UNASSIGNED: Group 3 innate lymphoid cells (ILC3s) are enriched in the intestinal mucosa and play important roles in host defense against infection and inflammatory diseases. Sirtuin 6 (SIRT6) is a nicotinamide adenine dinucleotide (NAD+)- dependent deacetylase and has been shown to control intestinal epithelial cell differentiation and survival. However, the role of SIRT6 in ILC3s remains unknown.
UNASSIGNED: To investigate the role of SIRT6 in gut ILC3s, we generated SIRT6 conditional knockout mice by crossing Rorccre and Sirt6flox/flox mice. Cell number and cytokine production was examined using flow cytometry. Citrobacter rodentium infection and dextran sodium sulfate-induced colitis models were used to determine the role of SIRT6 in gut defense. RT-qPCR, flow cytometry and immunohistochemistry were used to assess the intestinal inflammatory responses.
UNASSIGNED: Here we show that SIRT6 inhibits IL-22 expression in intestinal ILC3s in a cell-intrinsic manner. Deletion of SIRT6 in ILC3s does not affect the cell numbers of total ILC3s and subsets, but results in increased IL-22 production. Furthermore, ablation of SIRT6 in ILC3s protects mice against Citrobacter rodentium infection and dextran sodium sulfate-induced colitis. Our results suggest that SIRT6 may play a role in ILC3 function by regulating gut immune responses against bacterial infection and inflammation.
UNASSIGNED: Our finding provided insight into the relation of epigenetic regulators with IL-22 production and supplied a new perspective for a potential strategy against inflammatory bowel disease.

Interleukin-22, discovered in the year of 2000, is a pleiotropic Th17 cytokine from the IL-10 family of cytokines. IL-22 signals through the type 2 cytokine receptor complex IL-22R and predominantly activates STAT3. This pathway leads to the transcription of several different types of genes, giving IL-22 context-specific functions ranging from inducing antimicrobial peptide expression to target cell proliferation. In recent years, it has been shown that IL-22 is involved in the pathogenesis of neoplasia in some cancers through its pro-proliferative and anti-apoptotic effects. This review highlights studies with recent discoveries and conclusions drawn on IL-22 and its involvement and function in various cancers. Such a study may be helpful to better understand the role of IL-22 in cancer so that new treatment could be developed targeting IL-22.

Mammalian interleukin-22 (IL-22) attenuates organismal injury by inhibiting reactive oxygen species (ROS) and impeding the NLRP3 inflammasome activation. However, the role of fish IL-22 in this process remains unclear. We characterized MaIL-22, an IL-22 homolog in blunt snout bream (Megalobrama amblycephala). Despite its low sequence identity, it shares conserved structures and close evolutionary relationships with other teleost IL-22s. Furthermore, Aeromonas hydrophila (A. hydrophila) infection leads to tissue injury in M. amblycephala immune organs and concomitantly altered Mail-22 mRNA expression, suggesting that MaIL-22 was involved in the antimicrobial immune response. To explore MaIL-22\'s biological functions, we produced recombinant MaIL-22 (rMaIL-22) protein and demonstrated it significantly enhanced the survival of M. amblycephala post-A. hydrophila infection. To unravel its protective mechanisms, we explored the ROS/NLRP3 inflammasome axis and its downstream signaling responses. The results showed that rMaIL-22 treatment significantly elevated antioxidant enzyme (T-SOD, CAT and GSH-PX) activities to inhibit MDA activity and scavenge ROS in visceral tissues. Meanwhile, rMaIL-22 impeded the activation of NLRP3 inflammasome by suppressing NLRP3 protein and mRNA expression. This indicated that rMaIL-22 contributed to inhibit A. hydrophila-induced activation of the ROS/NLRP3 inflammasome axis. Consistent with these findings, rMaIL-22 treatment attenuated the expression of proinflammatory cytokines (il-1β, tnf-α and il-6) and proapoptotic genes (caspase-3 and caspase-8) while promoting antiapoptotic genes (bcl-2b and mcl-1a) expression, ultimately mitigating tissue injury in visceral tissues. In conclusion, our research underscores MaIL-22\'s key role in microbial immune regulation, offering insights for developing IL-22-targeted therapies and breeding programs.

Circular RNAs (circRNAs) are demonstrated to be involved in psoriasis progression. CircRNAs can act as RNA-binding protein (RBP) sponges. Here, we investigated the action of circAKR1B10 in psoriasis, and explored the potential proteins interacted with circAKR1B10. Levels of genes and proteins were assayed by qRT-PCR and western blotting analyses. Keratinocytes in functional groups were treated with interleukin (IL)-22. Functional analysis were conducted using MTT, 5-ethynyl-2\'-deoxyuridine (EdU), and transwell assays, respectively. Interaction analysis among circAKR1B10, Eukaryotic initiation factor 4 A-III (EIF4A3) and Aurora Kinase A (AURKA) was conducted using bioinformatics analysis, RNA pull-down assay, and RNA immunoprecipitation (RIP) assay. CircAKR1B10 was highly expressed in psoriasis patients and IL-22-induced keratinocytes. Functionally, knockdown of circAKR1B10 abolished IL-22-induced proliferation, migration and invasion in keratinocytes. AURKA expression was also higher in psoriasis patients and IL-22-induced keratinocytes, and was negatively correlated with circAKR1B10 expression. Moreover, AURKA silencing reduced the proliferative, migratory and invasive abilities of IL-22-induced keratinocytes. Mechanistically, circAKR1B10 interacted with EIF4A3 protein to stabilize and regulate AURKA expression. CircAKR1B10 contributes to IL-22-induced proliferation, migration and invasion in keratinocytes via up-regulating AURKA expression through interacting with EIF4A3 protein.

Nucleophosmin 1 (NPM1) is commonly mutated in myelodysplastic syndrome (MDS) and acute myeloid leukemia. Concurrent inflammatory bowel diseases (IBD) and MDS are common, indicating a close relationship between IBD and MDS. Here we examined the function of NPM1 in IBD and colitis-associated colorectal cancer (CAC). NPM1 expression was reduced in patients with IBD. Npm1+/- mice were more susceptible to acute colitis and experimentally induced CAC than littermate controls. Npm1 deficiency impaired the function of interleukin-22 (IL-22)-producing group three innate lymphoid cells (ILC3s). Mice lacking Npm1 in ILC3s exhibited decreased IL-22 production and accelerated development of colitis. NPM1 was important for mitochondrial biogenesis and metabolism by oxidative phosphorylation in ILC3s. Further experiments revealed that NPM1 cooperates with p65 to promote mitochondrial transcription factor A (TFAM) transcription in ILC3s. Overexpression of Npm1 in mice enhanced ILC3 function and reduced the severity of dextran sulfate sodium-induced colitis. Thus, our findings indicate that NPM1 in ILC3s protects against IBD by regulating mitochondrial metabolism through a p65-TFAM axis.

Salmonella is a foodborne pathogen that causes disruption of intestinal mucosal immunity, leading to acute gastroenteritis in the host. In this study, we found that Salmonella Typhimurium (STM) infection of the intestinal tract of mice led to a significant increase in the proportion of Lacticaseibacillus, while the secretion of IL-22 from type 3 innate lymphoid cells (ILC3) increased significantly. Feeding Lacticaseibacillus rhamnosus GG (LGG) effectively alleviated the infection of STM in the mouse intestines. TLR2-/- mice experiments found that TLR2-expressing dendritic cells (DCs) are crucial for LGG\'s activation of ILC3. Subsequent in vitro experiments showed that heat-killed LGG (HK-LGG) could promote DCs to secrete IL-23, which in turn further promotes the activation of ILC3 and the secretion of IL-22. Finally, organoid experiments further verified that IL-22 secreted by ILC3 can enhance the intestinal mucosal immune barrier and inhibit STM infection. This study demonstrates that oral administration of LGG is a potential method for inhibiting STM infection.

Inflammatory bowel disease (IBD), including Crohn\'s disease and ulcerative colitis, is a complex gastrointestinal condition influenced by genetic, microbial, and environmental factors, among which the gut microbiota plays a crucial role and has emerged as a potential therapeutic target. Ganoderic acid A (GAA), which is a lanostane triterpenoid compound derived from edible mushroom Ganoderma lucidum, has demonstrated the ability to modulate gut dysbiosis. Thus, we investigated the impact of GAA on IBD using a dextran sodium sulfate (DSS)-induced colitis mouse model. GAA effectively prevented colitis, preserved epithelial and mucus layer integrity, and modulated the gut microbiota. In addition, GAA promoted tryptophan metabolism, especially 3-IAld generation, activated the aryl hydrocarbon receptor (AhR), and induced IL-22 production. Fecal microbiota transplantation validated the mediating role of the gut microbiota in the IBD protection conferred by GAA. Our study suggests that GAA holds potential as a nutritional intervention for ameliorating IBD by influencing the gut microbiota, thereby regulating tryptophan metabolism, enhancing AhR activity, and ultimately improving gut barrier function.

Group 3 innate lymphoid cells (ILC3s) play key roles in intestinal inflammation. Olfactomedin 4 (OLFM4) is highly expressed in the colon and has a potential role in dextran sodium sulfate-induced colitis. However, the detailed mechanisms underlying the effects of OLFM4 on ILC3-mediated colitis remain unclear. In this study, we identify OLFM4 as a positive regulator of IL-22+ILC3. OLFM4 expression in colonic ILC3s increases substantially during intestinal inflammation in humans and mice. Compared to littermate controls, OLFM4-deficient (OLFM4-/-) mice are more susceptible to bacterial infection and display greater resistance to anti-CD40 induced innate colitis, together with impaired IL-22 production by ILC3, and ILC3s from OLFM4-/-mice are defective in pathogen resistance. Besides, mice with OLFM4 deficiency in the RORγt compartment exhibit the same trend as in OLFM4-/-mice, including colonic inflammation and IL-22 production. Mechanistically, the decrease in IL-22+ILC3 caused by OLFM4 deficiency involves the apoptosis signal-regulating kinase 1 (ASK1)- p38 MAPK signaling-dependent downregulation of RAR-related orphan receptor gamma (RORγt) protein. The OLFM4-metadherin (MTDH) complex upregulates p38/RORγt signaling, which is necessary for IL-22+ILC3 activation. The findings indicate that OLFM4 is a novel regulator of IL-22+ILC3 and essential for modulating intestinal inflammation and tissue homeostasis.

BACKGROUND: Colorectal cancer (CRC) is a prevalent malignancy with high morbidity and mortality rates. Previous studies have demonstrated that interleukin (IL)-22 is involved in CRC progression; however, the exact mechanism remains unclear. This study aimed to investigate the effects of IL-22 on CRC cell proliferation and metastasis.
METHODS: IL-22 levels in the serum and tissues of CRC patients were measured using enzyme-linked immunosorbent assay (ELISA). Cell counting kit-8 (CCK-8) assay was used to detect the viability of CRC (HCT116) cells treated with different IL-22 concentrations. Colony formation, Transwell invasion, and scratch assays were employed to assess the effects of IL-22 on cell proliferation, invasion, and migration. Western blotting was performed to measure the expression levels of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), p-PI3K, p-AKT, E-cadherin, matrix metalloproteinase (MMP)-2, MMP-9, SNAI1, and TWIST1 in HCT116 cells treated with IL-22 or a PI3K inhibitor.
RESULTS: ELISA results showed that the expression of IL-22 was significantly increased in the serum and tissues of CRC patients compared to controls. IL-22 treatment increased cell viability and colony formation in a concentration-dependent manner and enhanced cell invasion and migration. Western blotting analysis revealed that IL-22 stimulation upregulated p-PI3K and p-AKT expression, while total PI3K and AKT levels remained unchanged. Additionally, IL-22 also decreased E-cadherin expression and increased the expression of MMP-2, MMP-9, SNAI1, and TWIST1.
CONCLUSIONS: IL-22 activates the PI3K-AKT pathway and promotes HCT116 cell proliferation and metastasis. Targeting the regulation of the PI3K/AKT pathway may be a potential therapeutic strategy for CRC.

BACKGROUND: Intestinal barrier dysfunction is a significant contributor to the recurrence and refractory of ulcerative colitis (UC). Promoting the interaction between group 3 innate lymphoid cells (ILC3s) and gut flora is a valuable strategy for mucosal repair. Paeoniae decoction (PD) is a compound commonly used in clinical treatment of UC, but its exact mechanism remains unclear.
OBJECTIVE: We aimed to investigate the protective effect of PD on intestinal mucosal injury induced by dextran sulfate sodium (DSS) in chronic colitis, as well as to elucidate its potential mechanism.
METHODS: C57BL/6 mice were induced with chronic colitis by 2 % DSS and divided into four groups: control group, model group, PD low dose (4 g/kg), and high dose (8 g/kg) group. The effectiveness of PD in treating chronic colitis mice was evaluated based on changes in body weight, colon length, colon pathological tissue scores, and the mRNA levels of inflammatory factors IL-6 and IL-1β. The expressions of intestinal epithelial tight junction proteins (ZO-1 and Occludin), IL-22, and MUC2 were observed using immunofluorescence and RT-PCR. Additionally, the proportion of ILC3 and natural cytotoxicity receptor (NCR)+ ILC3 in the colon were detected using flow cytometry. Furthermore, UHPLC-QE-MS was utilized to identify chemical components of PD and network pharmacology was employed to predict potential pathways for PD intervention in UC. Subsequently, MNK-3 cells (ILC3 in vitro cell line) and NCM460 cells were used to verify the network pharmacology results. Finally, the effects of PD on UC gut flora have been explored using in vitro fermentation and 16S rDNA techniques.
RESULTS: The results showed that PD significantly restored body weight and colon length in mice with chronic colitis, while also reducing colon inflammatory cell infiltration and the expression of IL-6 and IL-1β. Additionally, PD notably promoted the expression of MUC2, ZO-1, Occludin, and IL-22, as well as increasing the ratio of ILC3 and NCR+ILC3. UHPLC-QE-MS analysis identified 443 components of PD, and network pharmacology suggested that PD could target the aryl hydrocarbon receptor (AHR) signaling pathway, which was confirmed by MNK-3 cells and in vitro fermentation experiments. Furthermore, MNK-3-conditioned medium (CM) increased the expression of ZO-1 and Occludin in NCM460 cells. In addition, 16S rDNA results indicated that PD promoted the abundance of Lactobacillales, thus contributing to mucosal damage repair by activating the AHR signal in ILC3s.
CONCLUSIONS: In summary, our study demonstrates that PD repairs intestinal mucosal damage in chronic colitis by regulating the interaction of gut flora with ILC3, and the specific mechanism is related to the activation of AHR signaling pathway.