Interleukin-33 facilitates liver regeneration through serotonin-involved gut-liver axis

Engineered EVs from LncEEF1G - overexpressing MSCs promote fibrotic liver regeneration by upregulating HGF release from hepatic stellate cells

Fibrosis is a disease that negatively affects liver regeneration, resulting in severe complications after liver surgery. However, there is still no clinically effective treatment for promoting fibrotic liver regeneration because the underlying hepatocellular mechanism remains poorly understood. Through microRNA microarrays combined with the application of AAV6, we found that high expression of miR-181a-5p in activated hepatic stellate cells (HSCs) suppressed the expression of hepatic growth factor (HGF) and partially contributed to impaired regeneration potential in mice with hepatic fibrosis that had undergone two-thirds partial hepatectomy. As nanotherapeutics, mesenchymal stem-cell-derived extracellular vesicles (MSC-EVs) have been verified as effective treatments for liver regeneration. Here we observe that MSC-EVs can also promote fibrotic liver regeneration via enriched lncEEF1G, which acts as a competing endogenous RNA to directly sponge miR-181a-5p, leading to the upregulated expression of HGF in HSCs. Finally, engineered MSC-EVs with high expression of lncEEF1G (lncEEF1GOE-EVs) were constructed, suggesting greater potential for this model. In summary, our findings indicate that lncEEF1GOE-EVs have a nanotherapeutic effect on promoting regeneration of fibrotic livers by modulating the miR-181a-5p/HGF pathway in HSCs, which highlights the potential of extracellular vesicle engineering technology for patients with hepatic fibrosis who have undergone hepatic surgery. Engineered mesenchymal stem cells that overexpress lncEEF1G can secrete extracellular vesicles that are rich in lncEEF1G (lncEEF1GOE-EVs). Upon injection of lncEEF1GOE-EVs into a fibrotic 70% partial hepatectomy mouse model, lncEEF1G competitively binds to miR-181a-5p in hepatic stellate cells, preventing the interaction between miR-181a-5p and the messenger RNA of hepatocyte growth factor. This consequently leads to an increase in the secretion of hepatocyte growth factor and the promotion of hepatocyte proliferation.

Inhibiting mechanotransduction prevents scarring and yields regeneration in a large animal model

Modulating mechanotransduction by inhibiting yes-associated protein (YAP) in mice yields wound regeneration without scarring. However, rodents are loose-skinned and fail to recapitulate key aspects of human wound repair. We sought to elucidate the effects of YAP inhibition in red Duroc pig wounds, the most human-like model of scarring. We show that one-time treatment with verteporfin, a YAP inhibitor, immediately after wounding is sufficient to prevent scarring and to drive wound regeneration in pigs. By performing single-cell RNA sequencing (scRNA-seq) on porcine wounds in conjunction with spatial proteomic analysis, we found perturbations in fibroblast dynamics with verteporfin treatment and the presence of putative pro-regenerative/profibrotic fibroblasts enriched in regenerating/scarring pig wounds, respectively. We also identified differences in enriched myeloid cell subpopulations after treatment and linked this observation to increased elaboration of interleukin-33 (IL-33) in regenerating wounds. Finally, we validated our findings in a xenograft wound model containing human neonatal foreskin engrafted onto nude mice and used scRNA-seq of human wound cells to draw parallels with fibroblast subpopulation dynamics in porcine wounds. Collectively, our findings provide support for the clinical translation of local mechanotransduction inhibitors to prevent human skin scarring, and they clarify a YAP/IL-33 signaling axis in large animal wound regeneration.

TGM2-mediated histone serotonylation promotes HCC progression via MYC signalling pathway

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is an aggressive malignancy for which there are few effective treatment options. H3Q5ser, a serotonin-based histone modification mediated by transglutaminase 2 (TGM2), affects diverse biological processes, such as neurodevelopment. The role of TGM2-mediated H3Q5ser in HCC progression remains unclear. This study investigated the role of TGM2 in promoting HCC progression and evaluated its potential as a therapeutic target for HCC treatment.

METHODS

Adeno-associated virus-mediated liver-specific overexpression models of Tgm2 or H3.3 were adopted to validate the effects of H3Q5ser on HCC progression. CUT&Tag and RNA sequencing was employed to investigate the underlying mechanisms. HCC organoids, subcutaneous xenograft models, and hydrodynamic tail vein injection models were used to evaluate the treatment efficiency of TGM2 inhibitors.

RESULTS

TMG2 expression positively correlated with higher alpha-fetoprotein levels, poor differentiation, and a later BCLC stage. Tgm2 deficiency or H3Q5ser inhibition notably inhibited HCC progression. CUT&Tag and RNA sequencing analyses revealed that downregulated genes were enriched in the MYC pathway following treatment with the TGM2 inhibitors. Furthermore, transcriptional intermediary factor 1 β mediated the recruitment of TGM2 to MYC, facilitating H3Q5ser modifications on MYC target genes. Finally, targeting the transglutaminase activity of TGM2 significantly suppressed HCC progression and showed synergy with sorafenib treatment in preclinical models. TGM2 inhibitors did not cause significant myelosuppression or tissue damage.

CONCLUSIONS

TGM2 serves as a prognostic biomarker and targeting its transglutaminase activity may be an effective strategy for inhibiting HCC progression.

IMPACT AND IMPLICATIONS

Transglutaminase 2 (TGM2)-mediated H3Q5ser modifications promote hepatocellular carcinoma (HCC) progression via MYC pathway signalling. Targeting the transglutaminase activity of TGM2 markedly inhibited HCC progression. TGM2 inhibitors did not induce significant myelosuppression or tissue damage. This preclinical study provides a theoretical basis to explore new strategies for HCC therapy.

Akkermansia muciniphila improve cognitive dysfunction by regulating BDNF and serotonin pathway in gut-liver-brain axis

BACKRGROUND

Akkermansia muciniphila, a next-generation probiotic, is known as a cornerstone regulating the gut-organ axis in various diseases, but the underlying mechanism remains poorly understood. Here, we revealed the neuronal and antifibrotic effects of A. muciniphila on the gut-liver-brain axis in liver injury.

RESULTS

To investigate neurologic dysfunction and characteristic gut microbiotas, we performed a cirrhosis cohort (154 patients with or without hepatic encephalopathy) and a community cognition cohort (80 participants in one region for three years) and validated the existence of cognitive impairment in a 3,5-diethoxycarbonyl-1,4-dihydrocollidine-induced hepatic injury mouse model. The effects of the candidate strain on cognition were evaluated in animal models of liver injury. The expression of brain-derived neurotrophic factor (BDNF) and serotonin receptors was accessed in patients with fibrosis (100 patients) according to the fibrosis grade and hepatic venous pressure gradient. The proportion of A. muciniphila decreased in populations with hepatic encephalopathy and cognitive dysfunction. Tissue staining techniques confirmed gut-liver-brain damage in liver injury, with drastic expression of BDNF and serotonin in the gut and brain. The administration of A. muciniphila significantly reduced tissue damage and improved cognitive dysfunction and the expression of BDNF and serotonin. Isolated vagus nerve staining showed a recovery of serotonin expression without affecting the dopamine pathway. Conversely, in liver tissue, the inhibition of injury through the suppression of serotonin receptor (5-hydroxytryptamine 2A and 2B) expression was confirmed. The severity of liver injury was correlated with the abundance of serotonin, BDNF, and A. muciniphila.

CONCLUSIONS

A. muciniphila, a next-generation probiotic, is a therapeutic candidate for alleviating the symptoms of liver fibrosis and cognitive impairment.

Liver regeneration after injury: Mechanisms, cellular interactions and therapeutic innovations

The liver possesses a distinctive capacity for regeneration within the human body. Under normal circumstances, liver cells replicate themselves to maintain liver function. Compensatory replication of healthy hepatocytes is sufficient for the regeneration after acute liver injuries. In the late stage of chronic liver damage, a large number of hepatocytes die and hepatocyte replication is blocked. Liver regeneration has more complex mechanisms, such as the transdifferentiation between cell types or hepatic progenitor cells mediated. Dysregulation of liver regeneration causes severe chronic liver disease. Gaining a more comprehensive understanding of liver regeneration mechanisms would facilitate the advancement of efficient therapeutic approaches. This review provides an overview of the signalling pathways linked to different aspects of liver regeneration in various liver diseases. Moreover, new knowledge on cellular interactions during the regenerative process is also presented. Finally, this paper explores the potential applications of new technologies, such as nanotechnology, stem cell transplantation and organoids, in liver regeneration after injury, offering fresh perspectives on treating liver disease.

The immunomodulatory of interleukin-33 in rheumatoid arthritis: A systematic review

Rheumatoid arthritis (RA) is a systemic chronic autoimmune disease that primarily affects the joints and surrounding soft tissues, characterized by chronic inflammation and proliferation of the synovium. Various immune cells are involved in the pathophysiology of RA. The complex interplay of factors such as chronic inflammation, genetic susceptibility, dysregulation of serum antibody levels, among others, contribute to the complexity of the disease mechanism, disease activity, and treatment of RA. Recently, the cytokine storm leading to increased disease activity in RA has gained significant attention. Interleukin-33 (IL-33), a member of the IL-1 family, plays a crucial role in inflammation and immune regulation. ST2 (suppression of tumorigenicity 2 receptor), the receptor for IL-33, is widely expressed on the surface of various immune cells. When IL-33 binds to its receptor ST2, it activates downstream signaling pathways to exert immunoregulatory effects. In RA, IL-33 regulates the progression of the disease by modulating immune cells such as circulating monocytes, tissue-resident macrophages, synovial fibroblasts, mast cells, dendritic cells, neutrophils, T cells, B cells, endothelial cells, and others. We have summarized and analyzed these findings to elucidate the pathways through which IL-33 regulates RA. Furthermore, IL-33 has been detected in the synovium, serum, and synovial fluid of RA patients. Due to inconsistent research results, we conducted a meta-analysis on the association between serum IL-33, synovial fluid IL-33, and the risk of developing RA in patients. The pooled SMD was 1.29 (95% CI: 1.15-1.44), indicating that IL-33 promotes the onset and pathophysiological progression of RA. Therefore, IL-33 may serve as a biomarker for predicting the risk of developing RA and treatment outcomes. As existing drugs for RA still cannot address drug resistance in some patients, new therapeutic approaches are needed to alleviate the significant burden on RA patients and healthcare systems. In light of this, we analyzed the potential of targeting the IL-33/ST2-related signaling pathway to modulate immune cells associated with RA and alleviate inflammation. We also reviewed IL-33 and RA susceptibility-related single nucleotide polymorphisms, suggesting potential involvement of IL-33 and macrophage-related drug-resistant genes in RA resistance therapy. Our review elucidates the role of IL-33 in the pathophysiology of RA, offering new insights for the treatment of RA.

Soluble suppression of tumourigenicity 2 as a predictor of postoperative hepatic failure

BACKGROUND

Posthepatectomy liver failure remains a potentially life-threatening complication after hepatectomy. Soluble suppression of tumourigenicity 2 is an injury-related biomarker. The aim of the study was to assess soluble suppression of tumourigenicity 2 elevation after hepatectomy and whether it can predict posthepatectomy liver failure.

METHODS

This was a single-centre retrospective study including all patients who underwent a liver resection between 2015 and 2019. Plasma concentrations of soluble suppression of tumourigenicity 2 were measured before surgery and at postoperative days 1, 2, 5 and 7. Posthepatectomy liver failure was defined according to the International Study Group of Liver Surgery and the morbidity rate was graded according to the Clavien-Dindo classification.

RESULTS

A total of 173 patients were included (75 underwent major and 98 minor resection); plasma levels of soluble suppression of tumourigenicity 2 increased from 43.42 (range 18.69-119.96) pg/ml to 2622.23 (range 1354.18-4178.27) pg/ml on postoperative day 1 (P < 0.001). Postoperative day 1 soluble suppression of tumourigenicity 2 concentration accurately predicted posthepatectomy liver failure ≥ grade B (area under curve = 0.916, P < 0.001) and its outstanding performance was not affected by underlying disease, liver pathological status and extent of resection. The cut-off value, sensitivity, specificity, positive predictive value and negative predictive value of postoperative day 1 soluble suppression of tumourigenicity 2 in predicting posthepatectomy liver failure ≥ grade B were 3700, 92%, 85%, 64% and 97% respectively. Soluble suppression of tumourigenicity 2high patients more frequently experienced posthepatectomy liver failure ≥ grade B (64.3% (n = 36) versus 2.6% (n = 3)) and Clavien-Dindo IIIa higher morbidity rate (23.2% (n = 13) versus 5.1% (n = 6)) compared with soluble suppression of tumourigenicity 2low patients.

CONCLUSIONS

Soluble suppression of tumourigenicity 2 may be a reliable predictor of posthepatectomy liver failure ≥ grade B as early as postoperative day 1 for patients undergoing liver resection. Its role in controlling hepatic injury/regeneration needs further investigation. Registration number: ChiCTR-OOC-15007210 (www.chictr.org.cn/).

Senescent fibroblast facilitates re-epithelization and collagen deposition in radiation-induced skin injury through IL-33-mediated macrophage polarization

BACKGROUND

The need for radiotherapy among the elderly rises with increasing life expectancy and a corresponding increase of elderly cancer patients. Radiation-induced skin injury is one of the most frequent adverse effects in radiotherapy patients, severely limiting their life quality. Re-epithelialization and collagen deposition have essential roles in the recovery of skin injuries induced by high doses of ionizing radiation. At the same time, radiation-induced senescent cells accumulate in irradiated tissues. However, the effects and mechanisms of senescent cells on re-epithelialization and collagen deposition in radiation-induced skin injury have not been fully elucidated.

RESULTS

Here, we identified a role for a population of senescent cells expressing p16 in promoting re-epithelialization and collagen deposition in radiation-induced skin injury. Targeted ablation of p16+ senescent cells or treatment with Senolytics resulted in the disruption of collagen structure and the retardation of epidermal coverage. By analyzing a publicly available single-cell sequencing dataset, we identified fibroblasts as a major contributor to the promotion of re-epithelialization and collagen deposition in senescent cells. Notably, our analysis of publicly available transcriptome sequencing data highlighted IL-33 as a key senescence-associated secretory phenotype produced by senescent fibroblasts. Neutralizing IL-33 significantly impedes the healing process. Finally, we found that the effect of IL-33 was partly due to the modulation of macrophage polarization.

CONCLUSIONS

In conclusion, our data suggested that senescent fibroblasts accumulated in radiation-induced skin injury sites participated in wound healing mainly by secreting IL-33. This secretion regulated the local immune microenvironment and macrophage polarization, thus emphasizing the importance of precise regulation of senescent cells in a phased manner.

Bifidobacterium longum promotes postoperative liver function recovery in patients with hepatocellular carcinoma

Timely liver function recovery (LFR) is crucial for postoperative hepatocellular carcinoma (HCC) patients. Here, we established the significance of LFR on patient long-term survival through retrospective and prospective cohorts and identified a key gut microbe, Bifidobacterium longum, depleted in patients with delayed recovery. Fecal microbiota transfer from HCC patients with delayed recovery to mice similarly impacted recovery time post hepatectomy. However, oral gavage of B. longum improved liver function and repair in these mice. In a clinical trial of HCC patients, orally administering a probiotic bacteria cocktail containing B. longum reduced the rates of delayed recovery, shortened hospital stays, and improved overall 1-year survival. These benefits, attributed to diminished liver inflammation, reduced liver fibrosis, and hepatocyte proliferation, were associated with changes in key metabolic pathways, including 5-hydroxytryptamine, secondary bile acids, and short-chain fatty acids. Our findings propose that gut microbiota modulation can enhance LFR, thereby improving postoperative outcomes for HCC patients.

Unveiling the power of microenvironment in liver regeneration: an in-depth overview

The liver serves as a vital regulatory hub for various physiological processes, including sugar, protein, and fat metabolism, coagulation regulation, immune system maintenance, hormone inactivation, urea metabolism, and water-electrolyte acid-base balance control. These functions rely on coordinated communication among different liver cell types, particularly within the liver's fundamental hepatic lobular structure. In the early stages of liver development, diverse liver cells differentiate from stem cells in a carefully orchestrated manner. Despite its susceptibility to damage, the liver possesses a remarkable regenerative capacity, with the hepatic lobule serving as a secure environment for cell division and proliferation during liver regeneration. This regenerative process depends on a complex microenvironment, involving liver resident cells, circulating cells, secreted cytokines, extracellular matrix, and biological forces. While hepatocytes proliferate under varying injury conditions, their sources may vary. It is well-established that hepatocytes with regenerative potential are distributed throughout the hepatic lobules. However, a comprehensive spatiotemporal model of liver regeneration remains elusive, despite recent advancements in genomics, lineage tracing, and microscopic imaging. This review summarizes the spatial distribution of cell gene expression within the regenerative microenvironment and its impact on liver regeneration patterns. It offers valuable insights into understanding the complex process of liver regeneration.