DNA sensor-associated type I interferon signaling is increased in ulcerative colitis and induces JAK-dependent inflammatory cell death in colonic organoids

DNA sensor pathways can initiate inflammasome, cell death, and type I interferon (IFN) signaling in immune-mediated inflammatory diseases (IMIDs), including type I interferonopathies. We investigated the involvement of these pathways in the pathogenesis of ulcerative colitis (UC) by analyzing the expression of DNA sensor, inflammasome, and type I IFN biomarker genes in colonic mucosal biopsy tissue from control (n = 31), inactive UC (n = 31), active UC (n = 33), and a UC single-cell RNA-Seq dataset. The effects of type I IFN (IFN-β), IFN-γ, and TNF-α on gene expression, cytokine production, and cell death were investigated in human colonic organoids. In organoids treated with cytokines alone, or in combination with NLR family pyrin domain-containing 3 (NLRP3), caspase, or JAK inhibitors, cell death was measured, and supernatants were assayed for IL-1β/IL-18/CXCL10. The expression of DNA sensor pathway genes-PYHIN family members [absent in melanoma 2 (AIM2), IFI16, myeloid cell nuclear differentiation antigen (MNDA), and pyrin and HIN domain family member 1 (PYHIN1)- as well as Z-DNA-binding protein 1 (ZBP1), cyclic GMP-AMP synthase (cGAS), and DDX41 was increased in active UC and expressed in a cell type-restricted pattern. Inflammasome genes (CASP1, IL1B, and IL18), type I IFN inducers [stimulator of interferon response cGAMP interactor 1 (STING), TBK1, and IRF3), IFNB1, and type I IFN biomarker genes (OAS2, IFIT2, and MX2) were also increased in active UC. Cotreatment of organoids with IFN-β or IFN-γ in combination with TNFα increased expression of IFI16, ZBP1, CASP1, cGAS, and STING induced cell death and IL-1β/IL-18 secretion. This inflammatory cell death was blocked by the JAK inhibitor tofacitinib but not by inflammasome or caspase inhibitors. Increased type I IFN activity may drive elevated expression of DNA sensor genes and JAK-dependent but inflammasome-independent inflammatory cell death of colonic epithelial cells in UC.NEW & NOTEWORTHY This study found that patients with active UC have significantly increased colonic gene expression of cytosolic DNA sensor, inflammasome, STING, and type I IFN signaling pathways. The type I IFN, IFN-β, in combination with TNF-α induced JAK-dependent but NLRP3 and inflammasome-independent inflammatory cell death of colonic organoids. This novel inflammatory cell death phenotype is relevant to UC immunopathology and may partially explain the efficacy of the JAKinibs tofacitinib and upadacitinib in patients with UC.

TNF-α synergises with IFN-γ to induce caspase-8-JAK1/2-STAT1-dependent death of intestinal epithelial cells

Rewiring of host cytokine networks is a key feature of inflammatory bowel diseases (IBD) such as Crohn's disease (CD). Th1-type cytokines-IFN-γ and TNF-α-occupy critical nodes within these networks and both are associated with disruption of gut epithelial barrier function. This may be due to their ability to synergistically trigger the death of intestinal epithelial cells (IECs) via largely unknown mechanisms. In this study, through unbiased kinome RNAi and drug repurposing screens we identified JAK1/2 kinases as the principal and nonredundant drivers of the synergistic killing of human IECs by IFN-γ/TNF-α. Sensitivity to IFN-γ/TNF-α-mediated synergistic IEC death was retained in primary patient-derived intestinal organoids. Dependence on JAK1/2 was confirmed using genetic loss-of-function studies and JAK inhibitors (JAKinibs). Despite the presence of biochemical features consistent with canonical TNFR1-mediated apoptosis and necroptosis, IFN-γ/TNF-α-induced IEC death was independent of RIPK1/3, ZBP1, MLKL or caspase activity. Instead, it involved sustained activation of JAK1/2-STAT1 signalling, which required a nonenzymatic scaffold function of caspase-8 (CASP8). Further modelling in gut mucosal biopsies revealed an intercorrelated induction of the lethal CASP8-JAK1/2-STAT1 module during ex vivo stimulation of T cells. Functional studies in CD-derived organoids using inhibitors of apoptosis, necroptosis and JAKinibs confirmed the causative role of JAK1/2-STAT1 in cytokine-induced death of primary IECs. Collectively, we demonstrate that TNF-α synergises with IFN-γ to kill IECs via the CASP8-JAK1/2-STAT1 module independently of canonical TNFR1 and cell death signalling. This non-canonical cell death pathway may underpin immunopathology driven by IFN-γ/TNF-α in diverse autoinflammatory diseases such as IBD, and its inhibition may contribute to the therapeutic efficacy of anti-TNFs and JAKinibs.

12-month interim results of a prospective study of patients with mild to moderate open-angle glaucoma undergoing combined viscodilation of Schlemm's canal and collector channels and 360° trabeculotomy as a standalone procedure or combined with cataract surgery

PURPOSE

To characterize clinical outcomes of combined viscodilation of Schlemm's canal and collector channels and 360° trabeculotomy as a standalone procedure or combined with cataract surgery in eyes with mild to moderate open-angle glaucoma (OAG).

METHODS

In this prospective case series, the OMNI glaucoma surgical platform (Sight Sciences, Menlo Park, CA) was utilized to perform the procedure either combined with phacoemulsification or as a standalone procedure. Changes from baseline in intraocular pressure (IOP) and IOP-lowering medications were evaluated through the first 12 months of a planned 24-month follow-up period.

RESULTS

Among 17 eyes of 15 subjects, mean IOP was reduced from 20.4 mmHg to 12.7-13.7 mmHg through 12 months of follow-up (p < 0.001 at every time point) and mean medications reduced from 2.5 to 0.1-0.6 (p < 0.001 at every time point). IOP reductions in eyes undergoing standalone surgery were approximately 2-4 mmHg greater at each time point compared to eyes undergoing surgery combined with phacoemulsification; this may be related to a higher baseline IOP in the former eyes (22.1 vs 18.5 mmHg). Six eyes developed hyphema, of which three required washout for elevated IOP on the first postoperative day; six additional eyes had IOP elevations that resolved with medical management.

CONCLUSION

Viscodilation of Schlemm's canal and collector channels paired with ab interno trabeculotomy performed with a single integrated instrument (OMNI), whether as standalone or combined with phacoemulsification, effectively lowers both IOP and the need for IOP-lowering medications through 12 months of follow-up.

Timed degradation of Mcl-1 controls mitotic cell death

Mitotic arrest can result in cell death through the process of apoptosis. We have shown by live-cell imaging that the ubiquitin-proteasome dependent proteolysis of the apoptotic regulator Mcl-1 under the control of the anaphase-promoting complex or cyclosome (APC/C) provides a timing mechanism that distinguishes prolonged mitotic arrest from normal mitosis.

Atypical APC/C-dependent degradation of Mcl-1 provides an apoptotic timer during mitotic arrest

The initiation of apoptosis in response to the disruption of mitosis provides surveillance against chromosome instability. Here, we show that proteolytic destruction of the key regulator Mcl-1 during an extended mitosis requires the anaphase-promoting complex or cyclosome (APC/C) and is independent of another ubiquitin E3 ligase, SCFFbw7 Using live-cell imaging, we show that the loss of Mcl-1 during mitosis is dependent on a D box motif found in other APC/C substrates, while an isoleucine-arginine (IR) C-terminal tail regulates the manner in which Mcl-1 engages with the APC/C, converting Mcl-1 from a Cdc20-dependent and checkpoint-controlled substrate to one that is degraded independently of checkpoint strength. This mechanism ensures a relatively slow but steady rate of Mcl-1 degradation during mitosis and avoids its catastrophic destruction when the mitotic checkpoint is satisfied, providing an apoptotic timer that can distinguish a prolonged mitotic delay from normal mitosis. Importantly, we also show that inhibition of Cdc20 promotes mitotic cell death more effectively than loss of APC/C activity through differential effects on Mcl-1 degradation, providing an improved strategy to kill cancer cells.

USP9X Limits Mitotic Checkpoint Complex Turnover to Strengthen the Spindle Assembly Checkpoint and Guard against Chromosomal Instability

Faithful chromosome segregation during mitosis depends on the spindle assembly checkpoint (SAC), which delays progression through mitosis until every chromosome has stably attached to spindle microtubules via the kinetochore. We show here that the deubiquitinase USP9X strengthens the SAC by antagonizing the turnover of the mitotic checkpoint complex produced at unattached kinetochores. USP9X thereby opposes activation of anaphase-promoting complex/cyclosome (APC/C) and specifically inhibits the mitotic degradation of SAC-controlled APC/C substrates. We demonstrate that depletion or loss of USP9X reduces the effectiveness of the SAC, elevates chromosome segregation defects, and enhances chromosomal instability (CIN). These findings provide a rationale to explain why loss of USP9X could be either pro- or anti-tumorigenic depending on the existing level of CIN.

The role of serum I-FABP concentration in assessment of small intestine mucosa among HIV-infected patients

Objectives:

The intestinal fatty acid binding protein (I-FABP) is a useful marker in the assessment of damages and inflammation to the small intestinal mucosa. We have investigated the influence of HIV infections and antiretroviral treatment on the small intestine mucosa aided by the evaluation of I-FABP concentration levels.

Methods:

We included in the study: 31 HIV-infected patients with antiretroviral therapy (ART) treatment (T), 32 HIV-infected patients not treated with ART (NT), and 18 healthy volunteers as a control group. The concentrations of I-FABP were measured in serum using a sandwich enzyme immunoassay kit: Human I-FABP.

Results:

The median level of I-FABP in the serum of HIV-infected patients was 2.10 ± 2.56 ng/mL and did not significantly differ between T and NT (2.32 ± 2.69 ng/mL vs. 1.89 ± 2.45 ng/mL). However, the I-FABP serum level was significantly higher in HIV-infected patients when compared to the group control (2.10 ± 2.56 ng/mL vs. 1.26 ± 1.18 ng/mL; P = 0.048). We recorded a correlation for treated HIV-infected patients between Viral load and I-FABP serum level (r = −0.66; P <0.05).

Conclusions:

Elevated serum I-FABP level in HIV-infected patients confirm that HIV causes damage to the intestinal mucosa. I-FAB is a useful marker in the assessment of intestinal damage in HIV-infected patients.

Innate immune properties of selected human neuropeptides against Moraxella catarrhalis and nontypeable Haemophilus influenzae

Background

Considerable evidence supports the concept of active communication between the nervous and immune systems. One class of such communicators are the neuropeptides (NPs). Recent reports have highlighted the antimicrobial activity of neuropeptides, placing them among the integral components of innate immune defense. This study examined the action of four human neuropeptides: calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), substance P (SP) and somatostatin (SOM), which are accessible in the upper respiratory tract, against two human-specific respiratory pathogens. We studied: (i) neuropeptide-mediated direct antibacterial activity exerted against Moraxella catarrhalis and nontypeable Haemophilus influenzae, and (ii) indirect immunomodulatory role of these neuropeptides in the neutrophil-mediated phagocytosis of indicated pathogens.

Results

We found that 100 micromolar concentrations of CGRP, NPY, SP, and SOM effectively permeabilized bacterial membranes and showed (except SOM) bactericidal activity against both pathogens. SOM acted only bacteriostatically. However the killing efficacy was dependent on the bactericidal assay used. The rank order of killing NP effect was: NPY ≥ CGRP > SP >> SOM and correlated with their potency to permeabilize bacterial membranes. The killing and permeabilization activity of the analyzed NPs showed significant correlation with several physicochemical properties and amino acid composition of the neuropeptides. M. catarrhalis was more sensitive to neuropeptides than nontypeable H. influenzae.

The immunomodulatory bimodal effect of physiological concentrations of CGRP, NPY, and SP on the phagocytic function of human neutrophils against M. catarrhalis and H. influenzae was observed both in the ingestion (pathogen uptake) and reactive oxygen species generation stages. This effect was also dependent on the distinct type of pathogen recognition (opsonic versus nonopsonic).

Conclusions

The present results indicate that neuropeptides such as CGRP, NPY, and SP can effectively participate in the direct and indirect elimination of human-specific respiratory pathogens. Because the studied NPs show both direct and indirect modulating antimicrobial potency, they seem to be important molecules involved in the innate host defense against M. catarrhalis and nontypeable H. influenzae.

Identification of essential and non-essential single-stranded DNA-binding proteins in a model archaeal organism

Single-stranded DNA-binding proteins (SSBs) play vital roles in all aspects of DNA metabolism in all three domains of life and are characterized by the presence of one or more OB fold ssDNA-binding domains. Here, using the genetically tractable euryarchaeon Haloferax volcanii as a model, we present the first genetic analysis of SSB function in the archaea. We show that genes encoding the OB fold and zinc finger-containing RpaA1 and RpaB1 proteins are individually non-essential for cell viability but share an essential function, whereas the gene encoding the triple OB fold RpaC protein is essential. Loss of RpaC function can however be rescued by elevated expression of RpaB, indicative of functional overlap between the two classes of haloarchaeal SSB. Deletion analysis is used to demonstrate important roles for individual OB folds in RpaC and to show that conserved N- and C-terminal domains are required for efficient repair of DNA damage. Consistent with a role for RpaC in DNA repair, elevated expression of this protein leads to enhanced resistance to DNA damage. Taken together, our results offer important insights into archaeal SSB function and establish the haloarchaea as a valuable model for further studies.