Type 1 regulatory T cells are associated with persistent split erythroid/lymphoid chimerism after allogeneic hematopoietic stem cell transplantation for thalassemia

Background

Thalassemia major can be cured with allogeneic hematopoietic stem cell transplantation. Persistent mixed chimerism develops in around 10% of transplanted thalassemic patients, but the biological mechanisms underlying this phenomenon are poorly understood.

Design and Methods

The presence of interleukin-10-producing T cells in the peripheral blood of eight patients with persistent mixed chimerism and five with full donor chimerism was investigated. A detailed characterization was then performed, by T-cell cloning, of the effector and regulatory T-cell repertoire of one patient with persistent mixed chimerism, who developed stable split erythroid/lymphoid chimerism after a hematopoietic stem cell transplant from an HLA-matched unrelated donor.

Results

Higher levels of interleukin-10 were produced by peripheral blood mononuclear cells from patients with persistent mixed chimerism than by the same cells from patients with complete donor chimerism or normal donors. T-cell clones of both host and donor origin could be isolated from the peripheral blood of one, selected patient with persistent mixed chimerism. Together with effector T-cell clones reactive against host or donor alloantigens, regulatory T-cell clones with a cytokine secretion profile typical of type 1 regulatory cells were identified at high frequencies. Type 1 regulatory cell clones, of both donor and host origin, were able to inhibit the function of effector T cells of either donor or host origin in vitro.

Conclusions

Overall these results suggest that interleukin-10 and type 1 regulatory cells are associated with persistent mixed chimerism and may play an important role in sustaining long-term tolerance in vivo. These data provide new insights into the mechanisms of peripheral tolerance in chimeric patients and support the use of cellular therapy with regulatory T cells following hematopoietic stem cell transplantation.     

A study of Adenosine-Deaminase genetic polymorphism in rheumatoid arthritis

Recent investigations suggest that Adenosine Deaminase (ADA) could play a role in susceptibility to rheumatoid arthritis (RA). The purpose of our study is to investigate the possible role of genetic variability of ADA in the susceptibility to RA. We studied three intragenic ADA polymorphisms, ADA1, ADA2 and ADA6, in a sample of 91 subjects with RA and in 246 healthy subjects from the same Caucasian population and compared genotype and pairwise haplotype distributions between cases and controls. No statistically significant differences between RA and controls are observed for ADA genotypes. A border line difference for ADA1-ADA2 haplotype distribution is observed due to a decreased proportion of ADA1 *2/ADA2 *2 haplotype in RA compared to controls. Our data indicate a border line effect of ADA gene polymorphism on susceptibility to RA that need to be confirmed in other clinical settings.     

Structural Basis for Benzothiazinone-Mediated Killing of Mycobacterium tuberculosis

The benzothiazinone BTZ043 is a tuberculosis drug candidate with nanomolar whole-cell activity. BTZ043 targets the DprE1 catalytic component of the essential enzyme decaprenylphosphoryl-β-d-ribofuranose-2'-epimerase, thus blocking biosynthesis of arabinans, vital components of mycobacterial cell walls. Crystal structures of DprE1, in its native form and in a complex with BTZ043, reveal formation of a semimercaptal adduct between the drug and an active-site cysteine, as well as contacts to a neighboring catalytic lysine residue. Kinetic studies confirm that BTZ043 is a mechanism-based, covalent inhibitor. This explains the exquisite potency of BTZ043, which, when fluorescently labeled, localizes DprE1 at the poles of growing bacteria. Menaquinone can reoxidize the flavin adenine dinucleotide cofactor in DprE1 and may be the natural electron acceptor for this reaction in the mycobacterium. Our structural and kinetic analysis provides both insight into a critical epimerization reaction and a platform for structure-based design of improved inhibitors.     

Efficacy and cost-effectiveness of stereotactic vacuum-assisted core biopsy of nonpalpable breast lesions: analysis of 602 biopsies performed over 5 years

Purpose

The authors sought to evaluate the diagnostic accuracy and cost-effectiveness of vacuum-assisted core biopsy (VACB) in comparison with diagnostic surgical excision for characterisation of nonpalpable breast lesions classified as Breast Imaging Reporting and Data System (BI-RADS) categories R3 and R4.

Materials and methods

From January 2004 to December 2008, we conducted 602 stereotactic, 11-gauge, VACB procedures on 243 nonpalpable breast lesions categorised as BI-RADS R3, 346 categorised as BI-RADS R4 and 13 categorised as BI-RADS R5. We calculated the diagnostic accuracy and cost savings of VACB by subtracting the cost of the stereotactic biopsy from that of the diagnostic surgical procedure.

Results

A total of 56% of the lesions were benign and required no further assessment. Lesions of uncertain malignant potential (B3) (23.6%) were debated at multidisciplinary meetings, and diagnostic surgical biopsy was recommended for 83.1% of them. All malignant lesions (B4 and B5) underwent surgical excision. VACB had a sensitivity of 94.9%, specificity of 98.3% and diagnostic accuracy of 97.7%. The cost savings per VACB procedure were 464.00 euro; by obviating 335 surgical biopsies, the overall cost savings was 155,440.00 euro over 5 years.

Conclusions

VACB proved to have high diagnostic accuracy for characterising abnormalities at low to intermediate risk of malignancy and obviated surgical excision in about half of the cases, allowing for considerable cost savings.     

Comparison of two different protocols of neonatal screening for cystic fibrosis

The results of two different protocols of neonatal cystic fibrosis (CF) screening in the Lazio region of Italy are reported. The first study, conducted from 1992 to 2000 on about 200,000 newborns, consisted of an immunoreactive trypsin (IRT) protocol without mutation analysis of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, referred to as the IRT/IRT protocol. Approximately 5% of the newborns with a positive first IRT test were also positive at the second test; approximately 57% of the newborns with a high IRT level at the second test were subsequently found to be affected by CF. In September 1998, a second protocol that included mutation analysis (IRT/DNA/IRT protocol) was started. Comparison of the two different screening protocols in terms of sensitivity in detecting CF patients demonstrated that the IRT/DNA/IRT protocol is more effective because it is able to detect a higher number of CF patients than the IRT/IRT protocol. In the same period, in addition to the overall diagnosis performed on a screening basis, 64 other subjects were identified as being affected by CF on the basis of symptomatic findings. The overall incidence of CF (screening + symptoms) was 1 : 2982, while that for carriers was 1 : 27. The sensitivity of the screening program increased over the period from 1992 to 2000, with the enhanced sensitivity in the past 2 years being due to the introduction of the IRT/DNA/IRT protocol.     

Inhibition of tyrosinase by 4H‐chromene analogs: Synthesis,kinetic studies,and computational analysis

Inhibition of mushroom tyrosinase was observed with synthetic dihydropyrano[3,2‐b]chromenediones. Among them, DHPC04 displayed the most potent tyrosinase inhibitory activity with a K_i value of 4 μm , comparable to the reference standard inhibitor kojic acid. A kinetic study suggested that these synthetic heterocyclic compounds behave as competitive inhibitors for the L‐DOPA binding site of the enzyme. Furthermore, molecular modeling provided important insight into the mechanism of binding interactions with the tyrosinase copper active site.     

Coexistence of two functioning T-cell repertoires in healthy ex-thalassemics bearing a persistent mixed chimerism years after bone marrow transplantation.

Bone marrow transplantation (BMT) from an HLA-identical donor is an established therapy to cure homozygous beta-thalassemia. Approximately 10% of thalassemic patients developed a persistent mixed chimerism (PMC) after BMT characterized by stable coexistence of host and donor cells in all hematopoietic compartments. Interestingly, in the erythrocytic lineage, close to normal levels of hemoglobin can be observed in the absence of complete donor engraftment. In the lymphocytic lineage, the striking feature is the coexistence of immune cells. This implies a state of tolerance or anergy, raising the issue of immunocompetence of the host. To understand the state of the T cells in PMC, repertoire analysis and functional studies were performed on cells from 3 ex-thalassemics. Repertoire analysis showed a profound skewing. This was due to an expansion of some T cells and not to a collapse of the repertoire, because phytohemagglutinin stimulation showed the presence of a complex repertoire. The immunocompetence of the chimeric immune systems was further established by showing responses to alloantigens and recall antigens in vitro. Both host and donor lymphocytes were observed in the cultures. These data suggest that the expanded T cells play a role in specific tolerance while allowing a normal immune status in these patients.     

Descriptive epidemiology of suicide attempts and suicide in the remote villages of French Guiana

Objective

The overall rate of suicide in French Guiana is estimated at 6 per 100,000, a rate that is lower than in mainland France. Given the frequent reports of suicide in Amerindian communities, our hypothesis was that this figure fails to capture a more contrasted reality. Our objective was to refine estimates and determine suicide rates in remote villages of French Guiana.

Methods

We included patients for whom a suicide attempt or suicide was mentioned in medical records. The Health centers were grouped into two zones according to geographical remoteness.

Results

The highest suicide rates observed in the remote Amerindian villages of Camopi and Trois Sauts were, respectively, 118 and 78/100,000. The median age at the time of suicide was significantly younger in remote zones [23 years (95% CI 21.59–25.06)] than in non-remote zones—[27 years (95% CI 24.47–29.31)]. The most frequent methods were hanging (78%) and intoxication (22%).

Conclusions

The suicide rate in remote areas in French Guiana was eight times higher than in France. The suicide of young people in remote areas in French Guiana and specifically in Amerindian villages must be better understood and prevented with contextualized and adapted care.

     

Role of axillary ultrasound in the preoperative diagnosis of lymph node metastases in patients affected by breast carcinoma

Purpose

This study was conducted to evaluate the diagnostic accuracy of axillary ultrasound (US) alone or in combination with fine-needle-aspiration cytology (FNAC) in patients with breast carcinoma, in comparison with the final histological examination (sentinel node biopsy and/or axillary dissection).

Materials and methods

Between January 2005 and June 2008, we evaluated 427 breast cancer patients with axillary US. The findings were classified according to the following criteria: hilum and cortex morphology, ratio between longitudinal and transverse diameter and ratio between hilar and longitudinal diameter of the lymph node. Patients with breast lesions ≤3 cm (n=147) underwent FNAC of the most suspicious lymph node.

Results

Overall concordance between axillary US and final histological examination was 85%, sensitivity was 72.3% and specificity was 93.4%. Concordance between FNAC and final histological examination was 93%, sensitivity was 88.1% and specificity was 100%.

Conclusions

In 48.3% of patients, the combination of axillary US and FNAC guided treatment decisions towards immediate axillary dissection, thus sparing the patients sentinel node biopsy, with a significant reduction of costs and hospitalization time.