Knockdown of microRNA-155 in Kupffer cells results in immunosuppressive effects and prolongs survival of mouse liver allografts. Transplantation. 2014;97:626-635. [PMID: 24531847 DOI: 10.1097/TP.0000000000000061]

Role of Kupffer cells in tolerance induction after liver transplantation

Currently, liver transplantation has reached a level of maturity where it is considered an effective treatment for end-stage liver disease and can significantly prolong the survival time of patients. However, acute and chronic rejection remain major obstacles to its efficacy. Although long-term use of immunosuppressants can prevent rejection, it is associated with serious side effects and significant economic burden for patients. Therefore, the investigation of induced immune tolerance holds crucial theoretical significance and socio-economic value. In fact, the establishment of immune tolerance in liver transplantation is intricately linked to the unique innate immune system of the liver. Kupffer cells, as a crucial component of this system, play a pivotal role in maintaining the delicate balance between inflammatory response and immune tolerance following liver transplantation. The important roles of different functions of Kupffer cells, such as phagocytosis, cell polarization, antigen presentation and cell membrane proteins, in the establishment of immune tolerance after transplantation is comprehensively summarized in this paper. Providing theoretical basis for further study and clinical application of Kupffer cells in liver transplantation.

The role of miR-155 on liver diseases by modulating immunity, inflammation and tumorigenesis

The liver is a well-known metabolic organ that can be susceptible to external stimuli to affect its normal physiological function. Worldwide, the morbidity and mortality of liver diseases are skyrocketing every year, causing human health crises. Recently, new approaches such as biotechnology have been introduced to achieve optimal treatment and prognostic management of liver diseases. microRNAs (miRNAs), a kind of small non-coding RNA molecule, have the advantages of biodiversity, wide distribution and numerous members. Among these miRNAs, miR-155 is an important regulator of inflammation, immunity and tumorigenesis. In this review, the PubMed and Web of Science databases were searched from 2009 to 2022. After inclusion and exclusion, 64 articles were selected for a systematic review to comprehensively summarize the mechanisms of miR-155 regulating inflammation, immunity and tumorigenesis in liver diseases and liver cancer, covering in vitro, in vivo and clinical studies. Existing preclinical studies and clinical trials have listed that the up-regulation and down-regulation of miR-155 are significant in alcoholic liver injury, viral hepatitis, autoimmune hepatitis, infectious liver injury, liver transplantation and liver cancer. The immune and inflammation effects of miR-155 are manifested by regulating macrophage polarization, NK cell killing, Th17 cell and Th1/Th2 cell differentiation. Additionally, miR-155 is also committed to participating in the cell cycle, invasion and metastasis, immune escape and other processes to promote and intensify the development of liver cancer. In conclusion, miR-155 is not only a biomarker for the diagnosis and prognosis of liver diseases, but also plays a therapeutic role via regulating immunity, inflammation and tumorigenesis.

A boronate-based modular assembly nanosystem to block the undesirable crosstalk between hepatic stellate cells and Kupffer cells

Crosstalk between Kupffer cells (KCs) and hepatic stellate cells (HSCs) plays an important role in multiple liver disease conditions, including the formation of liver fibrosis in alcohol-associated liver disease (AALD). Therapeutic targeting of the KC-HSC crosstalk is a prime target for therapeutic interventions. Herein, a novel modular nanosystem was designed and prepared through the self-assembly utilizing boric acid and catechol interactions to prepare polymers modified with a CXCR4-inhibiting moieties. The polymers were used to encapsulate anti-miR-155 and to block the undesirable crosstalk between HSCs and KCs by downregulating miR-155 expression in KCs with the parallel inhibition of CXCR4 signaling in activated HSCs. The combined inhibition of miR-155 and CXCR4 at two different liver cell types achieved improved antifibrosis effects in a mouse model of AALD fibrosis. Our finding highlights the key role that blocking the undesirable crosstalk between HSCs and KCs plays in reversing AALD fibrosis as well as demonstrates a proof-of-concept approach for designing and constructing multifunctional delivery nanosystems using orthogonal functional modules based on the understanding of disease mechanisms.

miR-155: An Important Role in Inflammation Response

MicroRNAs (miRNAs) are a class of small, mature, noncoding RNA that lead to posttranscriptional gene silencing to regulate gene expression. miRNAs are instrumental in biological processes such as cell development, cell differentiation, cell proliferation, and cell apoptosis. The miRNA-mediated gene silencing is an important part of the regulation of gene expression in many kinds of diseases. miR-155, one of the best-characterized miRNAs, has been found to be closely related to physiological and pathological processes. What is more, miR-155 can be used as a potential therapeutic target for inflammatory diseases. We analyze the articles about miR-155 for nearly five years, review the advanced study on the function of miR-155 in different inflammatory cells like T cells, B cells, DCs, and macrophages, and then summarize the biological functions of miR-155 in different inflammatory cells. The widespread involvement of miR-155 in human diseases has led to a novel therapeutic approach between Chinese and Western medicine.

miR-155-overexpressing monocytes resemble HLAhighISG15+ synovial tissue macrophages from patients with rheumatoid arthritis and induce polyfunctional CD4+ T-cell activation

MicroRNAs (miRs) are known to regulate pro-inflammatory effector functions of myeloid cells, and miR dysregulation is implicated in rheumatoid arthritis (RA), a condition characterized by inflammation and destruction of the joints. We showed previously that miR-155 is increased in myeloid cells in RA and induces pro-inflammatory activation of monocytes and macrophages; however, its role at the interface between innate and adaptive immunity was not defined. Here, RNA-sequencing revealed that overexpression of miR-155 in healthy donor monocytes conferred a specific gene profile which bears similarities to that of RA synovial fluid-derived CD14+ cells and HLAhighISG15+ synovial tissue macrophages, both of which are characterized by antigen-presenting pathways. In line with this, monocytes in which miR-155 was overexpressed, displayed increased expression of HLA-DR and both co-stimulatory and co-inhibitory molecules, and induced activation of polyfunctional T cells. Together, these data underpin the notion that miR-155-driven myeloid cell activation in the synovium contributes not only to inflammation but may also influence the adaptive immune response.

Macrophages in transplant rejection

Transplant rejection is one of the primary factors leading to loss of allograft function, and macrophages are involved in allograft rejection. Macrophages polarize into different phenotypes according to stimulation by different external factors. Different types of macrophages play distinct roles in inflammation, tumors, and autoimmune diseases and are involved in transplant rejection. In this review, we introduce the origin and migration of macrophages, outline the classification of macrophages and their polarization mechanisms, and review the currently understood mechanisms of their involvement in transplant rejection. Finally, we discuss the regulation of macrophage polarization and miRNA expression with respect to transplant rejection, which is important for the development of new anti-rejection therapies.

Immunomodulatory Role and Therapeutic Potential of Non-Coding RNAs Mediated by Dendritic Cells in Autoimmune and Immune Tolerance-Related Diseases

Dendritic cells (DCs) are professional antigen-presenting cells that act as a bridge between innate immunity and adaptive immunity. After activation, DCs differentiate into subtypes with different functions, at which point they upregulate co-stimulatory molecules and produce various cytokines and chemokines. Activated DCs also process antigens for presentation to T cells and regulate the differentiation and function of T cells to modulate the immune state of the body. Non-coding RNAs, RNA transcripts that are unable to encode proteins, not only participate in the pathological mechanisms of autoimmune-related diseases but also regulate the function of immune cells in these diseases. Accumulating evidence suggests that dysregulation of non-coding RNAs contributes to DC differentiation, functions, and so on, consequently producing effects in various autoimmune diseases. In this review, we summarize the main non-coding RNAs (miRNAs, lncRNAs, circRNAs) that regulate DCs in pathological mechanisms and have tremendous potential to give rise to novel therapeutic targets and strategies for multiple autoimmune diseases and immune tolerance-related diseases.

XBP1s repression regulates Kupffer cell polarization leading to immune suppressive effects protecting liver allograft in rats

BACKGROUND

Polarized kupffer cells (KCs) influence the immune response after liver transplantation. We report an undiscovered immune regulatory role of X-box binding protein 1 (XBP1) on immune function of kupffer cells (KCs).

METHODS

Acute rejection model using rats.

RESULTS

We found that suppression of XBP1s in lipopolysaccharide (LPS) -activated KCs could increase the expression of arginase-1 (Arg-1) and CD204 but also decrease the expression levels of MHC-II and CD40 and shift the phenotype markers of KCs toward M2 via the janus kinase (JAK) 3- Signal Transducer And Activator Of Transcription (STAT) 6 pathway, presenting an immunosuppressive function by enhancing anti-inflammatory cytokine secretion and accelerating apoptosis of activated T cells. XBP1s over-expression in KCs shift the phenotype markers on KCs towards M1 via the JAK1-STAT1 pathway and have shown a strong pro-inflammatory property. Down-regulation of XBP1s in KCs changed the phenotype and cytokine secretion profile towards M2 and markedly protected the function and structure of allograft liver, prolonging the recipient's survival compared with control and normal saline groups in rats.

CONCLUSIONS

Our findings reveal a novel regulatory mechanism of XBP1 in an induced immuno-suppressive state to protect rat's liver allograft via JAK-STAT mediated KCs polarization.

MicroRNAs in solid organ and vascularized composite allotransplantation: Potential biomarkers for diagnosis and therapeutic use

Nowadays, solid organ transplantation (SOT) is an established treatment for patients with end-organ dysfunction, which dramatically improves the quality-of-life. Vascularized composite allotransplants (VCAs) including hand and face have been reported worldwide over the last 20 years. However, VCAs, differently to SOT, are life-enhancing instead of life-saving and are not routinely performed due to the risk of immune rejection and the adverse effects of immunosuppression. Over the past decade, although considerable improvements in short-term outcomes after allotransplantation have been registered, these results have not been translated into major progress in long-term allograft acceptance and patient survival. Recently active researches in the field of biomarker discovery have been conducted to develop individualized therapies for allograft recipients. MicroRNAs (miRNAs) are a small noncoding RNAs functioning as critical regulators of gene and protein expression by RNA interference. They have been connected in numerous biological processes and diseases. Due to their immunomodulatory functions, miRNAs have been amended as potential diagnostic and prognostic biomarker for the detection of rejection in allotransplantation. Due to their specific circulating expression profile, they could act as noninvasive predictive tools for rejection that may help clinicians in an early adjustment of the immunosuppression protocol during acute rejections episodes. Indeed, specific anti-sense oligonucleotides suppressing miRNAs expressed in rejection could reduce the rejection rate in allografts and decrease the use of immunosuppressants. We present a literature review of the immunomodulatory properties and characteristics of miRNAs. We will summarize the current knowledge on miRNAs as potential biomarkers for allograft rejection and possible application in allotransplantation monitoring. Finally, we will discuss the advances in preclinical miRNA-based therapies for immunosuppression.

MicroRNAs and long non-coding RNAs in liver surgery: Diagnostic and therapeutic merits

BACKGROUND

Hepatectomy and liver transplantation (LT) are the two most commonly performed surgical procedures for various hepatic lesions. microRNA (miRNA) and long non-coding RNA (lncRNA) have been gradually unveiled their roles as either biomarkers for early diagnosis or potentially therapeutic tools to manipulate gene expression in many disease entities. This review aimed to discuss the effects of miRNA or lncRNA in the hepatectomy and LT fields.

DATA SOURCES

We did a literature search from 1990 through January 2018 to summarize the currently available evidence with respect to the effects of miRNA and lncRNA in liver regeneration after partial hepatectomy, as well as their involvement in several key issues related to LT, including ischemia-reperfusion injury, allograft rejection, tolerance, recurrence of original hepatic malignancies, etc. RESULTS: Certain miRNAs and lncRNAs are actively involved in the regulation of various aspects of liver resection and transplantation. During the process of liver regeneration after hepatectomy, the expression of miRNAs and lncRNAs shows dynamic changes.

CONCLUSIONS

It is now clear that miRNAs and lncRNAs orchestrate in various aspects of the pathophysiological process of LT and hepatectomy. Better understanding of the underlying mechanism and future clinical trials may strengthen their positions as either biomarkers or potential therapeutic targets in the management of complications after liver surgery.

TIM-4 interference in Kupffer cells against CCL4-induced liver fibrosis by mediating Akt1/Mitophagy signalling pathway

OBJECTIVES

T-cell immunoglobulin domain and mucin domain-4 (TIM-4) is selectively expressed on antigen-presenting cells (APCs) and modulates various immune responses. However, the role of TIM-4 expressed by Kupffer cells (KCs) in liver fibrosis remains unclear. The present study aimed to explore whether and how TIM-4 expressed by KCs is involved in liver fibrosis.

MATERIALS AND METHODS

Mice chronic liver fibrosis models were established and divided into the olive-induced control group, CCL4-induced control group, olive-induced TIM-4 interference group and CCL4-induced TIM-4 interference group. Different techniques were used to monitor the fibrotic effects of TIM-4, including histopathological assays, Western blotting, ELISA and transmission electron microscopy. Additionally, mice liver transplant models were established to determine the fibrotic effects of TIM-4 on fibrosis after liver transplantation (LT).

RESULTS

We found that the induction of liver fibrosis by CCL4 was associated with TIM-4 expression in KCs. TIM-4 interference essentially contributed to liver fibrosis resolution. KCs from the TIM-4 interference group had decreased levels of pro-fibrotic markers, reduced TGF-β1 secretion and inhibited hepatic stellate cell (HSC) differentiation into myofibroblast-like cells. In addition, we used GdCl3 to verify that KCs are the primary source of TGF-β1 during fibrosis progression. Moreover, KCs from CCL4-induced mice showed increased ROS production, mitophagy activation and TGF-β1 secretion. However, TIM-4 interference in the KCs inhibited Akt1-mediated ROS production, resulting in the suppression of PINK1, Parkin and LC3-II/I activation and the reduction of TGF-β1 secretion during liver fibrosis. Additionally, TIM-4 interference potentially attenuated development of fibrosis after LT.

CONCLUSIONS

Our findings revealed the underlying mechanisms of TIM-4 interference in KCs to mitigate liver fibrosis.

The extensive role of miR-155 in malignant and non-malignant diseases

MicroRNAs (miRNAs) have rapidly emerged as key molecules in cancer initiation and development, showing the capability to regulate pivotal oncogenic pathways. MiR-155 has gathered an increased attention especially in oncology, but also in non-malignanat pathologies. Nowadays, this noncoding RNA is one of the most important miRNAs in cancer, due to the extensive signaling network associated with it, implication in immune system regulation and also deregulation in disease states. Therefore, numerous research protocols are focused on preclinical modulation of miR-155 for therapeutic purposes, or investigation of its dynamic expression for diagnostic/prognostic assessments, with the final intention of bringing this miRNA into the clinical setting. This review comprehensively presents the extended role of miR-155 in cancer and other pathologies, where its expression is dysregulated. Finally, we assess the future steps toward miR-155 based therapeutics.

Increased expression of miR-155 correlates with abnormal allograft status in solid organ transplant patients and rat kidney transplantation model

AIMS

Increasing evidence has shown the diagnostic value of miR-155 in organ transplantation. The dysregulation of miR-155 is reported to be associated with development of acute or chronic complications in solid organ transplant recipients. Here, we summarized related evidence to explore the correlation between the dysregulation of miR-155 and various allograft dysfunction in transplant recipients, and verified the dynamic change of miR-155 level in acute rejection (AR) using a rat renal transplantation model.

MAIN METHODS

Eligible studies were retrieved from PubMed, Embase, and Cochrane Library databases. A meta-analysis method was performed to evaluate the diagnostic value of miR-155 in transplant recipients. Furthermore, the F344-Lewis rat renal transplantation model was established to validate the dynamic change of miR-155 expression during AR.

KEY FINDINGS

A total of 275 transplant patients, including renal, heart, and lung transplantation from 6 studies were analysed. The pooled SEN of miR-155 was 0.87 (95% CI, 0.78-0.93), the pooled SPE was 0.76 (95% CI, 0.63-0.85), the pooled PLR was 3.6 (95% CI, 2.2-5.8), the pooled NLR was 0.17 (95% CI, 0.09-0.31), the pooled DOR was 17.31 (95% CI, 7.20-41.65) and pooled AUC was 0.89 (95% CI, 0.86-0.92). The rat renal transplantation model (n = 24) and control model (n = 15) were successfully established. Expression of miR-155 in plasma was significantly increased in 7 d and 9 d post-transplantation compared to the control group (P < 0.05), and was consistent with the dynamic change of AR degree.

SIGNIFICANCE

miR-155 is a potential biomarker for monitoring the abnormal allograft status in solid organ transplantation.

Micro-RNAs in transplant tolerance

PURPOSE OF REVIEW

Micro-RNAs (miRNAs) are highly conserved small RNA molecules that have selective gene-regulatory functions. This posttranscriptional regulation by miRNAs is critical for many immunological processes. Many developments in establishing the biological role of miRNAs in solid organ transplantation have been generated in the last decade. Discoveries of immune regulation by miRNAs, resulting in graft prolongation and transplant tolerance, are rapidly advancing and are the subject of this review.

RECENT FINDINGS

Many elegant experimental studies have revealed intriguing associations between transplant tolerance and specific miRNA profiles. These findings have provided insight into the miRNAs critical for sustaining immune suppression, and have revealed common miRNA pathways that should be further investigated and/or targeted therapeutically. Further reports have strategized and corroborated different methods of manipulating miRNA expression for prolonging allograft survival, yielding promising preclinical evidence of the efficacy of miRNA-based therapies.

SUMMARY

The review covers these recent developments in miRNA research that can revolutionize how we implement diagnostics and prognostics and how we can strategize transplantation therapies.

IL-34 Inhibits Acute Rejection of Rat Liver Transplantation by Inducing Kupffer Cell M2 Polarization

BACKGROUND

Recent studies have demonstrated that IL-34 is implicated in the regulation of macrophage functions. However, the effect of IL-34 on Kupffer cells (KCs) in acute rejection (AR) of liver transplantation remains unclear.

METHODS

IL-34 expression was detected in graft and serum from allotransplantation and syngeneic transplantation groups. The adeno-associated virus-expressing IL-34 was used to assess the effect of IL-34 on AR of rat liver transplantation. The effect of IL-34 on KC polarization was evaluated by in vitro and in vivo assays. Kupffer cells in donors were depleted by clodronate treatment before transplantation, and the nontreated KCs or lipopolysaccharide-treated KCs were transferred into recipients during liver transplantation.

RESULTS

IL-34 expression levels in grafts and serum were decreased in the allotransplantation group compared with the syngeneic transplantation group. Adeno-associated virus-expressing IL-34 treatment induced KC M2 polarization in vivo and inhibited the AR of rat liver transplantation. Moreover, we found that IL-34 switched the phenotype of KCs from M1 to M2 by activating the PI3K/Akt pathway in vitro. In addition, the results of KC deletion and adaptive transfer experiments showed that the AR inhibition induced by IL-34 was M2 KC-dependent.

CONCLUSIONS

IL-34 plays an important role in KC M2 polarization-dependent AR inhibition of rat liver transplantation.

MiRNAs and inflammatory bowel disease: An interesting new story

Inflammatory bowel disease (IBD), as a chronic and recurrent inflammatory disorder, is caused by a dysregulated and aberrant immune response to exposed environmental factors in genetically susceptible individuals. Despite huge efforts in determining the molecular pathogenesis of IBD, an increasing worldwide incidence of IBD has been reported. MicroRNAs (miRNAs) are a set of noncoding RNA molecules that are about 22 nucleotides long, and these molecules are involved in the regulation of the gene expression. By clarifying the important role of miRNAs in a number of diseases, their role was also considered in IBD; numerous studies have been performed on this topic. In this review, we attempt to summarize a number of studies and discuss some of the recent developments in the roles of miRNAs in the pathophysiology, diagnosis, and treatment of IBD.

Silencing of microRNA-375 affects immune function in mice with liver failure by upregulating astrocyte elevated gene-1 through reducing apoptosis of Kupffer cells

This study aims to investigate how microRNA-375 (miR-375) improves immune function by regulating liver macrophages (Kupffer cells) in mice with liver failure. Forty mice were divided into ConA-1h, ConA-3h, ConA-6h, and control groups, with 10 mice in each group. Mice models of liver failure were established by injecting concanavalin A (ConA) solution via the tail veins of mice, and then primary Kupffer cells were isolated and cultured. Reverse transcription quantitative polymerase chain reaction, Western blot analysis, and enzyme-linked immunosorbent assay were conducted to examine the expressions of miR-375, astrocyte elevated gene-1 (AEG-1), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and IL-1β in Kupffer cells of mice with liver failure as well as after silencing of miR-375. Flow cytometry was used to determine cell apoptosis. During the liver failure process, miR-375, IL-6, TNF-α, and IL-1β expressions were increased over time, while AEG-1 expression decreased over time in the control, ConA-1h, ConA-3h, and ConA-6h groups. Opposite alternations were observed after silencing of miR-375. Dual-luciferase reporter gene assay showed that AEG-1 was a target gene of miR-375. Flow cytometry determination showed that the ratio of apoptotic Kupffer cells decreased after silencing of miR-375. Overexpression of AEG-1 could rescue the suppression of IL-6, TNF-α, and IL-1β expressions in Kupffer cells after the short-term induction of ConA and further inhibit cell apoptosis. Our study provides evidence that miR-375 could regulate Kupffer cells to improve immune function in mice with liver failure.

The Long Noncoding RNA MALAT1 Induces Tolerogenic Dendritic Cells and Regulatory T Cells via miR155/Dendritic Cell-Specific Intercellular Adhesion Molecule-3 Grabbing Nonintegrin/IL10 Axis

By shaping T cell immunity, tolerogenic dendritic cells (tDCs) play critical roles in the induction of immune tolerance after transplantation. However, the role of long noncoding RNAs (lncRNAs) in the function and immune tolerance of dendritic cells (DCs) is largely unknown. Here, we found that the lncRNA MALAT1 is upregulated in the infiltrating cells of tolerized mice with cardiac allografts and activated DCs. Functionally, MALAT1 overexpression favored a switch in DCs toward a tolerant phenotype. Mechanistically, ectopic MALAT1 promoted dendritic cell-specific intercellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN) expression by functioning as an miR155 sponge, which is essential for the tolerogenic maintenance of DCs and the DC-SIGN-positive subset with more potent tolerogenic ability. The adoptive transfer of MALAT1-overexpressing DCs promoted cardiac allograft survival and protected from the development of experimental autoimmune myocarditis, accompanied with increasing antigen-specific regulatory T cells. Therefore, overexpressed MALAT1 induces tDCs and immune tolerance in heart transplantation and autoimmune disease by the miRNA-155/DC-SIGH/IL10 axis. This study highlights that the lncRNA MALAT1 is a novel tolerance regulator in immunity that has important implications in settings in which tDCs are preferred.

Soluble fibrinogen-like protein 2 ameliorates acute rejection of liver transplantation in rat via inducing Kupffer cells M2 polarization

Soluble fibrinogen-like protein 2 (sFGL2) could ameliorate acute rejection (AR) in rat cardiac transplantation. However, the role of sFGL2 in AR of liver transplantation has not been addressed. In this study, we found that FGL2 was upregulated in rat orthotropic liver transplantation (OLT) models of tolerance and positive correlation with the frequency of M2 Kupffer cells (KCs). Gain-of-function experiments in vitro showed that sFGL2 promoted the secretion of anti-inflammatory cytokines (IL-10, TGF-β) and the expression of CD206, and inhibited the activities of STAT1 and NF-κB signaling pathway. Consistently, in vivo assays showed that adeno-associated virus-mediated FGL2 (AAV-FGL2) transfer to recipients could ameliorate AR of rat OLT and induce KCs M2 polarization in allografts. Notably, we found that the recipients receiving transferred KCs from AAV-FGL2-treated allograft showed alleviated AR. Taken together, we revealed that sFGL2 ameliorated AR by inducing KCs M2 polarization.

MicroRNAs as Immunotherapy Targets for Treating Gastroenterological Cancers

Gastroenterological cancers are the most common cancers categorized by systems and are estimated to comprise 18.4% of all cancers in the United States in 2017. Gastroenterological cancers are estimated to contribute 26.2% of cancer-related death in 2017. Gastroenterological cancers are characterized by late diagnosis, metastasis, high recurrence, and being refractory to current therapies. Since the current targeted therapies provide limited benefit to the overall response and survival, there is an urgent need for developing novel therapeutic strategy to improve the outcome of gastroenterological cancers. Immunotherapy has been developed and underwent clinical trials, but displayed limited therapeutic benefit. Since aberrant expressions of miRNAs are found in gastroenterological cancers and miRNAs have been shown to regulate antitumor immunity, the combination therapy combining the traditional antibody-based immunotherapy and novel miRNA-based immunotherapy is promising for achieving clinical success. This review summarizes the current knowledge about the miRNAs and long noncoding RNAs that exhibit immunoregulatory roles in gastroenterological cancers and precancerous diseases of digestive system, as well as the miRNA-based clinical trials for gastroenterological cancers. This review also analyzes the ongoing challenge of identifying appropriate therapy candidates for complex and dynamic tumor microenvironment, ensuring efficient and targeted delivery to specific cancer tissues, and developing strategy for avoiding off-target effect.

TIM‑4 blockade of KCs combined with exogenous TGF‑β injection helps to reverse acute rejection and prolong the survival rate of mice receiving liver allografts

An acute reaction response (AR) following liver transplantation (LT) is caused by immune responses that are primarily mediated by T lymphocytes. Kupffer cells (KCs) are the largest antigen presenting cell (APC) group in vivo and are the primary modulators of the inflammatory or tolerogenic immune response in liver tissues. T cell immunoglobulin-domain and mucin-domain-4 (TIM-4), the only TIM protein not expressed on T cells, is expressed on APCs; suggesting that it mediates the various immune responses. However, to the best of our knowledge, the role of TIM-4 expressed by KCs in LT injury remains unknown. The present study aimed to explore whether and how TIM-4 expressed by KCs is involved in the AR of liver allografts. Orthotopic liver transplantation (OLT) was performed in mice to establish a model of AR and results demonstrated that LT may lead to the augmented expression of TIM-4 in activated KCs. It was also revealed that TIM-4 blockade markedly attenuated AR injury in vivo via the nuclear factor-κB (NF-κB) and p38 mitogen-activated protein kinase (p38 MAPK) signaling pathways. In addition, levels of transforming growth factor-β (TGF-β) were increased following TIM-4 blockade. Furthermore, in a KC/cluster of differentiation (CD)4⁺ T cell co-culture system, blocking TIM-4 inhibited T helper 2 (Th2) differentiation, stimulated the conversion of naive (CD)4⁺ T cells into CD4⁺CD25⁺Forkhead box protein p3⁺ T regulatory cells and suppressed interleukin-4/signal transducer and activator of transcription 6/transcription factor gata3 signaling. These effects were enhanced following the addition of TGF-β. It was also demonstrated that LT mouse models treated with TIM-4 blockade in combination with exogenous TGF-β injections, increased the survival times of mice and enhanced the amelioration of AR in LT. These results indicate that blocking the expression of TIM-4 by KCs via exogenous TGF-β injection may be an effective therapeutic strategy to inhibit the AR of liver allografts.

Involvement of inflammation and its related microRNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most commonly diagnosed type of cancer. The tumor inflammatory microenvironment regulates almost every step towards liver tumorigenesis and subsequent progression, and regulation of the inflammation-related signaling pathways, cytokines, chemokines and non-coding RNAs influences the proliferation, migration and metastasis of liver tumor cells. Inflammation fine-tunes the cancer microenvironment to favor epithelial-mesenchymal transition, in which cancer stem cells maintain tumorigenic potential. Emerging evidence points to inflammation-related microRNAs as crucial molecules to integrate the complex cellular and molecular crosstalk during HCC progression. Thus understanding the mechanisms by which inflammation regulates microRNAs might provide novel and admissible strategies for preventing, diagnosing and treating HCC. In this review, we will update three hypotheses of hepatocarcinogenesis and elaborate the most predominant inflammation signaling pathways, i.e. IL-6/STAT3 and NF-κB. We also try to summarize the crucial tumor-promoting and tumor-suppressing microRNAs and detail how they regulate HCC initiation and progression and collaborate with other critical modulators in this review.

MicroRNA-155 Deficiency in Kupffer Cells Ameliorates Liver Ischemia-Reperfusion Injury in Mice

BACKGROUND

MicroRNA-155 (miR-155) is known to be involved in autoimmune diseases, inflammation, and transplantation. However, its role in a warm hepatic ischemia-reperfusion (IR) model has not been fully elucidated.

METHODS

Partial hepatic IR was performed in wild-type and miR-155-deficient mice treated with or without GdCl3, and then the serum transaminase concentration and histology were analyzed. Kupffer cells (KCs) were isolated from the liver after IR, and immunohistochemistry was used to evaluate activation and polarization. In addition, the mRNA concentrations of various inflammatory cytokines were measured. Macrophages were obtained from the abdominal cavity and challenged with or without lipopolysaccharide to determine the influence of miR-155 deficiency on macrophage polarization in vitro. Furthermore, we used in vitro coculture assays to determine the effect of miR-155 deficiency on hepatocyte apoptosis induced directly by KCs.

RESULTS

miR-155 deficiency ameliorated liver IR injury, and inhibition of KCs by GdCl3 abolished this protective effect. miR-155 deficiency decreased CD80, CD86, and major histocompatibility complex class II expression in KCs after IR and tipped the M1/M2 balance toward an anti-inflammatory profile, where proinflammatory cytokine secretion was suppressed and IL-10 was enhanced. In addition, hepatocyte apoptosis was reduced in coculture with miR-155-deficient KCs in vitro.

CONCLUSIONS

miR-155 deficiency plays an effective role in attenuating liver IR injury likely by regulating the activation and inflammatory response, as well as modifying the polarization of KCs.

Enhanced immunogenicity following miR-155 incorporation into the influenza A virus genome

Influenza A vaccine efficacy in the elderly is generally poor and so identification of novel molecular adjuvants to improve immunogenicity is important to reduce the overall burden of disease. Short non-coding RNAs, known as microRNAs (miRNAs) are known to regulate gene expression and have the potential to influence immune responses. One such miRNA, miR-155, has been shown to modulate T and B cell development and function. We incorporated miR-155 into the influenza A virus (IAV) genome creating a self-adjuvanting 'live vaccine' with the ability to modify immunogenicity. Infection of mice with a recombinant influenza virus encoding miR-155 in the NS gene segment altered epitope-specific expansion of influenza-specific CD8⁺ T cells and induced significantly higher levels of neutralising antibody.

The role of Kupffer cells in hepatic diseases

Kupffer cells (KCs) constitute 80-90% of the tissue macrophages present in the body. Essential to innate and adaptive immunity, KCs are responsible for the swift containment and clearance of exogenous particulates and immunoreactive materials which are perceived as foreign and harmful to the body. Similar to other macrophages, KCs also sense endogenous molecular signals that may result from perturbed homeostasis of the host. KCs have been implicated in host defense and the pathogenesis of various hepatic diseases, including endotoxin tolerance, liver transplantation, nonalcoholic fatty liver disease, and alcoholic liver disease. In this review, we summarized some novel findings associated with the role of KCs in hepatic diseases, such as the origin and mechanisms KCs polarization, molecular basis for caspase-1 activation called "non-canonical inflammasome pathway" involving the cleavage of Gsdmd by caspase-11, the important role of microRNA in liver transplantation, and so on. A better understanding of KCs biological characteristics and immunologic function in liver homeostasis and pathology may pave the way to investigate new diagnostic and therapeutic approaches for hepatic diseases.

Glucocorticoids regulate the proliferation of T cells via miRNA-155 in septic shock

Although previous studies have evaluated the roles of glucocorticoids and lymphocytes in septic shock, the precise mechanism remains unclear. The present study focused on investigating the influence of glucocorticoids on micro (mi)RNA-155 expression levels and the proliferation of T lymphocytes in septic shock. T cells were harvested from in the peripheral blood of patients with septic shock and healthy volunteers and were cultured in vitro. miRNA-155 levels and cell proliferation rates were subsequently analyzed. The proliferation of T cells from patients with septic shock was observed to be significantly lower as compared with that of T cells from healthy volunteers (P<0.05). Furthermore, miRNA-155 levels were significantly higher in the T cells from patients with septic shock, as compared with those from healthy volunteers (P<0.05). Notably, stimulation with dexamethasone increased the proliferation of T lymphocytes from patients with septic shock in a concentration-dependent manner, and markedly reduced miRNA-155 levels. Furthermore, transfection with an anti-miRNA-155 oligodoxynucleotide significantly increased the proliferation of T lymphocytes from patients with septic shock. In conclusion, the results of the present study indicate that glucocorticoids may regulate T-lymphocyte proliferation via the miRNA-155 pathway during septic shock. Therefore, miRNA-155 may be a potential therapeutic target in the treatment of septic shock.

MicroRNA-155 Mediates Augmented CD40 Expression in Bone Marrow Derived Plasmacytoid Dendritic Cells in Symptomatic Lupus-Prone NZB/W F1 Mice

Systemic lupus erythematosus (SLE) is a chronic multi-organ autoimmune disease characterized by hyperactivated immune responses to self-antigens and persistent systemic inflammation. Previously, we reported abnormalities in circulating and bone marrow (BM)-derived plasmacytoid dendritic cells (pDCs) from SLE patients. Here, we aim to seek for potential regulators that mediate functional aberrations of pDCs in SLE. BM-derived pDCs from NZB/W F1 mice before and after the disease onset were compared for toll-like receptor (TLR) induced responses and microRNA profile changes. While pDCs derived from symptomatic mice were phenotypically comparable to pre-symptomatic ones, functionally they exhibited hypersensitivity to TLR7 but not TLR9 stimulation, as represented by the elevated upregulation of CD40, CD86 and MHC class II molecules upon R837 stimulation. Upregulated induction of miR-155 in symptomatic pDCs following TLR7 stimulation was observed. Transfection of miR-155 mimics in pre-symptomatic pDCs induced an augmented expression of Cd40, which is consistent with the increased CD40 expression in symptomatic pDCs. Overall, our results provide evidence for miR-155-mediated regulation in pDC functional abnormalities in SLE. Findings from this study contribute to a better understanding of SLE pathogenesis and ignite future interests in evaluating the molecular regulation in autoimmunity.

Knockout of microRNA-155 ameliorates the Th1/Th17 immune response and tissue injury in chronic rejection

BACKGROUND

MicroRNAs (miRNAs) are integral for maintaining immune homeostasis and self-tolerance. The influence of miRNAs on T-cell differentiation and plasticity are critical in the development of chronic rejection of transplanted hearts. In this study, we sought to determine whether the knockout of miR-155 affects the development of cardiac allograft vasculopathy (CAV) in a murine model.

METHODS

miRNA microarray and quantitative polymerase chain reaction (qPCR) analyses were performed for allograft neointimal lesion samples in chronic rejection. A model of heterotopic murine heart transplantation (bm12 to miR-155^+/+ or miR-155^-/- mice) was then used to analyze allograft survival, histology, mRNA expression and T-cell sub-populations in spleens. The accelerated experiments were performed by intraperitoneal injection of either recombinant interleukin-17A or phosphate-buffered saline (PBS) after heart transplantation. For the competitive transfer experiments, CD4⁺ splenocytes from wild-type (WT) or miR-155^-/- mice were mixed and injected into Rag1^-/- mice, and cardiac transplantation was performed after 24 hours. The differentiation of T-helper subsets (Th1/Th17/iTreg) was investigated in vitro.

RESULTS

miR-155^-/- mice showed resistance to cardiac rejection along with weakened T-cell-mediated inflammation, especially for Th17 cells. Recombinant IL-17A could restore this relieved injury. The competitive experiments implied that miR-155 plays a vital role in the stability of the Th17 phenotype. In vitro, we also demonstrated that miR-155^-/- mice exhibit a defect in Th17 differentiation.

CONCLUSIONS

miR-155 regulates Th1/Th17-related inflammation in chronic cardiac rejection and may be a potential therapeutic target to attenuate cardiac allograft rejection. Despite advancements in immunosuppressive therapy, the immunologic mechanisms responsible for allograft rejection remain an important issue for both clinicians and researchers. Allograft rejection is a T-cell-dependent phenomenon and is critically dependent on inflammation mediated by CD4⁺ Th subsets, including Th1, Th2, Th17, Th9 and regulatory T (Treg) cells.

MicroRNA let-7i regulates dendritic cells maturation targeting interleukin-10 via the Janus kinase 1-signal transducer and activator of transcription 3 signal pathway subsequently induces prolonged cardiac allograft survival in rats

BACKGROUND

In this study, we investig1ated whether microRNA let-7i regulates dendric cell maturation targeting interleukin-10 (IL-10) via the Janus kinase 1-signal transducer and activator of transcription 3 (JAK1-STAT3) signal pathway subsequently prolongs rat cardiac allograft survival.

METHODS

Quantitative real-time reverse transcriptase polymerase chain reaction, enzyme linked immunosorbent assay, and dual-luciferase assay were performed to verify whether IL-10 was the target of let-7i, and regulatory T cells were assessed by flow cytometry and immunohistochemical study. Western blot was performed to detect JAK1, STAT3, and phosphorylated STAT3 expression. Lewis recipients of Dark Agouti hearts were transfused with phosphate-buffered saline, lipopolysaccharide (LPS)-mature dendritic cells (mDCs), or let-7i-inhibitor-mDCs. Allograft survival times were recorded, and histologic studies were performed.

RESULTS

Expression of IL-10 messenger RNA level and production of IL-10 were increased in let-7i-inhibitor-mDCs compared with LPS-mDCs. Luciferase activity showed that the translational level of the IL-10 luciferase reporter was decreased by let-7i mimic but increased by let-7i-inhibitor. MicroRNA let-7i inhibitor suppressed DC maturation; however, pretreatment of IL-10 small interfering RNA attenuated the suppression. Expression of JAK1, STAT3, and phosphorylated STAT3 in mDCs were suppressed by let-7i mimic, and pre-treatment of IL-10 small interfering RNA, however, were upregulated by let-7i inhibitor. Lewis recipients transfused with let-7i-inhibitor-mDCs significantly prolonged Dark Agouti cardiac allograft survival. The allografts transfused with let-7i-inhibitor-mDCs showed slight cell infiltration and significantly preserved graft structure. Inhibition of let-7i increased CD4(+)CD25(+)forkhead box P3(+) regulatory T cells and modulated cytokine profiles in vivo and in vitro.

CONCLUSIONS

MicroRNA let-7i regulated DC maturation and function targeting IL-10 through the JAK1-STAT3 pathway. Moreover, transfusion of LPS-induced mDCs transfected with let-7i inhibitor induced prolonged cardiac allograft survival and generated regulatory T cells.

Kupffer cells and liver transplantation

Nowadays, liver transplantation is globally considered the most effective treatment for end-stage liver diseases. Ischemia-reperfusion (I/R) injury and immune rejection response (IRR) are the two major imperfections which severely affect the recipients' prognosis and survival rate without satisfactory clinical management strategies. Therefore, exploring effective methods to improve I/R injury and IRR have important clinical significance under circumstances of shortage of donor livers. Kupffer cells (KCs) are the largest population of antigen representing cells (APCs) which settle in the liver. As the first defensive line of the live, KCs exhibit various biological effects. However, the exact mechanisms responsible for the role of KCs in I/R injury and IRR remain elusive. We hereby review the current finding about the role of KCs in I/R injury and IRR.

MicroRNA-155 knockout mice are susceptible to Mycobacterium tuberculosis infection

MicroRNAs (miRNAs) are short, conserved, non-coding RNA molecules that repress translation, followed by the decay of miRNA-targeted mRNAs that encode molecules involved in cell differentiation, development, immunity and apoptosis. At least six miRNAs, including microRNA-155 (miR-155), were up-regulated when born marrow-derived macrophages from C57BL/6 mice were infected with Mycobacterium tuberculosis Erdman. C57BL/6 mice intravenously infected with Erdman showed up-regulation of miR-155 in livers and lungs. Following infection, miR-155-deficient C57BL/6 mice died significantly earlier and had significantly higher numbers of CFU in lungs than wild-type mice. Moreover, fewer CD4(+) T cells, but higher numbers of monocytes and neutrophils, were present in the lungs of Erdman-infected miR-155 knockout (miR-155(-/-)) than of wild-type mice. These findings indicated that miR-155 plays a critical role in immune responses to M. tuberculosis.

Autophagy: an adaptive metabolic response to stress shaping the antitumor immunity

Several environmental-associated stress conditions, including hypoxia, starvation, oxidative stress, fast growth and cell death suppression, modulate both cellular metabolism and autophagy to enable cancer cells to rapidly adapt to environmental stressors, maintain proliferation and evade therapies. It is now widely accepted that autophagy is essential to support cancer cell growth and metabolism and that metabolic reprogramming in cancer can also favor autophagy induction. Therefore, this complex interplay between autophagy and tumor cell metabolism will provide unique opportunities to identify new therapeutic targets. As the regulation of the autophagic activity is related to metabolism, it is important to elucidate the exact molecular mechanism which drives it and the functional consequence of its activation in the context of cancer therapy. In this review, we will summarize the role of autophagy in shaping the cellular response to an abnormal tumor microenvironment and discuss some recent results on the molecular mechanism by which autophagy plays such a role in the context of the anti-tumor immune response. We will also describe how autophagy activation can behave as a double-edged sword, by activating the immune response in some circumstances, and impairing the anti-tumor immunity in others. These findings imply that defining the precise context-specific role for autophagy in cancer is critical to guide autophagy-based therapeutics which are becoming key strategies to overcome tumor resistance to therapies.