Paola Di Carlo

Multifunctional CD4+ T cells correlate with active Mycobacterium tuberculosis infection

Th1 CD4+ T cells and their derived cytokines are crucial for protection against Mycobacterium tuberculosis. Using multiparametric flow cytometry, we have evaluated the distribution of seven distinct functional states (IFN‐γ/IL‐2/TNF‐α triple expressors, IFN‐γ/IL‐2, IFN‐γ/TNF‐α or TNF‐α/IL‐2 double expressors or IFN‐γ, IL‐2 or TNF‐α single expressors) of CD4+ T cells in individuals with latent M. tuberculosis infection (LTBI) and active tuberculosis (TB). We found that triple expressors, while detectable in 85–90%TB patients, were only present in 10–15% of LTBI subjects. On the contrary, LTBI subjects had significantly higher (12‐ to 15‐fold) proportions of IL‐2/IFN‐γ double and IFN‐γ single expressors as compared with the other CD4+ T‐cell subsets. Proportions of the other double or single CD4+ T‐cell expressors did not differ between TB and LTBI subjects. These distinct IFN‐γ, IL‐2 and TNF‐α profiles of M. tuberculosis‐specific CD4+ T cells seem to be associated with live bacterial loads, as indicated by the decrease in frequency of multifunctional T cells in TB‐infected patients after completion of anti‐mycobacterial therapy. Our results suggest that phenotypic and functional signatures of CD4+ T cells may serve as immunological correlates of protection and curative host responses, and be a useful tool to monitor the efficacy of anti‐mycobacterial therapy.

Analysis of Mycobacterium tuberculosis-specific CD8 T-cells in patients with active tuberculosis and in individuals with latent infection.

CD8 T-cells contribute to control of Mycobacterium tuberculosis infection, but little is known about the quality of the CD8 T-cell response in subjects with latent infection and in patients with active tuberculosis disease. CD8 T-cells recognizing epitopes from 6 different proteins of Mycobacterium tuberculosis were detected by tetramer staining. Intracellular cytokines staining for specific production of IFN-γ and IL-2 was performed, complemented by phenotyping of memory markers on antigen-specific CD8 T-cells. The ex-vivo frequencies of tetramer-specific CD8 T-cells in tuberculous patients before therapy were lower than in subjects with latent infection, but increased at four months after therapy to comparable percentages detected in subjects with latent infection. The majority of CD8 T-cells from subjects with latent infection expressed a terminally-differentiated phenotype (CD45RA+CCR7−). In contrast, tuberculous patients had only 35% of antigen-specific CD8 T-cells expressing this phenotype, while containing higher proportions of cells with an effector memory- and a central memory-like phenotype, and which did not change significantly after therapy. CD8 T-cells from subjects with latent infection showed a codominance of IL-2+/IFN-γ+ and IL-2−/IFN-γ+ T-cell populations; interestingly, only the IL-2+/IFN-γ+ population was reduced or absent in tuberculous patients, highly suggestive of a restricted functional profile of Mycobacterium tuberculosis-specific CD8 T-cells during active disease. These results suggest distinct Mycobacterium tuberculosis specific CD8 T-cell phenotypic and functional signatures between subjects which control infection (subjects with latent infection) and those who do not (patients with active disease).

Selective Depression of Interferon-γ and Granulysin Production with Increase of Proliferative Response by Vγ9/Vδ2 T Cells in Children with Tuberculosis

Vgamma9/Vdelta2 T cells can contribute to protective immune response against Mycobacterium tuberculosis, although the extent to which and mechanisms by which they could actually protect against human tuberculosis remain unclear. We have previously reported that Vgamma9/Vdelta2 T cells from tuberculin purified protein derivative (PPD)-positive children, either healthy or affected by different clinical forms of tuberculosis, strongly proliferate to different phosphoantigens in vitro, whereas Vgamma9/Vdelta2 T cells from PPD-negative healthy subjects proliferate very poorly. We report here that Vgamma9/Vdelta2 T cells from tuberculous children have an increased proliferative activity, but decreased interferon (IFN)-gamma production and granulysin expression. After successful chemotherapy, the Vgamma9/Vdelta2 T cell proliferative response strongly decreased, whereas IFN-gamma and granulysin production consistently increased. Disease-associated changes in Vgamma9/Vdelta2 T cell effector functions in patients with tuberculosis are consistent with the possibility that these T cells may play a protective role in immune response against M. tuberculosis infection.

KPC - 3 Klebsiella pneumoniae ST258 clone infection in postoperative abdominal surgery patients in an intensive care setting: analysis of a case series of 30 patients.

BackgroundAbdominal surgery carries significant morbidity and mortality, which is in turn associated with an enormous use of healthcare resources. We describe the clinical course of 30 Intensive Care Unit (ICU) patients who underwent abdominal surgery and showed severe infections caused by Klebsiella pneumoniae sequence type (ST) 258 producing K. pneumoniae carbapenemase (KPC-Kp). The aim was to evaluate risk factors for mortality and the impact of a combination therapy of colistin plus recommended regimen or higher dosage of tigecycline.MethodsA prospective assessment of severe monomicrobial KPC-Kp infections occurring after open abdominal surgery carried out from August 2011 to August 2012 in the same hospital by different surgical teams is presented. Clinical and surgical characteristics, microbiological and surveillance data, factors associated with mortality and treatment regimens were analyzed. A combination regimen of colistin with tigecycline was used. A high dose of tigecycline was administered according to intra-abdominal abscess severity and MICs for tigecycline.ResultsThe mean age of the patients was 56.6 ± 15 and their APACHE score on admission averaged 22.72. Twenty out of 30 patients came from the surgical emergency unit. Fifteen patients showed intra-abdominal abscess, eight anastomotic leakage, four surgical site infection (SSI) and three peritonitis. The overall crude ICU mortality rate was 40% (12 out of 30 patients). Twelve of the 30 patients were started on a combination treatment of high-dose tigecycline and intravenous colistin. A significantly lower mortality rate was observed among those patients compared to patients treated with approved dose of tigecycline plus colistin. No adverse events were reported with high doses of tigecycline.ConclusionsCritically-ill surgical patients are prone to severe post-surgical infectious complications caused by KPC-Kp. Timely microbiological diagnosis and optimizing antibiotic dosing regimens are essential to prevent worse outcomes. Further studies and well-controlled clinical trials are needed to define the optimal treatment of infections by KPC-Kp and, more generally, carbapenem-resistant bacteria.

Cryptic Leishmania infantum infection in Italian HIV infected patients

BackgroundVisceral leishmaniasis (VL) is a protozoan diseases caused in Europe by Leishmania (L.) infantum. Asymptomatic Leishmania infection is more frequent than clinically apparent disease. Among HIV infected patients the risk of clinical VL is increased due to immunosuppression, which can reactivate a latent infection. The aims of our study were to assess the prevalence of asymptomatic L. infantum infection in HIV infected patients and to study a possible correlation between Leishmania parasitemia and HIV infection markers.MethodsOne hundred and forty-five HIV infected patients were screened for the presence of anti-Leishmania antibodies and L. infantum DNA in peripheral blood. Statistical analysis was carried out by using a univariate regression analysis.ResultsAntibodies to L. infantum were detected in 1.4% of patients. L. infantum DNA was detected in 16.5% of patients. Significant association for PCR-Leishmania levels with plasma viral load was documented (p = 0.0001).ConclusionIn our area a considerable proportion of HIV infected patients are asymptomatic carriers of L. infantum infection. A relationship between high HIV viral load and high parasitemic burden, possibly related to a higher risk of developing symptomatic disease, is suggested. PCR could be used for periodic screening of HIV patients to individuate those with higher risk of reactivation of L. infantum infection.

Ligand-Specific αβ and γδ T Cell Responses in Childhood Tuberculosis

The alphabeta and gammadelta T cell responses were analyzed in the peripheral blood of children affected by active tuberculosis (TB) and in healthy children who tested positive (PPD+) or negative (PPD-) for purified protein derivative. PPD+ healthy and diseased children responded equally well to PPD in vitro. In contrast, only 18% of PPD+ TB patients responded to peptide p38G derived from the 38-kDa protein of Mycobacterium tuberculosis. Analysis of the whole gammadelta T cell population and of its Vgamma9/Vdelta2 subset showed similar frequencies in PPD+ children with TB and in healthy PPD+ and PPD- children. Vgamma9/Vdelta2 cells from children with TB responded to 5 different phosphoantigens similarly to those from healthy PPD+ children, but healthy PPD- children responded very poorly. Chemotherapy had contrasting effects on the tested lymphocyte population, represented by increase of alphabeta and decline of Vgamma9/Vdelta2 T cell responses. T cell responses in childhood TB may be similar to those in adult TB.

Human CD8 T lymphocytes recognize Mycobacterium tuberculosis antigens presented by HLA-E during active tuberculosis and express type 2 cytokines

CD8 T cells contribute to protective immunity against Mycobacterium tuberculosis. In humans, M. tuberculosis reactive CD8 T cells typically recognize peptides associated to classical MHC class Ia molecules, but little information is available on CD8 T cells recognizing M. tuberculosis Ags presented by nonclassical MHC class Ib molecules. We show here that CD8 T cells from tuberculosis (TB) patients recognize HLA‐E‐binding M. tuberculosis peptides in a CD3/TCR αβ mediated and CD8‐dependent manner, and represent an additional type of effector cells playing a role in immune response to M. tuberculosis during active infection. HLA‐E‐restricted recognition of M. tuberculosis peptides is detectable by a significant enhanced ex vivo frequency of tetramer‐specific circulating CD8 T cells during active TB. These CD8 T cells produce type 2 cytokines upon antigenic in vitro stimulation, help B cells for Ab production, and mediate limited TRAIL‐dependent cytolytic and microbicidal activity toward M. tuberculosis infected target cells. Our results, together with the finding that HLA‐E/M. tuberculosis peptide specific CD8 T cells are detected in TB patients with or without HIV coinfection, suggest that this is a new human T‐cell population that participates in immune response in TB.

Vitamin D and Osteoporosis in HIV/HCV Coinfected Patients: A Literature Review

Vitamin D deficiency further increases the risk of osteoporosis in HIV-positive patients coinfected with hepatitis C virus (HCV); however, it is still unclear whether HCV-related increased fracture risk is a function of the severity of liver disease. The aim of this review was to identify studies on associative vitamin D deficiency patterns in high-risk populations such as HIV/HCV coinfected patients. We did this by searching MEDLINE and EMBASE databases, from inception to August 2014, and included bibliographies. The final 12 articles selected are homogeneous in terms of age but heterogeneous in terms of sample size, participant recruitment, and data source. Most of the HIV/HCV coinfected patients have less than adequate levels of vitamin D. After reviewing the selected articles, we concluded that vitamin D deficiency should be regarded as a continuum and that the lower limit of the ideal range is debatable. We found that vitamin D deficiency might influence liver disease progression in HIV/HCV coinfected patients. Methodological issues in evaluating vitamin D supplementation as a relatively inexpensive therapeutic option are discussed, as well as the need for future research, above all on its role in reducing the risk of HCV-related fracture by modifying liver fibrosis progression.

Two cases of monomicrobial intraabdominal abscesses due to KPC - 3 Klebsiella pneumoniae ST258 clone

BackgroundKnowledge of the etiology of pyogenic liver and pancreatic abscesses is an important factor in determining the success of combined surgical and antibiotic treatment. Literature shows geographical variations in the prevalence and distribution of causative organisms, and the spread of Klebsiella pneumoniae carbapenemase-producing bacteria is an emerging cause of abdominal infections.Case presentationWe herein describe two cases of intra-abdominal abscesses due to monomicrobial infection by Klebsiella pneumoniae Sequence Type 258 producing K. pneumoniae carbapenemase 3 (KPC-Kp). In case 1, a 50-year-old HIV-negative Italian woman with chronic pancreatitis showed infection of a pancreatic pseudocystic lesion caused by KPC-Kp. In case 2, a 64-year-old HIV- negative Italian woman with pancreatic neoplasm and liver metastases developed a liver abscess due to KPC after surgery. Both women were admitted to our hospital but to different surgical units. The clonal relationship between the two isolates was investigated by pulsed-field gel electrophoresis (PFGE). In case 2, the patient was already colonized at admission and inter-hospital transmission of the pathogen was presumed. A long-term combination regimen of colistin with tigecycline and percutaneous drainage resulted in full recovery and clearance of the multidrug-resistant (MDR) pathogen.ConclusionsTimely microbiological diagnosis, the combined use of new and old antibiotics and radiological intervention appeared to be valuable in managing these serious conditions. The emergence and dissemination of MDR organisms is posing an increasing challenge for physicians to develop new therapeutic strategies and control and prevention frameworks.

Prospective evaluation of hepatic steatosis in HIV-infected patients with or without hepatitis C virus co-infection

BACKGROUND Limited data are available on hepatic steatosis (HS) in HIV patients who are not infected with hepatitis C virus (HCV). The aims of this study were to assess the prevalence of HS and its risk factors in HIV patients with and without HCV infection, and to evaluate whether HS correlates with advanced liver fibrosis and/or cardiovascular disease risk. METHODS Fifty-seven HIV mono-infected and 61 HIV/HCV co-infected patients were enrolled consecutively. All patients underwent liver ultrasound and transient elastography. The main parameters of liver function, HIV and HCV viral loads, CD4+ cell counts, and data on highly active antiretroviral therapy (HAART) were recorded. Cardiovascular disease risk was evaluated using the 10-year Framingham risk score. RESULTS HS prevalence in the whole HIV population was 53% (54% in mono-infected patients and 51% in co-infected patients). HS was associated with lipodystrophy and triglyceride values (p<0.0001), metabolic syndrome (p<0.0004), and total cholesterol levels (p<0.001) in both HIV groups. In HIV mono-infected patients, HS was linked with HAART exposure of >1 year (p<0.01). By multivariate analysis, only triglyceride levels (p<0.02) and Framingham risk score (p<0.05) were independently associated with HS in both HIV groups. No correlation was observed between HS and advanced liver fibrosis, measured by transient elastography. CONCLUSIONS HS was common in HIV patients, occurring in about half of the population. HS was found to be linked with the Framingham risk score, but was not correlated with advanced liver fibrosis. We suggest that in our HIV population with HS, the burden of cardiovascular disease risk is greater than that of liver disease progression.