Immune responses upon Campylobacter jejuni infection of secondary abiotic mice lacking nucleotide-oligomerization-domain-2

TRIM22 governs tumorigenesis and protects against endometrial cancer-associated cachexia by inhibiting inflammatory response and adipose thermogenic activity

BACKGROUND

Endometrial cancer (EC) is one of the most common cancers in women, with a short overall survival and poor prognosis. Besides the biologically aggressive EC properties, Cancer-associated cachexia is the main factor. However, the detailed mechanism underlying EC-related cachexia and its harmful effects on EC progression and patient prognosis remains unclear.

METHODS

For clinical specimen and the vitro experiment, we detected TRIM22 expression level, EC patients' survival time, EC cell functional change, and adipose thermogenic changes to identify the function of TRIM22 in EC progression, EC-associated cachexia, and their molecular mechanisms. Then, for the vivo experiment, we exploited the xenografts in mice to identify the function of TRIM22 again, and to screen the drug therapeutic schedule.

RESULTS

Herein, we demonstrated that TRIM22 inhibited EC cell growth, invasion, and migration. Interleukin (IL)-6 mediated brown adipose tissue activation and white adipose tissue browning which induced EC-related cachexia. TRIM22 suppressed the EC cells' secretion of IL-6, and IL-6 mediated EC-related cachexia. Mechanistically, TRIM22 inhibited EC progression by suppressing the nucleotide-binding oligomerization domain 2(NOD2)/nuclear factor-kappaB (NF-κB) signaling pathway, with the purpose of impeding the production of IL-6. Moreover, we revealed that TRIM22 inhibited EC-associated cachexia by suppressing the IL-6/IL-6 receptor (IL-6R) signaling pathway. Therapeutically, we demonstrated that combination treatment with a TRIM22 inducer (progesterone) and a thermogenic inhibitor (IL-6R antibody) synergistically augmented the antitumor efficacy of carbotaxol (carboplatin and paclitaxel), in vivo.

CONCLUSION

Our data reveals that TRIM22-EC-IL-6-cachexia cross-communication has important clinical relevance and that the use of combined therapy holds great promise for enhancing the efficacy of anti-ECs. (Fig. graphical abstract).

Novel Clinical Campylobacter jejuni Infection Models Based on Sensitization of Mice to Lipooligosaccharide, a Major Bacterial Factor Triggering Innate Immune Responses in Human Campylobacteriosis

: Human Campylobacter jejuni infections inducing campylobacteriosis including post-infectious sequelae such as Guillain-Barré syndrome and reactive arthritis are rising worldwide and progress into a global burden of high socioeconomic impact. Intestinal immunopathology underlying campylobacteriosis is a classical response of the innate immune system characterized by the accumulation of neutrophils and macrophages which cause tissue destruction, barrier defects and malabsorption leading to bloody diarrhea. Clinical studies revealed that enteritis and post-infectious morbidities of human C. jejuni infections are strongly dependent on the structure of pathogenic lipooligosaccharides (LOS) triggering the innate immune system via Toll-like-receptor (TLR)-4 signaling. Compared to humans, mice display an approximately 10,000 times weaker TLR-4 response and a pronounced colonization resistance (CR) against C. jejuni maintained by the murine gut microbiota. In consequence, investigations of campylobacteriosis have been hampered by the lack of experimental animal models. We here summarize recent progress made in the development of murine C. jejuni infection models that are based on the abolishment of CR by modulating the murine gut microbiota and by sensitization of mice to LOS. These advances support the major role of LOS driven innate immunity in pathogenesis of campylobacteriosis including post-infectious autoimmune diseases and promote the preclinical evaluation of novel pharmaceutical strategies for prophylaxis and treatment.

Campylobacter concisus Impairs Sodium Absorption in Colonic Epithelium via ENaC Dysfunction and Claudin-8 Disruption

The epithelial sodium channel (ENaC) can increase the colonic absorptive capacity for salt and water. Campylobacter concisus is a common pathogenic epsilonproteobacterium, causing enteritis and diarrhea. It can induce barrier dysfunction in the intestine, but its influence on intestinal transport function is still unknown. Therefore, our study aimed to characterize C. concisus effects on ENaC using the HT-29/B6-GR/MR (epithelial cell line HT-29/B6 transfected with glucocorticoid and mineralocorticoid receptors) cell model and mouse colon. In Ussing chambers, C. concisus infection inhibited ENaC-dependent Na⁺ transport as indicated by a reduction in amiloride-sensitive short circuit current (−55%, n = 15, p < 0.001). This occurred via down-regulation of β- and γ-ENaC mRNA expression and ENaC ubiquitination due to extracellular signal-regulated kinase (ERK)1/2 activation, predicted by Ingenuity Pathway Analysis (IPA). In parallel, C. concisus reduced the expression of the sealing tight junction (TJ) protein claudin-8 and induced claudin-8 redistribution off the TJ domain of the enterocytes, which facilitates the back leakage of Na⁺ ions into the intestinal lumen. In conclusion, C. concisus caused ENaC dysfunction via interleukin-32-regulated ERK1/2, as well as claudin-8-dependent barrier dysfunction—both of which contribute to Na⁺ malabsorption and diarrhea.

Human Immunity Against Campylobacter Infection

Campylobacter is a worldwide foodborne pathogen, associated with human gastroenteritis. The efficient translocation of Campylobacter and its ability to secrete toxins into host cells are the 2 key features of Campylobacter pathophysiology which trigger inflammation in intestinal cells and contribute to the development of gastrointestinal symptoms, particularly diarrhoea, in humans. The purpose of conducting this literature review is to summarise the current understanding of: i) the human immune responses involved in the elimination of Campylobacter infection and ii) the resistance potential in Campylobacter against these immune responses. This review has highlighted that the intestinal epithelial cells are the preliminary cells which sense Campylobacter cells by means of their cell-surface and cytosolic receptors, activate various receptors-dependent signalling pathways, and recruit the innate immune cells to the site of inflammation. The innate immune system, adaptive immune system, and networking between these systems play a crucial role in bacterial clearance. Different cellular constituents of Campylobacter, mainly cell membrane lipooligosaccharides, capsule, and toxins, provide protection to Campylobacter against the human immune system mediated killing. This review has also identified gaps in knowledge, which are related to the activation of following during Campylobacter infection: i) cathelicidins, bactericidal permeability-increasing proteins, chemokines, and inflammasomes in intestinal epithelial cells; ii) siglec-7 receptors in dendritic cell; iii) acute phase proteins in serum; and iv) T-cell subsets in lymphoid nodules. This review evaluates the existing literature to improve the understanding of human immunity against Campylobacter infection and identify some of the knowledge gaps for future research.

NOD2 Expression in Intestinal Epithelial Cells Protects Toward the Development of Inflammation and Associated Carcinogenesis

Nucleotide-binding oligomerization domain 2 (NOD2) is an intracellular pattern recognition receptor that senses bacterial peptidoglycan-conserved motifs in cytosol and stimulates host immune response including epithelial and immune cells. The association of NOD2 mutations with a number of inflammatory pathologies including Crohn's disease (CD), graft-versus-host diseases, or Blau syndrome, highlights its pivotal role in inflammatory response and the associated-carcinogenesis development. Since its identification in 2001 and its association with CD, the role of NOD2 in epithelial cells and immune cells has been investigated extensively but the precise mechanism by which NOD2 mutations lead to CD and the associated carcinogenesis development is largely unknown. In this review, we present and discuss recent developments about the role of NOD2 inside epithelial cells on the control of the inflammatory process and its linked carcinogenesis development.

Toll-Like Receptor-4 Dependent Inflammatory Responses Following Intestinal Colonization of Secondary Abiotic IL10-Deficient Mice with Multidrug-Resistant Pseudomonas Aeruginosa

The rising incidences of infections with multidrug-resistant (MDR) Gram-negative bacteria including Pseudomonas aeruginosa (PA) have gained increasing attention in medicine, but also in the general public and global health politics. The mechanisms underlying opportunistic pathogen–host interactions are unclear, however. To address this, we challenged secondary abiotic IL10^–/– mice deficient for Toll-like receptor-4 (TLR4^–/– × IL10^–/–), the main receptor of the Gram-negative cell wall constituent lipopolysaccharide, with a clinical MDR PA isolate. Despite higher intestinal colonization densities, apoptotic colonic epithelial cell numbers were lower in TLR4^–/– × IL10^–/– mice as compared to IL10^–/– controls at day 14 postinfection (p.i.), whereas proliferating/regenerating cells had increased in the latter only. Furthermore, PA-colonized TLR4^–/– × IL10^–/– mice displayed less distinct innate and adaptive immune cell responses in the colon as compared to IL10^–/– counterparts that were accompanied by lower nitric oxide concentrations in mesenteric lymph nodes in the former at day 14 p.i. Conversely, splenic NO levels were higher in both naive and PA-colonized TLR4-deficient IL10^–/– mice versus IL10^–/– controls. Remarkably, intestinal MDR PA was able to translocate to extra-intestinal including systemic compartments of TLR4^–/– × IL10^–/– mice only. Hence, MDR PA-induced intestinal and systemic immune responses observed in secondary abiotic IL10^–/– mice are TLR4-dependent.