Regulatory T cells (Tregs) are a subpopulation of T cells with immuno-suppressive properties. Tregs play a key role in immune response regulation and tolerance to antigens, thereby preventing autoimmunity, and may be partly responsible for the lack of an appropriate immune response against tumor cells. However, a human microRNA (miR) Treg signature has not been described yet. We investigated human natural Tregs and identified a signature composed of five microRNAs (-21, -31, -125a, -181c and -374). Among those, two were considerably under-expressed (miR-31 and miR-125a). We identified a functional target sequence for miR-31 in the 3’ untranslated region (3’ UTR) of FOXP3 mRNA. Using lentiviral transduction of fresh cord blood T cells, we demonstrated that miR-31 and miR-21 had opposite effects on FOXP3 expression. We showed that miR-31 negatively regulates FOXP3 expression by binding directly to its potential target site in the 3’ UTR of FOXP3 mRNA. We next demonstrated that miR-21 acted as a positive, though indirect, regulator of FOXP3 expression.Recent reports have shown that histone deacetylase inhibitors increased FOXP3 expression in T cells. We therefore decided to investigate in non-Treg CD4-positive cells, the mechanisms by which an aspecific opening of the chromatin could lead to an increased FOXP3 expression. We focused on the binding of potentially activating transcription factors to the promoter region of FOXP3 and on modifications in the five miRs constituting the Treg signature. Valproate treatment induced binding of Ets-1 and Ets-2 transcription factors to the FOXP3 promoter and acted positively on its expression, by increasing the acetylation of histone H4 lysines. Valproate treatment also induced the acquisition of the miRs of Treg signature. To elucidate whether the changes in the miRs expression could be due to the increased FOXP3expression, we transduced these non-Tregs with a FOXP3 lentiviral expression vector, and found no changes in miRs expression. Therefore, the modification in their miR expression profile is not due to an increased expression of FOXP3 but directly results from histone deacetylase inhibition. Rather, the increased FOXP3 expression results from the additive effects of Ets factors binding and the change in the expression level of miR-21 and miR-31. These data, by allowing a better understanding of the molecular phenomena underlying the number and function of Tregs, could open the door to novel therapeutic approaches in cancer immunotherapy and treatment of autoimmune disorders.
This study was carried out to assess the reliability of measurements of the remaining dentin thickness under deep carious lesions as estimated from digital radiographs. The goal is to allow clinicians to correlate the radiographic measurement to the exact value of the remaining dentin thickness. The results obtained will be tested further in a study that will evaluate the histopathologic pulpal state according to the caries' lesion depth.The study was conducted in the Pediatric Dentistry Department at the Lebanese University, in collaboration with the research platform of the same university. Fifty deciduous molars with deep caries on proximal surfaces liable to extraction were collected. Before extraction, a digital in vivo periapical radiograph was taken, followed by manual excavation of the caries. After excavation, another radiograph was taken before the tooth was sectioned through the deepest site of the lesion. Another radiograph was then obtained for each tooth fragment. To evaluate the exact thickness of the remaining dentin, each fragment was measured on a histologic macropho-tograph. The measurements were then compared statistically using a paired-samples t-test, and a correlation was sought.No significant difference was observed in the radiographs between the measurement of the remaining dentin thickness before and after the excavation of caries. In contrast, the radiographic measurements of remaining dentin thickness were underestimated by an average of 20% compared with those made with macrophotographs.Interpretation of radiographs varies from one practitioner to another and is a function of the operator's visual acuity.Measuring the residual dentin thickness on a radiograph underestimates the actual thickness by about 20%. Further studies are needed to confirm these results.Our results indicate that remaining dentin thickness is greater in reality than is shown on a radiograph. This information can help clinicians to refine their diagnoses and treatment plans.How to cite this article: Berbari R, Khairallah A, Kazan HF, Ezzedine M, Bandon D, Sfeir E. Measurement Reliability of the Remaining Dentin Thickness below Deep Carious Lesions in Primary Molars. Int J Clin Pediatr Dent 2018;11(1):23-28.
Sepsis is characterized by a strong systemic inflammatory reaction. The pathogenesis is driven by alterations in the immune system and is associated with high neutrophil counts related to a specific delay in apoptosis [1]. The apolipoproteins L (ApoLs) family comprises six members in humans (ApoL1 to ApoL6). In light of their deregulated expression in several pathologies, they are likely to be important molecular players of programmed cell death [2]. We analyzed ApoL expression in cohorts of septic and nonseptic ICU patients and healthy volunteers in order to test whether ApoLs could be involved in the neutrophil apoptotic program.
Regulatory T cells (Tregs) are characterized by the expression of CD25 and FOXP3, the latter being essential for their development and function. Another major player in the regulatory function is the CTLA-4 surface molecule that inhibits cytotoxic responses. Despite this, the regulation of CTLA-4 expression remains less well explored than that of FOXP3. We therefore studied the microRNA signature of peripheral blood (PB) CD4+CD25+CD127low Tregs isolated from healthy volunteers, with a special focus on FOXP3 and CTLA-4 regulation, and we also studied their transcriptional profile. We confirmed that the investigated population was indeed a regulatory one (high expression of CTLA-4, FOXP3, IL-2 receptor and exhibition of a suppressive function) and pointed at other crucial genes expression that could be in the future subject of investigations. We identified a signature composed of fifteen differentially expressed microRNAs. Among those, miR-24, miR-145 and miR-210 were down regulated in Tregs compared to controls; miR-24 and miR-210 negatively regulated FOXP3 expression by binding directly to two target sites in its 3’UTR. On the other hand, miR-95, which is highly expressed in PB Tregs, positively regulated FOXP3 expression via an indirect mechanism yet to be identified. Finally, we showed that miR-145 negatively regulated CTLA-4 expression in human CD4+ PB Tregs by binding to its target site in CTLA-4 transcript 3’UTR. To our knowledge, this is the first characterization of human PB CD4+ Tregs. Moreover, unveiling one mechanism regulating CTLA-4 expression is novel and may lead to a better understanding of the regulation of this crucial gene.
