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

IL-20 controls resolution of experimental colitis by regulating epithelial IFN/STAT2 signalling

OBJECTIVE

We sought to investigate the role of interleukin (IL)-20 in IBD and experimental colitis.

DESIGN

Experimental colitis was induced in mice deficient in components of the IL-20 and signal transducer and activator of transcription (STAT)2 signalling pathways. In vivo imaging, high-resolution mini-endoscopy and histology were used to assess intestinal inflammation. We further used RNA-sequencing (RNA-Seq), RNAScope and Gene Ontology analysis, western blot analysis and co-immunoprecipitation, confocal microscopy and intestinal epithelial cell (IEC)-derived three-dimensional organoids to investigate the underlying molecular mechanisms. Results were validated using samples from patients with IBD and non-IBD control subjects by a combination of RNA-Seq, organoids and immunostainings.

RESULTS

In IBD, IL20 levels were induced during remission and were significantly higher in antitumour necrosis factor responders versus non-responders. IL-20RA and IL-20RB were present on IECs from patients with IBD and IL-20-induced STAT3 and suppressed interferon (IFN)-STAT2 signalling in these cells. In IBD, experimental dextran sulfate sodium (DSS)-induced colitis and mucosal healing, IECs were the main producers of IL-20. Compared with wildtype controls, Il20-/-, Il20ra-/- and Il20rb-/- mice were more susceptible to experimental DSS-induced colitis. IL-20 deficiency was associated with increased IFN/STAT2 activity in mice and IFN/STAT2-induced necroptotic cell death in IEC-derived organoids could be markedly blocked by IL-20. Moreover, newly generated Stat2ΔIEC mice, lacking STAT2 in IECs, were less susceptible to experimental colitis compared with wildtype controls and the administration of IL-20 suppressed colitis activity in wildtype animals.

CONCLUSION

IL-20 controls colitis and mucosal healing by interfering with the IFN/STAT2 death signalling pathway in IECs. These results indicate new directions for suppressing gut inflammation by modulating IL-20-controlled STAT2 signals.

Gene expression of pro-inflammatory (IL-8, IL-18, TNF-α, and IFN-γ) and anti-inflammatory (IL-10) cytokines in the duodenum of broiler chickens exposed to lipopolysaccharides from Escherichia coli and Bacillus subtilis

Background and Aim

Intestinal infections are associated with Gram-negative bacteria like Escherichia coli. When eliminated by treatments during replication, E. coli release lipopolysaccharides (LPS) that can activate the intestinal immune system and increase the expression of cytokines, such as interleukin (IL)-8, IL-18, tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ), by the intestinal epithelium under pathological conditions. This study aimed to evaluate the addition of Bacillus subtilis to the duodenal gene expression of pro-inflammatory and anti-inflammatory cytokines in broilers exposed to LPS from E. coli.

Materials and Methods

RNA was extracted using the Zymo Research total RNA commercial kit, according to the manufacturer's specifications, from the intestinal tissue of the duodenum previously resuspended in the lysis buffer of the kit. The expression of the cytokines of interest was measured using the QuantiNova SYBR green real-time polymerase chain reaction kit (Qiagen). Transcript quantification was performed by the ΔΔC(t) method using glyceraldehyde 3-phosphate dehydrogenase as a normalizing constitutive gene.

Results

For the measurement of pro-inflammatory (IL-8, IL-18, TNF-α, and IFN-γ) and anti-inflammatory (IL-10) cytokines, there was no statistically significant difference (p > 0.05) between the basal diet and the diet with antibiotic (avilamycin). There was a statistical difference (p < 0.05) between diets with LPS. The diet with B. subtilis presented the lowest expression; the results differed on each sampling day (days 14, 28, and 42).

Conclusion

A decrease in the expression of pro-inflammatory cytokines (IL-8, IL-18, TNF-α, and IFN-γ) and an increase in IL-10 (anti-inflammatory) was observed; in this way, a balance of the inflammatory response to bacterial infection is achieved, suggesting that the use of B. subtilis as an additive in a broiler diet has a similar effect to that produced with antibiotic growth promoter.

Paneth cells as the cornerstones of intestinal and organismal health: a primer

Paneth cells are versatile secretory cells located in the crypts of Lieberkühn of the small intestine. In normal conditions, they function as the cornerstones of intestinal health by preserving homeostasis. They perform this function by providing niche factors to the intestinal stem cell compartment, regulating the composition of the microbiome through the production and secretion of antimicrobial peptides, performing phagocytosis and efferocytosis, taking up heavy metals, and preserving barrier integrity. Disturbances in one or more of these functions can lead to intestinal as well as systemic inflammatory and infectious diseases. This review discusses the multiple functions of Paneth cells, and the mechanisms and consequences of Paneth cell dysfunction. It also provides an overview of the tools available for studying Paneth cells.

Type I interferon-related kidney disorders

Type I interferon (IFN-I) mediates tissue damage in a wide range of kidney disorders, directly affecting the biology and function of several renal cell types including podocytes, mesangial, endothelial and parietal epithelial cells (PECs).Enhanced IFN-I signalling is observed in the context of viral infections, autoimmunity (e.g., systemic lupus erythematosus, SLE), and the type 1 interferonopathies (T1Is), rare monogenic disorders characterised by constitutive activation of the IFN-I pathway. All of these IFN I-related disorders can cause renal dysfunction, and share pathogenic and histopathological features. Collapsing glomerulopathy, a histopathological lesion characterised by podocyte loss, collapse of the vascular tuft and PEC proliferation, is commonly associated with viral infections, has been described in T1Is such as Aicardi-Goutières syndrome and STING-associated vasculopathy with onset in infancy (SAVI), and can also be induced by recombinant IFN-therapy. In all of these conditions, podocytes and PECs seem to be the primary target of IFN I-mediated damage. Additionally, immune-mediated glomerular injury is common to viral infections, SLE, and T1Is such as COPA syndrome and DNASE1L3 deficiency, diseases in which IFN-I apparently promotes immune-mediated kidney injury. Finally, kidney pathology primarily characterised by vascular lesions (e.g., thrombotic microangiopathy, vasculitis) is a hallmark of the T1I ADA2 deficiency as well as of SLE, viral infections and IFN-therapy.Defining the nosology, pathogenic mechanisms and histopathological patterns of IFN I-related kidney disorders has diagnostic and therapeutic implications, especially considering the likely near-term availability of novel drugs targeting the IFN-I pathway.

Selective tyrosine kinase 2 inhibitors in inflammatory bowel disease

Recent significant advances have been made in the treatment of chronic inflammatory diseases with initiation of the era of biologics. However, an unmet medical need still exists for novel targeted therapies. Compared with biologics, Janus kinase inhibitors (JAKis) are a new drug class of orally administered small molecules that have been shown to efficiently modulate complex cytokine-driven inflammation in preclinical models and human studies. Unfortunately, serious adverse effects have been reported with the first introduced pan-JAKi, tofacitinib. Here, we review tyrosine kinase 2 (TYK2) signaling in the pathophysiology of inflammatory bowel disease (IBD), examine mechanisms of action of selective TYK2 inhibitors (TYK2is), and discuss the potential for these inhibitors in efforts to balance benefits and harms.