Treatment Perspectives in Crohn's Disease

Interferons at the crossroad of cell death pathways during gastrointestinal inflammation and infection

Interferons (IFNs) are pleiotropic immune-modulatory cytokines that are well known for their essential role in host defense against viruses, bacteria, and other pathogenic microorganisms. They can exert both, protective or destructive functions depending on the microorganism, the targeted tissue and the cellular context. Interferon signaling results in the induction of IFN-stimulated genes (ISGs) influencing different cellular pathways including direct anti-viral/anti-bacterial response, immune-modulation or cell death. Multiple pathways leading to host cell death have been described, and it is becoming clear that depending on the cellular context, IFN-induced cell death can be beneficial for both: host and pathogen. Accordingly, activation or repression of corresponding signaling mechanisms occurs during various types of infection but is also an important pathway for gastrointestinal inflammation and tissue damage. In this review, we summarize the role of interferons at the crossroad of various cell death pathways in the gut during inflammation and infection.

Clinical Practice of Adalimumab and Infliximab Biosimilar Treatment in Adult Patients With Crohn's Disease

The introduction of tumor necrosis factor (TNF) inhibitors has significantly changed the treatment landscape in Crohn's disease (CD). The overall therapeutic achievements with TNF inhibitors such as infliximab, adalimumab, and certolizumab pegol paved the way to push the boundaries of treatment goals beyond symptomatic relief and toward cessation of objective signs of inflammation, including endoscopic remission. Even though these agents are widely used for the treatment of moderate to severe CD, heterogeneity still exists in translating evidence-based guidelines on the use of anti-TNF agents into actual treatment algorithms in CD. This might be due to several reasons including disparities in health expenditure policies; lack of harmonization between countries; and variations in assessment of disease severity, use of disease monitoring tools, or application of treatment targets by physicians. With the advent of biosimilars, patent-free versions of reference biologics are now available to minimize health inequalities in drug availability. In this context, this article aims to provide practical clinical guidance for the use of infliximab and adalimumab biosimilars in patients with moderate to severe CD by outlining different clinical scenarios that patients may encounter during their treatment journey.

Interferon Lambda Promotes Paneth Cell Death Via STAT1 Signaling in Mice and Is Increased in Inflamed Ileal Tissues of Patients With Crohn's Disease

BACKGROUND & AIMS

Interferon lambda (IFNL) is expressed at high levels by intestinal epithelial cells (IECs) and mucosal immune cells in response to infection and inflammation. We investigated whether IFNL might contribute to pathogenesis of Crohn's disease (CD).

METHODS

We obtained serum samples and terminal ileum biopsies from 47 patients with CD and 16 healthy individuals (controls). We measured levels of IFNL by enzyme-linked immunosorbent assay and immunohistochemistry and location of expression by confocal microscopy. Activation of IFNL signaling via STAT1 was measured in areas of no, mild, moderate, and severe inflammation and correlated with Paneth cell homeostasis and inflammation. IFNL expression and function were studied in wild-type mice and mice with intestinal epithelial cell-specific (ΔIEC) disruption or full-body disruption of specific genes (Mlkl^-/-, Stat1^ΔIEC, Casp8^ΔIEC, Casp8^ΔIECRipk3^-/-, Casp8^ΔIECTnfr^-/-, Casp8^ΔIECMlkl^-/-, and Nod2^-/- mice). Some mice were given tail vein injections of a vector encoding a secreted form of IFNL. Intestinal tissues were collected from mice and analyzed by immunohistochemistry and immunoblots. We generated 3-dimensional small intestinal organoids from mice and studied the effects of IFNL and inhibitors of STAT-signaling pathway.

RESULTS

Patients with CD had significant increases in serum and ileal levels of IFNL compared with controls. Levels of IFNL were highest in ileum tissues with severe inflammation. High levels of IFNL associated with a reduced number of Paneth cells and increased cell death at the crypt bottom in inflamed ileum samples. Intestinal tissues from the ileum of wild-type mice injected with a vector expressing IFNL had reduced numbers of Paneth cells. IFNL-induced death of Paneth cells in mice did not occur via apoptosis, but required Mixed Lineage Kinase Domain Like (MLKL) and activation of Signal transducer and activator of transcription 1 (STAT1). In organoids, inhibitors of Janus kinase (JAK) signaling via STAT1 (glucocorticoids, tofacitinib, or filgotinib) reduced expression of proteins that mediate cell death and prevented Paneth cell death.

CONCLUSIONS

Levels of IFNL are increased in serum and inflamed ileal tissues from patients with CD and associated with a loss of Paneth cells. Expression of a secreted form of IFNL in mice results in loss of Paneth cells from intestinal tissues, via STAT1 and MLKL, controlled by caspase 8. Strategies to reduce IFNL or block its effects might be developed for treatment of patients with CD affecting the terminal ileum.

Inhibitors of the Janus Kinases: A New Oral Treatment Option for Ulcerative Colitis

BACKGROUND

The treatment of ulcerative colitis (UC) is based on conventional therapies (aminosalicylates, corticosteroids, and immunosuppressants) and when these are ineffective, biologic drugs. However, in a substantial portion of patients undergoing treatment with biologic agents there is primary or secondary loss of response. Thus, new therapeutic options are been actively explored; among these, there is interest in the Janus kinase (JAK) inhibitors, small molecules that can be administered orally.

METHODS

We carried out an extensive literature search concerning the effects of JAK inhibitors for the treatment of patients with UC.

RESULTS

Tofacitinib is the drug more extensively studied in this setting, and it was recently approved in Europe for the treatment of moderate to severe UC. The available data suggest that this drug can be effective in obtaining clinical and endoscopic remission in UC patients unresponsive to other treatments, even in those previously treated with biologic drugs. In addition, the drug was able to improve significantly the quality of life of these patients. There are still few data available for the treatment of UC with other JAK inhibitors.

CONCLUSIONS

The JAK inhibitors, in particular tofacitinib, are a new class of orally administered drugs effective for the treatment of UC. However, more studies are needed to ascertain the safety of tofacitinib in the long term and whether other compounds of this class may be equally effective.