Complement C3 activation regulates the production of tRNA-derived fragments Gly-tRFs and promotes alcohol-induced liver injury and steatosis

tRNA-derived small RNAs in digestive tract diseases: Progress and perspectives

tRNA-derived small RNAs (tsRNAs) are non-coding small RNAs that are produced through the precise cleavage of tRNA molecules under specific conditions. tsRNA has multiple functions, including inhibiting translation, acting in association with classical small RNA effector mechanisms, or acting in conjunction with Argonaute proteins that affect cell proliferation, migration, cycle, and apoptosis. Recent studies have revealed the clinical potential of tsRNAs in numerous diseases. This article aims to provide a comprehensive and up-to-date review of the classification and biological function of tsRNAs in gastrointestinal diseases. Furthermore, this review explores the underlying mechanisms by which tsRNAs are believed to exert their effects in both tumor and non-tumor digestive tract diseases. Therefore, specific tsRNAs prove promising for disease diagnosis, prognosis prediction, and therapeutic interventions as novel biomarkers for digestive tract diseases.

Research progress on the roles of complement in liver injury

The complement system is crucial for maintaining immunological homeostasis in the liver, playing a significant role in both innate and adaptive immune responses. Dysregulation of this system is closely linked to the pathogenesis of various liver diseases. Modulating the complement system can affect the progression of these conditions. To provide insights into treating liver injury by targeting the regulation of the complement system, we conducted a comprehensive search of major biomedical databases, including MEDLINE, PubMed, EMBASE, and Web of Science, to identify articles on complement and liver injury and reviewed the functions and mechanisms of the complement system in liver injury.

Complement C3a promotes the formation of osteoclasts by inhibiting Sirt1 to activate the PI3K/PDK1/SGK3 pathway in patients with multiple myeloma

BACKGROUND

Myeloma bone disease (MBD) is the most common complication of multiple myeloma (MM). Our previous study showed that the complement C3a activates osteoclasts to participate in the pathogenesis of MBD; however, its mechanism of action is diverse and complex. Studies have shown that the Sirtuin (Sirt) family of proteins (i.e., Sirt1-7) are expressed in human bone and cartilage, and participate in bone metabolic balance.

METHODS AND RESULTS

We measured the levels of complement C3a, Sirt1, osteoclast-related genes, and bone disease-related biological indicators using enzyme-linked immunosorbent assay (ELISA), quantitative real-time PCR and western blotting. Sirt1 expression in osteoclasts was observed to be lower in patients with MM compared to healthy donors and negatively correlated with complement C3a levels, osteoclast-related gene expression, and osteolysis-related markers. Co-immunoprecipitation (Co-IP) and immunostaining were used to verify the interaction between C3a and Sirt1 in RAW264.7 cells. Osteoclasts were then induced from bone marrow mononuclear cells (BMMCs) in patients with MM or cultured RAW264.7 cells, using C3a and/or Sirt1 activator (SRT1720)/inhibitors (EX527) in vitro. Sirt1 inhibits osteoclast formation and complement C3a reverses this inhibitory function of Sirt1 to activate osteoclasts. RAW264.7 cells with induced overexpression or knockdown Sirt1 were transfected with plasmid or shRNA, and RNA-seq analysis was performed. Increased Sirt1 expression resulted in the inhibition of the PI3K/PDK1/SGK3 pathway, which could be reactivated by complement C3a. Sirt1 knockdown activated the PI3K/PDK1/SGK3 pathway, which was further enhanced by complement C3a. A mouse model of MBD was successfully constructed. We injected this model with complement C3a or SRT1720, which further verified that complement C3a can significantly increase the degree of MBD bone damage, whereas SRT1720 can reduce the bone damage aggravated by C3a and treat MBD.

CONCLUSION

We demonstrated that complement C3a interacts with Sirt1 in osteoclasts to participate in the pathogenesis of MBD. Complement C3a promotes osteoclast formation by inhibiting Sirt1 to activate the PI3K/PDK1/SGK3 pathway in patients with MM, which is reduced by treatment with a Sirt1 activator. The application of a Sirt1 activator can reduce the formation of osteoclasts and reduce the severity of bone diseases in vivo and may be useful for the treatment of MBD. This study identified novel potential therapeutic targets and strategies for patients with MBD.

Exosomal tRF-1003 induces angiogenesis via regulating the HIF1α/VEGF signaling in multiple myeloma

BACKGROUND

Multiple myeloma (MM) remains a therapeutically challenging hematologic malignancy characterized by frequent relapse and disease progression. Angiogenesis regulated by non-coding RNAs plays a vital role in MM pathogenesis. Despite the potential clinical applications of tsRNAs, the specific mechanisms by which they contribute to MM progression, particularly through angiogenesis within the bone marrow microenvironment, remain elusive.

METHODS

In this study, we focused on the role of exosomal tRF-1003 in MM progression. Serum and bone marrow samples from relapsed and refractory multiple myeloma (R/RMM) and newly diagnosed multiple myeloma (NDMM) patients were analyzed for tsRNA expression. Functional assays, including transwell migration, wound-healing assays, and in vivo tumor formation studies, were employed to assess the angiogenic potential of tRF-1003 in HUVEC. Mechanistic studies were conducted to understand how tRF-1003 modulates the HIF-1α/VEGF signaling pathway through interaction with MAPK1.

RESULTS

We found that tRF-1003 was significantly upregulated in serum exosomes derived from R/RMM patients. Exosomal tRF-1003 was efficiently delivered to endothelial cells, leading to enhanced angiogenesis both in vitro and in vivo. Mechanistically, tRF-1003 was shown to activate HIF-1α/VEGF signaling in endothelial cells by downregulating MAPK1 expression, thereby promoting angiogenesis. Overexpression of MAPK1 in endothelial cells partially reversed the angiogenic effects induced by exosomal tRF-1003.

CONCLUSION

Our findings reveal that exosomal tRF-1003 plays a pivotal role in MM angiogenesis by modulating the HIF-1α/VEGF signaling pathway through MAPK1. These insights provide a novel perspective on the mechanisms driving MM progression and highlight the potential therapeutic value of targeting tRF-1003 in managing multiple myeloma.

Lipocalin-2 silencing alleviates sepsis-induced liver injury through inhibition of ferroptosis

INTRODUCTION AND OBJECTIVES

Liver plays a key role in sepsis, a systemic inflammatory response syndrome caused by infection. Ferroptosis is involved in sepsis-induced liver injury. We aimed to assess the changes in ferroptosis in cecal ligation and puncture (CLP)-induced septic mice, and determine the role of lipocalin-2 (LCN2) in liver ferroptosis.

MATERIALS AND METHODS

CLP was used to induce sepsis in mice. The morphological changes in liver tissues and mitochondrial structure were observed using hematoxylin and eosin staining and transmission electron microscopy. The levels of serum alanine transaminase, aspartate aminotransferase, superoxide dismutase, and malondialdehyde were detected using the corresponding kits. The changes of reactive oxygen species level in liver tissues were detected using dihydroethidium as a fluorescence probe. LCN2, cysteine-glutamate reverse transport system, and dihydroorotate dehydrogenase protein levels in the liver were detected by western blotting. The ferroptosis inhibitor ferrostatin-1 (Fer-1), iron chelator dexrazoxane (DXZ), iron-dextran, and LCN2 knockdown studies were performed to determine role of ferroptosis and LCN2 in liver injury during sepsis.

RESULTS

Ferroptosis levels increased in the liver tissues of CLP-induced septic mice. Both Fer-1 and DXZ suppressed ferroptosis and attenuated liver injury following sepsis challenge, whereas iron-dextran increased ferroptosis and liver injury in mice with sepsis. LCN2 knockdown suppressed ferroptosis and reduced oxidative stress in the liver.

CONCLUSIONS

Ferroptosis inhibition attenuates septic liver injury. LCN2 knockdown alleviates sepsis-induced liver injury by inhibiting ferroptosis and reducing oxidative stress.

Unveiling the hidden world of transfer RNA-derived small RNAs in inflammation

Transfer RNA-derived small RNAs (tsRNAs) are a newly discovered class of small noncoding RNAs (sncRNAs) that include tRNA-derived stress-induced RNAs (tiRNAs) and tRNA-derived fragments (tRFs). Following the development of high-throughput sequencing technology, an increasing number of tsRNAs have been discovered with vital functions in different physiological and pathophysiological processes. Extensive research has revealed that tsRNAs are involved in various diseases, such as cancers, autoimmune illnesses and other diseases. This review focuses on the role and significance of tsRNAs in inflammation, such as the regulation of substances including inflammatory inducers, inflammatory cells and inflammatory factors, which contribute to the pathogenesis of inflammation-related diseases. Moreover, we discuss in-depth the molecular pathogenic mechanisms of tsRNAs in inflammation-related diseases through different signaling pathways and assess their clinical value, providing new perspectives for the exploration of tsRNA functions and inflammation-related diseases.

Hepatocyte-derived Fetuin-A promotes alcohol-associated liver disease in mice by inhibiting autophagy-lysosome degradation of TLR and M2 macrophage polarization

BACKGROUND

Alcohol-associated liver disease (ALD) is one of the most common chronic liver diseases worldwide. Fetuin-A (FetA) is a plasma glycoprotein closely related to fat accumulation in the liver. However, the role of FetA in ALD remains unclear.

METHODS

Both National Institute on Alcohol Abuse and Alcoholism (NIAAA) model and ethanol (EtOH) treated cell were used in this study. The effect of FetA deficiency on the progression of ALD was analyzed and the underlying mechanism was explored.

RESULTS

The expression of FetA was upregulated in the liver tissues of ethanol-fed mice and ALD patients, as well as in AML12 cells treated with ethanol. FetA deletion reduced hepatic steatosis, oxidative stress, and inflammation in ALD mice. Interestingly, the absence of FetA led to a reduction of TLR4 protein level in liver tissue of EtOH-fed mice, without a corresponding change of its mRNA level. Conversely, the administration of recombinant FetA elevated TLR4 protein level in ethanol-treated RAW264.7 cells. FetA knockout significantly impeded the polarization of M1 macrophage in vivo or in vitro. Mechanistically, FetA deficiency drived the autophagy-lysosomal degradation of TLR4, subsequently inhibiting the activation of NF-kB/NLRP3 inflammasome pathway. Furthermore, knockdown of FetA using an adeno-associated virus 8 (AAV8)-shRNA can effectively prevent the progression of ALD in mice.

CONCLUSION

Our results indicate that inhibition of FetA reverses the progression of ALD in mice, implying that FetA can serve as a therapeutic target for the treatment of ALD.

Emerging roles of tRNA-derived small RNAs in injuries

tRNA-derived small RNAs (tsRNAs) are a novel class of small noncoding RNAs, precisely cleaved from tRNA, functioning as regulatory molecules. The topic of tsRNAs in injuries has not been extensively discussed, and studies on tsRNAs are entering a new era. Here, we provide a fresh perspective on this topic. We systematically reviewed the classification, generation, and biological functions of tsRNAs in response to stress, as well as their potential as biomarkers and therapeutic targets in various injuries, including lung injury, liver injury, renal injury, cardiac injury, neuronal injury, vascular injury, skeletal muscle injury, and skin injury. We also provided a fresh perspective on the association between stress-induced tsRNAs and organ injury from a clinical perspective.

The Complement System Is Essential for Arteriogenesis by Enhancing Sterile Inflammation as a Relevant Step in Collateral Artery Growth

Arteriogenesis is an inflammatory driven mechanism, describing the growth of a natural bypass from pre-existing collateral arteries to compensate for an occluded artery. The complement system component C3 is a potent natural inflammatory activator. Here, we investigated its impact on the process of collateral artery growth using C3-deficient (C3 -/-) and wildtype control mice in a murine hindlimb model of arteriogenesis. Induction of arteriogenesis by unilateral femoral artery ligation resulted in decreased perfusion recovery in C3 -/- mice on day 7 as shown by Laser Doppler imaging. Immunofluorescence staining revealed a reduced vascular cell proliferation in C3 -/- mice. Gene expression analysis displayed a significant reduction in monocyte chemoattractant protein-1 (MCP-1) expression in C3 -/- mice. Interestingly, 3 days after induction of arteriogenesis, the number of macrophages (CD68+) recruited to growing collaterals was not affected by C3 deficiency. However, a significant reduction in inflammatory M1-like polarized macrophages (CD68+/MRC1-) was noted. Forced mast cell activation by Compound 48/80 as well as exogenous MCP-1 application rescued the number of M1-like polarized macrophages along with perfusion recovery in C3 -/- mice. In summary, this study demonstrates that complement C3 influences arteriogenesis by mediating MCP-1 expression, which is essential for the induction and enhancement of sterile inflammation.

Tectorigenin improves metabolic dysfunction-associated steatohepatitis by down-regulating tRF-3040b and promoting mitophagy to inhibit pyroptosis pathway

Tectorigenin (TEC) as a plant extract has the advantage of low side effects on metabolic dysfunction-associated steatohepatitis (MASH) treatment. Our previous study have shown that tRNA-derived RNA fragments (tRFs) associated with autophagy and pyroptosis in MASH, but whether TEC can mitigate MASH through tRFs-mediated mitophagy is not fully understood. This study aims to investigate whether TEC relies on tRFs to adjust the crosstalk of hepatocyte mitophagy with pyroptosis in MASH. Immunofluorescence results of PINK1 and PRKN with MitoTracker Green-labeled mitochondria verified that TEC enhanced mitophagy. Additionally, TEC inhibited pyroptosis, as reflected by the level of GSDME, NLRP3, IL-1β, and IL-18 decreased after TEC treatment, while the effect of pyroptosis inhibition by TEC was abrogated by Pink1 silencing. We found that the upregulation expression of tRF-3040b caused by MASH was suppressed by TEC. The promotion of mitophagy and the suppression of pyroptosis induced by TEC were abrogated by tRF-3040b mimics. TEC reduced lipid deposition, inflammation, and pyroptosis, and promoted mitophagy in mice, but tRF-3040b agomir inhibited these effects. In summary, our findings provided that TEC significantly reduced the expression of tRF-3040b to enhance mitophagy, thereby inhibiting pyroptosis in MASH. We elucidated a powerful theoretical basis and provided safe and effective potential drugs for MASH with the prevention and treatment.

Curcumin improves atrial fibrillation susceptibility by regulating tsRNA expression in aging mouse atrium

Age is an independent risk factor for atrial fibrillation (AF), and curcumin can delay aging related disease through reducing oxidative stress and inflammation. However, its target in aging-related AF remains unclear. Transfer RNA-derived small RNA (tsRNA) is a novel short non-coding RNA (sncRNA), and exerts a potential regulatory function in aging. This study was to explore the therapeutic targets of curcumin in atrium of aged mice by PANDORA-seq. Aged mice (18 month) were treated with curcumin (100 mg/kg). Rapid transjugular atrial pacing was performed to observe AF inducibility. SA-β-gal staining, reactive oxygen species (ROS) detection and qRT-PCR were used to assess the degree of aging and oxidative stress/inflammation levels. PANDORA-seq was performed to reveal the differentially expressed sncRNAs in the atrium of mice. The results showed that curcumin reduced the susceptibility AF of aged mice by improving aging-related atrial fibrosis. Compared to young mice (5 month) group, aged mice yielded 473 significantly altered tsRNA sequences, while 947 tsRNA sequences were significantly altered after treated with curcumin. Enrichment analysis revealed that the target genes were mainly related to DNA damage and protein modification. Compared with the 5 month group, the expression levels of mature-mt_tRNA-Val-TAC_CCA_end, mature-mt_tRNA-Glu-TTC_CCA_end, and mature-tRNA-Asp-GTC_CCA_end were up-regulated in the 18 month group, while the expression of mature-mt_tRNA-Thr-TGT_5_end was down-regulated. This trend was reversed in the 18 month + curcumin group. Increased cellular ROS levels, inflammation expression and senescence in aged mice atrium were improved by the down-regulation of mature-mt_tRNA-Val-TAC_CCA_end. In conclusion, our findings identified mature-mt_tRNA-Val-TAC_CCA_end participated in the mechanism of aging-related atrial fibrosis, providing new intervention target of aging-related AF.

The role of gut microbiota, exosomes, and their interaction in the pathogenesis of ALD

BACKGROUND

The liver disorders caused by alcohol abuse are termed alcoholic-related liver disease (ALD), including alcoholic steatosis, alcoholic steatohepatitis, alcoholic hepatitis, and alcoholic cirrhosis, posing a significant threat to human health. Currently, ALD pathogenesis has not been completely clarified, which is likely to be related to the direct damage caused by alcohol and its metabolic products, oxidative stress, gut dysbiosis, and exosomes.

AIMS

The existing studies suggest that both the gut microbiota and exosomes contribute to the development of ALD. Moreover, there exists an interaction between the gut microbiota and exosomes. We discuss whether this interaction plays a role in the pathogenesis of ALD and whether it can be a potential therapeutic target for ALD treatment.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Chronic alcohol intake alters the diversity and composition of gut microbiota, which greatly contributes to ALD's progression. Some approaches targeting the gut microbiota, including probiotics, fecal microbiota transplantation, and phage therapy, have been confirmed to effectively ameliorate ALD in many animal experiments and/or several clinical trials. In ALD, the levels of exosomes and the expression profile of microRNA have also changed, which affects the pathogenesis of ALD. Moreover, there is an interplay between exosomes and the gut microbiota, which also putatively acts as a pathogenic factor of ALD.

Small non-coding RNA signatures in atrial appendages of patients with atrial fibrillation

The development of high-throughput technologies has enhanced our understanding of small non-coding RNAs (sncRNAs) and their crucial roles in various diseases, including atrial fibrillation (AF). This study aimed to systematically delineate sncRNA profiles in AF patients. PANDORA-sequencing was used to examine the sncRNA profiles of atrial appendage tissues from AF and non-AF patients. Differentially expressed sncRNAs were identified using the R package DEGseq 2 with a fold change >2 and p < 0.05. The target genes of the differentially expressed sncRNAs were predicted using MiRanda and RNAhybrid. Gene Ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed. In AF patients, the most abundant sncRNAs were ribosomal RNA-derived small RNAs (rsRNAs), followed by transfer RNA-derived small RNAs (tsRNAs), and microRNAs (miRNAs). Compared with non-AF patients, 656 rsRNAs, 45 miRNAs, 191 tsRNAs and 51 small nucleolar RNAs (snoRNAs) were differentially expressed in AF patients, whereas no significantly differentially expressed piwi-interacting RNAs were identified. Two out of three tsRNAs were confirmed to be upregulated in AF patients by quantitative reverse transcriptase polymerase chain reaction, and higher plasma levels of tsRNA 5006c-LysCTT were associated with a 2.55-fold increased risk of all-cause death in AF patients (hazard ratio: 2.55; 95% confidence interval, 1.56-4.17; p < 0.001). Combined with our previous transcriptome sequencing results, 32 miRNA, 31 snoRNA, 110 nucleus-encoded tsRNA, and 33 mitochondria-encoded tsRNA target genes were dysregulated in AF patients. GO and KEGG analyses revealed enrichment of differentially expressed sncRNA target genes in AF-related pathways, including the 'calcium signaling pathway' and 'adrenergic signaling in cardiomyocytes.' The dysregulated sncRNA profiles in AF patients suggest their potential regulatory roles in AF pathogenesis. Further research is needed to investigate the specific mechanisms of sncRNAs in the development of AF and to explore potential biomarkers for AF treatment and prognosis.

Inflammatory liver diseases and susceptibility to sepsis

Patients with inflammatory liver diseases, particularly alcohol-associated liver disease and metabolic dysfunction-associated fatty liver disease (MAFLD), have higher incidence of infections and mortality rate due to sepsis. The current focus in the development of drugs for MAFLD is the resolution of non-alcoholic steatohepatitis and prevention of progression to cirrhosis. In patients with cirrhosis or alcoholic hepatitis, sepsis is a major cause of death. As the metabolic center and a key immune tissue, liver is the guardian, modifier, and target of sepsis. Septic patients with liver dysfunction have the highest mortality rate compared with other organ dysfunctions. In addition to maintaining metabolic homeostasis, the liver produces and secretes hepatokines and acute phase proteins (APPs) essential in tissue protection, immunomodulation, and coagulation. Inflammatory liver diseases cause profound metabolic disorder and impairment of energy metabolism, liver regeneration, and production/secretion of APPs and hepatokines. Herein, the author reviews the roles of (1) disorders in the metabolism of glucose, fatty acids, ketone bodies, and amino acids as well as the clearance of ammonia and lactate in the pathogenesis of inflammatory liver diseases and sepsis; (2) cytokines/chemokines in inflammatory liver diseases and sepsis; (3) APPs and hepatokines in the protection against tissue injury and infections; and (4) major nuclear receptors/signaling pathways underlying the metabolic disorders and tissue injuries as well as the major drug targets for inflammatory liver diseases and sepsis. Approaches that focus on the liver dysfunction and regeneration will not only treat inflammatory liver diseases but also prevent the development of severe infections and sepsis.

Day L, Ouyang X, Suyavaran A, Mehal WZ, Jacobs JM, Goodman RP, Rotroff DM, Nagy LE. Proteomics identifies complement protein signatures in patients with alcohol-associated hepatitis

Diagnostic challenges continue to impede development of effective therapies for successful management of alcohol-associated hepatitis (AH), creating an unmet need to identify noninvasive biomarkers for AH. In murine models, complement contributes to ethanol-induced liver injury. Therefore, we hypothesized that complement proteins could be rational diagnostic/prognostic biomarkers in AH. Here, we performed a comparative analysis of data derived from human hepatic and serum proteome to identify and characterize complement protein signatures in severe AH (sAH). The quantity of multiple complement proteins was perturbed in liver and serum proteome of patients with sAH. Multiple complement proteins differentiated patients with sAH from those with alcohol cirrhosis (AC) or alcohol use disorder (AUD) and healthy controls (HCs). Serum collectin 11 and C1q binding protein were strongly associated with sAH and exhibited good discriminatory performance among patients with sAH, AC, or AUD and HCs. Furthermore, complement component receptor 1-like protein was negatively associated with pro-inflammatory cytokines. Additionally, lower serum MBL associated serine protease 1 and coagulation factor II independently predicted 90-day mortality. In summary, meta-analysis of proteomic profiles from liver and circulation revealed complement protein signatures of sAH, highlighting a complex perturbation of complement and identifying potential diagnostic and prognostic biomarkers for patients with sAH.

GenX analogs exposure induced greater hepatotoxicity than GenX mainly via activation of PPARα pathway while caused hepatomegaly in the absence of PPARα in female mice

Despite their use as substitutes for perfluorooctanoic acid, the potential toxicities of hexafluoropropylene oxide dimer acid (HFPO-DA, commercial name: GenX) and its analogs (PFDMOHxA, PFDMO2HpA, and PFDMO2OA) remain poorly understood. To assess the hepatotoxicity of these chemicals on females, each chemical was orally administered to female C57BL/6 mice at the dosage of 0.5 mg/kg/d for 28 d. The contribution of peroxisome proliferator-activated receptors (PPARα and γ) and other nuclear receptors involving in these toxic effects of GenX and its analogs were identified by employing two PPAR knockout mice (PPARα-/- and PPARγΔHep) in this study. Results showed that the hepatotoxicity of these chemicals increased in the order of GenX < PFDMOHxA < PFDMO2HpA < PFDMO2OA. The increases of relative liver weight and liver injury markers were significantly much lower in PPARα-/- mice than in PPARα+/+ mice after GenX analog exposure, while no significant differences were observed between PPARγΔHep and its corresponding wildtype groups (PPARγF/F mice), indicating that GenX analog induce hepatotoxicity mainly via PPARα instead of PPARγ. The PPARα-dependent complement pathways were inhibited in PFDMO2HpA and PFDMO2OA exposed PPARα+/+ mice, which might be responsible for the observed liver inflammation. In PPARα-/- mice, hepatomegaly and increased liver lipid content were observed in PFDMO2HpA and PFDMO2OA treated groups. The activated pregnane X receptor (PXR) and constitutive activated receptor (CAR) pathways in the liver of PPARα-/- mice, which were highlighted by bioinformatics analysis, provided a reasonable explanation for hepatomegaly in the absence of PPARα. Our results indicate that GenX analogs could induce more serious hepatotoxicity than GenX whether there is a PPARα receptor or not. These chemicals, especially PFDMO2HpA and PFDMO2OA, may not be appropriate PFOA alternatives.

Multiple regulatory roles of the transfer RNA-derived small RNAs in cancers

With the development of sequencing technology, transfer RNA (tRNA)-derived small RNAs (tsRNAs) have received extensive attention as a new type of small noncoding RNAs. Based on the differences in the cleavage sites of nucleases on tRNAs, tsRNAs can be divided into two categories, tRNA halves (tiRNAs) and tRNA-derived fragments (tRFs), each with specific subcellular localizations. Additionally, the biogenesis of tsRNAs is tissue-specific and can be regulated by tRNA modifications. In this review, we first elaborated on the classification and biogenesis of tsRNAs. After summarizing the latest mechanisms of tsRNAs, including transcriptional gene silencing, post-transcriptional gene silencing, nascent RNA silencing, translation regulation, rRNA regulation, and reverse transcription regulation, we explored the representative biological functions of tsRNAs in tumors. Furthermore, this review summarized the clinical value of tsRNAs in cancers, thus providing theoretical support for their potential as novel biomarkers and therapeutic targets.

From complement to complosome in non-alcoholic fatty liver disease: When location matters

Non-alcoholic fatty liver disease (NAFLD) is a growing public health threat and becoming the leading cause of liver transplantation. Nevertheless, no approved specific treatment is currently available for NAFLD. The pathogenesis of NAFLD is multifaceted and not yet fully understood. Accumulating evidence suggests a significant role of the complement system in the development and progression of NAFLD. Here, we provide an overview of the complement system, incorporating the novel concept of complosome, and summarise the up-to-date evidence elucidating the association between complement dysregulation and the pathogenesis of NAFLD. In this process, the extracellular complement system is activated through various pathways, thereby directly contributing to, or working together with other immune cells in the disease development and progression. We also introduce the complosome and assess the evidence that implicates its potential influence in NAFLD through its direct impact on hepatocytes or non-parenchymal liver cells. Additionally, we expound upon how complement system and the complosome may exert their effects in relation with hepatic zonation in NAFLD. Furthermore, we discuss the potential therapeutic implications of targeting the complement system, extracellularly and intracellularly, for NAFLD treatment. Finally, we present future perspectives towards a better understanding of the complement system's contribution to NAFLD.

Pan-cancer tRNA-derived fragment CAT1 coordinates RBPMS to stabilize NOTCH2 mRNA to promote tumorigenesis

Transfer RNA-derived fragments (tRFs) are a class of small non-coding regulatory RNAs that are involved in the pathophysiology of many diseases. However, the role of tRFs in cancer progression remains largely elusive. Here, we demonstrate that a pan-cancer 3'-tRF, CAT1 (cancer associated tRF 1), is ubiquitously upregulated in tumors and associated with poor prognosis of a variety of cancers, including lung cancer. The upregulated CAT1 in cancer cells binds to RNA-binding protein with multiple splicing (RBPMS) and displaces NOTCH2 association from RBPMS, thereby inhibiting the subsequent CCR4-NOT deadenylation-complex-mediated NOTCH2 mRNA decay. The CAT1-enhanced NOTCH2 expression promotes lung cancer cell proliferation and metastasis in vitro and in vivo. In addition, plasma CAT1 levels are substantially increased in patients with lung cancer compared to non-cancer control subjects. Our findings reveal an intrinsic connection between cancer-specific upregulation of CAT1 and cancer progression, show the regulation of NOTCH signaling in cancer by a 3'-tRF, and highlight its great clinical potential.

Biological function and clinical application prospect of tsRNAs in digestive system biology and pathology

tsRNAs are small non-coding RNAs originating from tRNA that play important roles in a variety of physiological activities such as RNA silencing, ribosome biogenesis, retrotransposition, and epigenetic inheritance, as well as involvement in cellular differentiation, proliferation, and apoptosis. tsRNA-related abnormalities have a significant influence on the onset, development, and progression of numerous human diseases, including malignant tumors through affecting the cell cycle and specific signaling molecules. This review introduced origins together with tsRNAs classification, providing a summary for regulatory mechanism and physiological function while dysfunctional effect of tsRNAs in digestive system diseases, focusing on the clinical prospects of tsRNAs for diagnostic and prognostic biomarkers. Video Abstract.

Digging out the biology properties of tRNA-derived small RNA from black hole

An unique subclass of functional non-coding RNAs generated by transfer RNA (tRNA) under stress circumstances is known as tRNA-derived small RNA (tsRNA). tsRNAs can be divided into tRNA halves and tRNA-derived fragments (tRFs) based on the different cleavage sites. Like microRNAs, tsRNAs can attach to Argonaute (AGO) proteins to target downstream mRNA in a base pairing manner, which plays a role in rRNA processing, gene silencing, protein expression and viral infection. Notably, tsRNAs can also directly bind to protein and exhibit functions in transcription, protein modification, gene expression, protein stabilization, and signaling pathways. tsRNAs can control the expression of tumor suppressor genes and participate in the initiation of cancer. It can also mediate the progression of diseases by regulating cell viability, migration ability, inflammatory factor content and autophagy ability. Precision medicine targeting tsRNAs and drug therapy of plant-derived tsRNAs are expected to be used in clinical practice. In addition, liquid biopsy technology based on tsRNAs indicates a new direction for the non-invasive diagnosis of diseases.

Physicochemical properties of superfine grinding-microwave modified artichoke soluble dietary fiber and their alleviation of alcoholic fatty liver in mice

The effects of superfine grinding (SG) and microwave treatment (MT) on the structure and physicochemical properties of artichoke soluble dietary fiber (ASDF) and its protective effects on mice with alcoholic fatty liver (AFL) were studied. We compared the changes in structural characteristics and physicochemical properties of ASDF, SG-ASDF (ASDF treated by SG), MT-ASDF (ASDF treated by MT), and CM-ASDF (ASDF treated by SG and MT). Moreover, we evaluated the effects of the obtained ASDF on the growth characteristics, blood lipid levels, and liver of mice with AFL. Our results of the study showed that CM-ASDF had a more concentrated and uniform particle size, a higher extraction rate of ASDF and significantly improved water-holding capacity (WHC), oil-holding capacity (OHC) and water swelling capacity (WSC) of ASDF (p < 0.05). After the ASDF intervention, mice with AFL exhibited a significant improvement in body lipid levels and reduce liver inflammation. Specifically, aspartate aminotransferase (AST), alanine aminotransferase (ALT), malonaldehyde (MDA), Tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6) were significantly decreased, while superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were significantly increased (p < 0.05). And the hematoxylin-eosin (HE) staining results showed significant improvement of hepatic steatosis in mice with AFL. In summary, our study found that both SG and MT could improve the structure and physicochemical properties of ASDF, with CM-ASDF being the most effective. Additionally, CM-ASDF was selected to continue the investigation and demonstrated an excellent protective effect on mice with AFL, with the high dose group (H-ASDF) showing the greatest benefit. These findings provided some new insights for future comprehensive utilization of ASDF and drug development for the treatment of AFL.

Global Profile of tRNA-Derived Small RNAs in Pathological Cardiac Hypertrophy Plasma and Identification of tRF-21-NB8PLML3E as a New Hypertrophy Marker

BACKGROUND

It remains unclear whether transfer RNA-derived small RNAs (tsRNAs) play a role in pathological cardiac hypertrophy (PCH). We aimed to clarify the expression profile of tsRNAs and disclose their relationship with the clinical phenotype of PCH and the putative role.

METHODS

Small RNA sequencing was performed on the plasma of PCH patients and healthy volunteers. In the larger sample size and angiotensin II (Ang II)-stimulated H9c2 cells, the data were validated by real-time qPCR. Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were examined in Ang II-stimulated H9c2 cells. The potential role of tsRNAs in the pathogenesis of PCH was explored by bioinformatics analysis.

RESULTS

A total of 4185 differentially expressed tsRNAs were identified, of which four and five tsRNAs were observed to be significantly upregulated and downregulated, respectively. Of the five downregulated tsRNAs, four were verified to be significantly downregulated in the larger sample group, including tRF-30-3JVIJMRPFQ5D, tRF-16-R29P4PE, tRF-21-NB8PLML3E, and tRF-21-SWRYVMMV0, and the AUC values for diagnosis of concentric hypertrophy were 0.7893, 0.7825, 0.8475, and 0.8825, respectively. The four downregulated tsRNAs were negatively correlated with the left ventricular posterior wall dimensions in PCH patients (r = -0.4227; r = -0.4517; r = -0.5567; r = -0.4223). The levels of ANP and BNP, as well as cell size, were decreased in Ang II-stimulated H9c2 cells with 21-NB8PLML3E mimic transfection. Bioinformatics analysis revealed that the target genes of tRF-21-NB8PLML3E were mainly enriched in the metabolic pathway and involved in the regulation of ribosomes.

CONCLUSIONS

The plasma tRF-21-NB8PLML3E might be considered as a biomarker and offers early screening potential in patients with PCH.

The Expression Pattern of tRNA-Derived Small RNAs in Adult Drosophila and the Function of tRF-Trp-CCA-014-H3C4 Network Analysis

tRNA-derived small RNAs (tsRNAs) are derived from tRNA and include tRNA halves (tiRNAs) and tRNA fragments (tRFs). tsRNAs have been implicated in a variety of important biological functions, such as cell growth, transcriptional regulation, and apoptosis. Emerging evidence has shown that Ago1-guided and Ago2-guided tsRNAs are expressed at 3 and 30 days in Drosophila and that tRF biogenesis in fruit flies affects tRNA processing and tRNA methylation. However, a wide analysis of tsRNA patterns in different ages of Drosophila have not been reported via the small RNA sequencing method. In the present study, tsRNAs of young (7 days) and old (42 days) Drosophila were sequenced and their expression characteristics were analysed. Then, a specific tRF (named tRF-Trp-CCA-014) was determined and was found to be conserved in fruit flies, mice, and humans. The expression patterns of tRF-Trp-CCA-014 in different tissues and stages of fruit flies and mice, and mouse NIH/3T3 cells were detected. Furthermore, mouse embryonic fibroblast NIH/3T3 cells were used as a model to analyse the function and targets of tRF-Trp-CCA-014. The RNA-seq data of six groups (Mimics, Mimic NC, Inhibitors, Inhibitor NC, Aging (adriamycin), and Control (Normal)) in mouse NIH3T3 cells were analysed. The results showed that the number of tsRNAs at 42 days (417) was more than at 7 days (288); thus, it was enriched with age. tRFs-1 were the most enriched, followed by 5'-tRFs and 3'-tRFs. Twenty-one differentially expressed tsRNAs were identified between 7 days and 42 days. Then, the conserved tRF tRF-Trp-CCA-014 was identified and found to accumulate in aged fruit flies and aged mouse NIH3T3 cells. RNA-seq data showed that most differentially expressed genes were involved in the immune system, cancer: overview, and signal translation. Furthermore, tRF-Trp-CCA-014 was found to bind to the 3'UTR of H3C4 in a dual-luciferase reporter gene assay. tRF-Trp-CCA-014 and H3C4 were detected in the cytoplasm of aged NIH3T3 cells by RNA in situ hybridization. These results suggest that the H3C4 gene is the target of tRF-Trp-CCA-014. This study will advance the current understanding of tRF roles and their implication in Drosophila and mouse studies.

Hepatoprotective Effect of Albumin Peptide Fractions from Corn Germ Meal against Alcohol-Induced Acute Liver Injury in Mice

Acute alcoholic liver disease can cause serious liver damage. This study reports on the hepatoprotective effect of albumin peptide fractions from corn germ meal (MW < 1 kDa) (APF4) on acute alcohol hepatic damage in mice. In the mice model, the results indicated that APF4 at a dose of 800 mg/kg/bw could markedly boost alcohol metabolism, which was shown in the reduced duration of the loss of the righting reflex; the reduced level of blood alcohol concentration (BAC), cytochrome P450 2E1 (CYP2E1), alanine aminotransferase (ALT), aminotransferase (AST), triglycerides (TG), and malondialdehyde (MDA) (p < 0.01); the enhanced activity of aldehyde dehydrogenase (ALDH); and the superoxide dismutase (SOD) and glutathione (GSH) levels being increased by up to 84.02% and 193.22% (p < 0.01) compared to the control group. The antioxidant capability and lipid peroxidation inhibition activity of APF4 may be responsible for its protective effect against liver damage induced by alcohol. The findings suggested that APF4 had the hepatoprotective property against liver damage induced by alcohol.

Differential expression profiling of tRNA-Derived small RNAs and their potential roles in methamphetamine self-administered rats

Transfer RNA-derived small RNAs (tsRNAs) are a novel class of short, non-coding RNAs that are closely associated with the pathogenesis of various diseases. Accumulating evidence has demonstrated their critical functional roles as regulatory factors in gene expression regulation, protein translation regulation, regulation of various cellular activities, immune mediation, and response to stress. However, the underlying mechanisms by which tRFs & tiRNAs affect methamphetamine-induced pathophysiological processes are largely unknown. In this study, we used a combination of small RNA sequencing, quantitative reverse transcription-polymerase chain reaction (qRT‒PCR), bioinformatics, and luciferase reporter assays to screen the expression profiles and identify the functional roles of tRFs and tiRNAs in the nucleus accumbens (NAc) of methamphetamine self-administration rat models. A total of 461 tRFs & tiRNAs were identified in the NAc of rats after 14 days of methamphetamine self-administration training. Of those, 132 tRFs & tiRNAs were significantly differentially expressed: 59 were significantly upregulated, whereas 73 were significantly downregulated in the rats with methamphetamine self-administration. Decreased expression levels of tiRNA-1-34-Lys-CTT-1 and tRF-1-32-Gly-GCC-2-M2, as well as increased expression levels of tRF-1-16-Ala-TGC-4 in the METH group compared with the saline control were validated by using RT‒PCR. Then, bioinformatic analysis was performed to analyse the possible biological functions of tRFs & tiRNAs in methamphetamine-induced pathogenesis. Furthermore, tRF-1-32-Gly-GCC-2-M2 was identified to target BDNF using the luciferase reporter assay. An altered tsRNA expression pattern was proven, and tRF-1-32-Gly-GCC-2-M2 was shown to be involved in methamphetamine-induced pathophysiologic processes by targeting BDNF. The current study provides new insights for future investigations to explore the mechanisms and therapeutic methods for methamphetamine addiction.

Protective roles of tRNA-derived small RNA tRF-Ile-AAT-019 in pathological progression of psoriasis

Psoriasis is a chronic recurrent inflammatory skin disease that is characterized by abnormal proliferation and differentiation of keratinocytes (KCs), angiogenesis and skin inflammation. Transfer RNA fragments (tRFs) are tRNA-derived small RNAs (tsRNAs), which possess regulatory functions in many diseases. Their potential roles in the pathological development of psoriasis have not been established. We first identified differentially expressed (DE) tRFs from psoriatic skin lesions using small RNA sequencing, and collected additional clinical samples for validation. Then, we investigated the function and mechanism of target tRFs in vitro. As a result of our investigation: we identified 234 DE transcripts in psoriatic skin lesions compared with normal controls. Further functional analysis showed the downregulation of tRF-Ile-AAT-019 in psoriatic lesions plays a critical role in pathogenesis since it could target 3'UTR of the serine protease serpin protein E1 (SERPINE1) gene. We next demonstrated that tRF-Ile-AAT-019 could suppress SERPINE1, thus leading to decreased expressions of vascular endothelial growth factor but increased expressions of keratinocytes (KCs) differentiation markers including Keratin1 and Involucrin. In conclusion, tRF-Ile-AAT-019 plays a protective role in the pathological progression of psoriasis via targeting SERPINE1, resulting in regulation of KCs differentiation and vascular proliferation biomarkers and providing a potential novel targeting pathway for the disease treatment.

Recent Advances in Understanding of Pathogenesis of Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) is one of the major diseases arising from chronic alcohol consumption and is one of the most common causes of liver-related morbidity and mortality. ALD includes asymptomatic liver steatosis, fibrosis, cirrhosis, and alcohol-associated hepatitis and its complications. The progression of ALD involves complex cell-cell and organ-organ interactions. We focus on the impact of alcohol on dysregulation of homeostatic mechanisms and regulation of injury and repair in the liver. In particular, we discuss recent advances in understanding the disruption of balance between programmed cell death and prosurvival pathways, such as autophagy and membrane trafficking, in the pathogenesis of ALD. We also summarize current understanding of innate immune responses, liver sinusoidal endothelial cell dysfunction and hepatic stellate cell activation, and gut-liver and adipose-liver cross talk in response to ethanol. In addition,we describe the current potential therapeutic targets and clinical trials aimed at alleviating hepatocyte injury, reducing inflammatory responses, and targeting gut microbiota, for the treatment of ALD.

tRNA derived fragments:A novel player in gene regulation and applications in cancer

The heterogeneous species of tRNA-derived fragments (tRFs) with specific biological functions was recently identified. Distinct roles of tRFs in tumor development and viral infection, mediated through transcriptional and post-transcriptional regulation, has been demonstrated. In this review, we briefly summarize the current literatures on the classification of tRFs and the effects of tRNA modification on tRF biogenesis. Moreover, we highlight the tRF repertoire of biological roles such as gene silencing, and regulation of translation, cell apoptosis, and epigenetics. We also summarize the biological roles of various tRFs in cancer development and viral infection, their potential value as diagnostic and prognostic biomarkers for different types of cancers, and their potential use in cancer therapy.

C3-dependent effector functions of complement

C3 is the central effector molecule of the complement system, mediating its multiple functions through different binding sites and their corresponding receptors. We will introduce the C3 forms (native C3, C3 [H₂ O], and intracellular C3), the C3 fragments C3a, C3b, iC3b, and C3dg/C3d, and the C3 expression sites. To highlight the important role that C3 plays in human biological processes, we will give an overview of the diseases linked to C3 deficiency and to uncontrolled C3 activation. Next, we will present a structural description of C3 activation and of the C3 fragments generated by complement regulation. We will proceed by describing the C3a interaction with the anaphylatoxin receptor, followed by the interactions of opsonins (C3b, iC3b, and C3dg/C3d) with complement receptors, divided into two groups: receptors bearing complement regulatory functions and the effector receptors without complement regulatory activity. We outline the molecular architecture of the receptors, their binding sites on the C3 activation fragments, the cells expressing them, the diversity of their functions, and recent advances. With this review, we aim to give an up-to-date analysis of the processes triggered by C3 activation fragments on different cell types in health and disease contexts.

tRFs and tRNA Halves: Novel Cellular Defenders in Multiple Biological Processes

tRNA fragments derived from angiogenin or Dicer cleavage are referred to as tRNA-derived fragments (tRFs) and tRNA halves. tRFs and tRNA halves have been identified in both eukaryotes and prokaryotes and are precisely cleaved at specific sites on either precursor or mature tRNA transcripts rather than via random degradation. tRFs and tRNA halves are highly involved in regulating transcription and translation in a canonical or non-canonical manner in response to cellular stress. In this review, we summarize the biogenesis and types of tRFs and tRNA halves, clarify the biological functions and molecular mechanisms of tRNA fragments in both physiological and pathological processes with a particular focus on their cytoprotective roles in defending against oxidation and apoptosis, and highlight their potential application as biomarkers in determining cell fate.

Expression profiles of tRNA‑derived fragments in high glucose‑treated tubular epithelial cells

Transfer RNA-derived fragments (tRFs), a novel class of small non-coding RNA produced by the cleavage of pre- and mature tRNAs, are involved in various diseases. Renal tubulointerstitial fibrosis is a common final pathway in diabetic nephropathy (DN) in which hyperglycemia-induced tubular extracellular matrix (ECM) accumulation serves a vital role. The present study aimed to detect and investigate the role of tRFs in the accumulation of tubular ECM. Differentially expressed tRFs were analysed with high-throughput sequencing in primary mouse tubular epithelial cells treated with high glucose (HG). The Gene Ontology (GO) was used to analyze the potential molecular functions of these differentially expressed tRFs, and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to analyze the associated signaling pathways involved in these differentially expressed tRFs. tRF-1:30-Gln-CTG-4 was overexpressed using tRF-1:30-Gln-CTG-4 mimic, followed by HG treatment. A total of 554 distinct tRFs were detected and 64 differentially expressed tRFs (fold change >2; P<0.05) were identified in tubular epithelial cells following high glucose (HG) treatment, among which 27 were upregulated and 37 were downregulated. Ten selected tRFs with the greatest difference (fold change >2; P<0.05) were verified to be consistent with small RNA-sequencing data, of which tRF-1:30-Gln-CTG-4 showed the most pronounced difference in expression and was significantly decreased in response to HG. GO analysis indicated that the differentially expressed tRFs were associated with 'cellular process', 'biological regulation' and 'metabolic process'. An analysis of the KEGG database suggested that these differentially expressed tRFs were involved in 'autophagy' and signaling pathways for 'forkhead box O', 'the mammalian target of rapamycin' and 'mitogen-activated protein kinase'. Finally, the overexpression of tRF-1:30-Gln-CTG-4 ameliorated HG-induced ECM accumulation in tubular epithelial cells. Therefore, the present study demonstrated that there may be a significant association between tRFs and HG-induced ECM accumulation in tubular epithelial cells; these differentially expressed tRFs warrant further study to explore the pathogenesis of DN.

tRF-3013b inhibits gallbladder cancer proliferation by targeting TPRG1L

BACKGROUND

tRNA-derived fragments (tRFs) are newly discovered noncoding RNAs and regulate tumor progression via diverse molecular mechanisms. However, the expression and biofunction of tRFs in gallbladder cancer (GBC) have not been reported yet.

METHODS

The expression of tRFs in GBC was detected by tRF and tiRNA sequencing in GBC tissues and adjacent tissues. The biological function of tRFs was investigated by cell proliferation assay, clonal formation assay, cell cycle assay, and xenotransplantation model in GBC cell lines. The molecular mechanism was discovered and verified by transcriptome sequencing, fluorescence in situ hybridization (FISH), target gene site prediction, and RNA binding protein immunoprecipitation (RIP).

RESULTS

tRF-3013b was significantly downregulated in GBC compared with para-cancer tissues. Decreased expression of tRF-3013b in GBC patients was correlated with poor overall survival. Dicer regulated the production of tRF-3013b, and its expression was positively correlated with tRF-3013b in GBC tissues. Functional experiments demonstrated that tRF-3013b inhibited GBC cell proliferation and induced cell-cycle arrest. Mechanically, tRF-3013b exerted RNA silencing effect on TPRG1L by binding to AGO3, and then inhibited NF-κB. TPRG1L overexpression could rescue the effects of tRF-3013b on GBC cell proliferation.

CONCLUSIONS

This study indicated that Dicer-induced tRF-3013b inhibited GBC proliferation by targeting TPRG1L and repressed NF-κB, pointing to tRF-3013b as a novel potential therapeutic target of GBC.

Transfer RNA-derived fragment 5'tRF-Gly promotes the development of hepatocellular carcinoma by direct targeting of carcinoembryonic antigen-related cell adhesion molecule 1

Transfer RNA-derived fragments are a group of small noncoding single-stranded RNA that play essential roles in multiple diseases. However, their biological functions in carcinogenesis are not well understood. In this study, 5'tRF-Gly was found to have significantly high expression in hepatocellular carcinoma (HCC), and the upregulation of 5'tRF-Gly was positively correlated with tumor size and tumor metastasis. Overexpression of 5'tRF-Gly induced increased growth rate and metastasis in HCC cells in vitro and in nude mice, while knockdown showed the opposite effect. Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) was confirmed to be a direct target of 5'tRF-Gly in HCC. In addition, the cytological effect of CEACAM1 knockdown proved to be similar to the overexpression of 5'tRF-Gly. Moreover, attenuation of CEACAM1 expression rescued the 5'tRF-Gly-mediated promoting effects on HCC cells. These data show that 5'tRF-Gly is a new tumor-promoting factor and could be a potential diagnostic biomarker or new therapeutic target for HCC.

Change of tumor-infiltrating lymphocyte of associating liver partition and portal vein ligation for staged hepatectomy for hepatocellular carcinoma

BACKGROUND

The role of tumor-infiltrating lymphocytes (TILs) in the growth and progression of hepatocellular carcinoma (HCC) has attracted widespread attention.

AIM

To evaluate the feasibility of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) for massive HCC by exploring the role of TIL in the tumor microenvironment.

METHODS

Fifteen massive HCC patients who underwent ALPPS treatment and 46 who underwent hemi-hepatectomy were selected for this study. Propensity score matching was utilized to match patients in ALPPS and hemi-hepatectomy groups (1:1). Quantitative analysis of TILs in tumor and adjacent tissues between the two groups was performed by immunofluorescence staining and further analyses with oncological characteristics. In the meantime, trends of TILs in peripheral blood were compared between the two groups during the perioperative period.

RESULTS

Continuous measurement of tumor volume and necrosis volume showed that the proportion of tumor necrosis volume on the seventh day after stage-I ALPPS was significantly higher than the pre-operative value (P = 0.024). In the preoperative period of stage-I ALPPS, the proportion of tumor necrosis volume in the high CD8⁺ T cell infiltration group was significantly higher than that in the low group (P = 0.048).

CONCLUSION

TIL infiltration level maintained a dynamic balance during the preoperative period of ALPPS. Compared with right hemi-hepatectomy, the ALPPS procedure does not cause severe immunosuppression with the decrease in TIL infiltration and pathological changes in immune components of peripheral blood. Our results suggested that ALPPS is safe and feasible for treating massive HCC from the perspective of immunology. In addition, high CD8⁺ T cell infiltration is associated with increasing tumor necrosis in the perioperative period of ALPPS.

Potential Functions of the tRNA-Derived Fragment tRF-Gly-GCC Associated With Oxidative Stress in Radiation-Induced Lung Injury

Objective

Transfer RNA-derived small RNAs (tsRNAs) are a novel type of non-coding RNA with various regulatory functions. They are associated with oxidative stress in various diseases, but their potential functions in radiation-induced lung injury (RILI) remain uncertain.

Methods

To explore the role of tsRNAs in RILI, we used X-rays to irradiate human bronchial epithelial cells and examined the expression profile of altered tsRNAs by RNA sequencing and bioinformatics analysis. Sequencing results were verified by qRT-PCR. tsRNA functions were explored using several methods, including CCK-8, reactive oxygen species (ROS) assays, cell transfection, and western blotting.

Results

Eighty-six differentially expressed tRNA-derived fragments (tRFs) were identified: 64 were upregulated, and 22 were downregulated. Among them, the regulation of tRF-Gly-GCC, associated with oxidative stress, may be mediated by the inhibition of cell proliferation, promotion of ROS production, and apoptosis in the occurrence and development of RILI. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that the underlying molecular mechanism may involve the PI3K/AKT and the FOXO1 signaling pathways.

Conclusion

Our findings provide new insights into the molecular mechanisms underpinning RILI, advancing the clinical prevention and treatment of this disease.

Transfer RNA-Derived Small RNAs: Novel Regulators and Biomarkers of Cancers

Transfer RNA-derived small RNAs (tsRNAs) are conventional non-coding RNAs (ncRNAs) with a length between18 and 40 nucleotides (nt) playing a crucial role in treating various human diseases including tumours. Nowadays, with the use of high-throughput sequencing technologies, it has been proven that certain tsRNAs are dysregulated in multiple tumour tissues as well as in the blood serum of cancer patients. Meanwhile, data retrieved from the literature show that tsRNAs are correlated with the regulation of the hallmarks of cancer, modification of tumour microenvironment, and modulation of drug resistance. On the other side, the emerging role of tsRNAs as biomarkers for cancer diagnosis and prognosis is promising. In this review, we focus on the specific characteristics and biological functions of tsRNAs with a focus on their impact on various tumours and discuss the possibility of tsRNAs as novel potential biomarkers for cancer diagnosis and prognosis.

The monomer TEC of blueberry improves NASH by augmenting tRF-47-mediated autophagy/pyroptosis signaling pathway

Background

Nonalcoholic steatohepatitis (NASH) is one of the most common liver diseases and has no safe and effective drug for treatment. We have previously reported the function of blueberry, but the effective monomer and related molecular mechanism remain unclear.

Methods

The monomer of blueberry was examined by ultra performance liquid chromatography-mass spectrometry (UPLC-MS). The NASH cell model was constructed by exposing HepG2 cells to free fatty acids. The NASH mouse model was induced by a high-fat diet for 12 weeks. NASH cell and mouse models were treated with different concentrations of blueberry monomers. The molecular mechanism was studied by Oil Red O staining, ELISA, enzyme activity, haematoxylin–eosin (H&E) staining, immunohistochemistry, immunofluorescence, western blot, RNA sequencing, and qRT-PCR.

Results

We identified one of the main monomer of blueberry as tectorigenin (TEC). Cyanidin-3-O glucoside (C3G) and TEC could significantly inhibit the formation of lipid droplets in steatosis hepatocytes, and the effect of TEC on the formation of lipid droplets was significantly higher than that of C3G. TEC can promote cell proliferation and inhibit the release of inflammatory mediators in NASH cell model. Additionally, TEC administration provided a protective role against high-fat diets induced lipid damage, and suppressed lipid accumulation. In NASH mouse model, TEC can activate autophagy, inhibit pyroptosis and the release of inflammatory mediators. In NASH cell model, TEC inhibited pyroptosis by stimulating autophagy. Then, small RNA sequencing revealed that TEC up-regulated the expression of tRF-47-58ZZJQJYSWRYVMMV5BO (tRF-47). The knockdown of tRF-47 blunted the beneficial effects of TEC on NASH in vitro, including inhibition of autophagy, activation of pyroptosis and release of inflammatory factors. Similarly, suppression of tRF-47 promoted the lipid injury and lipid deposition in vivo.

Conclusions

These results demonstrated that tRF-47-mediated autophagy and pyroptosis plays a vital role in the function of TEC to treat NASH, suggesting that TEC may be a promising drug for the treatment of NASH.

Plasma tRNA-derived small RNAs signature as a predictive and prognostic biomarker in lung adenocarcinoma

Background

The prevalence of lung adenocarcinoma (LUAD) has increased, thus novel biomarkers for its early diagnosis is becoming more important than ever. tRNA-derived small RNA (tsRNA) is a new class of non-coding RNA which has important regulatory roles in cancer biology. This study was designed to identify novel predictive and prognostic tsRNA biomarkers.

Methods

tsRNAs were identified and performed differential expression analysis from 10 plasma samples (6 LUAD and 4 normal, SRP266333) and 96 tissue samples (48 LUAD and 48 normal, SRP133217). Then a tsRNA-mRNA regulatory network was constructed to find hub tsRNAs. Functional enrichment analysis was performed to infer the potential pathways associated with tsRNAs. Afterwards, a Support Vector Machine (SVM) algorithm was used to explore the potential biomarkers for diagnosing LUAD. Lastly, the function of tRF-21-RK9P4P9L0 was explored in A549 and H1299 cell lines.

Results

A significant difference of read distribution was observed between normal people and LUAD patients whether in plasma or tissue. A tsRNA-mRNA regulatory network consisting of 155 DEtsRNAs (differential expression tsRNAs) and 406 DEmRNAs (differential expression mRNAs) was established. Three tsRNAs (tRF-16-L85J3KE, tRF-21-RK9P4P9L0 and tRF-16-PSQP4PE) were identified as hub genes with degree > 100. We found Co-DEmRNAs (intersection of DEtsRNAs target mRNAs and differentially expressed mRNAs in LUAD) were engaged in a number of cancer pathways. The AUC of the three hub tsRNAs’ expression for diagnosing LUAD reached 0.92. Furthermore, the qPCR validation of the three hub tsRNAs in 37 paired normal and LUAD tissues was consistent with the RNA-Seq results. In addition, tRF-21-RK9P4P9L0 was negatively associated with LUAD prognosis. Inhibition of tRF-21-RK9P4P9L0 expression reduced the proliferation, migration and invasion ability of A549 and H1299 cell lines.

Conclusion

These findings will help us further understand the molecular mechanisms of LUAD and contribute to novel diagnostic biomarkers and therapeutic target discovery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02481-6.

An emerging role of the 5' termini of mature tRNAs in human diseases: Current situation and prospects

The fundamental biological roles of a class of small noncoding RNAs (sncRNAs), derived from mature tRNAs or pre-tRNAs, in human diseases have received increasing attention in recent years. These ncRNAs are called tRNA-derived fragments (tRFs) or tRNA-derived small RNAs (tsRNAs). tRFs mainly include tRF-1, tRF-5, tRF-3 and tRNA halves (tiRNAs or tRHs), which are produced by enzyme-specific cleavage of tRNAs. Here, we classify tRF-5 and 5' tiRNAs into the same category: 5'-tRFs and review the biological functions and regulatory mechanisms of 5'-tRFs in cancer and other diseases (metabolic diseases, neurodegenerative diseases, pathological stress injury and virus infection) to provide a new theoretical basis for the diagnosis and treatment of diseases.

Complement Inhibition Alleviates Cholestatic Liver Injury Through Mediating Macrophage Infiltration and Function in Mice

BACKGROUND AND AIMS

Cholestatic liver injury (CLI), which is associated with inflammatory reactions and oxidative stress, is a serious risk factor for postoperative complications. Complement system is involved in a wide range of liver disorders, including cholestasis. The present study assessed the role of complement in CLI and the therapeutic effect of the site-targeted complement inhibitor CR2-Crry in CLI.

METHODS

Wild-type and complement gene deficient mice underwent common bile duct ligation (BDL) to induce CLI or a sham operation, followed by treatment with CR2-Crry or GdCl3. The roles of complement in CLI and the potential therapeutic effects of CR2-Crry were investigated by biochemical analysis, flow cytometry, immunohistochemistry, ELISA, and quantitative RT-PCR.

RESULTS

C3 deficiency and CR2-Crry significantly reduced liver injuries in mice with CLI, and also markedly decreasing the numbers of neutrophils and macrophages in the liver. C3 deficiency and CR2-Crry also significantly reduced neutrophil expression of Mac-1 and liver expression of VCAM-1. More importantly, C3 deficiency and CR2-Crry significantly inhibited M1 macrophage polarization in these mice. Intravenous injection of GdCl3 inhibited macrophage infiltration and activation in the liver. However, the liver injury increased significantly. BDL significantly increased the level of lipopolysaccharide (LPS) in portal blood, but not in peripheral blood. GdCl3 significantly increased LPS in peripheral blood, suggesting that macrophages clear portal blood LPS. Oral administration of ampicillin to in GdCl3 treated mice reduced LPS levels in portal blood and alleviated liver damage. In contrast, intraperitoneal injection LPS increased portal blood LPS and reversed the protective effect of ampicillin. Interestingly, C3 deficiency did not affect the clearance of LPS.

CONCLUSIONS

Complement is involved in CLI, perhaps mediating the infiltration and activation of neutrophils and macrophage M1 polarization in the liver. C3 deficiency and CR2-Crry significantly alleviated CLI. Inhibition of complement could preserve the protective function of macrophages in clearing LPS, suggesting that complement inhibition could be useful in treating CLI.

Genome-wide interrogation of transfer RNA-derived small RNAs in a mouse model of traumatic brain injury

Transfer RNA (tRNA)-derived small RNAs (tsRNAs) are a recently established family of regulatory small non-coding RNAs that modulate diverse biological processes. Growing evidence indicates that tsRNAs are involved in neurological disorders and play a role in the pathogenesis of neurodegenerative disease. However, whether tsRNAs are involved in traumatic brain injury-induced secondary injury remains poorly understood. In this study, a mouse controlled cortical impact model of traumatic brain injury was established, and integrated tsRNA and messenger RNA (mRNA) transcriptome sequencing were used. The results revealed that 103 tsRNAs were differentially expressed in the mouse model of traumatic brain injury at 72 hours, of which 56 tsRNAs were upregulated and 47 tsRNAs were downregulated. Based on microRNA-like seed matching and Pearson correlation analysis, 57 differentially expressed tsRNA-mRNA interaction pairs were identified, including 29 tsRNAs and 26 mRNAs. Moreover, Gene Ontology annotation of target genes revealed that the significantly enriched terms were primarily associated with inflammation and synaptic function. Collectively, our findings suggest that tsRNAs may be associated with traumatic brain injury-induced secondary brain injury, and are thus a potential therapeutic target for traumatic brain injury. The study was approved by the Beijing Neurosurgical Institute Animal Care and Use Committee (approval No. 20190411) on April 11, 2019.

Effects of Different Green Tea Extracts on Chronic Alcohol Induced-Fatty Liver Disease by Ameliorating Oxidative Stress and Inflammation in Mice

Alcoholic fatty liver disease (AFLD) is a common chronic liver disease and has become a critical global public health problem. Green tea is a popular drink worldwide and contains several bioactive compounds. Different green teas could contain diverse compounds and possess distinct bioactivities. In the present study, the effects of 10 green teas on chronic alcohol induced-fatty liver disease in mice were explored and compared. The results showed that several green teas significantly reduced triacylglycerol levels in serum and liver as well as the aminotransferase activities in mice at a dose of 200 mg/kg, suggesting that they possess hepatoprotective effects. Moreover, several green teas remarkably decreased the expression of cytochrome P450 2E1, the levels of malondialdehyde and 4-hydroxynonenoic acid, and the contents of proinflammatory cytokines, indicating that they could alleviate oxidation damage and inflammation induced by chronic alcohol exposure. In addition, Seven Star Matcha Tea and Selenium-Enriched Matcha Tea could increase glutathione level. Furthermore, the main phytochemical components in green teas were determined and quantified by high-performance liquid chromatography, and the correlation analysis showed that gallic acid, gallocatechin, catechin, chlorogenic acid, and epigallocatechin gallate might at least partially contribute to protective effects on AFLD. In conclusion, Selenium-Enriched Chaoqing Green Tea, Xihu Longjing Tea, Taiping Houkui Tea, and Selenium-Enriched Matcha Tea showed the strongest preventive effects on AFLD. This research also provides the public with new insights about the effects of different green teas on AFLD.

Deciphering the tRNA-derived small RNAs: origin, development, and future

Transfer RNA (tRNA)-derived small RNAs (tsRNAs), a novel category of small noncoding RNAs, are enzymatically cleaved from tRNAs. Previous reports have shed some light on the roles of tsRNAs in the development of human diseases. However, our knowledge about tsRNAs is still relatively lacking. In this paper, we review the biogenesis, classification, subcellular localization as well as action mechanism of tsRNAs, and discuss the association between chemical modifications of tRNAs and the production and functions of tsRNAs. Furthermore, using immunity, metabolism, and malignancy as examples, we summarize the molecular mechanisms of tsRNAs in diseases and evaluate the potential of tsRNAs as new biomarkers and therapeutic targets. At the same time, we compile and introduce several resource databases that are currently publicly available for analyzing tsRNAs. Finally, we discuss the challenges associated with research in this field and future directions.

Regulatory roles of tRNA-derived RNA fragments in human pathophysiology

Hundreds of tRNA genes and pseudogenes are encoded by the human genome. tRNAs are the second most abundant type of RNA in the cell. Advancement in deep-sequencing technologies have revealed the presence of abundant expression of functional tRNA-derived RNA fragments (tRFs). They are either generated from precursor (pre-)tRNA or mature tRNA. They have been found to play crucial regulatory roles during different pathological conditions. Herein, we briefly summarize the discovery and recent advances in deciphering the regulatory role played by tRFs in the pathophysiology of different human diseases.

tRNA Derivatives in Multiple Myeloma: Investigation of the Potential Value of a tRNA-Derived Molecular Signature

Multiple myeloma (MM) is a hematologic malignancy arising from the clonal proliferation of malignant plasma cells. tRNA-derived RNA fragments (tRFs) constitute a class of small non-coding RNAs, deriving from specific enzymatic cleavage of tRNAs. To the best of our knowledge, this is one of few studies to uncover the potential clinical significance of tRFs in MM. Total RNA was extracted from CD138+ plasma cells of MM and smoldering MM patients, and in vitro polyadenylated. First-strand cDNA synthesis was performed, priming from an oligo-dT-adaptor sequence. Next, real-time quantitative PCR (qPCR) assays were developed for the quantification of six tRFs. Biostatistical analysis was performed to assess the results and in silico analysis was conducted to predict the function of one of the tRFs. Our results showed that elevated levels of five out of six tRFs are indicators of favorable prognosis in MM, predicting prolonged overall survival (OS), while two of them constitute potential molecular biomarkers of favorable prognosis in terms of disease progression. Moreover, three tRFs could be used as surrogate prognostic biomarkers along with the R-ISS staging system to predict OS. In conclusion, tRFs show molecular biomarker utility in MM, while their mechanisms of function merit further investigation.

Inflammatory cytokine-regulated tRNA-derived fragment tRF-21 suppresses pancreatic ductal adenocarcinoma progression

The tumorigenic mechanism for pancreatic ductal adenocarcinoma (PDAC) is not clear, although chronic inflammation is implicated. Here, we identified an inflammatory cytokine-regulated transfer RNA-derived (tRNA-derived) fragment, tRF-21-VBY9PYKHD (tRF-21), as a tumor suppressor in PDAC progression. We found that the biogenesis of tRF-21 could be inhibited by leukemia inhibitory factor and IL-6 via the splicing factor SRSF5. Reduced tRF-21 promoted AKT2/1-mediated heterogeneous nuclear ribonucleoprotein L (hnRNP L) phosphorylation, enhancing hnRNP L to interact with dead-box helicase 17 (DDX17) to form an alternative splicing complex. The provoked hnRNP L-DDX17 activity preferentially spliced Caspase 9 and mH2A1 pre-mRNAs to form Caspase 9b and mH2A1.2, promoting PDAC cell malignant phenotypes. The tRF-21 levels were significantly lower in PDACs than in normal tissues, and patients with low tRF-21 levels had a poor prognosis. Treatment of mouse PDAC xenografts or patient-derived xenografts (PDXs) with tRF-21 mimics repressed tumor growth and metastasis. These results demonstrate that tRF-21 has a tumor-suppressive effect and is a potential therapeutic agent for PDAC.

Association between complement C3 and the prevalence of metabolic-associated fatty liver disease in a Chinese population: a cross-sectional study

OBJECTIVES

Recently studies demonstrated that adipose tissue can produce and release complement C3 and serum complement C3 levels were associated with diabetes mellitus, metabolic syndrome and non-alcoholic fatty liver disease (NAFLD). Thus, we plan to investigate the association of complement C3 levels and the presence of metabolic-associated fatty liver disease (MAFLD).

DESIGN

Observational study with a cross-sectional sample.

SETTING

This study surveyed 4729 participants in Zhejiang province, China.

PARTICIPANTS

55 participants were excluded for acute infection and 1001 participants were excluded for lack of ultrasonography diagnoses and complete or partial absence of laboratory tests. The final sample size was 3673 participants.

OUTCOME MEASURES

Spearman correlation analysis was used to examine the correlations between complement C3 levels and variables. Binary logistic regression was carried out to evaluate the association between complement C3 levels and the presence of MAFLD after adjustment for demographic and biochemical variables. Mediation effects were used to explore whether insulin resistance (IR), hyperlipidaemia and obesity mediated the association between complement C3 and MAFLD.

RESULTS

Participants with MAFLD had higher complement C3 levels and complement C3 levels were closely associated with body mass index, waist circumference, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase and homoeostasis model assessment (HOMA)-IR. The presence of MAFLD increased with the increase of complement C3 levels and the presence of MAFLD were highest in the HOMA-IR ≥2.5 participants. We found the OR and Cl of standardised C3 for MAFLD was 1.333 (1.185-1.500), each 1 SD increase in C3 would increase the presence of MAFLD by 33.3%, and obesity partly mediated the effect of complement C3 on the presence of MAFLD.

CONCLUSIONS

The present results suggest that complement C3 can be used as a risk factor for the presence of MAFLD after adjustment for confounding variables and obesity may partly mediate the effect of complement C3 on the presence of MAFLD.

Endogenous tRNA-derived small RNA (tRF3-Thr-AGT) inhibits ZBP1/NLRP3 pathway-mediated cell pyroptosis to attenuate acute pancreatitis (AP)

Endogenous transfer RNA‐derived small RNAs (tsRNAs) are newly identified RNAs that are closely associated with the pathogenesis of multiple diseases, but the involvement of tsRNAs in regulating acute pancreatitis (AP) development has not been reported. In this study, we screened out a novel tsRNA, tRF3‐Thr‐AGT, that was aberrantly downregulated in the acinar cell line AR42J treated with sodium taurocholate (STC) and the pancreatic tissues of STC‐induced AP rat models. In addition, STC treatment suppressed cell viability, induced pyroptotic cell death and cellular inflammation in AP models in vitro and in vivo. Overexpression of tRF3‐Thr‐AGT partially reversed STC‐induced detrimental effects on the AR42J cells. Next, Z‐DNA‐binding protein 1 (ZBP1) was identified as the downstream target of tRF3‐Thr‐AGT. Interestingly, upregulation of tRF3‐Thr‐AGT suppressed NOD‐like receptor protein 3 (NLRP3)‐mediated pyroptotic cell death in STC‐treated AR42J cells via degrading ZBP1. Moreover, the effects of tRF3‐Thr‐AGT overexpression on cell viability and inflammation in AR42J cells were abrogated by upregulating ZBP1 and NLRP3. Collectively, our data indicated that tRF3‐Thr‐AGT suppressed ZBP1 expressions to restrain NLRP3‐mediated pyroptotic cell death and inflammation in AP models. This study, for the first time, identified the role and potential underlying mechanisms by which tRF3‐Thr‐AGT regulated AP pathogenesis.

Thermochemotherapy Meets Tissue Engineering for Rheumatoid Arthritis Treatment

Rheumatoid arthritis (RA) is an autoimmune disease that progresses from inflammation to cartilage destruction. Inspired by the similar characteristics of inflammatory granulation tissue to those of tumors, the newly emerged tumor therapy called thermochemotherapy is proposed to treat RA. Meanwhile, the repair of cartilage injury via tissue engineering is paid attention simultaneously. A first‐line antirheumatic drug (MTX; methotrexate) and transforming growth factor β1 (TGF‐β1) are loaded in nano‐Fe3O4 composite chitosan‐polyolefin to construct a multifunctional hydrogel (DN‐Fe‐MTX‐TGFβ1). The mechanical properties of the hydrogel are equivalent to that of articular cartilage to guarantee its role as a scaffold. A long‐term release ability and the magnetocaloric properties of the hydrogel assure its effect to provide sustained local thermochemotherapy. The effective ability of the hydrogel for both anti‐inflammation and cartilage repair is demonstrated. This work indicates a promising way to combine thermochemotherapy and tissue engineering for the effective treatment of RA for the first time.