Effect of lysed and non-lysed sickle red cells on the activation of NLRP3 inflammasome and LTB4 production by mononuclear cells.

OBJECTIVE AND DESIGN: This study tested the hypothesis that sickle red blood cell (SS-RBC) can induce inflammasome NLRP3 components gene expression in peripheral blood mononuclear cells (PBMCs) as well as interleukin-1ß (IL-1ß) and leukotriene B4 (LTB4) production. Additionally, we investigated the effect of hydroxyurea (HU) treatment in these inflammatory markers. METHODS: PBMCs from healthy donors (AA-PBMC) were challenged with intact and lysed RBCs from SCA patients (SS-RBC) and from healthy volunteers (AA-RBC). NLRP3, IL-1ß, IL-18 and Caspase-1 gene expression levels were assessed by quantitative PCR (qPCR). IL-1ß protein levels and LTB4 were measured by ELISA. RESULTS: We observed that lysed SS-RBC induced the expression of inflammasome NLRP3 components, but this increase was more prominent for CASP1 and IL18 expression levels. Moreover, we observed that intact SS-RBC induced higher production of IL-1ß and LTB4 than lysed SS-RBC. Although SCA patients treated with HU have a reduction in NLRP3 gene expression and LTB4 production, this treatment did not modulate the expression of other inflammasome components or IL-1ß production. CONCLUSIONS: Thus, our data suggest that caspase-1, IL-1ß and IL-18 may contribute to the inflammatory status observed in SCA and that HU treatment may not interfere in this inflammatory pathway.

Associations between TGF-ß1 Levels and Markers of Hemolysis, Inflammation, and Tissue Remodeling in Pediatric Sickle Cell Patients.

Transforming growth factor beta (TGF-ß) is a cytokine with important involvement in biological processes related to the pathogenesis of sickle cell disease (SCD), including endothelial and vascular dysfunction, inflammation, and hematopoietic homeostasis. This study is aimed at investigating associations between levels of TGF-ß1 and classical laboratory biomarkers and inflammatory mediators, as well as the tissue inhibitor of metalloproteases-1 (TIMP-1) and matrix metalloproteinase-9 (MMP-9), in pediatric patients (n = 123) with SCD in steady state: 84 with sickle cell anemia (HbSS) and 39 with hemoglobin SC disease (HbSC). A healthy control (HC) group of 59 individuals was also included. Hematological and biochemical analyses were carried out using electronic methods. TGF-ß1, TIMP-1, and MMP-9 plasma quantifications were performed by ELISA. TGF-ß1 plasma levels were higher in HbSS individuals than in HbSC and HC. In individuals with HbSS, TGF-ß1 levels were positively correlated with red blood cells, hemoglobin, hematocrit, platelets, and TIMP-1. In addition, HbSS individuals with TGF-ß1 levels above the median (≥72.29 ng/mL) also presented increased monocyte counts and decreased albumin levels. In patients with HbSC, TGF-ß1 levels were positively correlated with leukocytes, eosinophils, lymphocytes, monocytes, and platelets, as well as levels of TIMP-1, VLDL-C, triglycerides, heme, and AST. Additionally, HbSC individuals with TGF-ß1 levels above the median (≥47.80 ng/mL) presented increased leukocyte and platelet counts, as well as increased levels of triglycerides, VLDL-C, MMP-9, and TIMP-1, and decreased HDL-C. Our findings suggest that TGF-ß1 may play important roles in vascular remodeling, vasculopathy, angiogenesis, and inflammation in pediatric patients with SCD.

Sickle red cells as danger signals on proinflammatory gene expression, leukotriene B4 and interleukin-1 beta production in peripheral blood mononuclear cell.

This study tested the hypothesis that sickle red blood cell (SS-RBC) induce Toll-like receptors (TLR) and Nod-like receptor family, pyrin domain containing 3 (NLRP3)- inflammasome expression in peripheral blood mononuclear cells (PBMC). TLR and NLRP3 inflammasome could contribute to the maintenance of the inflammatory status in sickle cell anemia (SCA) patients, since SS-RBC act as danger signals activating these pathways. In this study, first, we evaluated TLR (2, 4, 5 and 9), NLRP3, Caspase-1, interleukin (IL)-1ß and IL-18 expression in PBMC freshly isolated from SCA patients (SS-PBMC) in comparison with PBMC from healthy individuals (AA-PBMC). In the second moment, we investigated whether SS-RBC could interfere with the expression of these molecules in PBMC from healthy donor, in the absence or presence of hydroxyurea (HU) in vitro. TLRs and NLRP3 inflammasome expression were investigated by qPCR. IL-1ß, Leukotriene-B4 (LTB4) and nitrite production were measured in PBMC (from healthy donor) culture supernatants. TLR2, TLR4, TLR5, NLRP3 and IL-1ß were highly expressed in SS-PBMC when compared to AA-PBMC. Additionally, SS-RBC induced TLR9, NLRP3, Caspase-1, IL-1ß and IL-18 expression and induced IL-1ß, LTB4 and nitrite production in PBMC cultures. HU did not prevent TLR and NLRP3 inflammasome expression, but increased TLR2 and IL-18 expression and reduced nitrite production. In conclusion, our data suggest that TLR and inflammasome complexes may be key inducers of inflammation in SCA patients, probably through SS-RBC; also, HU does not prevent NLRP3 inflammasome- and TLR-dependent inflammation, indicating the need to develop new therapeutic strategies to SCA patients that act with different mechanisms of those observed for HU.

Nasopharyngeal and Oropharyngeal Colonization by Staphylococcus aureus and Streptococcus pneumoniae and Prognostic Markers in Children with Sickle Cell Disease from the Northeast of Brazil.

We investigated the nasopharynx and oropharynx microbiota in sickle cell disease (SCD) to identify the microorganisms, antibiotic sensitivity, prevalent serotypes, and association of with laboratorial markers. Oropharynx/nasopharynx secretions were investigated in 143 SCD children aging 6 months to 17 years. Pathogens were isolated using standard procedures, and laboratorial markers were performed by automated methods. Staphylococcus aureus (S. aureus) was isolated from nasopharynx and oropharynx of 64 and of 17 SCD children respectively. Streptococcus pneumoniae (S. pneumoniae) was isolated from the nasopharynx and oropharynx of eight SCD patients. Serotypes of S. pneumoniae were 19F, 23F, and 14. All isolates were susceptible to penicillin, and patients whose nasopharynx and oropharynx were colonized by S. pneumoniae had high concentrations of aspartate transaminase, alanine transaminase, and ferritin. S. pneumoniae isolated were not penicillin-resistant serotypes suggesting that the use of penicillin for prophylaxis and/or treatment of infections is safe. Our finding of colonization and laboratory evaluation in SCD patients suggests that microorganisms are involved in the modulation of chronic inflammatory. The association of colonized microorganisms and laboratorial markers suggest a new approach to these patients follow-up, and additional studies of microorganism colonization and their association with SCD patients' clinical outcome will improve control and prevention strategies.

Endothelial Nitric Oxide Synthase (-786T>C) and Endothelin-1 (5665G>T) Gene Polymorphisms as Vascular Dysfunction Risk Factors in Sickle Cell Anemia.

Sickle cell anemia (SCA) patients have vascular complications, and polymorphisms in endothelin-1 (ET-1) and endothelial nitric oxide synthase (eNOS) genes were associated with ET-1 and nitric oxide disturbance. We investigate the association of ET-1 5665G>T and eNOS -786T>C polymorphisms with soluble adhesion molecules (sVCAM-1 and sICAM-1), biochemical markers, and medical history. We studied 101 SCA patients; carriers of eNOS minor allele (C) had the highest levels of sVCAM-1, and carriers of ET-1 minor allele had more occurrence of acute chest syndrome (ACS). The multivariate analysis suggested the influence of the ET-1 gene on ACS outcome and an association of the eNOS gene with upper respiratory tract infection. We suggest that eNOS and ET-1 gene polymorphisms can influence SCA pathophysiology and that eNOS variant in SCA patients might be important to nitric oxide activity and vascular alteration. We found an association of the ET-1 minor allele in ACS, showing the importance of genetic screening in SCA.

Sickle cell disease retinopathy: characterization among pediatric and teenage patients from northeastern Brazil.

OBJECTIVE: The aim of the present study was to characterize sickle cell disease retinopathy in children and teenagers from Bahia, the state in northeastern Brazil with the highest incidence and prevalence of sickle cell disease. METHODS: A group of 51 sickle cell disease patients (36 hemoglobin SS and 15 hemoglobin SC) with ages ranging from 4 to 18 years was studied. Ophthalmological examinations were performed in all patients. Moreover, a fluorescein angiography was also performed in over 10-year-old patients. RESULTS: The most common ocular lesions were vascular tortuosity, which was found in nine (25%) hemoglobin SS patients, and black sunburst, in three (20%) hemoglobin SC patients. Peripheral arterial closure was observed in five (13.9%) hemoglobin SS patients and in three (13.3%) hemoglobin SC patients. Arteriovenous anastomoses were present in six (16.5%) hemoglobin SS patients and six (37.5%) hemoglobin SC patients. Neovascularization was not identified in any of the patients. CONCLUSIONS: This study supports the use of early ophthalmological examinations in young sickle cell disease patients to prevent the progression of retinopathy to severe disease and further blindness.

Sickle cell disease retinopathy: characterization among pediatric and teenage patients from northeastern Brazil

Objective: The aim of the present study was to characterize sickle cell disease retinopathy in children and teenagers from Bahia, the state in northeastern Brazil with the highest incidence and prevalence of sickle cell disease. Methods: A group of 51 sickle cell disease patients (36 hemoglobin SS and 15 hemoglobin SC) with ages ranging from 4 to 18 years was studied. Ophthalmological examinations were performed in all patients. Moreover, a fluorescein angiography was also performed in over 10-year-old patients. Results: The most common ocular lesions were vascular tortuosity, which was found in nine (25%) hemoglobin SS patients, and black sunburst, in three (20%) hemoglobin SC patients. Peripheral arterial closure was observed in five (13.9%) hemoglobin SS patients and in three (13.3%) hemoglobin SC patients. Arteriovenous anastomoses were present in six (16.5%) hemoglobin SS patients and six (37.5%) hemoglobin SC patients. Neovascularization was not identified in any of the patients. Conclusions: This study supports the use of early ophthalmological examinations in young sickle cell disease patients to prevent the progression of retinopathy to severe disease and further blindness...