Emma M. Creagh

Of all the gynecologic malignancies, Ovarian cancer (OC) has the highest mortality rate, partly attributable to its propensity for chemotherapy resistance. The most common sub-type of OC is serous, of which High-Grade Serous Ovarian Cancer (HGSOC) is the most lethal sub-type. Elevated expression of Protein Tyrosine Phosphatase 4 A3 (PTP4A3) is implicated in tumour cell invasion and metastasis, by upregulating the PI3K/Akt/mTORC1 axis. Previously we reported PTP4A3 increased the survival of non-serous OC cells in vitro by activating the autophagy pathway. The present study focused on understanding the impact of PTP4A3 on cell growth, proliferation, and autophagy in HGSOC cells. In particular, we sought to understand whether targeting PTP4A3 in cancer cells that overexpress this phosphatase would sensitise HGSOC cells to existing chemotherapeutic drugs. We report that shRNA-mediated gene silencing of PTP4A3 resulted in the upregulation of compensatory mechanisms that may render PTP4A3 targeting redundant as a monotherapy. However, pan-PTP4A inhibition with JMS-053 overcame this. Finally, silencing of PTP4A3 expression sensitized HGSOC cells to clinically relevant chemotherapeutic drugs. Since mAb therapies targeting PTP4A3 are already in clinical trials, therapeutic targeting of PTP4A3 may have significant value in improving outcomes for those patients with HGSOC, in the clinical setting.

Excessive inflammation-associated coagulation is a feature of infectious diseases, occurring in such conditions as bacterial sepsis and COVID-19. It can lead to disseminated intravascular coagulation, one of the leading causes of mortality worldwide. Recently, type I interferon (IFN) signaling has been shown to be required for tissue factor (TF; gene name F3) release from macrophages, a critical initiator of coagulation, providing an important mechanistic link between innate immunity and coagulation. The mechanism of release involves type I IFN-induced caspase-11 which promotes macrophage pyroptosis. Here we find that F3 is a type I IFN-stimulated gene. Furthermore, F3 induction by lipopolysaccharide (LPS) is inhibited by the anti-inflammatory agents dimethyl fumarate (DMF) and 4-octyl itaconate (4-OI). Mechanistically, inhibition of F3 by DMF and 4-OI involves suppression of Ifnb1 expression. Additionally, they block type I IFN- and caspase-11-mediated macrophage pyroptosis, and subsequent TF release. Thereby, DMF and 4-OI inhibit TF-dependent thrombin generation. In vivo, DMF and 4-OI suppress TF-dependent thrombin generation, pulmonary thromboinflammation, and lethality induced by LPS, E. coli, and S. aureus, with 4-OI additionally attenuating inflammation-associated coagulation in a model of SARS-CoV-2 infection. Our results identify the clinically approved drug DMF and the pre-clinical tool compound 4-OI as anticoagulants that inhibit TF-mediated coagulopathy via inhibition of the macrophage type I IFN-TF axis.

Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disease of the gastrointestinal tract, associated with high levels of inflammatory cytokine production. Human caspases-4 and -5, and their murine ortholog caspase-11, are essential components of the innate immune pathway, capable of sensing and responding to intracellular lipopolysaccharide (LPS), a component of Gram-negative bacteria. Following their activation by LPS, these caspases initiate potent inflammation by causing pyroptosis, a lytic form of cell death. While this pathway is essential for host defence against bacterial infection, it is also negatively associated with inflammatory pathologies. Caspases-4/-5/-11 display increased intestinal expression during IBD and have been implicated in chronic IBD inflammation. This review discusses the current literature in this area, identifying links between inflammatory caspase activity and IBD in both human and murine models. Differences in the expression and functions of caspases-4, -5 and -11 are discussed, in addition to mechanisms of their activation, function and regulation, and how these mechanisms may contribute to the pathogenesis of IBD.

Exploring the intricacies of host-pathogen communication is vital in order to understand why some microbes persist within a host, while others are effectively cleared. As such, host-pathogen communication is an urgent area of research underpinning human health and disease, especially given the emerging concerns of antibiotic resistance. Understanding host-pathogen pathways requires intricate knowledge in the fields of both microbiology and immunology. Living in a world of specialists, where scientists sometimes invest their whole career studying one organism, a specific pathway or a protein, multidisciplinary discussions of host-pathogen interactions are highly needed. This international conference will provide such a forum for scientific exchange at the highest level, between scientists from different research areas related to host-pathogen interactions, with the aim to trigger fruitful collaborations addressing the urgent questions in the field. This meeting has an additional special focus of bringing researchers from Ireland, Denmark and Israel together to learn about cutting edge biology and form new collaborations. Thus, the conference will be a showcase for the exciting and original research emanating from these three small but innovative countries.

Chronic inflammation plays an important role in the pathogenesis of oesophageal adenocarcinoma (EAC) and its only known precursor, Barrett’s oesophagus (BE). Recent studies have shown that oesophageal TLR2 levels increase from normal epithelium towards EAC. TLR2 signalling is therefore likely to be important during EAC development and progression, which requires an inflammatory microenvironment. Here, we show that, in response to TLR2 stimulation, BE organoids and early-stage EAC cells secrete pro-inflammatory cytokines and chemokines which recruit macrophages to the tumour site. Factors secreted from TLR2-stimulated EAC cells are shown to subsequently activate TLR2 on naïve macrophages, priming them for inflammasome activation and inducing their differentiation to an M2/TAM-like phenotype. We identify the endogenous TLR2 ligand, HMGB1, as the factor secreted from EAC cells responsible for the observed TLR2-mediated effects on macrophages. Our results indicate that HMGB1 signalling between EAC cells and macrophages creates an inflammatory tumour microenvironment to facilitate EAC progression. In addition to identifying HMGB1 as a potential target for early-stage EAC treatment, our data suggest that blocking TLR2 signalling represents a mechanism to limit HMGB1 release, inflammatory cell infiltration and inflammation during EAC progression.

Western blot and enzyme-linked immunosorbent assay (ELISA) are antibody-mediated techniques which are widely used for the detection and characterization of alterations in host protein expression following H. pylori infection. Both techniques are highly specific and sensitive for protein detection, with Western blot detection sensitivity as low as picogram amounts of the protein of interest, while the typical ELISA detection range is 0.01–0.1 ng. Here we provide an experimental example to demonstrate the application of these techniques for the determination of macrophage inflammatory responses following H. pylori infection.

Caspase-11 is a pro-inflammatory enzyme that is stringently regulated during its expression and activation. As caspase-11 is not constitutively expressed in cells, it requires a priming step for its upregulation, which occurs following the stimulation of pathogen and cytokine receptors. Once expressed, caspase-11 activation is triggered by its interaction with lipopolysaccharide (LPS) from Gram-negative bacteria. Being an initiator caspase, activated caspase-11 functions primarily through its cleavage of key substrates. Gasdermin D (GSDMD) is the primary substrate of caspase-11, and the GSDMD cleavage fragment generated is responsible for the inflammatory form of cell death, pyroptosis, via its formation of pores in the plasma membrane. Thus, caspase-11 functions as an intracellular sensor for LPS and an immune effector. This review provides an overview of caspase-11—describing its structure and the transcriptional mechanisms that govern its expression, in addition to its activation, which is reported to be regulated by factors such as guanylate-binding proteins (GBPs), high mobility group box 1 (HMGB1) protein, and oxidized phospholipids. We also discuss the functional outcomes of caspase-11 activation, which include the non-canonical inflammasome, modulation of actin dynamics, and the initiation of blood coagulation, highlighting the importance of inflammatory caspase-11 during infection and disease.

Peptic ulcers are caused by the interaction between bacterial and host factors. This study demonstrates enhanced expression of caspase-4 in peptic ulcer patient biopsies, indicating that pyroptosis and noncanonical inflammasome activity may be processes involved in peptic ulcer disease. We show that primary murine macrophages infected with Helicobacter pylori upregulate caspase-11 (the ortholog of human caspase-4), activate caspase-1, and secrete IL-1β. We demonstrate that misoprostol (a stable PGE₁ analogue) decreased IL-1β secretion and delayed lethality in vivo in a murine peritonitis model. PGE₂ was shown to inhibit caspase-11–driven pyroptosis and IL-1β secretion in macrophages. Overall, we provide evidence for a pathological role of caspase-4/11 in peptic ulcer disease and propose that targeting caspase-4 or inhibiting pyroptosis may have therapeutic potential in the management of peptic ulcers.