Aleš Goropevšek

A Co-Culture Model of the Developing Small Intestine Offers New Insight in the Early Immunomodulation of Enterocytes and Macrophages by Lactobacillus spp. through STAT1 and NF-kB p65 Translocation

The early establishment of a complete microbiome has been shown to play an integral part in the development and maintenance of an intact intestine and its immune system, although much remains unknown about the specific mechanisms of immune modulation in newborns. In our study we show in a co-culture model of the undeveloped small intestine that members of Lactobacillus spp. influence STAT1 and NF-kB p65 nuclear translocation in both intestinal epithelial cells as well as underlying macrophages. Moreover, by using imaging flow cytometry we were able to monitor each individual cell and create a framework of the percentage of cells in which translocation occurred in challenged versus control cell populations. We also observed a significant difference in baseline translocation in intestinal cells when cultured alone versus those in a co-culture model, underpinning the importance of 3D models over monolayer set-ups in epithelial in vitro research. In conclusion, our work offers new insights into the potential routes by which the commensal microbiome primes the early immune system to fight pathogens, and shows how strain-specific these mechanisms really are.

The Role of STAT Signaling Pathways in the Pathogenesis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder with a broad spectrum of clinical presentations and association with multiple immunological abnormalities. Recent research of the Janus kinase (JAK)—signal transducer and activator of transcription (STAT) signaling pathway—revealed aberrant STAT signaling in inflammatory conditions and autoimmune diseases including SLE. STAT proteins are major components in interferon (IFN)-dependent gene expression and are responsible for signal transduction of over 50 cytokines, hormones, and growth factors regulating key cellular processes such as survival, proliferation, and differentiation. This review summarizes the present evidence from experimental animal models and patients with SLE for the involvement of STAT pathways in the pathogenesis of SLE underlining the role of different members of the STAT family. Genome-wide association studies provided evidence that variations in STAT4 gene are linked to the development of SLE in humans. First integration with genome-wide epigenomics data suggests that control of CD4+ T cell differentiation in which STATs play a major role may be an important component of the genetic contribution to disease susceptibility. Increased transcript and total protein STAT1 levels were described both in SLE T and B cells suggestive of the priming mechanisms that augment STAT1 signaling responses to IFN. STAT3 has a crucial role in Th17 differentiation, T follicular helper, and B cells, and STAT3 inhibition could represent a possible future therapeutic target in SLE. STAT5B appears to act as a critical modulator of human Treg development and function. While the imbalance between phosphorylated STAT5 and STAT3 in human SLE T cells was implicated in dysregulated IL-10 expression, Treg-specific deletion of STAT3 in mouse model even enhanced Th17-mediated inflammation. Finally, we present also a comprehensive analysis of studies investigating STAT signaling responses in conventional and regulatory subsets of SLE T and B cells and possible implications of STAT inhibition for clinical therapy.

Dideoxy fluoro-ketopyranosyl nucleosides as potent antiviral agents: Synthesis and biological evaluation of 2,3- and 3,4-dideoxy-3-fluoro-4-and -2-keto-β-D-glucopyranosyl derivatives of N4-benzoyl cytosine

Abstract The synthesis of the dideoxy fluoro ketopyranonucleoside analogues, 1-(2,3-dideoxy-3-fluoro-6-O-trityl-β-d-glycero-hexopyranosyl-4-ulose)-N 4-benzoyl cytosine (7a), 1-(3,4-dideoxy-3-fluoro-6-O-trityl-β-d-glycero-hexopyranosyl-2-ulose)-N 4-benzoyl cytosine (13a) and their detritylated analogues 8a and 14a, respectively, is described. Condensation of peracetylated 3-deoxy-3-fluoro-d-glucopyranose (1) with silylated N 4-benzoyl cytosine, followed by selective deprotection and isopropylidenation afforded compound 2. Routine deoxygenation at position 2′, followed by a deprotection-selective reprotection sequence afforded the partially tritylated dideoxy nucleoside of cytosine 6, which upon oxidation of the free hydroxyl group at the 4′-position, furnished the desired tritylated 2,3-dideoxy-3-fluoro ketonucleoside 7a in equilibrium with its hydrated form 7b. Compound 2 was the starting material for the synthesis of the dideoxy fluoro ketopyranonucleoside 13a. Similarly, several subsequent protection and deprotection steps as well as routine deoxygenation at position 4′, followed by oxidation of the free hydroxyl group at the 2′-position of the partially tritylated dideoxy nucleoside 12, yielded the desired carbonyl compound 13a in equilibrium with its hydrated form 13b. Finally, trityl removal from 7a/b and 13a/b provided the unprotected 2,3-dideoxy-3-fluoro-4-keto and 3,4-dideoxy-3-fluoro-2-ketopyranonucleoside analogues 8a and 14a, in equilibrium with their gem-diol forms 8b and 14b. None of the compounds showed inhibitory activity against a wide variety of DNA and RNA viruses at subtoxic concentrations, except 7a/b that was highly efficient against rotavirus infection. Nucleoside 7a/b also exhibited cytostatic activity against cells of various cancers. BrdU-cell cycle analysis revealed that the mechanism of cytostatic activity may be related to a delay in G1/S phase and initiation of programmed cell death.

Age-Related Differences in Percentages of Regulatory and Effector T Lymphocytes and Their Subsets in Healthy Individuals and Characteristic STAT1/STAT5 Signalling Response in Helper T Lymphocytes

The dynamic process of the development of the immune system can in itself result in age-related immune malfunctions. In this study, we analysed lymphocyte subsets in the peripheral blood of 60 healthy donors, divided into groups of children, adolescents, and adults, focusing on effector (Teff) and regulatory (Treg) T lymphocytes and STAT1/STAT5 signalling response in helper T lymphocytes (Th) in adults, using flow cytometry. Our results demonstrate a decrease in the percentage of total Tregs and an increase in the percentage of total Teffs with age and a consequential immense increase in the Teff/Treg ratio. The increase of Teffs was most apparent in Th1, Th1Th17, and Th17CD161− subsets. Significant Th lymphocyte STAT1 expression differences were observed between children and adolescents, which were associated with the decrease in activated Tregs. Higher expression of STAT1 was found in FoxP3hi than in FoxP3low Th lymphocytes, while significant IL-2 induced STAT5 phosphorylation differences were found among the subsets of Th lymphocytes in adults. Our study demonstrates age-related changes in circulating Teff and Treg, as well as significant differences in STAT5/STAT1 signalling among FoxP3+ Th lymphocytes, providing new advances in the understanding of immunosenescence.

STAT5 phosphorylation in CD4 T cells from patients with SLE is related to changes in their subsets and follow-up disease severity

Activation of the STAT5 signaling pathway up‐regulates antiapoptotic protein Bcl2 and drives proliferation of autoreactive conventional CD4 T cells (Tcons). In systemic lupus erythematosus (SLE), an increased T cell Bcl2 content and perturbed homeostasis of CD45RA−FOXP3hi activated regulatory T cells (aTregs) were described. We assessed Tcon/Treg subsets and phosphorylation of STAT5 (pSTAT5) in blood T cells from patients with SLE by using conventional and imaging flow cytometry. Forty‐one patients with SLE, 33 healthy controls, and 29 patients with rheumatoid arthritis were included. Long‐term monitoring was performed in 39 patients with SLE, which were followed longitudinally for up to 1000 d. Significantly increased Bcl2 protein content in T cells from patients with SLE was associated with IL‐7–dependent STAT5 activation, expressed as increased basal levels and nuclear localization of pSTAT5. pSTAT5 levels were significantly increased in the FOXP3 low‐expressing CD4+ T cell subsets but not in the aTreg subset, which was significantly decreased in patients with SLE. In contrast to aTreg, SLE Tcon displayed significantly increased pSTAT5 and Bcl2 levels. Moreover, the percentage of Tcon‐expressing proliferation marker Ki‐67 was significantly increased in patients with SLE and was positively correlated with CD4 T cell pSTAT5 levels. Finally, a subgroup of patients characterized by an increased Tcon–pSTAT5/aTreg–pSTAT5 ratio experienced a more aggressive‐relapsing disease course and displayed higher time‐adjusted cumulative CD4 T cell pSTAT5 levels during follow‐up, which were positively correlated with time‐adjusted cumulative disease activity. Our results indicate that imbalanced STAT5 phosphorylation, which is related to Bcl2 and Ki‐67 expression, may confer survival and proliferative advantage to Tcon over aTreg and could represent a possible marker of SLE disease severity.

Flow cytometry as the new ‘gold standard’ for detection of free tumour cells in abdominal lavage fluid in gastric cancer patients: A comparative study of molecular and conventional methods: A comparative study of tumour cell detection with flow cytrometry, RT-qPCR and cytology

The ideal method for detection of free tumour cells in abdominal lavage fluid should be rapid, reliable and widely available. Flow cytometry potentially covers these properties, but there are only a few studies directly comparing flow cytometry for detecting gastric cancer cells to other methods. Therefore, we compared free tumour‐cell detection in abdominal lavage fluids using cytology with immunocytochemistry, RT‐qPCR and flow cytometry.

NEW BIOMARKERS AND MONITORING INTRACELLULAR SIGNALINGPATHWAYS IN AUTOIMMUNE DISEASES

BACKGROUND Almost all current therapeutic concepts in many autoimmune and chronic inflammatorydiseases are based on the systemic suppression of immune functions and are not curative.Identification of cytokines TNF and IFN-alpha as major factors in the pathogenesis of diseases such as rheumatoid arthritis and systemic lupus erythematosus (SLE) represent asubstantial improvement in understanding of autoimmune diseases. Intracellular signalling pathways that are activated in response to those clinically relevant cytokines, mediatesignals through kinase phosphorylation of proteins and are at the core of immune cellfunction. However, little is known about their changes in autoimmune disease states. Recent trials emphasized the importance of directly assessing the human immune responses,and that not all of what we learn for example in the mouse can be directly translated tohumans. Thus, there is a need for the development of tools and assays to directly assess thehuman immune system, and to predict its responses to novel therapeutic entities. Newlydiscovered biomarkers represent promising tools. Even more promising are approaches,that are based on monitoring immune signaling on the single cell level.Conclusions A series of assay systems for flow cytometric-based biochemical analysis at the single-celllevel for kinase and phosphoprotein profiling have been developed.This will give us opportunity to study signal pathways also in autoimmune and chronic inflammatory diseases,as the analysing systems are adapted to immunocytes for example in peripheral blood.First results show characteristic phospho-signature of cytokines (interferons) in immunecells from SLE patients.Monitoring signaling pathways on the single cell level can lead to developments in newdiagnostic tools, especially in monitoring of disease activity. RESULTS can also identify newtargets of more specific and less toxic therapy with kinase inhibitors