TLR2 activation in corneal stromal cells by Staphylococcus aureus‐induced keratitis

The Toll‐Like Receptor 2 (TLR2) plays an active and important role in Staphylococcus aureus‐induced chronic ocular inflammation. The aim of this study was to investigate the expression and function of TLR2 of corneal stromal cells in ex vivo rabbit model of S. aureus keratitis. Corneal buttons with sclera rims placed in an ex vivo air‐interface organ culture were assigned to two groups: corneas with epithelial and stromal abrasions. Each group was then divided into two sub‐groups exposed to UV‐killed S. aureus ATCC 6538P and S. aureus ATCC 29213, respectively. TLR2 and IL‐8 mRNA expressions were analyzed by quantitative real‐time RT‐PCR. TLR2 localization was visualized by immunofluorescence analysis. The results demonstrated that TLR2 and IL‐8 mRNA were significantly expressed in the stromal cells of the groups exposed to S. aureus strains. Moreover, it has been demonstrated that, after corneal injury, keratocytes differentiated into myofibroblasts became able to express TLR2 only when exposed to S. aureus. Identification of mechanisms regulation of corneal TLRs may lead to development of therapeutic interventions aimed at controlling corneal inflammation. This ex vivo model can be used to clarify the molecular events of bacterial‐corneal tissue interactions and their inflammatory consequences.     

Extracellular survivin up-regulates adhesion molecules on the surface of leukocytes changing their reactivity pattern

Rheumatoid arthritis (RA) is an autoimmune disease with joints as a principal target of inflammation. We have shown recently that the extracellular expression of the antiapoptotic protein survivin is associated with a destructive course of RA. Here, we address the potential impact of extracellular survivin on peripheral blood leukocytes (PBL). The binding of survivin to the surface of human PBL as well as the expression of adhesion molecules were assessed by FACS. The expression of adhesion molecules on leukocytes as a function of circulating survivin was analyzed in blood of 24 patients with RA and compared with eight healthy individuals. We show that extracellular survivin expresses immunomodulatory properties. It binds to the surface of the majority of granulocytes and a significant part of lymphocytes and monocytes inducing the activation of alpha-chains of beta-integrins and their ligand ICAM-1. Survivin-induced expression of alpha-chains of beta 2-integrins is regulated by p38 MAPK and PI-3K but not by the NF-kappaB signaling pathway. Clinical relevance of our findings is supported by the in vivo association of high circulating survivin levels with an increased expression of CD11c on monocytes and granulocytes in RA patients. The results of our study demonstrate that extracellular survivin affects the phenotype of leukocytes having a possible impact on homing of inflammatory cells during arthritis.     

Exploring Autoimmunity in a Cohort of Children with Genetically Confirmed Aicardi–Goutières Syndrome

Purpose

The purpose of this study was to explore the presence of autoimmune manifestations and characterize the autoantibody production in a cohort of patients with Aicardi–Goutières syndrome (AGS).

Methods

Seventeen patients with a genetically-confirmed diagnosis of AGS were recruited. At the time of enrollment, past medical and family history was reviewed, looking for possible signs or symptoms of autoimmune disorders. Blood samples were taken, for the detection of a panel of autoantibodies: anti-nuclear, anti-double-stranded-DNA, anti-nucleosome, anti-extractable nuclear antigens, anti-cardiolipin IgG/IgM, anti-β2glycoprotein I IgG/IgM, and anti-neutrophil cytoplasmic. We also measured complement levels determined as C3 and C4 quantification and total complement activity, measured as CH50.

Results

Nine of seventeen patients presented with at least one first- or second-degree relative with a history of autoimmune diseases (the childrens’ mother or grand-mother in the majority of cases). A specific autoimmune disease was present in only one AGS patient, namely an autoimmune thyroiditis. Autoantibodies were present in 9/17 patients, with different patterns of positivity. Complement levels were normal in all the patients. There was no correlation between auto-antibody production and personal or family history of autoimmune diseases.

Conclusions

Definite autoimmune diseases are not common in patients with AGS. Autoantibodies are mainly directed towards nucleic acids-containing elements but seem not to be pathogenic and, rather, may represent an epiphenomenon of the enhanced interferon production.

     

Synonymous Mutations in RNASEH2A Create Cryptic Splice Sites Impairing RNase H2 Enzyme Function in Aicardi–Goutières Syndrome

Aicardi–Goutières syndrome is an inflammatory disorder resulting from mutations in TREX1, RNASEH2A/2B/2C, SAMHD1, or ADAR1. Here, we provide molecular, biochemical, and cellular evidence for the pathogenicity of two synonymous variants in RNASEH2A. Firstly, the c.69G>A (p.Val23Val) mutation causes the formation of a splice donor site within exon 1, resulting in an out of frame deletion at the end of exon 1, leading to reduced RNase H2 protein levels. The second mutation, c.75C>T (p.Arg25Arg), also introduces a splice donor site within exon 1, and the internal deletion of 18 amino acids. The truncated protein still forms a heterotrimeric RNase H2 complex, but lacks catalytic activity. However, as a likely result of leaky splicing, a small amount of full‐length active protein is apparently produced in an individual homozygous for this mutation. Recognition of the disease causing status of these variants allows for diagnostic testing in relevant families.     

Human bocavirus infection in hospitalized children in Italy

Background Human bocavirus (HBoV) was first discovered in Sweden in 2005 and has now been found worldwide; however its role in clinically relevant diseases has not yet been clearly defined. Objectives To gain new insight into HBoV infection among children hospitalized with acute respiratory infections in Rome. Methods Between November 2004 and May 2007, 415 nasal washings were tested for the presence of an extensive range of respiratory viruses using molecular methods. Results Viral pathogens were detected in 214 children (51·6%), 28·9% being respiratory syncytial virus (RSV) and 9·6% being rhinovirus positive. Of the 34 children (8·2%) who tested positive for HBoV, 21 (61·8%) were co‐infected with another respiratory virus, mainly RSV. Human bocavirus was the only pathogen identified in four pneumonia and six bronchiolitis cases in March 2005 and January 2007, respectively. Human bocavirus was also detected in one child hospitalized with gastroenteritis and in another with erythema. Conclusions In the examined population, HBoV was the third most common virus detected but with a high rate of co‐infection with other respiratory viruses. Human bocavirus appeared to be the etiological agent in some pneumonia and bronchiolitis cases in which tests for all likely respiratory pathogens were negative.