (OVLT) nuclei, as well as plasma AVP concentration were increased at 6 h but reduced to basal levels 24 h after CLP. Aminoguanidine pre-treatment prevented the increase in plasma nitrate levels and hypotension in the first 6 h. It also reduced AVP secretion and hypothalamic c-fos expression. After 24 h, the pre-treatment reduced plasma nitrate levels, protein leakage and caused a partial recovery of c-fos expression in SON and OVLT but did not affect AVP release. Furthermore, mortality was reduced to 43%. We conclude that during the early phase of severe sepsis hypotension caused by the iNOS-derived NO is partially responsible for the hypothalamic activation and AVP release. In the late phase, however, the iNOS-derived NO prevents brain activation blunting AVP secretion contributing to hypotension, irreversible shock and animal death.