Nitric oxide inhibits T cell adhesion and migration by down-regulation of β1-integrin expression in immunologically liver-injured mice

Enhanced cell survival and therapeutic benefits of IL-10-expressing multipotent mesenchymal stromal cells for muscular dystrophy

BACKGROUND

Multipotent mesenchymal stromal cells (MSCs) are potentially therapeutic for muscle disease because they can accumulate at the sites of injury and act as immunosuppressants. MSCs are attractive candidates for cell-based strategies that target diseases with chronic inflammation, such as Duchenne muscular disease (DMD). We focused on the anti-inflammatory properties of IL-10 and hypothesized that IL-10 could increase the typically low survival of MSCs by exerting a paracrine effect after transplantation.

METHODS

We developed a continuous IL-10 expression system of MSCs using an adeno-associated virus (AAV) vector. To investigate the potential benefits of IL-10 expressing AAV vector-transduced MSCs (IL-10-MSCs), we examined the cell survival rates in the skeletal muscles after intramuscular injection into mice and dogs. Systemic treatment with IL-10-MSCs derived from dental pulp (DPSCs) was comprehensively analyzed using the canine X-linked muscular dystrophy model in Japan (CXMD_J), which has a severe phenotype similar to that of DMD patients.

RESULTS

In vivo bioluminescence imaging analysis revealed higher retention of IL-10-MSCs injected into the hindlimb muscle of mice. In the muscles of dogs, myofiber-like tissue was formed after the stable engraftment of IL-10-MSCs. Repeated systemic administration of IL-10-DPSCs into the CXMD_J model resulted in long-term engraftment of cells and slightly increased the serum levels of IL-10. IL-10-hDPSCs showed significantly reduced expression of pro-inflammatory MCP-1 and upregulation of stromal-derived factor-1 (SDF-1). MRI and histopathology of the hDPSC-treated CXMD_J indicated the regulation of inflammation in the muscles, but not myogenic differentiation from treated cells. hDPSC-treated CXMD_J showed improved running capability and recovery in tetanic force with concomitant increase in physical activity. Serum creatine kinase levels, which increased immediately after exercise, were suppressed in IL-10-hDPSC-treated CXMD_J.

CONCLUSIONS

In case of local injection, IL-10-MSCs could maintain the long-term engraftment status and facilitate associated tissue repair. In case of repeated systemic administration, IL-10-MSCs facilitated the long-term retention of the cells in the skeletal muscle and also protected muscles from physical damage-induced injury, which improved muscle dysfunction in DMD. We can conclude that the local and systemic administration of IL-10-producing MSCs offers potential benefits for DMD therapy through the beneficial paracrine effects of IL-10 involving SDF-1.

Epigallocatechin-3-gallate sensitizes IFN-γ-stimulated CD4+ T cells to apoptosis via alternative activation of STAT1

Epigallocatechin-3-gallate (EGCG) exerts anti-inflammatory properties on immune cells and binds to CD4 molecules. However, the effects of EGCG on CD4(+) T cells remain largely unknown. Here, we found that EGCG enhanced IFN-γ-induced signal transducer and activator of transcription 1 (STAT1) activation in primary CD4(+) T cells from C57BL/6 mice and in a human leukemic CD4(+) T-cell line of Hut 78 cells, while it inhibited the classical pathway of IFN-γ signaling including activating phosphorylations of Janus kinase (JAK) 1, JAK2 and STAT3, forming interferon-γ activated sequence (GAS)-binding STAT1 homodimers, and producing pro-inflammatory chemokine (C-X-C motif) ligand 9 (CXCL9). CD4 blockade did not suppress the increase in IFN-γ-induced STAT1 activation in CD4(+) T cells by EGCG. Furthermore, activation of Src kinase was also triggered by IFN-γ plus EGCG in both Hut 78 and primary CD4(+) T cells. Interestingly, EGCG promoted apoptosis of CD4(+) T cells treated with IFN-γ. The increases in STAT1 activation and apoptosis induced by EGCG in IFN-γ-activated CD4(+) T cells were almost completely abolished by a selective Src family kinase inhibitor, SU6656. Moreover, EGCG alleviates CD4(+) CD45RB(hi) CD25(-) T cell transfer induced colitis with less accumulation of CD4(+) T cells in the colon. In conclusion, the present study reports an alternative activation of STAT1 via Src by EGCG in IFN-γ-activated CD4(+) T cells, which promotes the apoptosis of IFN-γ-activated CD4(+) T cells and contributes to the improvement of T cell-mediated colitis. Our findings suggest a novel role of EGCG in regulating IFN-γ signaling and controlling inflammation.

Nitric oxide in cancer metastasis

Cancer metastasis is the spread and growth of tumor cells from the original neoplasm to further organs. This review analyzes the role of nitric oxide (NO), a signaling molecule, in the regulation of cancer formation, progression, and metastasis. The action of NO on cancer relies on multiple factors including cell type, metastasis stage, and organs involved. Various chemotherapy drugs cause cells to release NO, which in turn induces cytotoxic death of breast, liver, and skin tumors. However, NO has also been clinically connected to a poor cancer prognosis because of its role in angiogenesis and intravasation. This supports the claim that NO can be characterized as both pro-metastatic and anti-metastatic, depending on specific factors. The inhibition of cell proliferation and anti-apoptosis pathways by NO donors has been proposed as a novel therapy to various cancers. Studies suggest that NO-releasing non-steroidal anti-inflammatory drugs act on cancer cells in several ways that may make them ideal for cancer therapy. This review summarizes the biological significance of NO in each step of cancer metastasis, its controversial effects for cancer progression, and its therapeutic potential.

Multiple sclerosis: molecular mechanisms and therapeutic opportunities

The pathophysiology of multiple sclerosis (MS) involves several components: redox, inflammatory/autoimmune, vascular, and neurodegenerative. All of them are supported by the intertwined lines of evidence, and none of them should be written off. However, the exact mechanisms of MS initiation, its development, and progression are still elusive, despite the impressive pace by which the data on MS are accumulating. In this review, we will try to integrate the current facts and concepts, focusing on the role of redox changes and various reactive species in MS. Knowing the schedule of initial changes in pathogenic factors and the key turning points, as well as understanding the redox processes involved in MS pathogenesis is the way to enable MS prevention, early treatment, and the development of therapies that target specific pathophysiological components of the heterogeneous mechanisms of MS, which could alleviate the symptoms and hopefully stop MS. Pertinent to this, we will outline (i) redox processes involved in MS initiation; (ii) the role of reactive species in inflammation; (iii) prooxidative changes responsible for neurodegeneration; and (iv) the potential of antioxidative therapy.

Adult skeletal muscle stem cell migration is mediated by a blebbing/amoeboid mechanism

Adult skeletal muscle possesses a resident stem cell population called satellite cells, which are responsible for tissue repair following damage. Satellite cell migration is crucial in promoting rapid tissue regeneration, but it is a poorly understood process. Furthermore, the mechanisms facilitating satellite cell movement have yet to be elucidated. This study investigates the process of satellite cell migration, revealing that they undergo two distinct phases of movement, first under the basal lamina and then rapidly increasing their velocity when on the myofiber surface. Most significantly, we show that satellite cells move using a highly dynamic blebbing or amoeboid-based mechanism and not via lamellipodia-mediated propulsion. We show that nitric oxide and noncanonical Wnt signaling pathways are necessary for regulating the formation of blebs and the migration of satellite cells. In summary, we propose that the formation of blebs and their necessity for satellite cell migration has significant implications in the future development of therapeutic regimes aimed at promoting skeletal muscle regeneration.

Icariin, a natural flavonol glycoside, induces apoptosis in human hepatoma SMMC-7721 cells via a ROS/JNK-dependent mitochondrial pathway

In this study, the anticancer effect of icariin, a natural flavonol glycoside, against human hepatoma SMMC-7721 cells and the underlying mechanisms were investigated. Icariin triggered the mitochondrial/caspase apoptotic pathway indicated by enhanced Bax-to-Bcl-2 ratio, loss of mitochondrial membrane potential, cytochrome c release, and caspase cascade. Moreover, icariin induced a sustained activation of the phosphorylation of c-Jun N-terminal kinase (JNK) but not p38 and ERK1/2, and SP600125 (an inhibitor of JNK) almost reversed icariin-induced apoptosis in SMMC-7721 cells. In addition, icariin provoked the generation of reactive oxygen species (ROS) in SMMC-7721 cells, while the antioxidant N-acetyl cysteine almost completely blocked icariin-induced JNK activation and apoptosis. Taken together, these findings suggest that icariin induces apoptosis through a ROS/JNK-dependent mitochondrial pathway.

Interferon-gamma limits Th1 lymphocyte adhesion to inflamed endothelium: a nitric oxide regulatory feedback mechanism

CD4(+) T helper (Th1 and Th2) cell localization to a site of inflammation is important for the development, maintenance and regulation of an immune response. The factors that regulate Th1 and Th2 cell recruitment into tissue are not fully understood. The aim of the present study was to examine the effect of different cytokine microenvironments on the recruitment of Th1 and Th2 lymphocytes into tissue. Fluorescently labelled Th1 or Th2 lymphocyte-endothelial interactions were observed via intravital microscopy of the cytokine-treated cremaster muscle. Our results show that TNF-alpha alone is sufficient to maximally recruit Th1 cells. Surprisingly, treatment with TNF-alpha + IFN-gamma significantly decreased Th1 adhesion and emigration in comparison to TNF-alpha treatment alone. The decreased adhesion of Th1 cells in response to TNF-alpha + IFN-gamma reflected a decreased ability to bind to ICAM-1 and was iNOS-dependent. This phenomenon was not observed with Th2 cells. These results suggest that IFN-gamma may play a key immunomodulatory role in the recruitment of different T lymphocyte subsets. Indeed, blockade of IFN-gamma or iNOS function during the Th1-mediated contact hypersensitivity response resulted in an acceleration and exacerbation of the late-phase inflammatory response.

IL-12/IFN-gamma/NO axis plays critical role in development of Th1-mediated experimental autoimmune encephalomyelitis

The importance of the IL-12/IFN-gamma/nitric oxide (NO) axis in the pathogenesis of autoimmune diseases remains controversial. In parallel experiments, we explored the role of the IL-12/IFN-gamma/NO axis in the development of MOG 35-55-induced experimental autoimmune encephalomyelitis (EAE) in mice lacking IL-12, IFN-gamma receptor (IFN-gammaR) and inducible nitric oxide synthase (NOS2), respectively. In comparison with wide-type control mice, IL-12-/-, IFN-gammaR-/- and NOS2-/- mice displayed more severe clinical signs of EAE both in remission and at subsequent relapse. Given the relatively low IFN-gamma production in IL-12-/- mice and the lack of IFN-gamma/IFN-gammaR signaling pathway in IFN-gammaR-/- mice, IL-12-/-, IFN-gammaR-/- and NOS2-/- mice with EAE exhibited low NO production. This correlated negatively with MOG 35-55-induced T cell proliferation. Both ED1-positive macrophages and CD4-positive T cells were increased in spinal cords from IL-12-/-, IFN-gammaR-/- and NOS2-/- compared to control mice. In vitro experiments demonstrate that spleen mononuclear cells from IL-12-/-, IFN-gammaR-/- and NOS2-/-mice with EAE present stronger migration capacity when compared to control mice. These results reveal that the IL-12/IFN-gamma/NO axis plays a critical role in the development of MOG 35-55-induced EAE, possibly over failing NO production.