Over-expression of Runx1 transcription factor impairs the development of thymocytes from the double-negative to double-positive stages.

Runx1 transcription factor is highly expressed at a CD4/CD8-double-negative (DN) stage of thymocyte development but is down-regulated when cells proceed to the double-positive (DP) stage. In the present study, we examined whether the down-regulation of Runx1 is necessary for thymocyte differentiation from the DN to DP stage. When Runx1 was artificially over-expressed in thymocytes by Lck-driven Cre, the DN3 population was unaffected, as exemplified by proper pre-T-cell receptor expression, whereas the DN4 population was perturbed as shown by the decrease in the CD27(hi) sub-fraction. In parallel, the growth rate of DN4 cells was reduced by half, as measured by bromodeoxyuridine incorporation. These events impaired the transition of DN4 cells to the DP stage, resulting in the drastic reduction of the number of DP thymocytes. The Runx1 gene has two promoters, a proximal and a distal promoter; and, in thymocytes, endogenous Runx1 was mainly transcribed from the distal promoter. Interestingly, only distal, but not proximal, Runx1 over-expression exhibited an inhibitory effect on thymocyte differentiation, suggesting that the distal Runx1 protein may fulfil a unique function. Our collective results indicate that production of the distal Runx1 protein must be adequately down-regulated for thymocytes to transit from the DN to the DP stage, a critical step in the massive expansion of the T-cell lineage.

Immune Biomarkers for Diagnosis and Treatment Monitoring of Tuberculosis: Current Developments and Future Prospects.

Tuberculosis (TB) treatment monitoring is paramount to clinical decision-making and the host biomarkers appears to play a significant role. The currently available diagnostic technology for TB detection is inadequate. Although GeneXpert detects total DNA present in the sample regardless live or dead bacilli present in clinical samples, all the commercial tests available thus far have low sensitivity. Humoral responses against Mycobacterium tuberculosis (Mtb) antigens are generally low, which precludes the use of serological tests for TB diagnosis, prognosis, and treatment monitoring. Mtb-specific CD4+ T cells correlate with Mtb antigen/bacilli burden and hence might serve as good biomarkers for monitoring treatment progress. Omics-based techniques are capable of providing a more holistic picture for disease mechanisms and are more accurate in predicting TB disease outcomes. The current review aims to discuss some of the recent advances on TB biomarkers, particularly host biomarkers that have the potential to diagnose and differentiate active TB and LTBI as well as their use in disease prognosis and treatment monitoring.

Mutagenicity evaluation of Anastatica hierochuntica L. aqueous extract in vitro and in vivo.

Anastatica hierochuntica L. ( A. hierochuntica), a folk medicinal plant, was evaluated for mutagenic potential via in vitro and in vivo assays. The in vitro assay was conducted according to modified Ames test, while the in vivo study was performed according to Organisation for Economic Co-operation and Development guideline for mammalian erythrocyte micronucleus assay. Four groups ( n= 5 males and 5 females per group) Sprague Dawley rats were randomly chosen as the negative control, positive control (received a single intramuscular injection of cyclophosphamide 50 mg/kg), 1000 and, 2000 mg/kg A. hierochuntica aqueous extracts. All groups except the positive control were treated orally for three days. Findings of the in vitro assay showed mutagenic potential of AHAE at 0.04 and 0.2 mg/ml. However, no mutagenic effect was demonstrated in the in vivo study up to 2000 mg/kg. No significant reduction in the polychromatic and normochromatic erythrocytes ratio was noted in any of the groups. Meanwhile, high micronucleated polychromatic erythrocytes frequency was seen in cyclophosphamide-treated group only. These findings could perhaps be due to insufficient dosage of A. hierochuntica aqueous extracts to cause genetic damage on the bone marrow target cells. Further acute and chronic in vivo toxicity studies may be required to draw pertinent conclusion on the safety aspect of A. hierochuntica aqueous extracts consumption. Impact statement In this paper, we report on the mutagenicity evaluation of Anastatica hierochuntica aqueous extract. This is a significant research in view of the popularity of this herb consumption by the people across the globe despite of limited scientific evidence on its toxicity potential. This study is intended to encourage more extensive related research in order to provide sufficient evidence and guidance for determining its safe dosage.