Mucosal Administration of Flagellin Protects Mice from Streptococcus pneumoniae Lung Infection

Streptococcus pneumoniae is a major cause of pneumonia in infants and the elderly. Innate defenses are essential to the control of pneumococcal infections, and deficient responses can trigger disease in susceptible individuals. Here we showed that flagellin can locally activate innate immunity and thereby increase the resistance to acute pneumonia. Flagellin mucosal treatment improved S. pneumoniae clearance in the lungs and promoted increased survival of infection. In addition, lung architecture was fully restored after the treatment of infected mice, indicating that flagellin allows the reestablishment of steady-state conditions. Using a flagellin mutant that is unable to signal through Toll-like receptor 5 (TLR5), we established that TLR5 signaling is essential for protection. In the respiratory tract, flagellin induced neutrophil infiltration into airways and upregulated the expression of genes coding for interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), CXCL1, CXCL2, and CCL20. Using depleting antibodies, we demonstrated that neutrophils are major effectors of protection. Further, we found that B- and T-cell-deficient SCID mice clear S. pneumoniae challenge to the same extent as immunocompetent animals, suggesting that these cell populations are not required for flagellin-induced protection. In conclusion, this study emphasizes that mucosal stimulation of innate immunity by a TLR not naturally engaged by S. pneumoniae can increase the potential to cure pneumococcal pneumonia.Streptococcus pneumoniae (pneumococcus) causes respiratory infections among infants and the elderly worldwide (40, 44). Capsular polysaccharide is the main virulence factor, and its composition defines 91 serotypes of pneumococcus (42). Certain serotypes colonize the human nasopharynx asymptomatically, representing a reservoir for interindividual transmission of the bacteria. In some individuals, colonization may progress to pneumococcal pneumonia and invasive disease (19, 36). In contrast, other serotypes, such as serotype 1, are rarely associated with colonization but cause invasive infections (28).Activation of innate defenses is essential for the control of pneumococcal infection (1, 20). Toll-like receptor 2 (TLR2), TLR4, and TLR9, as well as the adaptor MyD88, participate in the early detection and clearance of pneumococcus in the lungs (reviewed in reference 42). The cytosolic receptors Nod1 (nucleotide-binding oligomerization domain 1) and Nod2 are also involved in the recognition of pneumococci (29). TLR signaling activates mucosal innate responses that culminate with the recruitment of phagocytes, such as polymorphonuclear neutrophils (PMN) and macrophages, and the production of microbicidal agents (for a review, see reference 8). This process triggers rapid eradication of the pathogen by phagocytosis as well as by extracellular killing. In MyD88-deficient animals, S. pneumoniae is unable to intrinsically trigger any PMN recruitment into the airways, and animals thus have increased susceptibility to pneumonia (1). The contribution of TLR signaling in humans has been highlighted by a recent study showing that some MyD88 polymorphisms are associated with increased susceptibility to pneumococcal infection (43).The modulation of immunity by the activity of innate receptors to elicit protective responses against infections is an emerging concept (6, 35). The rationale is to promote innate responses that greatly exceed in magnitude, quality, and dynamics the innate response triggered by the pathogen itself. The effectiveness of TLR agonists for therapeutic treatment of infectious diseases has been demonstrated in several animal models, including models of respiratory infections (6, 21, 35). TLR5 senses bacterial flagellins, which are the main constituents of flagella. Various cells of the pulmonary tract, including the epithelial cells (14, 33), express TLR5, and mucosal administration of flagellin induces MyD88-dependent signaling, characterized by the swift production of various proinflammatory cytokines and chemokines (3, 10, 15, 16, 27, 33), as well as by rapid and heavy neutrophil infiltration into the airways (2, 10, 16). Although S. pneumoniae does not have flagella, we hypothesized that activation of TLR5 signaling may promote new and appropriate protective innate defenses against ongoing acute pneumococcal infections. Here we report that local stimulation of innate immunity by flagellin from Salmonella enterica serovar Typhimurium blocks the progression of pneumococcal pneumonia in mice.     

Phacomatosis pigmentovascularis type Va in a 3-month old

Abstract:  Phacomatosis pigmentovascularis is a rare genodermatosis characterized by a combination of melanocytic nevi and vascular malformations. A new type of phacomatosis pigmentovascularis was recently described which included cutis marmorata telangiectatica congenita and aberrant Mongolian spots and was named type V. We report a 3-month-old girl with diagnosis of phacomatosis pigmentovascularis type V.     

Renal involvement as a rare complication of Dorfman-Chanarin syndrome: a case report

Abstract:  Dorfman-Chanarin syndrome is a rare, autosomal recessive inherited lipid storage disease with congenital ichthyotic erythroderma due to an acylglycerol recycling defect. It is characterized by accumulation of neutral lipids in different tissues. Liver, muscle, ear, eye, and central nervous system are generally involved, so we presented a patient with severe ichthyosis, lipid vacuoles in neutrophils, and multiorgan involvement including a very rare complication, renal involvement. A 7-month-old girl was presented with frequent respiratory infection, congenital ichthyotic erithroderma and suspicion for immune deficiency. On her physical examination hepatomegaly, developmental delay, palmar and plantar hyperkeratosis and increased deep tendon reflexes with clonus and high tonus were found. Laboratory investigations revealed elevation at transaminases levels, hypoalbuminemia, hypergammaglobulinemia, presence of autoantibodies and eosinophilia. Vacuolization in leukocytes confirmed Dorfman-Chanarin syndrome, whereas no mutation at RAG1-2 and ARTEMIS genes ruled-out immune deficient status of the patient. At the age of eight months the patient died from severe renal failure. Her necropsies demonstrated microvesicular lipid accumulation not only at the liver but also at the renal species. The variability of involvement of different systems in Dorfman-Chanarin syndrome is well described, however the renal findings has not been reported previously at the literature.     

Characterization of bacterial DNA binding to human neutrophil surface

Bacterial DNA activates neutrophils through a CpG- and TLR9-independent mechanism. Neutrophil activation does not require DNA internalization, suggesting that it results from the interaction of bacterial DNA with a neutrophil surface receptor. The aim of this study was to characterize the interaction of bacterial DNA with the neutrophil surface. Bacterial DNA binding showed saturation and was inhibited by unlabeled DNA but not by other polyanions like yeast tRNA and poly-A. Resembling the conditions under which bacterial DNA triggers neutrophil activation, binding was not modified in the presence or absence of calcium, magnesium or serum. Treatment of neutrophils with proteases not only dramatically reduced bacterial DNA binding but also inhibited neutrophil activation induced by bacterial DNA. Experiments performed with DNA samples of different lengths obtained after digestion of bacterial DNA with DNase showed that only DNA fragments greater than approximately 170-180 nucleotides competed bacterial DNA binding and retained the ability to trigger cell activation. Treatment of neutrophils with chemoattractants or conventional agonists significantly increased bacterial DNA binding. Moreover, neutrophils that underwent transmigration through human endothelial cell monolayers even in the absence of chemoattractants, exhibited higher binding levels of bacterial DNA. Together, our findings provide evidence that binding of bacterial DNA to neutrophils is a receptor-mediated process that conditions the ability of DNA to trigger cell activation. We speculate that neutrophil recognition of bacterial DNA might be modulated by the balance of agonists present at inflammatory foci. This effect might be relevant in bacterial infections with a biofilm etiology, in which extracellular DNA could function as a potent neutrophil agonist.     

Effect of host selective pressure on Newcastle disease virus virulence

Newcastle disease virus (NDV) causes an economically important disease that can vary from clinically inapparent to highly virulent forms. Generally, NDV strains isolated from wild birds are non-pathogenic for chicken. However, there are evidences supporting the fact that avirulent viruses maintained in feral birds could have caused outbreaks of virulent NDV in poultry. The strain-specific difference in virulence is determined by structural variations on the fusion glycoprotein (F). More basic amino acids are present in the F cleavage site of virulent strains. Nevertheless, other regions have been involved in virulence determination. When we subjected an avirulent NDV isolated from a wild bird to a host change we found that the virus arose was virulent for chicken. Nucleotide changes in the F protein cleavage site amino acid sequence and in the hemagglutinin-neuraminidase protein sequence are reported.     

4G/5G plasminogen activator inhibitor-1 and −308 A/G tumor necrosis factor-α promoter gene polymorphisms in Argentinean lupus patients: focus on lupus nephritis

We investigated the relationship between the 4G/5G plasminogen activator inhibitor (PAI-1) and ?308 A/G tumor necrosis factor-α (TNF-α) polymorphisms and the clinical and biochemical features of systemic lupus erythematosus (SLE) in an Argentinean patient cohort. A total of 402 patients were studied, including 179 SLE patients and 223 healthy individuals. PCR-RLFP was used to determine the genotypes of the 4G/5G PAI-1 and ?308 A/G TNF-α polymorphisms. SLE patients with lupus nephritis (LN) (n = 86) were compared with patients without LN (n = 93). Additionally, LN patients were divided into proliferative LN and non-proliferative LN groups according to the results of the renal biopsies. No significant differences were noted in the genotype distributions or allele frequencies of these TNF-α and PAI-1 polymorphisms between SLE patients and controls. There were higher numbers of criteria for SLE, more lupus flares and higher damage scores in LN patients, but there were similar frequencies of anti-phospholipid antibody (APA) positivity and anti-phospholipid syndrome. No significant difference was noted for any studied variable between the proliferative LN and non-proliferative LN groups except for the presence of APA. We found no significant differences in the TNF-α and PAI-1 genotype distributions or allele frequencies between groups. We found that the ?308 A/G TNF-α and 4G/5G PAI-1 polymorphisms are not associated with susceptibility to SLE in an Argentinean population. We also did not find any association between the presence of any specific allele or genotype and the development of LN in SLE patients. Finally, no association was noted between either of the two polymorphisms and the severity of renal disease.     

Adjunctive serial post-operative intravitreal methotrexate injections in the management of advanced proliferative vitreoretinopathy

Graefe's Archive for Clinical and Experimental Ophthalmology - To assess the effects of weekly post-operative intravitreal methotrexate injections on eyes with grade C proliferative...