Expansion of CCR4+ activated T cells is associated with memory B cell reduction in DOCK8-deficient patients.

Hyper-IgE syndrome (HIES) is a genetic disorder characterized by elevated IgE serum levels, mostly due to mutations in STAT3 or DOCK8. Despite clinical heterogeneity between the two forms of the disease, clinical manifestations may not be conclusive for diagnosis and immunological differences are still unclear. Herein, we performed a detailed characterization of the T- and B-cell compartments by flow cytometry in seven HIES patients with homozygous DOCK8 mutations and six patients presenting heterozygous STAT3 mutations. We observed that DOCK8-deficient patients showed a marked reduction of naive and recent thymic emigrant (RTE) T lymphocytes together with a relative increase of activated T cells, most of which co-expressed the chemokine receptor CCR4, a marker of Th2 polarization. Moreover, an extreme reduction of memory B cells was detected, despite a normal/increased proportion of immunoglobulin-secreting cells. These observations indicate that DOCK8-deficient patients display a distinctive immunophenotype which is characteristic of this form of HIES.

Incidence and antibiotic susceptibility of Mycoplasma hominis and Ureaplasma urealyticum isolated in Brescia, Italy, over 7 years.

The prevalence and antimicrobial susceptibility of Ureaplasma urealyticum and Mycoplasma hominis collected during 2004-2011 were determined. A total of 9956 individuals was analyzed. Identification was performed by use of the mycoplasma IST-2 kit. Antimicrobial susceptibility against doxycycline, josamycin, ofloxacin, erythromycin, tetracycline, ciprofloxacin, azithromycin, clarithromycin, and pristinamycin was also tested by use of this commercial kit. Our results show a prevalence of 1856 positive patients for genital mycoplasmas (18.6 %). Among positive cultures, 89 and 1.1 % of isolates were Ureaplasma urealyticum and Mycoplasma hominis, respectively. For 9.8 % of isolates both urogenital mycoplasmas were grown. Doxycycline was the most active tetracycline for mycoplasma infections, and this is still the drug of first choice. Among macrolides, josamycin and clarithromycin are the most active agents against ureaplasmas; josamycin is also active against mycoplasmas and is an alternative to tetracyclines and erythromycin for mixed infections, especially for pregnant women and neonates. Fluoroquinolones had low efficacy against urogenital mycoplasmas. For Ureaplasma urealyticum, cross-resistance was found between erythromycin and macrolides (except josamycin) (40-80 %) and between erythromycin and ciprofloxacin (79 %). Antibiotic resistance over the test period did not vary significantly. Because of geographical differences among antibiotic resistance, local in-vitro susceptibility testing is recommended to avoid failure of therapy.

HIV-1 matrix protein p17 binds to monocytes and selectively stimulates MCP-1 secretion: role of transcriptional factor AP-1.

HIV-1 matrix protein p17 activates a variety of cell responses which play a critical role in viral replication and infection. Its activity depends on the expression of p17 receptors (p17R) on the surface of target cells. Whether p17 also plays a role in stimulating human monocytes, a major HIV-1 reservoir, is not known. Here we show that human monocytes constitutively express p17Rs and that p17 selectively triggers these cells to produce MCP-1. The effect of p17 on MCP-1 expression was observed at the transcriptional level and was primarily dependent on the activation of the transcription factor AP-1. p17 increased the binding activity of AP-1 complexes in a time- and dose-dependent manner. Deletion of the AP-1 binding sites in the MCP-1 promoter resulted in the lack of p17-induced MCP-1 transcription. In particular, the P3 binding site located between -69 and -63 position seems to be essential to MCP-1 mRNA induction in p17-treated monocytes. An ever increasing amount of evidences shows a tight link between biologically dysregulated monocytes, AP-1 activation, MCP-1 release and HIV-1 pathogenesis. Overall our results suggest that p17 may play a critical role in the monocyte-mediated inflammatory processes, which are suspected to be major precipitating events in AIDS-defining diseases.

HIV-1 matrix protein p17 prevents loss of CD28 expression during IL-2-induced maturation of naïve CD8(+) T cells.

Naïve CD8(+) T cells differentiate into effectors secreting various cytokines that modulate immune functions. A striking finding for most HIV-1-infected patients is that they accumulate CD8(+) T cells belonging to early and intermediate differentiated elements. Structural HIV-1 proteins, and among these the matrix protein p17, have been associated with loss of functional competence by different immune cells. We therefore evaluated the influence of p17 on naïve CD8(+) T-cell activation and maturation. Anti-CD3 mAb preactivation and subsequent IL-2 stimulation are able to drive human naive CD(+) T cells to an effector phenotype characterized, among other features, by downregulation of the co-stimulatory molecule CD28. Strikingly, however, IL-2-induced downmodulation of CD28 was completely prevented by p17, and cells derived from p17-stimulated cultures showed a strong Tc1 polarization that was fourfold higher than that observed in IL-2-stimulated cultures.Moreover, p17 preserved a markedly high proportion of CD8(+) T cells that were able to respond to CD28 triggering with a proinflammatory cytokine storm. Our evidence suggests that p17 has important effects on cytokine polarization and phenotype of terminally differentiated CD8(+) T cells, and that new p17-based therapeutic approaches could control or prevent HIV-1-related immune disorders.

Human metapneumovirus infection in young children hospitalized with acute respiratory tract disease: virologic and clinical features.

BACKGROUND: Human metapneumovirus (hMPV) is an emerging virus associated with acute respiratory tract infections (ARIs) in young children. OBJECTIVES: To evaluate virologic and clinical features of hMPV infection during 2 consecutive winter-spring seasons. METHODS: Nasal washes were obtained from children younger than 5 years of age hospitalized for ARI. Specimens were tested for hMPV by reverse transcription-polymerase chain reaction. The hMPV F gene amplification products were sequenced, and phylogenetic trees were constructed. RESULTS: A high incidence of hMPV infection (25.3%) was observed during the 2005-2006 winter-spring season, whereas a much lower rate of infection (4.7%) during the following season was found. Phylogenetic analysis revealed that, during the 2 seasons, 60.4% of the hMPV detected were A2a, 22.9% were A2b, 4.2% were B1, and 12.5% were B2. hMPV A1 strains were not detected in any tested specimen. Clinical diagnosis was bronchiolitis in 57.1%; pneumonia in 25%; and a upper respiratory tract illness in 17.8%. Bronchiolitis was more frequent in children less than 1 year of age (80%) than in children more than 1 year of age (30.8%) (P < 0.05). When hMPV was found frequently, the hMPV spread overlapped with that of respiratory syncytial virus (RSV) and hMPV/RSV coinfections were common events (19 of 39; 48.7%). hMPV/RSV-coinfected children developed pneumonia more frequently than hMPV-infected patients (57.9% versus 20%) but no differences in disease severity (gauged by duration of hospitalization and requirement of oxygen) were observed. CONCLUSIONS: These results provide further evidence of the importance of hMPV as a pathogen associated with ARI in young children. Involvement of hMPV/RSV coinfection in cases of pneumonia is suspected.

Replication-deficient mutant Herpes Simplex Virus-1 targets professional antigen presenting cells and induces efficient CD4+ T helper responses.

Both neutralizing antibodies and cytotoxic T-cells are necessary to control a viral infection. However, vigorous T helper responses are essential for their elicitation and maintenance. Here we show that a recombinant replication-deficient Herpes Simplex Virus (HSV)-1 vector encoding the Human Immunodeficiency Virus (HIV)-1 matrix protein p17 (T0-p17) was capable of infecting professional antigen presenting cells (APCs) in vitro and in vivo. The injection of T0-p17 in the mouse dermis generated a strong p17-specific CD4+ T helper response preceding both p17-specific humoral and effector T cell responses. Moreover, we show that T0-p17 infection did not interfere with the endogenous processing of the transgene encoded antigen, since infected APCs were able to evoke a strong recall response in vitro. Our results demonstrate that replication-deficient HSV vectors can be appealing candidates for the development of vaccines able to trigger T helper responses.

Detection of sporadic cases of Norovirus infection in hospitalized children in Italy.

This study was performed to investigate the role of Noroviruses (NV) in sporadic cases of acute diarrhoea among hospitalized children in Brescia Hospital. NV were the most frequently involved viruses (23.7%) and were more common in children >5 years (23/63) than in children <5 years (6/59). The majority of the NV-positive specimens belonged to genotype II (GII). The frequency of rotavirus, enteric adenovirus and astrovirus was 12.2%, 1.6% and 2.4%, respectively. Results obtained confirm the relevance of NV as a causative agent of pediatric diarrhoea and highlight the need for continued surveillance of NV to prevent and control virus spreading.

Functions of the HIV-1 matrix protein p17.

HIV-1 replication is a dynamic process influenced by a combination of viral and host factors. The HIV-1 matrix protein p17 is a structural protein critically involved in most stages of the life cycle of the retrovirus. It participates in the early stages of virus replication as well as in RNA targeting to the plasma membrane, incorporation of the envelope into virions and particle assembly. Besides its well established functions, p17 acts as a viral cytokine that works on preactivated--but not on resting--human T cells promoting proliferation, proinflammatory cytokines release and HIV-1 replication after binding to a cellular receptor (p17R). Thus, p17 might play a key role in the complex network of host- and virus-derived stimulatory factors contributing to create a favourable environment for HIV-1 infection and replication. Here, we present a brief overview of the functions played by the matrix protein p17 in the HIV-1 life cycle and summarize the current understanding of how p17 could contribute to the pathogenesis of HIV-1 disease.