One of the therapeutic options for the treatment of fulminant hepatitis is repopulation of intrahepatic regulatory cells because their pool is significantly reduced during acute liver failure. Although it is known that mesenchymal stem cells (MSCs), which have beneficent effects in the therapy of fulminant hepatitis, may promote expansion of regulatory T cells (Tregs) and regulatory B cells (Bregs), the role of these regulatory cells in MSC‐mediated attenuation of acute liver injury is unknown. Herewith, we described the molecular mechanisms involved in the crosstalk between MSCs and liver regulatory cells and analyzed the potential of MSC‐based therapy for the expansion of intrahepatic regulatory cells in mouse model of acute liver failure. MSC‐dependent attenuation of α‐galactosylceramide (α‐GalCer)–induced acute liver injury in mice was accompanied with an increased presence of interleukin (IL) 10–producing CD4⁺CD25⁺forkhead box P3⁺Tregs and IL10– and transforming growth factor β–producing marginal zone–like Bregs in the liver. Depletion of Bregs did not alter MSC‐based alleviation of acute liver failure, whereas depletion of Tregs completely abrogated hepatoprotective effects of MSCs and inhibited their capacity to attenuate hepatotoxicity of liver natural killer T cells (NKTs), indicating that Tregs, and not Bregs, were critically involved in MSC‐based modulation of acute liver inflammation. MSCs, in a paracrine, indoleamine 2,3‐dioxygenase–dependent manner, significantly increased the capacity of Tregs to produce immunosuppressive IL10 and to suppress hepatotoxicity of liver NKTs. Accordingly, adoptive transfer of MSC‐primed Tregs resulted in the complete attenuation of α‐GalCer–induced acute liver failure. In conclusion, our findings highlighted the crucial importance of Tregs for MSC‐based attenuation of acute liver failure and indicated the significance of MSC‐mediated priming of Tregs as a new therapeutic approach in Treg‐based therapy of acute liver injury.Liver Transplantation 24 687–702 2018AASLD.

Indoleamine 2,3-dioxygenase (IDO) has the most important role in modulation of tryptophan-dependent effects in the gastrointestinal tract, including modulation of intestinal immune response. An increased IDO activity maintains immune tolerance and attenuates ongoing inflammation but allows immune escape and uncontrolled growth of gastrointestinal tumors. Accordingly, IDO represents a novel therapeutic target for the treatment of inflammatory and malignant diseases of the gastrointestinal tract. In this review article, we summarize current knowledge about molecular and cellular mechanisms that are involved in IDO-dependent effects. We provide a brief outline of experimental and clinical studies that increased our understanding of how enhanced IDO activity: controls host–microbiota interactions in the gut; regulates detrimental immune response in inflammatory disorders of the gastrointestinal system; and allows immune escape and uncontrolled growth of gastrointestinal tumors. Additionally, we present future perspectives regarding modulation of IDO activity in the gut as possible new therapeutic approaches for the treatment of inflammatory and malignant diseases of the gastrointestinal system.

Background: Dendritic cell (DC)-derived indolamine 2,3-dioxygenase (IDO) degrades tryptophan to kynurenine, which promotes conversion of inflammatory T cells in immunosuppressive regulatory T cells (Tregs). We analyzed the significance of the IDO:Treg axis for inducing and maintaining mucosal healing in ulcerative colitis (UC). Methods: Dextran sodium sulphate (DSS)-induced colitis in BALB/c mice (model for mucosal healing) and C57BL/6 mice (model for persistent disease) was used. Serum, fecal samples and colon-infiltrating immune cells of 65 patients with UC with mucosal healing or persistent colitis were analyzed. Results: Significantly higher serum levels of kynurenine and downregulated inflammatory cytokines were noticed in DSS-treated BALB/c mice compared with C57BL/6 mice. Increased IDO activity and attenuated capacity for antigen presentation and production of inflammatory cytokines, observed in BALB/c DCs, was followed by a significantly lower number of inflammatory T helper 1 (Th1) and Th17 cells and a notably increased number of Tregs in the colons of DSS-treated BALB/c mice. DCs and Tregs were crucially important for the maintenance of mucosal healing since their depletion aggravated colitis. Mucosal healing, followed by an increase in kynurenine and intestinal Tregs, was re-established when BALB/c DCs were transferred into DC-depleted or Treg-depleted DSS-treated BALB/c mice. This phenomenon was completely abrogated by the IDO inhibitor. Significantly higher serum and fecal levels of kynurenine, accompanied by an increased presence of intestinal Tregs, were noticed in patients with UC with mucosal healing and negatively correlated with disease severity, fecal calprotectin, colon-infiltrating interferon γ and interleukin-17-producing cells, serum and fecal levels of inflammatory cytokines. Conclusion: IDO-dependent expansion of endogenous Tregs should be further explored as a new approach for the induction and maintenance of mucosal healing in patients with UC.

Alchemilla vulgaris L. (lady’s mantle) was used for centuries in Europe and Balkan countries for treatments of numerous conditions and diseases of the reproductive system, yet some of the biological activities of lady’s mantle have been poorly studied and neglected. The present study aimed to estimate the potential of A. vulgaris ethanolic extract from Southeast Serbia to prevent and suppress tumor development in vitro, validated by antioxidant, genoprotective, and cytotoxic properties. A total of 45 compounds were detected by UHPLC–HRMS analysis in A. vulgaris ethanolic extract. Measurement of antioxidant activity revealed the significant potential of the tested extract to scavenge free radicals. In addition, the analysis of micronuclei showed an in vitro protective effect on chromosome aberrations in peripheral human lymphocytes. A. vulgaris extract strongly suppressed the growth of human cell lines derived from different types of tumors (MCF-7, A375, A549, and HCT116). The observed antitumor effect is realized through the blockade of cell division, caspase-dependent apoptosis, and autophagic cell death. Our study has shown that Alchemilla vulgaris L. is a valuable source of bioactive compounds able to protect the subcellular structure from damage, thus preventing tumorigenesis as well as suppressing tumor cell growth.

There is still a lively debate about whether mesenchymal stem cells (MSCs) promote or suppress antitumor immune response. Although several possible explanations have been proposed, including different numbers of injected and engrafted MSCs, heterogeneity in phenotype, and function of tumor cells, the exact molecular mechanisms responsible for opposite effects of MSCs in modulation of antitumor immunity are still unknown. Herewith, we used a B16F10 murine melanoma model to investigate whether timing of MSC administration in tumor-bearing mice was crucially important for their effects on antitumor immunity. MSCs, intravenously injected 24 h after melanoma induction (B16F10+MSC^1d-treated mice), significantly enhanced natural killer (NK) and T cell-driven antitumor immunity, suppressed tumor growth, and improved survival of melanoma-bearing animals. Significantly higher plasma levels of antitumorigenic cytokines (TNF-αand IFN-γ), remarkably lower plasma levels of immunosuppressive cytokines (TGF-βand IL-10), and a significantly higher number of tumor-infiltrating, IFN-γ-producing, FasL- and granzyme B-expressing NK cells, IL-17-producing CD4+Th17 cells, IFN-γ- and TNF-α-producing CD4+Th1 cells, and CD8+cytotoxic T lymphocytes (CTLs) were observed in B16F10+MSC^1d-treated mice. On the contrary, MSCs, injected 14 days after melanoma induction (B16F10+MSC^14d-treated mice), promoted tumor growth by suppressing antigen-presenting properties of tumor-infiltrating dendritic cells (DCs) and macrophages and by reducing tumoricidal capacity of NK cells and T lymphocytes. Significantly higher plasma levels of TGF-βand IL-10, remarkably lower plasma levels of TNF-αand IFN-γ, and significantly reduced number of tumor-infiltrating, I-A-expressing, and IL-12-producing macrophages, CD80- and I-A-expressing DCs, granzyme B-expressing CTLs and NK cells, IFN-γ- and IL-17-producing CTLs, CD4+Th1, and Th17 cells were observed in B16F10+MSC^14d-treated animals. In summing up, the timing of MSC administration into the tumor microenvironment was crucially important for MSC-dependent modulation of antimelanoma immunity. MSCs transplanted during the initial phase of melanoma growth exerted tumor-suppressive effect, while MSCs injected during the progressive stage of melanoma development suppressed antitumor immunity and enhanced tumor expansion.

The aim of this study is to describe the morphological characteristics, the number of roots and number of root canals of mandibular central incisors, lateral incisors and canines, and the relationship of these characteristics with the sex and the jaw side where the tooth is located, in the Serbian population using cone-beam computed tomography (CBCT). CBCT images of a total of 902 mandible front teeth, including 296 central incisors, 294 lateral incisors and 312 canines were analyzed in the database. For assessing the morphology of the root canal, Vertucci method of classification was used. Central incisors had two canals in 27%, similar as lateral incisor which had two canals in 26.5%. Mandibular canines had two canals in 7.1% and there was a significant difference between genders. The most prevalent root canal configuration type in all mandibular anterior teeth was type I. In the groups of mandibular incisors with two root canals the most common was type III. In the group of mandibular canines with two root canals, type V had the greatest occurrence. Most mandibular anterior teeth had one root canal. Two root canals were found in 27% of the mandibular incisors. There is a significant difference in root morphology between genders. It is important for dental practitioner to expect different morphological variations when performing endodontic treatment. More studies are needed to further define morphological characteristics of roots of mandibular anterior teeth in Serbian population.