Alessandra Bandera

Molecular Epidemiology Study of Exogenous Reinfection in an Area with a Low Incidence of Tuberculosis

ABSTRACT In geographical areas with a low incidence of tuberculosis, recurrent tuberculosis is generally due to reactivation of the disease. However, the relative contribution of tuberculosis reinfection increases in parallel with the incidence of disease and is likely to depend on the epidemiological context: factors such as the spread of multidrug resistance, human immunodeficiency virus (HIV) infection, and immigration from developing countries could modify disease transmission in areas at low risk for tuberculosis. A molecular epidemiology study was performed in Lombardy, Northern Italy, where the incidence of tuberculosis is 17.5 cases per 100,000 persons. A total of 2,452 cases of culture-confirmed tuberculosis in 2,127 patients were studied. A group of 32 patients (1.5%), each of whom had two episodes of tuberculosis with cure as the outcome of the first episode and with more than 6 months between the two episodes, were studied by means of restriction fragment length polymorphism DNA fingerprinting analysis. For 5 of the 32 patients (16%), the DNA fingerprinting patterns ofMycobacterium tuberculosis strains responsible for the second episode did not match those of the corresponding isolates of the first episode, indicating exogenous reinfection. Two of these patients developed multidrug-resistant tuberculosis during the second episode, and in three cases the isolates belonged to clusters of M. tuberculosis strains spreading in the community. A fourfold-increased risk for reinfection was observed in immigrant patients compared to Italian subjects. In contrast, a higher risk of relapse rather than reinfection was evidenced in HIV-positive subjects and in patients infected with multidrug-resistant tuberculosis. Episodes of tuberculosis reinfection in areas with a low incidence of tuberculosis are rare compared to those in high-incidence geographical regions. In populations that have immigrated from high-risk areas, reinfection may represent a considerable contributor to the rate of recurrent tuberculosis. This finding emphasizes the importance of containing the spread of epidemic strains in close communities, in order to prevent changes in global tuberculosis trends for developed countries.

Specific prebiotics modulate gut microbiota and immune activation in HAART-naive HIV-infected adults: results of the “COPA” pilot randomized trial

Intestinal mucosal immune system is an early target for human immunodeficiency virus type 1 (HIV-1) infection, resulting in CD4+ T-cell depletion, deterioration of gut lining, and fecal microbiota composition. We evaluated the effects of a prebiotic oligosaccharide mixture in highly active antiretroviral therapy (HAART)-naive HIV-1-infected adults. In a pilot double-blind, randomized, placebo-controlled study, 57 HAART-naive HIV-1-infected patients received a unique oligosaccharide mixture (15 or 30 g short chain galactooligosaccharides/long chain fructooligosaccharides/pectin hydrolysate-derived acidic oligosaccharides (scGOS/lcFOS/pAOS) daily) or a placebo for 12 weeks. Microbiota composition improved significantly with increased bifidobacteria, decreased Clostridium coccoides/Eubacterium rectale cluster, and decreased pathogenic Clostridium lituseburense/Clostridium histolyticum group levels upon prebiotic supplementation. In addition, a reduction of soluble CD14 (sCD14), activated CD4+/CD25+ T cells, and significantly increased natural killer (NK) cell activity when compared with control group were seen in the treatment group. The results of this pilot trial highly significantly show that dietary supplementation with a prebiotic oligosaccharide mixture results in improvement of the gut microbiota composition, reduction of sCD14, CD4+ T-cell activation (CD25), and improved NK cell activity in HAART-naive HIV-infected individuals.

Immune activation, apoptosis, and Treg activity are associated with persistently reduced CD4+ T-cell counts during antiretroviral therapy.

Background:Persistently reduced CD4+ T-lymphocyte counts in the face of undetectable HIV viremia are seen in a sizable percentage of HIV-infected patients undergoing antiretroviral therapy (ART). We analyzed the immune correlates of this phenomenon. Materials and methods:Sixty-seven HIV-infected patients with undetectable viremia (<50 copies/μl) after more than 7 years of ART were enrolled in the study and divided into two groups (CD4 cell counts >500 cells/μl or <500 cells/μl). Duration of HIV infection (>16 years) was comparable. Peripheral blood mononuclear cell were stimulated with gag+env or with cytomegalovirus peptides. Activated T cells (Ki67+), Treg lymphocytes (CD4+/CD25high/Foxp3+), divided into naive and activated cells based on PD1 expression, interleukin (IL)-10 and transforming growth factor (TGF)-β production, annexin V, activation of caspases 8 and 9, Toll-like receptor (TLR)2 and TLR4 expression on immune cells, and plasma lipopolysaccharide (LPS) concentration were analyzed. Results:CD4+/Ki67+ T cells; plasma LPS; total, naive, and activated Treg; TLR2-expressing and TLR4-expressing Treg; IL-10 production; and early and late apoptotic CD4 T cells, were significantly increased in patients with undetectable viremia and CD4 cell counts less than 500 cells/μl after more than 7 years of ART. As previously shown, CD4 nadir were also lower in these individuals. Immune activation, LPS concentration, Treg, and degree of apoptosis were negatively correlated with CD4 cell counts. Conclusion:Lack of CD4 recovery in individuals in whom ART suppresses HIV replication is associated with complex immune alterations. Immune activation, likely driven by altered gut permeability and resulting in augmented Treg activity could play a pivotal role in this process.

Spoligotyping and Mycobacterium tuberculosis

Speed of spoligotyping could be a benefit in the clinical setting.

Nosocomial Bacterial Pneumonia in HIV-Infected Patients: Risk Factors for Adverse Outcome and Implications for Rational Empiric Antibiotic Therapy

Background:Nosocomial bacterial pneumonia (NBP) was once considered a common cause of morbidity and mortality among advanced AIDS patients. However, clinical and microbiological characteristics and outcome-associated risk factors in this population are poorly defined.Patients:We conducted a retrospective study of all HIV-infected patients admitted during the period 1988–2002 at the Infectious Diseases Clinic of Milan, Italy, to determine incidence rate and factors affecting mortality of NBP, and to gather clinical and microbiological findings about the condition.Results:We identified 120 episodes of NBP among 4,967 admissions of HIV-infected individuals. A reduction of incidence became evident after the introduction of highly active antiretroviral therapy (HAART). The more common causative agents were Pseudomonas aeruginosa (33%) Staphylococcus aureus (25%) and Streptococcus pneumoniae (21%). Methicillin resistance was frequent among staphylococci (65%). The mortality rate of NBP was 25.8%. Non-statistically significant factors associated with shorter survival were: CD4+ count < 10 cells/ml, concomitant lung neoplasm, and complicated roentgenographic picture. Only one factor was significantly associated with lower survival, both in univariate and multivariate analysis: a methicillin-resistant Staphylococcus serving as an etiologic agent of pneumonia (RR 4.05; 95% CI, 1.076–15.239; p = 0.039).Conclusion:A decline in incidence of NBP in HIV-infected individuals was observed after introduction of HAART. S. aureus and P. aeruginosa were the leading causes of NBP, but frequency of pneumococcal pneumonia was significant. The sole predictor for mortality was methicillin-resistant Staphylococcus as a pneumonia-causing agent.

CD4+ T cell depletion, immune activation and increased production of regulatory T cells in the thymus of HIV-infected individuals.

Mechanisms by which HIV affects the thymus are multiple and only partially known, and the role of thymic dysfunction in HIV/AIDS immunopathogenesis remains poorly understood. To evaluate the effects of HIV infection on intra-thymic precursors of T cells in HIV-infected adults, we conducted a detailed immunophenotypic study of thymic tissue isolated from 7 HIV-infected and 10 HIV-negative adults who were to undergo heart surgery. We found that thymuses of HIV-infected individuals were characterized by a relative depletion of CD4+ single positive T cells and a corresponding enrichment of CD8+ single positive T cells. In addition, thymocytes derived from HIV-infected subjects showed increased levels of activated and proliferating cells. Our analysis also revealed a decreased expression of interleukin-7 receptor in early thymocytes from HIV-infected individuals, along with an increase in this same expression in mature double- and single-positive cells. Frequency of regulatory T cells (CD25+FoxP3+) was significantly increased in HIV-infected thymuses, particularly in priorly-committed CD4 single positive cells. Our data suggest that HIV infection is associated with a complex set of changes in the immunophenotype of thymocytes, including a reduction of intrathymic CD4+ T cell precursors, increased expression of activation markers, changes in the expression pattern of IL-7R and enrichment of T regulatory cells generation.

Neurocognitive Impairment in HIV-Infected Naïve Patients with Advanced Disease: The Role of Virus and Intrathecal Immune Activation

Objective. To investigate intrathecal immune activation parameters and HIV-RNA in HIV-associated neurocognitive disorders (HAND) of advanced naïve HIV-infected patients and to evaluate their dynamics before and after initiation of antiretroviral therapy (ART). Methods. Cross-sectional and longitudinal analysis of HIV RNA, proinflammatory cytokines (IL-6, IL-10, INF-γ, TNF-α, TGF-β1, and TGF-β2) and chemokines (MIP-1α, MIP-1β, and MCP-1) in plasma and cerebrospinal fluid (CSF) of HIV-infected patients with CD4 <200/μL. Results. HAND was diagnosed at baseline in 6/12 patients. Baseline CSF HIV-RNA was comparable in patients with or without HAND, whereas CSF concentration of IL-6 and MIP-1β, proinflammatory cytokines, was increased in HAND patients. CSF evaluation at 12 weeks was available in 10/12 cases. ART greatly reduced HIV-RNA in all patients. Nevertheless, IL-6 and MIP-1β remained elevated after 12 weeks of therapy in HAND patients, in whom CSF HIV RNA decay was slower than the plasmatic one as well. Conclusion. Immune activation, as indicated by inflammatory cytokines, but not higher levels of HIV-RNA is observed in advanced naïve HIV-infected patients with HAND. In HAND patients, ART introduction resulted in a less rapid clearance of CSF viremia compared to plasma and no modifications of intratechal immune activation.

Under Representation of the Inhibitory KIR3DL1 Molecule and the KIR3DL1+/BW4+ Complex in HIV Exposed Seronegative Individuals

The activation of natural killer (NK) cells is modulated by surface molecules. We analyzed NK cells in human immunodeficiency virus (HIV)-exposed seronegative (HESN) individuals by means of molecular typing of HLA B, Cw, and killer cell immunoglobulin-like receptor (KIR) molecules. In HESN individuals, compared with HIV patients, the frequency of the inhibitory KIR3DL1 allele and of the KIR3DL1(+)/Bw4(+) inhibitory complex was reduced, whereas that of the activatory KIR3DS1(+) ligand and the activatory Bw4(+)/3DL1(-)/3DS1(+) complex was increased, resulting in a statistically significant diversion from Hardy-Weinberg equilibrium (KIR3DS1 homozygote) in HESN individuals. The reciprocal equilibrium between inhibitory and activatory NK receptors and their ligands favors NK activation in HESN individuals.

Interleukin-2 immunotherapy exerts a differential effect on CD4 and CD8 T cell dynamics.

Background: Emerging evidence indicates that CD4 and CD8 T cell recovery is differentially regulated during HIV infection. The hallmark of interleukin-2 (IL-2)-induced immune reconstitution is the selective outgrowth of CD4 through undefined mechanisms. Objective: To delineate the effect of IL-2 on T cell homeostasis by analysing the differential impact of IL-2 immunotherapy on CD4 and CD8 dynamics. Design: A randomized trial of 15 HIV-positive patients, eight receiving IL-2 immunotherapy with highly active antiretroviral therapy (HAART) and seven with HAART alone. Patients were followed for a 48-week period following three IL-2 cycles (overall, 10 weeks in duration). Methods: CD4 and CD8 count, naive and memory immunophenotype, proliferation by Ki67, and CD8+CD38+ activated pattern were measured longitudinally by flow cytometry. Thymic output contribution to both CD4 and CD8 was evaluated by measurement of T cell receptor excision circles (TREC). Wilcoxon test was used to compare results. Results: Compared with changes seen with HAART alone, IL-2 induced a more significant rise in CD4 than CD8 T cell count (P < 0.01), associated with a significant increase in Ki67-proliferating CD4 (P < 0.05), whereas no changes were seen in CD8+Ki67+ (P > 0.05). Furthermore, IL-2 administration was associated with CD4 TREC increase, whereas CD8 TREC remained stable (P > 0.05). Modifications in CD4 and CD8 T cells seen in patients taking only HAART were not associated with changes in CD4 and CD8 TREC. Conclusions: By showing a differential impact on CD4 and CD8 homeostasis, the study suggests that IL-2-associated immune reconstitution results from protean interactions between T cell compartments; this has significant implications for the correct planning of immunotherapeutic strategies.

Interferon-γ and Granulocyte-Macrophage Colony Stimulating Factor Therapy in Three Patients with Pulmonary Aspergillosis

An immune response mediated by type 2 cytokines is thought to contribute to the development and unfavorable outcome of aspergillosis. Adjuvant therapy with interferon-γ (IFN-γ) and granulocyte-macrophage colony stimulating factor (GM-CSF) was added to antifungal treatment in three nonneutropenic patients (one HIV-positive and two HIV-negative patients) with culture proven aspergillosis refractory to classical antifungal therapy. Clinical improvement was observed concomitantly with an increase in peripheral blood leukocyte proliferation and type 1 cytokines production. Our findings suggest an association between the improvement in type 1 cytokine production observed during IFN-γ and GM-CSF administration and a better control of Aspergillus infection in patients with progressive disease despite adequate antifungal therapy.