The role of signal transducers and activators of transcription in T inflammatory bowel diseases

Upadacitinib Induction and Maintenance Therapy for Crohn's Disease

BACKGROUND

Upadacitinib, an oral selective Janus kinase (JAK) inhibitor, is under investigation for the treatment of Crohn's disease.

METHODS

In two phase 3 induction trials (U-EXCEL and U-EXCEED), we randomly assigned patients with moderate-to-severe Crohn's disease to receive 45 mg of upadacitinib or placebo (2:1 ratio) once daily for 12 weeks. Patients who had a clinical response to upadacitinib induction therapy were randomly assigned in the U-ENDURE maintenance trial to receive 15 mg of upadacitinib, 30 mg of upadacitinib, or placebo (1:1:1 ratio) once daily for 52 weeks. The primary end points for induction (week 12) and maintenance (week 52) were clinical remission (defined as a Crohn's Disease Activity Index score of <150 [range, 0 to 600, with higher scores indicating more severe disease activity]) and endoscopic response (defined as a decrease in the Simple Endoscopic Score for Crohn's Disease [SES-CD; range, 0 to 56, with higher scores indicating more severe disease] of >50% from baseline of the induction trial [or for patients with an SES-CD of 4 at baseline, a decrease of ≥2 points from baseline]).

RESULTS

A total of 526 patients underwent randomization in U-EXCEL, 495 in U-EXCEED, and 502 in U-ENDURE. A significantly higher percentage of patients who received 45-mg upadacitinib than those who received placebo had clinical remission (in U-EXCEL, 49.5% vs. 29.1%; in U-EXCEED, 38.9% vs. 21.1%) and an endoscopic response (in U-EXCEL, 45.5% vs. 13.1%; in U-EXCEED, 34.6% vs. 3.5%) (P<0.001 for all comparisons). At week 52 in U-ENDURE, a higher percentage of patients had clinical remission with 15-mg upadacitinib (37.3%) or 30-mg upadacitinib (47.6%) than with placebo (15.1%), and a higher percentage had an endoscopic response with 15-mg upadacitinib (27.6%) or 30-mg upadacitinib (40.1%) than with placebo (7.3%) (P<0.001 for all comparisons). Herpes zoster infections occurred more frequently in the 45-mg and 30-mg upadacitinib groups than in the respective placebo groups, and hepatic disorders and neutropenia were more frequent in the 30-mg upadacitinib group than in the other maintenance groups. Gastrointestinal perforations developed in 4 patients who received 45-mg upadacitinib and in 1 patient each who received 30-mg or 15-mg upadacitinib.

CONCLUSIONS

Upadacitinib induction and maintenance treatment was superior to placebo in patients with moderate-to-severe Crohn's disease. (Funded by AbbVie; U-EXCEL, U-EXCEED, and U-ENDURE ClinicalTrials.gov numbers, NCT03345849, NCT03345836, and NCT03345823.).

Current advances in the anti-inflammatory effects and mechanisms of natural polysaccharides

Inflammatory bowel disease (IBD) is a chronic, multifactorial and inflammatory disease occurring in the colon tract. Bioactive polysaccharides from natural resources have attracted extensive attention due to their safety, accessibility and good bioactivities. In recent years, a variety of natural bioactive polysaccharides have been proven to possess anti-inflammatory effects on treating acute colitis. The objective of this review was to give an up-to-date review on the anti-inflammatory effects and mechanisms of natural polysaccharides on acute colitis. The anti-inflammatory effects of natural polysaccharides on acute colitis concerning clinical symptoms amelioration, colon tissue repairment, anti-oxidative stress alleviation, anti-inflammation, immune regulation, and gut microbiota modulation were comprehensively summarized. In addition, inducible murine models for assessing the anti-inflammatory effects of natural polysaccharides on acute colitis were also concluded. This review will offer the comprehensive understanding of anti-inflammatory mechanisms of natural polysaccharides in acute colitis, and render theoretical basis for the development and application of natural polysaccharides in drug and functional food.

Neuronal IL-4Rα modulates neuronal apoptosis and cell viability during the acute phases of cerebral ischemia

Ischemic stroke caused by an embolus or local thrombosis results in neural tissue damage (an infarct) in the territory of the occluded cerebral artery. Decades of studies have increased our understanding of the molecular events during cerebral infarction; however, translation of these discoveries to druggable targets for ischemic stroke treatment has been largely disappointing. Interleukin-4 (IL-4) is a multifunctional cytokine that exerts its cellular activities via the interleukin-4 receptor α (IL-4Rα). This cytokine receptor complex is associated with diverse immune and inflammatory responses. Recent studies have suggested a role of the cytokine IL-4 in long-term ischemic stroke recovery, involving immune cell activity. In contrast, the role of the receptor, IL-4Rα especially in the acute phase of infarction is unclear. In this study, we determined that IL-4Rα is expressed on neurons and that during the early phases of cerebral infarction (24 h) levels of this receptor are increased to regulate cellular apoptosis factors through activation of STAT6. In this context, we show a neuroprotective role for IL-4Rα in an in vivo surgical model of cerebral ischemia and in ex vivo brain slice explants, using both genetic knockout of this receptor and RNAi-mediated gene knockdown. IL-4Rα may therefore represent a novel target and pathway for therapeutic development in ischemic stroke.

Effector/memory CD4 T cells making either Th1 or Th2 cytokines commonly co-express T-bet and GATA-3

Naïve CD4 T (NCD4T) cells post-activation undergo programming for inducible production of cytokines leading to generation of memory cells with various functions. Based on cytokine based polarization of NCD4T cells in vitro, programming for either ‘Th1’ (interferon-gamma [IFNg]) or ‘Th2’ (interleukin [IL]-4/5/13) cytokines is thought to occur via mutually exclusive expression and functioning of T-bet or GATA-3 transcription factors (TFs). However, we show that a high proportion of mouse and human memory-phenotype CD4 T (MCD4T) cells generated in vivo which expressed either Th1 or Th2 cytokines commonly co-expressed T-bet and GATA-3. While T-bet levels did not differ between IFNg-expressing and IL-4/5/13-expressing MCD4T cells, GATA-3 levels were higher in the latter. These observations were also confirmed in MCD4T cells from FVB/NJ or aged C57BL/6 or IFNg-deficient mice. While MCD4T cells from these strains showed greater Th2 commitment than those from young C57BL/6 mice, pattern of co-expression of TF was similar. Effector T cells generated in vivo following immunization also showed TF co-expression in Th1 or Th2 cytokine producing cells. We speculated that the difference in TF expression pattern of MCD4T cells generated in vivo and those generated in cytokine polarized cultures in vitro could be due to relative absence of polarizing conditions during activation in vivo. We tested this by NCD4T cell activation in non-polarizing conditions in vitro. Anti-CD3 and anti-CD28-mediated priming of polyclonal NCD4T cells in vitro without polarizing milieu generated cells that expressed either IFNg or IL-4/5/13 but not both, yet both IFNg- and IL-4/5/13-expressing cells showed upregulation of both TFs. We also tested monoclonal T cell populations activated in non-polarizing conditions. TCR-transgenic NCD4T cells primed in vitro by cognate peptide in non-polarizing conditions which expressed either IFNg or IL-4/5/13 also showed a high proportion of cells co-expressing TFs, and their cytokine commitment varied depending on genetic background or priming conditions, without altering pattern of TF co-expression. Thus, the model of mutually antagonistic differentiation programs driven by mutually exclusively expressed T-bet or GATA-3 does not completely explain natural CD4 T cell priming outcomes.

Enteric bacteria and cancer stem cells

Intestinal bacteria can contribute to cell proliferation and cancer development, particularly in chronic infectious diseases in which bacteria and/or bacterial components might interfere with cell function. The number of microbial cells within the gut lumen is estimated to be 100 trillion, which is about 10-times larger than the number of eukaryotic cells in the human body. Because of the complexity of the gut flora, identifying the specific microbial agents related to human diseases remains challenging. Recent studies have demonstrated that the stemness of colon cancer cells is, in part, orchestrated by the microenvironment and is defined by high Wnt activity. In this review article, we will discuss recent progress with respect to intestinal stem cells, cancer stem cells, and the molecular mechanisms of enteric bacteria in the activation of the Wnt pathway. We will also discuss the roles of other pathways, including JAK-STAT, JNK, and Notch, in regulating stem cell niches during bacterial infections using Drosophila models. Insights gained from understanding how host-bacterial interaction during inflammation and cancer may serve as a paradigm for understanding the nature of self-renewal signals.

Phytosphingosine derivatives ameliorate skin inflammation by inhibiting NF-κB and JAK/STAT signaling in keratinocytes and mice

Phytosphingosine is abundant in plants and fungi and is found in mammalian epidermis, including the stratum corneum. Phytosphingosine and its derivatives N-acetyl phytosphingosine and tetraacetyl phytosphingosine are part of the natural defense system of the body. However, these molecules exhibit strong toxicities at high concentrations. We synthesized phytosphingosine derivatives, mYG-II-6 ((Z)-4-oxo-4-(((2S,3S,4R)-1,3,4-trihydroxyoctadecan-2-yl)amino)but-2-enoic acid) and fYG-II-6 ((E)-4-oxo-4-(((2S,3S,4R)-1,3,4-trihydroxyoctadecan-2-yl)amino)but-2-enoic acid), to increase efficacy and decrease toxicity, and the biological activities of the derivatives in the inflammatory response were examined. Both YG-II-6 compounds effectively suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammatory skin damage and inflammatory response in a mouse model. In addition, topical application of fYG-II-6 suppressed ear swelling and psoriasiform dermatitis in the ears of IL-23-injected mice. Anti-inflammatory and antipsoriatic activities of the phytosphingosine derivatives inhibited NF-κB, JAK/signal transducer and activator of transcription (JAK/STAT), and mitogen-activated protein kinase (MAPK) signaling. Finally, the YG-II-6 compounds induced programmed cell death in keratinocytes and mouse skin and were less toxic than phytosphingosine. Our study demonstrated that the phytosphingosine-derived YG-II-6 compounds have much stronger biological potencies than the lead compounds. The YG-II-6 compounds ameliorated inflammatory skin damage. Thus, YG-II-6 compounds are potential topical agents for treating chronic inflammatory skin diseases, such as psoriasis.

Global analysis of the eukaryotic pathways and networks regulated by Salmonella typhimurium in mouse intestinal infection in vivo

BACKGROUND

Acute enteritis caused by Salmonella is a public health concern. Salmonella infection is also known to increase the risk of inflammatory bowel diseases and cancer. Therefore, it is important to understand how Salmonella works in targeting eukaryotic pathways in intestinal infection. However, the global physiological function of Salmonella typhimurium in intestinal mucosa in vivo is unclear. In this study, a whole genome approach combined with bioinformatics assays was used to investigate the in vivo genetic responses of the mouse colon to Salmonella. We focused on the intestinal responses in the early stage (8 hours) and late stage (4 days) after Salmonella infection.

RESULTS

Of the 28,000 genes represented on the array, our analysis of mRNA expression in mouse colon mucosa showed that a total of 856 genes were expressed differentially at 8 hours post-infection. At 4 days post-infection, a total of 7558 genes were expressed differentially. 23 differentially expressed genes from the microarray data was further examined by real-time PCR. Ingenuity Pathways Analysis identified that the most significant pathway associated with the differentially expressed genes in 8 hours post-infection is oxidative phosphorylation, which targets the mitochondria. At the late stage of infection, a series of pathways associated with immune and inflammatory response, proliferation, and apoptosis were identified, whereas the oxidative phosphorylation was shut off. Histology analysis confirmed the biological role of Salmonella, which induced a physiological state of inflammation and proliferation in the colon mucosa through the regulation of multiple signaling pathways. Most of the metabolism-related pathways were targeted by down-regulated genes, and a general repression process of metabolic pathways was observed. Network analysis supported IFN-γ and TNF-α function as mediators of the immune/inflammatory response for host defense against pathogen.

CONCLUSION

Our study provides novel genome-wide transcriptional profiling data on the mouse colon mucosa's response to the Salmonella typhimurium infection. Building the pathways and networks of interactions between these genes help us to understand the complex interplay in the mice colon during Salmonella infection, and further provide new insights into the molecular cascade, which is mobilized to combat Salmonella-associated colon infection in vivo.

Aberrant activation of nuclear factor of activated T cell 2 in lamina propria mononuclear cells in ulcerative colitis

AIM: To investigate the role of nuclear factor of activated T cell 2 (NFAT2), the major NFAT protein in peripheral T cells, in sustained T cell activation and intractable inflammation in human ulcerative colitis (UC).

METHODS: We used two-dimensional gel-electrophoresis, immunohistochemistry, double immunohistochemical staining, and confocal microscopy to inspect the expression of NFAT2 in 107, 15, 48 and 5 cases of UC, Crohn’s disease (CD), non-specific colitis, and 5 healthy individuals, respectively.

RESULTS: Up-regulation with profound nucleo-translocation/activation of NFAT2 of lamina propria mononuclear cells (LPMC) of colonic mucosa was found specifically in the affected colonic mucosa from patients with UC, as compared to CD or NC (P < 0.001, Kruskal-Wallis test). Nucleo-translocation/activation of NFAT2 primarily occurred in CD8+T, but was less prominent in CD4+ T cells or CD20+B cells. It was strongly associated with the disease activity, including endoscopic stage (τ = 0.2145, P = 0.0281) and histologic grade (τ = 0.4167, P < 0.001).

CONCLUSION: We disclose for the first time the nucleo-translocation/activatin of NFAT2 in lamina propria mononuclear cells in ulcerative colitis. Activation of NFAT2 was specific for ulcerative colitis and highly associated with disease activity. Since activation of NFAT2 is implicated in an auto-regulatory positive feedback loop of sustained T-cell activation and NFAT proteins play key roles in the calcium/calcineurin signaling pathways, our results not only provide new insights into the mechanism for sustained intractable inflammation, but also suggest the calcium-calcineurin/NFAT pathway as a new therapeutic target for ulcerative colitis.

Activation of STAT3 in thymic epithelial tumours correlates with tumour type and clinical behaviour

The STAT3 (signal transducers and activators of transcription 3) signalling pathway plays a pivotal role in oncogenesis and appears essential for postnatal maintenance of thymic architecture and thymocyte survival. The association of STAT3 activation with thymic epithelial tumours (TETs) and myasthenia gravis (MG) has not been elucidated. In this study, 118 cases of TET and 25 non-neoplastic thymic tissue samples were evaluated for STAT3 and phospho-STAT3 (pSTAT3) expression immunohistochemically. In addition, 44 normal thymuses of different ages were included for comparison. It was found that STAT3 activation in thymic epithelial cells (TECs), as evidenced by pSTAT3 expression and/or nuclear STAT3, was present in the majority of non-neoplastic thymuses (88%, 22/25), including those from young children, but not in fetal thymus. In thymoma (n = 73), activated STAT3 was noted at a significantly higher frequency in the cases of lymphocyte-rich thymoma (ie types AB, B1, and B2, 46%, 23/50) in comparison with lymphocyte-depleted thymoma (types A and B3, 1/23) (p = 0.009). Thymoma with activated STAT3 tended to present at an earlier stage, show complete resectability and less aggressive behaviour, and have a higher correlation with MG than the STAT3-negative/inactive group (p < 0.05). In contrast, thymic carcinoma with activated STAT3 (14/45, 31%) had significantly higher rates of unresectability, vascular invasion, and regional lymph node metastasis (p < 0.05). These data provide the first evidence that constitutive STAT3 activation is seen in both benign and neoplastic thymic tissue and is associated with the persistence of thymic tissue and the presence of MG. It is likely to be induced by different factors in thymoma and thymic carcinoma.

Smad7 in TGF-beta-mediated negative regulation of gut inflammation

Mice with targeted disruptions of the transforming growth factor-beta1 (TGF-beta1) gene or TGF-beta1 intracellular signalling pathways develop intestinal inflammation. Conversely, TGF-beta1-producing regulatory T cells protect against experimental colitis. Paradoxically, however, TGF-beta1 production is high in the gut of patients with chronic inflammatory intestinal disease, and yet inflammation proceeds unchecked. Here we discuss the functional role of Smad7, an intracellular inhibitor of TGF-beta1 signalling, in the control of gut inflammation by TGF-beta1. In particular, we delineate a scenario in which the high expression of Smad7 in inflammatory cells renders them unresponsive to TGF-beta1 and propose that control of Smad7, not TGF-beta1 production, is a key determinant in understanding how TGF-beta1 negatively regulates gut inflammation.

Extracorporeal Photopheresis Differentially Regulates the Expression of Phosphorylated STAT-1 and STAT-5 in Treated Monocytes and T cells, Respectively

BACKGROUND

Extracorporeal photopheresis (ECP) is effective in conditions with opposing immune etiology. ECP induces an immunomodulatory response through simultaneous monocyte activation and apoptosis induction of lymphocytes. However, ECP is also immunosuppressive, downregulating proinflammatory cytokines. Signal transducers and activators of transcription (STATs) are important mediators of cell-signaling systems, including cytokines. Ultraviolet (UV) immunosuppression is linked to reductions in cytokine-induced STAT phosphorylation.

OBJECTIVE

The aim of this study was to find whether ECP downregulates STAT phosphorylation.

METHODS

Pre- and post-ECP mononuclear cells from cutaneous T-cell lymphoma and chronic graft-versus-host disease patients were stimulated with either IFNbeta, IL2, or IL15. The percentage of IFNbeta-stimulated monocytes positive for phosphorylated STAT-1 (pSTAT-1) and the number of IL2- and IL15-stimulated T cells expressing phosphorylated STAT-5 (pSTAT-5) were determined at 0 and 24 h.

RESULTS

Post-ECP, pSTAT-1 levels in monocytes remained unchanged; however, at 24 h post-ECP the number of T cells expressing pSTAT-5 was reduced.

CONCLUSION

Following ECP, monocytes retain their ability to phosphorylate STAT-1, while pSTAT-5 expression is lost in lymphocytes. This differential effect of ECP may account for the diverse population of diseases that benefit.