Total coumarins from Urtica dentata Hand prevent murine autoimmune diabetes via suppression of the TLR4-signaling pathways

Ethnomedicinal Uses, Geographical Distribution, Botanical Description, Phytochemistry, Pharmacology, and Quality Control of Laportea bulbifera (Sieb. et Zucc.) Wedd.: A Review

Laportea bulbifera (Sieb. et Zucc.) Wedd. (L. bulbifera) is a significant plant in the Laportea genus. Traditionally, it has been used in ethnomedicine for treating various conditions such as rheumatic arthralgia, fractures, falling injuries, nephritis dropsy, limb numbness, pruritus, fatigue-induced internal imbalances, and irregular menstruation. Modern pharmacological studies have confirmed its therapeutic potential, including anti-inflammatory, immunosuppressive, analgesic, and anti-rheumatoid arthritis properties. To gather comprehensive information on L. bulbifera, a thorough literature search was conducted using databases like Web of Science, PubMed, ProQuest, and CNKI. This review aims to provide a comprehensive understanding of L. bulbifera, covering various aspects such as ethnomedicinal uses, geographical distribution, botanical description, phytochemistry, pharmacology, and quality control. The goal is to establish a solid foundation and propose new research avenues for exploring and developing potential applications of L. bulbifera. So far, a total of one hundred and eighty-nine compounds have been isolated and identified from L. bulbifera, including flavonoids, phenolics, nitrogen compounds, steroids, terpenoids, coumarins, phenylpropanoids, fatty acids and their derivatives, and other compounds. Notably, flavonoids and fatty acids have demonstrated remarkable antioxidant and anti-inflammatory properties. Additionally, these compounds show promising potential in activities such as analgesia, hypoglycemia, and hypolipidemia, as well as toxicity. Despite extensive fundamental studies on L. bulbifera, further research is still needed to enhance our understanding of its mechanism of action and improve quality control. This requires more comprehensive investigations to explore the specific material basis, uncover new mechanisms of action, and refine quality control methods related to L. bulbifera. By doing so, we could contribute to the further development and utilization of this plant.

Identification of Laportea bulbifera using the complete chloroplast genome as a potentially effective super-barcode

Laportea bulbifera, a Miao medicine grown in karst areas, has exerted a unique curative effect on skin itching in the elderly, with an annual sales of > 100 million Yuan. Owing to the shortage of resources and large morphological variations in L. bulbifera, it is difficult to identify the species correctly using only traditional methods, which seriously affects the safety of drug usage for patients. This study obtained the complete high-quality L. bulbifera chloroplast (cp) genome, using second- and third-generation high-throughput sequencing. The cp genome was 149,911 bp in length, with a typical quadripartite structure. A total of 127 genes were annotated, including 83 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. There was an inverted small single copy (SSC) structure in the L. bulbifera cp genome, one large-scale rearrangement of ~ 39 kb excised in the SSC and IR regions. The complete cp genome sequence is used as a potentially effective super-barcode and the highly variable regions (ycf1, matK, and ndhD) can be used as potentially specific barcodes to accurately distinguish L. bulbifera from counterfeits and closely related species. This study is important for the identification of L. bulbifera and lays a theoretical foundation for elucidating the phylogenetic relationship of the species.

Paeoniflorin protects NOD mice from T1D through regulating gut microbiota and TLR4 mediated myD88/TRIF pathway

This study aimed to explore the effect of PF in regulating the progression of T1D through regulating gut microbiota and inhibiting TLR4-myD88/TRIF pathway. T1D mouse models were established and received PF treatment through intraperitoneal injection. The glucose, sugar tolerance, the incidence of T1D and H&E staining were detected to verify the effect of PF on T1D. Meanwhile, the changes of gut microbiota and the permeability of intestines in mice were also measured. On parallel, the number and function of immune cells were detected by Flow Cytometry. The expressions of ZO-1, ZO-2 and TLR4-myD88/TRIF pathway related proteins were detected by western blotting. Mice received PF treatment had decreased incidence of T1D and inflammatory infiltration in islet tissues compared with those received PBS treatment. In addition to that, PF treated mice had increased Sutterella species and decreased intestinal permeability, in which the decreased ratio of Th1/Th17 and increased Treg cells were also identified. The expression of TLR4-myD88/TRIF pathway was also suppressed in response to PF treatment. Moreover, further treatment with TLR4 agonist, LPS, could reverse the effect of PF on T1D mice. PF can suppress the TLR4 mediated myD88/TRIF pathway to change the distribution of gut microbiota, so as to protect NOD mice from T1D.

The Complete Chloroplast Genome Sequence of Laportea bulbifera (Sieb. et Zucc.) Wedd. and Comparative Analysis with Its Congeneric Species

Laportea bulbifera (L. bulbifera) is an important medicinal plant of Chinese ethnic minorities, with high economic and medicinal value. However, the medicinal materials of the genus Laportea are prone to be misidentified due to the similar morphological characteristics of the original plants. Thus, it is crucial to discover their molecular marker points and to precisely identify these species for their exploitation and conservation. Here, this study reports detailed information on the complete chloroplast (cp) of L. bulbifera. The result indicates that the cp genome of L. bulbifera of 150,005 bp contains 126 genes, among them, 37 tRNA genes and 81 protein-coding genes. The analysis of repetition demonstrated that palindromic repeats are more frequent. In the meantime, 39 SSRs were also identified, the majority of which were mononucleotides Adenine-Thymine (A-T). Furthermore, we compared L. bulbifera with eight published Laportea plastomes, to explore highly polymorphic molecular markers. The analysis identified four hypervariable regions, including rps16, ycf1, trnC-GCA and trnG-GCC. According to the phylogenetic analysis, L. bulbifera was most closely related to Laportea canadensis (L. canadensis), and the molecular clock analysis speculated that the species originated from 1.8216 Mya. Overall, this study provides a more comprehensive analysis of the evolution of L. bulbifera from the perspective of phylogenetic and intrageneric molecular variation in the genus Laportea, which is useful for providing a scientific basis for further identification, taxonomic, and evolutionary studies of the genus.

Application and prospect of targeting innate immune sensors in the treatment of autoimmune diseases

Dysregulation of auto-reactive T cells and autoantibody-producing B cells and excessive inflammation are responsible for the occurrence and development of autoimmune diseases. The suppression of autoreactive T cell activation and autoantibody production, as well as inhibition of inflammatory cytokine production have been utilized to ameliorate autoimmune disease symptoms. However, the existing treatment strategies are not sufficient to cure autoimmune diseases since patients can quickly suffer a relapse following the end of treatments. Pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), Nod-like receptors (NLRs), RIG-I like receptors (RLRs), C-type lectin receptors (CLRs) and various nucleic acid sensors, are expressed in both innate and adaptive immune cells and are involved in the development of autoimmune diseases. Here, we have summarized advances of PRRs signaling pathways, association between PRRs and autoimmune diseases, application of inhibitors targeting PRRs and the corresponding signaling molecules relevant to strategies targeting autoimmune diseases. This review emphasizes the roles of different PRRs in activating both innate and adaptive immunity, which can coordinate to trigger autoimmune responses. The review may also prompt the formulation of novel ideas for developing therapeutic strategies against autoimmune diseases by targeting PRRs-related signals.

The complete chloroplast genome of Laportea bulbifera (Sieb. et Zucc.) Wedd. and its phylogenetic analysis

The circle complete chloroplast genome of Laportea bulbifera (Sieb. et Zucc.) Wedd. was sequenced for the first time. The genome length of L. bulbifera is 150,042 bp with 36.80% of GC content. The genome consists of a large single copy (LSC) region of 82,414 bp, a small single copy (SSC) region of 17,714 bp, and two inverted repeat (IRa and IRb) regions of 24,957 bp each. A total of 129 genes were annotated, including 84 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic analysis was conducted by 29 species from the Rosales, the results presented a closed relationship between the species Laportea bulbifera and Poikilospermum lanceolatum.

Overview of key molecular and pharmacological targets for diabetes and associated diseases

Diabetes epidemiological quantities are demonstrating one of the most important communities' health worries. The essential diabetic difficulties are including cardiomyopathy, nephropathy, inflammation, and retinopathy. Despite developments in glucose decreasing treatments and drugs, these diabetic complications are still ineffectively reversed or prohibited. Several signaling and molecular pathways are vital targets in the new therapies of diabetes. This review assesses the newest researches about the key molecules and signaling pathways as targets of molecular pharmacology in diabetes and diseases related to it for better treatment based on molecular sciences. The disease is not cured by current pharmacological strategies for type 2 diabetes. While several drug combinations are accessible that can efficiently modulate glycemia and mitigate long-term complications, these agents do not reverse pathogenesis, and in practice, they are not established to modify the patient's specific molecular profiling. Therapeutic companies have benefited from human genetics. Genome exploration, which is agnostic to the information that exists, has revealed tens of loci that impact glycemic modulation. The physiological report has begun to examine subtypes of diseases, illustrate heterogeneity and propose biochemical therapeutic pathways.

Genetic variants in toll-like receptor 4 are associated with lack of steroid-responsiveness in pediatric ITP patients

Although the most common front-line therapies for immune thrombocytopenia (ITP) have been in use for decades, it is still not possible to predict an individual patient's clinical course and response to therapy. Patients are managed with a trial-and-error approach and often suffer side effects of therapies which could have been avoided if response prediction were possible. Corticosteroids are the most frequently used upfront therapy for adults and children with ITP. Our group performed whole exome sequencing on a cohort of pediatric ITP patients, and identified two missense single nucleotide variants (SNV) in Toll-like receptor 4 (TLR4). These coding variants in TLR4 had an increased frequency in Caucasian patients with poor response to upfront steroid therapy. Both TLR4 (D299G; rs4986790) and TLR4 (T399I; rs4986791) had a minor allele frequency (MAF) of 20.7% in those patients unresponsive to steroids, but were present at lower allele frequencies of 2.3% and 3.4% in responders respectively (P < .001). These findings were consistent with the trend identified in an independent cohort of pediatric ITP patients treated with corticosteroids who underwent direct genotyping for both SNVs. This study identified two candidate genetic variants in two unique cohorts of ITP patients which may contribute to steroid response and have prognostic implications for treatment response in ITP.

TLR4 Signaling Pathway Modulators as Potential Therapeutics in Inflammation and Sepsis

Toll-Like Receptor 4 (TLR4) signal pathway plays an important role in initiating the innate immune response and its activation by bacterial endotoxin is responsible for chronic and acute inflammatory disorders that are becoming more and more frequent in developed countries. Modulation of the TLR4 pathway is a potential strategy to specifically target these pathologies. Among the diseases caused by TLR4 abnormal activation by bacterial endotoxin, sepsis is the most dangerous one because it is a life-threatening acute system inflammatory condition that still lacks specific pharmacological treatment. Here, we review molecules at a preclinical or clinical phase of development, that are active in inhibiting the TLR4-MyD88 and TLR4-TRIF pathways in animal models. These are low-molecular weight compounds of natural and synthetic origin that can be considered leads for drug development. The results of in vivo studies in the sepsis model and the mechanisms of action of drug leads are presented and critically discussed, evidencing the differences in treatment results from rodents to humans.

Coumarins as potential antidiabetic agents

OBJECTIVES

Even with great advances in modern medicine and therapeutic agent development, the search for effective antidiabetic drugs remains challenging. Coumarins are secondary metabolites found widely in nature plants and used mainly in anticoagulation and antithrombotic therapy. Over the past two decades, however, there has been an increasing body of literatures related to the effects of coumarins and their derivatives on diabetes and its complications. This review aimed to focus on research findings concerning the effects of coumarins against diabetes and its complications using in-vitro and in-vivo animal models, and also to discuss cellular and molecular mechanisms underlying these effects.

KEY FINDINGS

The search for new coumarins against diabetes and it complications, either isolated from traditional medicine or chemically synthesized, has been constantly expanding. The cellular and molecular mechanisms involved include protecting pancreatic beta cells from damage, improving abnormal insulin signalling, reducing oxidative stress/inflammation, activating AMP-activated protein kinase (AMPK), inhibiting α-glucosidases and ameliorating diabetic complications.

CONCLUSIONS

The effects and mechanisms of coumarins and their derivatives upon diabetes and its complications are discussed in current review. Further investigations remain to be carried out to develop a promising antidiabetic agent based on coumarin cores.

Reg3g overexpression promotes β cell regeneration and induces immune tolerance in nonobese-diabetic mouse model

The regenerating islet-derived gene was first isolated in regenerated pancreas tissues, greatly contributing to β cell regeneration. It is an anti-inflammatory in response to cellular stress. This encouraged us to investigate the exact role of a novel member of Reg family, regenerating islet-derived gene γ, in type 1 diabetes of nonobese-diabetic mice. For this, Reg3g gene was overexpressed in pancreatic islets, and conferred beneficial effects on β cell regeneration through activating the Janus kinase 2/signal transducer and activator of transcription 3/nuclear factor κB signaling pathway. Lentiviral vector-encoding regenerating islet-derived gene γ treatment also decreased lymphocyte infiltrates of the intra-islet and peri-islet by inducing both differentiation of regulatory T cell and immature dendritic cells of tolerogenic properties, which attenuated autoimmunity. This treatment further contributed to rebalanced levels of type 1/2 helper T cell cytokines and elevated α1-antitrypsin levels in the serum. These results were not observed in phosphate-buffered saline-treated mice or in lentivirus-control mice. We have shown, for the first time, to our knowledge, that regenerating islet-derived gene γ promotes β cell regeneration and preserves β cells from autoimmunity damage by increasing regulatory T cell differentiation and inducing tolerated dendritic cells. This regenerating islet-derived gene γ infusion could probably be developed into an optimal gene therapy for the prevention and reversal of type 1 diabetes.

The immunoregulatory effects of Chinese herbal medicine on the maturation and function of dendritic cells

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese herbal medicine (CHM) has a long-history for treatment of various human diseases including tumors, infection, autoimmune diseases in Asian countries, especially in China, Japan, Korea and India. CHM was traditionally used as water extracts and many Chinese herbs were considered to be good for health, which can regulate immune system to protect host from diseases. With the progress of technology, the components of CHM were identified and purified, which included polysaccharides, saponins, phenolic compounds, flavonoids and so on. Recently, accumulating evidence indicates that CHM and its components can regulate immune system through targeting dendritic cells (DCs). We hereby reviewed the immunoregulatory effects of CHM on the maturation, cytokine production and function of DCs. This should help to shed light on the potential mechanism of CHM to improve the usage and clinical efficacy of CHM.

MATERIALS AND METHODS

Literatures about the effects of CHM on DCs were searched in electronic databases such as Pubmed, Google Scholar and Scopus from 2000 to 2014. 'CHM', 'DC' or 'immune' were used as keywords for the searches. We only reviewed literatures published in English.

RESULTS

Over 600 publications were found about 'CHM&immune' and around 120 literatures about 'CHM&DC' were selected and reviewed in this paper. All publications are backed by preclinical or clinical evidences both in vitro and in vivo. Some CHM and its components promote the maturation, pro-inflammatory cytokine production and function of DCs and as the adjuvant enhance immune responses against tumor and infection. In contrast, other CHM and its components suppress the activation status of DCs to induce regulatory T cells, inhibit allergic and inflammatory responses, ameliorate autoimmune diseases, and prolong the allograft survival. A large body of evidence shows that CHM and its components regulate the activation status of DCs through TLRs, NF-κB, MAPK signaling pathways.

CONCLUSION

This review provides useful information for understanding the mechanism of CHM on the treatment of diseases, which facilitates to improve the efficacy of CHM. Based on the immunoregulatory effects of CHM on DCs, it indicated that some CHM and its components could be use to develop adjuvant to enhance antigen-specific immune responses or tolerogenic adjuvant to generate antigen-specific immune tolerance.

TLR2 and TLR4 in autoimmune diseases: a comprehensive review

Autoimmune diseases are immune disorders characterized by T cell hyperactivity and B cell overstimulation leading to overproduction of autoantibodies. Although the pathogenesis of various autoimmune diseases remains to be elucidated, environmental factors have been thought to contribute to the initiation and maintenance of auto-respond inflammation. Toll-like receptors (TLRs) are pattern recognition receptors belonging to innate immunity that recognize and defend invading microorganisms. Besides these exogenous pathogen-associated molecular patterns, TLRs can also bind with damage-associated molecular patterns produced under strike or by tissue damage or cells apoptosis. It is believed that TLRs build a bridge between innate immunity and autoimmunity. There are five adaptors to TLRs including MyD88, TRIF, TIRAP/MAL, TRAM, and SARM. Upon activation, TLRs recruit specific adaptors to initiate the downstream signaling pathways leading to the production of inflammatory cytokines and chemokines. Under certain circumstances, ligation of TLRs drives to aberrant activation and unrestricted inflammatory responses, thereby contributing to the perpetuation of inflammation in autoimmune diseases. In the past, most studies focused on the intracellular TLRs, such as TLR3, TLR7, and TLR9, but recent studies reveal that cell surface TLRs, especially TLR2 and TLR4, also play an essential role in the development of autoimmune diseases and afford multiple therapeutic targets. In this review, we summarized the biological characteristics, signaling mechanisms of TLR2/4, the negative regulators of TLR2/4 pathway, and the pivotal function of TLR2/4 in the pathogenesis of autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, Sjogren's syndrome, psoriasis, multiple sclerosis, and autoimmune diabetes.

Multiple mechanisms involved in diabetes protection by lipopolysaccharide in non-obese diabetic mice

Toll-like receptor 4 (TLR4) activation has been proposed to be important for islet cell inflammation and eventually β cell loss in the course of type 1 diabetes (T1D) development. However, according to the "hygiene hypothesis", bacterial endotoxin lipopolysaccharide (LPS), an agonist on TLR4, inhibits T1D progression. Here we investigated possible mechanisms for the protective effect of LPS on T1D development in non-obese diabetic (NOD) mice. We found that LPS administration to NOD mice during the prediabetic state neither prevented nor reversed insulitis, but delayed the onset and decreased the incidence of diabetes, and that a multiple-injection protocol is more effective than a single LPS intervention. Further, LPS administration suppressed spleen T lymphocyte proliferation, increased the generation of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs), reduced the synthesis of strong Th1 proinflammatory cytokines, and downregulated TLR4 and its downstream MyD88-dependent signaling pathway. Most importantly, multiple injections of LPS induced a potential tolerogenic dendritic cell (DC) subset with low TLR4 expression without influencing the DC phenotype. Explanting DCs from repeated LPS-treated NOD mice into NOD/SCID diabetic mice conferred sustained protective effects against the progression of diabetes in the recipients. Overall, these results suggest that multiple mechanisms are involved in the protective effects of LPS against the development of diabetes in NOD diabetic mice. These include Treg induction, down-regulation of TLR4 and its downstream MyD88-dependent signaling pathway, and the emergence of a potential tolerogenic DC subset.