Francesc Marti

Targeting Wnt/β-catenin pathway in hepatocellular carcinoma treatment

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Liver cancer is generally related to hepatitis B or C infection and cirrhosis. Usually, patients with HCC are asymptomatic and are diagnosed at late stages when surgical treatment is no longer suitable. Limited treatment options for patients with advanced HCC are a major concern. Therefore, there is an urge for finding novel therapies to treat HCC. Liver cancer is highly heterogeneous and involved deregulation of several signaling pathways. Wnt/β-catenin pathway is frequently upregulated in HCC and it is implicated in maintenance of tumor initiating cells, drug resistance, tumor progression, and metastasis. A great effort in developing selective drugs to target components of the β-catenin pathway with anticancer activity is underway but only a few of them have reached phase I clinical trials. We aim to review the role of β-catenin pathway on hepatocarcinogenesis and liver cancer stem cell maintenance. We also evaluated the use of small molecules targeting the Wnt/β-catenin pathway with potential application for treatment of HCC.

Mitochondrial and cytosolic roles of PINK1 shape induced regulatory T‐cell development and function

Mutations in PTEN‐induced kinase 1 (PINK1), a serine/threonine kinase linked to familial early‐onset Parkinsonism, compromise mitochondrial integrity and metabolism and impair AKT signaling. As the activation of a naïve T cell requires an AKT‐dependent reorganization of a cells metabolic machinery, we sought to determine if PINK1‐deficient T cells lack the ability to undergo activation and differentiation. We show that CD4+ T cells from PINK1 knockout mice fail to properly phosphorylate AKT upon activation, resulting in reduced expression of the IL‐2 receptor subunit CD25. Following, deficient IL‐2 signaling mutes the activation‐induced increase in respiratory capacity and mitochondrial membrane potential. Under polarization conditions favoring the development of induced regulatory T cells, PINK1−/− T cells exhibit a reduced ability to suppress bystander T‐cell proliferation despite normal FoxP3 expression kinetics. Our results describe a critical role for PINK1 in integrating extracellular signals with metabolic state during T‐cell fate determination, and may have implications for the understanding of altered T‐cell populations and immunity during the progression of active Parkinsons disease or other immunopathologies.

Generation of Induced Regulatory T Cells from Primary Human Naïve and Memory T Cells

The development and maintenance of immunosuppressive CD4+ regulatory T cells (Tregs) contribute to the peripheral tolerance needed to remain in immunologic homeostasis with the vast amount of self and commensal antigens in and on the human body. Perturbations in the balance between Tregs and inflammatory conventional T cells can result in immunopathology or cancer. Although therapeutic injection of Tregs has been shown to be efficacious in murine models of colitis, type I diabetes, rheumatoid arthritis and graft versus host disease, several fundamental differences in human versus mouse Treg biology has thus far precluded clinical use. The lack of sufficient number, purity, stability and homing specificity of therapeutic Tregs necessitated a dynamic platform of human Treg development on which to optimize conditions for their ex vivo expansion. Here we describe a method for the differentiation of induced Tregs (iTregs) from a single human peripheral blood donor which can be broken down into four stages: isolation of peripheral blood mononuclear cells, magnetic selection of CD4+ T cells, in vitro cell culture and fluorescence activated cell sorting (FACS) of T cell subsets. Since the Treg signature transcription factor forkhead box P3 (FoxP3) is an activation-induced transcription factor in humans and no other unique marker exists, a combinatorial panel of markers must be used to identify T cells with suppressor activity. After six days in culture, cells in our system can be demarcated into naïve T cells, memory T cells or iTregs based on their relative expression of CD25 and CD45RA. As memory and naïve T cells have different reported polarization requirements and plasticities, pre-sorting of the initial T cell population into CD45RA(+) and CD45RO(+) subsets can be used to examine these discrepancies. Consistent with others, our CD25(Hi)CD45RA(-) iTregs express high levels of FoxP3, GITR and CTLA-4 and low levels of CD127. Following FACS of each population, resultant cells can be used in a suppressor assay which evaluates the relative ability to retard the proliferation of carboxyfluorescein succinimidyl ester (CFSE)-labeled autologous T cells.

Peripherally induced human regulatory T cells uncouple Kv1.3 activation from TCR-associated signaling

Peripherally induced Tregs (iTregs) are being recognized as a functional and physiologically relevant T‐cell subset. Understanding the molecular basis of their development is a necessary step before the therapeutic potential of iTreg manipulation can be exploited. In this study, we report that the differentiation of primary human T cells to suppressor iTregs involves the relocation of key proximal TCR signaling elements to the highly active IL‐2‐Receptor (IL‐2‐R) pathway. In addition to the recruitment of lymphocyte‐specific protein tyrosine kinase (Lck) to the IL‐2‐R complex, we identified the dissociation of the voltage‐gated K+ channel Kv1.3 from the TCR pathway and its functional coupling to the IL‐2‐R. The regulatory switch of Kv1.3 activity in iTregs may constitute an important contributing factor in the signaling rewiring associated with the development of peripheral human iTregs and sheds new light upon the reciprocal crosstalk between the TCR and the IL‐2‐R pathways.

Diffuse traumatic brain injury induces prolonged immune dysregulation and potentiates hyperalgesia following a peripheral immune challenge

Background Nociceptive and neuropathic pain occurs as part of the disease process after traumatic brain injury (TBI) in humans. Central and peripheral inflammation, a major secondary injury process initiated by the traumatic brain injury event, has been implicated in the potentiation of peripheral nociceptive pain. We hypothesized that the inflammatory response to diffuse traumatic brain injury potentiates persistent pain through prolonged immune dysregulation. Results To test this, adult, male C57BL/6 mice were subjected to midline fluid percussion brain injury or to sham procedure. One cohort of mice was analyzed for inflammation-related cytokine levels in cortical biopsies and serum along an acute time course. In a second cohort, peripheral inflammation was induced seven days after surgery/injury with an intraplantar injection of carrageenan. This was followed by measurement of mechanical hyperalgesia, glial fibrillary acidic protein and Iba1 immunohistochemical analysis of neuroinflammation in the brain, and flow cytometric analysis of T-cell differentiation in mucosal lymph. Traumatic brain injury increased interleukin-6 and chemokine ligand 1 levels in the cortex and serum that peaked within 1–9 h and then resolved. Intraplantar carrageenan produced mechanical hyperalgesia that was potentiated by traumatic brain injury. Further, mucosal T cells from brain-injured mice showed a distinct deficiency in the ability to differentiate into inflammation-suppressing regulatory T cells (Tregs). Conclusions We conclude that traumatic brain injury increased the inflammatory pain associated with cutaneous inflammation by contributing to systemic immune dysregulation. Regulatory T cells are immune suppressors and failure of T cells to differentiate into regulatory T cells leads to unregulated cytokine production which may contribute to the potentiation of peripheral pain through the excitation of peripheral sensory neurons. In addition, regulatory T cells are identified as a potential target for therapeutic rebalancing of peripheral immune homeostasis to improve functional outcome and decrease the incidence of peripheral inflammatory pain following traumatic brain injury.

Enhanced Generation of Suppressor T Cells in Patients with Asthma Taking Oral Contraceptives

Introduction. A dysregulation of regulatory T cells (Tregs) could play a major role in the pathogenesis of bronchial asthma. Sex-dependent differences as well as the impact of hormonal changes in the incidence and severity of asthma are widely recognized. Emerging evidence suggests that asthma symptoms are alleviated in female patients taking hormone oral contraceptives (OCs). The impact of OCs on the generation of induced Tregs (iTregs) was assessed in a cohort of female patients with asthma. Methods. Thirteen patients were included in this pilot study. During three distinct phases of their menstrual cycles, we measured exhaled nitric oxide (eNO) levels, forced expiratory volume at 1 second (FEV1s), asthma control test (ACT) score, sex steroid hormone levels in serum, natural Tregs in peripheral blood, and the ability of CD4+ T cells to generate iTregs ex vivo. Results. The luteal serum levels of estradiol and progesterone negatively correlated with the proportion of iTregs generated ex vivo in patients not taking OCs. In addition, physiological doses of estradiol and progesterone prevented the acquisition of a suppressor T cell phenotype in vitro. Interestingly, patients taking OCs had reduced serum sex hormone levels associated with higher iTreg induction, a better ACT score, and a tendency toward lower eNO levels. Conclusions. Our results identify an impact of sex hormones on the capacity of T cells to polarize towards a regulatory phenotype and suggest the regulation of peripheral T cell lineage plasticity as a potential mechanism underlying the beneficial effects of OCs in women with asthma.

Combined liver–kidney transplantation for polycystic liver and kidney disease: analysis from the United Network for Organ Sharing dataset

The purpose of this study was to evaluate predictors of outcomes in combined liver–kidney transplants for polycystic liver and kidney disease.

The balancing act of AKT in T cells

The serine/threonine-specific protein kinase AKT is gaining recognition as a major crossroad in numerous cellular signaling pathways through its ability to regulate cell differentiation, proliferation, survival and metabolism. This review focuses on the recent advances in AKT signaling and downstream events in T cells, emphasizing its contrasting role in conventional and regulatory (Treg) Tcell populations. Activation of AKT has been known for many years to be critical in the development and function of conventional Tcells. However, it has just recently been uncovered that AKTexerts an inhibitory effect on Treg generation and suppressor function. These studies have placed AKTat the nexus of Treg development and function, thus opening novel avenues for therapeutic manipulation.

Evidence of the immunomodulatory role of dual PI3K/mTOR inhibitors in transplantation: an experimental study in mice

The PI3K/mTOR signaling cascade is fundamental in T‐cell activation and fate decisions. We showed the distinct regulation of PI3K/mTOR in regulatory and effector T‐cells and proposed the potential therapeutic benefit of targeting this pathway to control the balance between effector and regulatory T‐cell activities. Substantial adverse effects in long‐term clinical usage of rapamycin suggest the use of alternative treatments in restraining effector T‐cell function in transplant patients. We hypothesize that dual PI3K/mTOR inhibitors may represent an immunosuppressant alternative. Here we show that dual PI3K/mTOR PI‐103 and PKI‐587 inhibitors interfered IL‐2‐dependent responses in T‐cells. However, in contrast to the inhibitory effects in non‐Treg T‐cell proliferation and effector functions, dual inhibitors increased the differentiation, preferential expansion, and suppressor activity of iTregs. Rapamycin, PI‐103, and PKI‐587 targeted different signaling events and induced different metabolic patterns in primary T‐cells. Similar to rapamycin, in vivo administration of PI‐103 and PKI‐587 controlled effectively the immunological response against allogeneic skin graft. These results characterize specific regulatory mechanisms of dual PI3K/mTOR inhibitors in T‐cells and support their potential as a novel therapeutic option in transplantation.

Novel biomarkers in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths and the fifth most common cancer worldwide. Most of these patients are seen with advanced disease at the time of presentation. In spite of its high prevalence, there are not many therapeutic options available for patients with advanced-stage HCC. There is an urgent need for improving early detection and prognostication of patients with HCC. In addition, the development of new therapies targeting specific pathways involved in the pathogenesis of HCC should be a major goal for future research, with the objective of improving outcomes of patients with HCC. Biomarkers represent a relatively easy and noninvasive way to detect and estimate disease prognosis. In spite of the numerous efforts to find molecules as possible biomarkers, there is not a single ideal marker in HCC. Many new findings have shown promising results both in diagnosing and treating HCC. In this review, we summarized the most recent and relevant biomarkers in HCC.