Regenerative effects of glycyrrhizin and/or platelet rich plasma on type-II collagen induced arthritis: Targeting autophay machinery markers, inflammation and oxidative stress

Wutou decoction alleviates arthritis inflammation in CIA mice by regulating Treg cell stability and Treg/Th17 balance via the JAK2/STAT3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Wutou Decoction (WTD) is a classic traditional Chinese medicine formula, which has shown clinical efficacy in treating rheumatoid arthritis (RA). The Treg stability and Th17/Treg imbalance is an important immunological mechanism in RA progression. Whether WTD regulates CD4+ T cell subsets has not been thoroughly investigated yet.

AIM OF THE STUDY

This study aimed to explore the potential role and mechanisms of WTD in regulating the diminished stability of Treg cells and the imbalance of CD4+ T cell subsets via in vivo and in vitro experiments.

MATERIALS AND METHODS

Firstly, the therapeutic effects of WTD on the collagen-induced arthritis (CIA) mouse and its potential regulatory function on CD4+ T cell subsets were evaluated in vivo. Animal specimens were collected after 31 days of treatment with WTD. The anti-arthritic and anti-inflammatory effects of WTD were assessed through arthritis scoring, body weight, spleen index, serum IL-6 levels, and micro-PET/CT imaging. Gene enrichment analysis was performed to evaluate the activation T cell-related signaling pathway. Flow cytometry was used to determine the proportions of CD4+ T cell subsets in vitro and in vitro. Additionally, ELISA was used to assess the secretion of IL-10 and TGF-β by Treg cells under inflammatory conditions. The suppressive function of Treg cells on cell proliferation under inflammatory conditions was examined using CFSE labeling. Immunofluorescence staining was performed to detect the phosphorylation levels of STAT3 in CD4+ T cells from mouse spleen tissues. Western blotting was used to evaluate the phosphorylation levels of JAK2/STAT3 in Treg cells.

RESULTS

WTD significantly alleviated joint inflammation in CIA mice. WTD reduced serum IL-6 levels in CIA mice, improved their body weight and spleen index. WTD treatment inhibited the activation of CD4+ T cell subgroup-related signaling in the joint tissues of CIA mice. In vitro and in vitro experiments showed that WTD increased the proportion of Treg cells and decreased the proportion of Th17 cells in CIA mice spleen. Furthermore, WTD promoted the secretion of IL-10 and TGF-β by Treg cells and enhanced the inhibitory capacity of Treg cells on cell proliferation under inflammatory conditions. Immunofluorescence detected decreased STAT3 phosphorylation levels in CD4+ T cells from CIA mice spleen, while western blotting revealed a decrease in JAK2/STAT3 phosphorylation levels in Treg cells in vitro.

CONCLUSIONS

Inhibiting JAK2/STAT3 phosphorylation is a potential mechanism through which WTD improves Treg cell stability, balances CD4+ T cell subsets, and attenuates RA joint inflammation.

Could serum HMGB1 levels be a predictor associated with psoriatic arthritis?

Background/aim: Psoriasis is a chronic autoimmune disease that predominantly affects the skin and musculoskeletal system. We hypothesized that HMGB1, an inflammatory nuclear protein, may play a role in the musculoskeletal involvement of psoriasis. Methods: Forty patients with psoriasis and 45 with psoriatic arthritis were involved in the study; the results were compared with 22 healthy controls. Serum HMGB1 levels were evaluated from peripheral blood samples. Results: Serum HMGB1 levels were found to be significantly higher in patients with psoriasis regardless of joint involvement (p < 0.001). Also, HMGB1 levels were correlated with the extent of psoriasis. Conclusion: Serum HMGB1 levels may contribute to the progression of psoriasis to psoriatic arthritis and correlate with the severity of skin involvement.

A Review of the Antiviral Activities of Glycyrrhizic Acid, Glycyrrhetinic Acid and Glycyrrhetinic Acid Monoglucuronide

Licorice, a natural medicine derived from the roots and rhizomes of Glycyrrhiza species, possesses a wide range of therapeutic applications, including antiviral properties. Glycyrrhizic acid (GL) and glycyrrhetinic acid (GA) are the most important active ingredients in licorice. Glycyrrhetinic acid 3-O-mono-β-d-glucuronide (GAMG) is the active metabolite of GL. GL and its metabolites have a wide range of antiviral activities against viruses, such as, the hepatitis virus, herpes virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and so on. Although their antiviral activity has been widely reported, the specific mechanism of action involving multiple links such as the virus itself, cells, and immunity are not clearly established. In this review, we will give an update on the role of GL and its metabolites as antiviral agents, and detail relevant evidence on the potential use and mechanisms of actions. Analyzing antivirals, their signaling, and the impacts of tissue and autoimmune protection may provide promising new therapeutic strategies.

A comprehensive review of advanced drug delivery systems for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA), a chronic autoimmune disease, is characterized by articular pain and swelling, synovial hyperplasia, and cartilage and bone destruction. Conventional treatment strategies for RA involve the use of anti-rheumatic drugs, which warrant high-dose, frequent, and long-term administration, resulting in serious adverse effects and poor patient compliance. To overcome these problems and improve clinical efficacy, drug delivery systems (DDS) have been designed for RA treatment. These systems have shown success in animal models of RA. In this review, representative DDS that target RA through passive or active effects on inflammatory cells are discussed and highlighted using examples. In particular, DDS allowing controlled and targeted drug release based on a variety of stimuli, intra-articular DDS, and transdermal DDS for RA treatment are described. Thus, this review provides an improved understanding of these DDS and paves the way for the development of novel DDS for efficient RA treatment.

Wutou decoction attenuates the synovial inflammation of collagen-induced arthritis rats via regulating macrophage M1/M2 type polarization

ETHNOPHARMACOLOGICAL RELEVANCE

Thousands of years of clinical practice in the treatment of joint-related diseases support the efficacy and safety of Wutou decoction (WTD). Nevertheless, the lack of pharmacological evidence and unclear mechanisms make it difficult for WTD to become a recognized complementary therapy for the treatment of rheumatoid arthritis (RA).

AIM OF THE STUDY

This study aimed to investigate the effect of WTD against synovial inflammation in RA and whether this effect depends on the regulation of macrophage polarization.

MATERIALS AND METHODS

Sprague-Dawley rats were used to establish the collagen-induced arthritis (CIA) model. WTD with low and high doses was administered for 45 days. RAW264.7 cells were stimulated by lipopolysaccharide (LPS) or interleukin (IL)-4 to polarize M1 and M2 macrophages, which were pre-treated with WTD extract for 4 h. The anti-arthritic and anti-inflammatory effects of WTD were studied using arthritis score, histopathological staining, immunostaining, and enzyme-linked immunosorbent assay (ELISA). The polarization state of RAW264.7 cells and related pro/anti-inflammatory cytokines was detected by ELISA, reverse transcription quantitative polymerase chain reaction and western blotting. Western blotting and immunofluorescence were used to investigate the effect of WTD on nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and peroxisome proliferator-activated receptors γ (PPARγ) activation both in vivo and in vitro.

RESULTS

WTD significantly reduced the arthritis score and the pathological damage of the knee joint and decreased the expression of tumor necrosis factor alpha (TNF-α), IL-6 in serum, TNF-α, IL-1β, monocyte chemoattractant protein-1 (MCP-1), and matrix metalloproteinase-3 (MMP3) in the knee synovium. WTD inhibited M1 type polarization and promoted M2 type polarization, both in vitro and in vivo, and reduced the expression of pro-inflammatory cytokines while increasing the expression of anti-inflammatory cytokines. Experiments showed that WTD inhibited the phosphorylation of NF-κB and downstream p38 in the synovium of CIA rats and LPS-induced M1 type polarized RAW264.7 cells. In addition, PPARγ expression in the synovium of CIA rats was mainly located in the cytoplasm, and WTD treatment increased the nuclear translocation of PPARγ, which was further verified in RAW264.7 cells.

CONCLUSIONS

NF-κB and PPARγ regulating M1 and M2 macrophage polarization and subsequent secretion of pro-inflammatory and anti-inflammatory cytokines are the underlying mechanisms of WTD that ameliorate RA synovial inflammation.

Effects of Glycyrrhiza Glabra (Licorice) Root Extract on the Hormones, Serum Biochemicals, and Hematological Parameters in Dogs with Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is the most common prostate disorder in non-neutered dogs and is often caused by androgenic stimulation or changes in the ratio of androgen to estrogen. Also, it is commonly seen in neutered older dogs. Clinical signs may not be presented, but persistent or intermittent hematuria, hemospermia, or a primary hemorrhagic discharge are usually reported. In this research, ethanolic extract of licorice root (EELR) was used as the treatment, which has various antioxidant and healing properties and can reduce lesions by establishing an antioxidant balance and reducing inflammation. For this experiment, 30 dogs of approximately the same age and weight were randomly divided into 6 groups of 5 each. The treatment groups received the EELR at doses of 10 and 20 mg/kg separately, while the control group received no medications. At the end of the 9-week treatment period, biochemical and hormonal factors were measured and analyzed by blood sampling. The results showed that the EELR has multiple positive effects on the serum biochemical indices and also positively affects hormone levels, while it can decrease the prostate-specific antigen (PSA) level in BPH dogs. In conclusion, the EELR can effectively reduce BPH-induced lesions without any side effects.

Research progress on antiviral constituents in traditional Chinese medicines and their mechanisms of action

CONTEXT

Viruses have the characteristics of rapid transmission and high mortality. At present, western medicines still lack an ideal antiviral. As natural products, many traditional Chinese medicines (TCM) have certain inhibitory effects on viruses, which has become the hotspot of medical research in recent years.

OBJECTIVE

The antiviral active ingredients and mechanisms of TCM against viral diseases was studied in combination with the pathogenesis of viral diseases and antiviral effects.

MATERIALS AND METHODS

English and Chinese literature from 1999 to 2021 was collected from databases including Web of Science, PubMed, Elsevier, Chinese Pharmacopoeia 2020 (CP), and CNKI (Chinese). Traditional Chinese medicines (TCM), active ingredients, antiviral, mechanism of action, and anti-inflammatory effect were used as the key words.

RESULTS

The antiviral activity of TCM is clarified to put forward a strategy for discovering active compounds against viruses, and provide reference for screening antivirus drugs from TCM. TCM can not only directly kill viruses and inhibit the proliferation of viruses in cells, but also prevent viruses from infecting cells and causing cytophilia. It can also regulate the human immune system, enhance human immunity, and play an indirect antiviral role.

DISCUSSION AND CONCLUSION

Based on the experimental study and antiviral mechanism of TCM, this paper can provide analytical evidence that supports the effectiveness of TCM in treating virus infections, as well as their mechanisms against viruses. It could be helpful to provide reference for the research and development of innovative TCMs with multiple components, multiple targets and low toxicity.

Jieduquyuziyin prescription promotes the efficacy of prednisone via upregulating Nrf2 in MRL/lpr kidneys

ETHNOPHARMACOLOGICAL RELEVANCE

The Jieduquyuziyin prescription (JP), a traditional Chinese medicine (TCM) formula, has been used as an approved hospital prescription to improve the efficacy of prednisone (Pred) in systemic lupus erythematosus (SLE) and lupus nephritis (LN) treatment. Although the synergistic effect of JP and Pred is prominent, the underlying mechanisms require further investigation.

AIM OF THE STUDY

To explore the key therapeutic targets of JP in improving the role of Pred in the treatment of LN.

MATERIALS AND METHODS

Lupus-prone female MRL/lpr mice were administered JP, Pred, or JP combined with Pred. The effect of JP on LN was estimated by evaluating renal function and inflammation levels in the kidneys. On this basis, RNA sequencing of kidney tissues was performed, and the differentially expressed genes were analyzed and summarized. The role of JP in the expression of nuclear factor erythroid 2-related factor 2 (NFE2L2 or Nrf2) in the kidneys was further confirmed by real-time PCR, immunohistochemistry, and western blotting.

RESULTS

JP combined with Pred exhibited the most remarkable therapeutic effect compared with JP or Pred alone. Transcriptome analysis indicated that Nrf2, a central mediator of the antioxidative response, was significantly upregulated by JP. Based on these results, we speculated that Nrf2 is a critical factor for JP, improving the efficacy of Pred in treating LN by notably suppressing the oxidative stress level in the kidneys. Furthermore, we found that Nrf2 expression decreased with the exacerbation of LN in MRL/lpr mice. In addition, the downregulated Nrf2 was notably restored after JP treatment, accompanied by suppressed oxidative stress levels in the kidneys. It includes inhibited accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), restored mitochondrial membrane potential (MMP) levels, and increased antioxidant enzyme activity of superoxide dismutase (SOD).

CONCLUSIONS

Our findings show that JP increases Pred efficacy by increasing Nrf2 expression, implying that Nrf2 may be a promising therapeutic target for the treatment of LN.

The Effects of Intra-Articular Platelet-Rich Plasma Injections in Rheumatoid Arthritis: A Narrative Review

Platelet-rich plasma injections have been a therapeutic option with exponential growth in several pathologies in the last decades, particularly musculoskeletal for their effect on improving pain and functionality. Rheumatoid arthritis is a chronic joint disease, which involves inflammation of the synovial membrane with cartilage and juxta-articular bone destruction. Conventional and biological disease-modifying anti-rheumatoid drugs are the cornerstone of the treatment of this disease. However, the use of intra-articular glucocorticoids is often necessary and the role of platelet-rich plasma injections in these patients remains uncertain.

A literature review was carried out through the PubMed database, Cochrane and Google Scholar for the search terms “rheumatoid arthritis” and “platelet-rich plasma”. Eleven studies have been included in this review: two of these are in vitro studies, five are animal studies, one case report, two case series and one randomized controlled trial. Most of the studies demonstrated a decrease in pain and inflammatory mediators and improvement of functional outcomes, with no severe adverse effects reported.

However, the quantity and quality of literature about the effects and safety of plasma-rich plasma injections in rheumatoid arthritis patients are still scarce. It is essential that well-designed randomized controlled trials are made on this topic to understand if platelet-rich plasma may be useful as a coadjuvant therapy in rheumatoid arthritis.

Drug Candidates for Autoimmune Diseases

Most of the immunosuppressive drugs used in the clinic to prevent organ rejection or to treat autoimmune disorders were originally isolated from fungi or bacteria. Therefore, in addition to plants, these are valuable sources for identification of new potent drugs. Many side effects of established drugs limit their usage and make the identification of new immunosuppressants necessary. In this review, we present a comprehensive overview of natural products with potent anti-inflammatory activities that have been tested successfully in different models of chronic inflammatory autoimmune diseases. Some of these candidates already have passed first clinical trials. The anti-inflammatory potency of these natural products was often comparable to those of established drugs, and they could be used at least in addition to standard therapy to reduce their dose to minimize unwanted side effects. A frequent mode of action is the inhibition of classical inflammatory signaling pathways, such as NF-κB, in combination with downregulation of oxidative stress. A drawback for the therapeutic use of those natural products is their moderate bioavailability, which can be optimized by chemical modifications and, in addition, further safety studies are necessary. Altogether, very interesting candidate compounds exist which have the potential to serve as starting points for the development of new immunosuppressive drugs.

Glycyrrhizin regulates rat TMJOA progression by inhibiting the HMGB1-RAGE/TLR4-NF-κB/AKT pathway

To investigate the role of glycyrrhizin on the progression of temporomandibular joint osteoarthritis (TMJOA) and the underlying mechanism by regulation of the high‐mobility group box 1 (HMGB1) receptor for advanced glycation end products (RAGE)/toll‐like receptor 4 (TLR4)‐nuclear factor kappa B (NF‐κB)/protein kinase B (AKT) pathway. After a rat model of TMJOA was built by intra‐articular injection of monosodium iodoacetate, glycyrrhizin was intragastrically administered at low concentration (20 mg/kg) or high concentration (50 mg/kg). Micro‐computed tomography, histological and immunohistochemical analysis were used to reveal the progression of TMJOA. Rat TMJ chondrocytes and disc cells were cultured in inflammatory condition with different doses of glycyrrhizin. Western blot was used to evaluate the effect of glycyrrhizin on the HMGB1‐RAGE/TLR4‐NF‐κB/AKT pathway. Administration of glycyrrhizin alleviated cartilage degeneration, lowered the levels of inflammatory and catabolic mediators and reduced the production of HMGB1, RAGE and TLR4 in TMJOA animal model. Increased production of RAGE and TLR4, and activated intracellular NF‐κB and/or AKT signalling pathways in chondrocytes and disc cells were found in inflammatory condition. Upon activation, matrix metalloprotease‐3 and interleukin‐6 were upregulated. Glycyrrhizin inhibited not only HMGB1 release but also RAGE and TLR4 in inflammatory condition. Glycyrrhizin alleviated the pathological changes of TMJOA by regulating the HMGB1‐RAGE/TLR4‐NF‐kB/AKT signalling pathway. This study revealed the potential of glycyrrhizin as a novel therapeutic drug to suppress TMJ cartilage degradation.

A molecular insight of inflammatory cascades in rheumatoid arthritis and anti-arthritic potential of phytoconstituents

Rheumatoid arthritis (RA) is an auto-immune inflammatory disorder of the synovial lining of joints marked by immune cells infiltration and hyperplasia of synovial fibroblasts which results in articular cartilage destruction and bone erosion. The current review will provide comprehensive information and results obtained from the recent research on the phytochemicals which were found to have potential anti-arthritic activity along with the molecular pathway that were targeted to control RA progression. In this review, we have summarized the scientific data from various animal studies about molecular mechanisms, possible side effects, associations with conventional therapies, and the role of complementary and alternative medicines (CAM) for RA such as ayurvedic medicines in arthritis. In the case of RA, phytochemicals have been shown to act through different pathways such as regulation of inflammatory signaling pathways, T cell differentiation, inhibition of angiogenic factors, induction of the apoptosis of fibroblast-like synoviocytes (FLS), inhibition of autophagic pathway by inhibiting High-mobility group box 1 protein (HMGB-1), Akt/ mTOR pathway and HIF-1α mediated Vascular endothelial growth (VEGF) expression. Also, osteoclasts differentiation is inhibited by down-regulating the VEGF expression by decreasing the accumulation of the ARNT (Aryl Hydrocarbon Receptor Nuclear Translocator)-HIF-1α complex Although phytochemicals have shown to exert potential anti-arthritic activity in many animal models and further clinical data is needed to confirm their safety, efficacy, and interactions in humans.

"Platelet-rich plasma holds promise in management of rheumatoid arthritis"-systematic review

The treatment of rheumatoid arthritis (RA) has been closely evolving with an understanding of disease pathogenesis with disease modifying anti-rheumatoid drugs (DMARDS) and Biologic DMARDS being the main stay. platelet rich plasma (PRP) has been the center of research in many specialties in the past decade. Its ability to stop and reverse inflammation have attracted researchers to try PRP in RA. A systematic review of studies on PRP in RA is lacking. The study protocol was prospectively registered in PROSPERO. Detailed search of Cochrane, Scopus, Medline, Embase, and Web of science databases were made to identify the relevant articles till Sep 2020 following Cochrane and PRISMA guidelines. Number of subjects, Animal model used, cell lines used for the study, method of induction of arthritis, PRP dose, concentration used, frequency of administration and clinical, histologic, and molecular changes from baseline following PRP use were extracted and analysed. Eight studies were included for the review. Four of these were in-vitro studies. Two were exclusive animal studies. One study analysed the effects of PRP in RA in both animal models (mice) and Hela cell lines. One study was a report of a series of patients of resistant RA treated with PRP. In the in vitro studies while platelets increase the migration and invasion of RA-FLS, they suppressed the inflammation on the whole. Available animal studies and the Human study have shown encouraging results. There has been no evidence of exacerbation of inflammation in these studies. The quantity and quality of literature on the effects of PRP in treating joint pathologies in RA is limited. Preclinical studies show decrease in disease activity with good safety profile. Invitro studies show suppression of inflammation. Thus, the available literature is encouraging towards the use of PRP in RA. Larger trials and molecular studies to understand the exact role of platelets in disease pathogenesis and treatment mechanisms are needed to decide the future course of PRP in RA.

WTD Attenuating Rheumatoid Arthritis via Suppressing Angiogenesis and Modulating the PI3K/AKT/mTOR/HIF-1α Pathway

Background: Wutou Decoction (WTD), as a classic prescription, has been generally used to treat rheumatoid arthritis (RA) for two thousand years in China. However, the potential protective effects of WTD on rheumatoid arthritis and its possible mechanism have rarely been reported.

Purpose: The aim of this study was to explore the possible mechanism of WTD against RA and a promising alternative candidate for RA therapy.

Methods: A model of collagen-induced arthritis (CIA) was constructed in rats to assess the therapeutic effects of WTD. Histopathological staining, immunofluorescence, and western blotting of synovial sections were conducted to detect the antiangiogenic effects of WTD. Then, cell viability assays, flow cytometry, scratch healing assays, and invasion assays were conducted to explore the effects of WTD on MH7A human fibroblast-like synoviocyte (FLS) cell proliferation, apoptosis, migration, and invasion in vitro. The ability of WTD to induce blood vessel formation after MH7A cell and human umbilical vein endothelial cell line (HUVEC) coculture with WTD intervention was detected by a tube formation assay. The mechanisms of WTD were screened by network pharmacology and confirmed by in vivo and in vitro experiments.

Results: WTD ameliorated the symptoms and synovial pannus hyperplasia of CIA rats. Treatment with WTD inhibited MH7A cell proliferation, migration, and invasion and promoted MH7A apoptosis. WTD could inhibit MH7A cell expression of proangiogenic factors, including VEGF and ANGI, to induce HUVEC tube formation. Furthermore, the PI3K-AKT-mTOR-HIF-1α pathway was enriched as a potential target of WTD for the treatment of RA through network pharmacology enrichment analysis. Finally, it was confirmed in vitro and in vivo that WTD inhibits angiogenesis in RA by interrupting the PI3K-AKT-mTOR-HIF-1α pathway.

Conclusion: WTD can inhibit synovial hyperplasia and angiogenesis, presumably by inhibiting the migration and invasion of MH7A cells and blocking the production of proangiogenic effectors in MH7A cells. The possible underlying mechanism by which WTD ameliorates angiogenesis in RA is the PI3K-AKT-mTOR-HIF-1α pathway.

Platelet-Rich Plasma Induces Autophagy and Promotes Regeneration in Human Dental Pulp Cells

Regenerative endodontic procedures using autologous platelet-rich plasma (PRP) can improve the biologic outcome of treatment. However, its mechanism of action on improving pulp regeneration is not fully elucidated. Autophagy was recently shown to be related to tissue repair and osteogenesis. Therefore, the objective of this study was to investigate the effect of PRP in dental pulp regeneration and to elucidate the role of autophagy involved in this process. Human dental pulp cells (hDPCs) were isolated from healthy dental pulp and co-cultured with an increasing concentration of PRP. Cellular migration and proliferation were determined by scratch assay, transwell assay, and cell-counting kit 8 assay. Osteogenic differentiation was clarified by using alkaline phosphatase staining, alizarin red staining, and real-time polymerase chain reaction (RT-PCR) to measure the gene expression levels of alkaline phosphatase, collagen-1, osteocalcin, dentin matrix protein 1, and dentin sialophosphoprotein. Autophagic bodies were observed by transmission electron microscopy and the expression of autophagy marker light chain 3B (LC3B) was determined by immunofluorescence staining. The mRNA and protein expression level of LC3B and Beclin-1 were quantified by qRT-PCR and western blotting. The effect of PRP on cellular migration, proliferation, and osteogenic differentiation was further investigated in the milieu of autophagy activator, rapamycin, and inhibitor, 3-methyladenine. Results showed that PRP promoted cell migration, proliferation, and osteogenic differentiation. Autophagic bodies were strongly activated and the expression level of LC3B and Beclin-1 was significantly promoted by PRP. Autophagy inhibition suppressed PRP-induced hDPCs migration, proliferation, and osteogenic differentiation, whereas autophagy activator substantially augmented PRP-stimulated migration, proliferation, and differentiation. Taken together, these findings suggested that PRP could effectively promote regenerative potentials associated with autophagy.

Platelet-rich plasma attenuates intervertebral disc degeneration via delivering miR-141-3p-containing exosomes

Oxidative stress mediated apoptotic and pyroptotic cell death contributes to intervertebral disc (IVD) degeneration, and platelet-rich plasma (PRP) exerts protective effects to attenuate IVD degeneration. Hence, the present study aimed to validate this issue and uncover the potential underlying mechanisms. The mice and cellular models for IVD degeneration were established by using puncture method and H2O2 exposure, respectively, and we evidenced that NLRP3-mediated cell pyroptosis, apoptosis and inflammatory responses occurred during IVD degeneration progression in vitro and in vivo. Then, the PRP-derived exosomes (PRP-exo) were isolated and purified, and we noticed that both PRP-exo and ROS scavenger (NAC) reversed the detrimental effects of H2O2 treatment on the nucleus pulposus (NP) cells. Further results supported that PRP-exo exerted its protective effects on H2O2 treated NP cells by modulating the Keap1-Nrf2 pathway. Mechanistically, PRP-exo downregulated Keap1, resulting in the release of Nrf2 from the Keap1-Nrf2 complex, which further translocated from cytoplasm to nucleus to achieve its anti-oxidant biological functions, and H2O2 treated NP cells with Nrf2-deficiency did not respond to PRP-exo treatment. In addition, miR-141-3p was enriched in PRP-exo, and miR-141-3p targeted the 3' untranslated region (3'UTR) of Keap1 mRNA for its degradation, leading to Nrf2 translocation. Furthermore, overexpression of miR-141-3p ameliorated the cytotoxic effects of H2O2 on NP cells, which were abrogated by upregulating Keap1 and silencing Nrf2. Taken together, we concluded that PRP secreted exosomal miR-141-3p to activate the Keap1-Nrf2 pathway, which helped to slow down IVD degeneration.

Glycyrrhizin Ameliorates Radiation Enteritis in Mice Accompanied by the Regulation of the HMGB1/TLR4 Pathway

Radiation enteritis is a common side effect of radiotherapy for abdominal and pelvic malignancies, which can lead to a decrease in patients' tolerance to radiotherapy and the quality of life. It has been demonstrated that glycyrrhizin (GL) possesses significant anti-inflammatory activity. However, little is known about its anti-inflammatory effect in radiation enteritis. In the present study, we aimed to investigate the potential anti-inflammatory effects of GL on radiation enteritis and elucidate the possible underlying molecular mechanisms involved. The C57BL/6 mice were subjected to 6.5 Gy abdominal X-ray irradiation to establish a model of radiation enteritis. Hematoxylin and eosin staining was performed to analyze the pathological changes in the jejunum. The expression of TNF-α in the jejunum was analyzed by immunochemistry. The levels of inflammatory cytokines, such as TNF-α, IL-6, IL-1β, and HMGB1 in the serum were determined by enzyme-linked immunosorbent assay. The intestinal absorption capacity was tested using the D-xylose absorption assay. The levels of HMGB1 and TLR4 were analyzed by western blotting and immunofluorescence staining. We found that GL significantly alleviated the intestinal damage and reduced the levels of inflammatory cytokines, such as TNF-α, IL-6, IL-1β, and HMGB1 levels. Furthermore, the HMGB1/TLR4 signaling pathway was significantly downregulated by GL treatment. In conclusion, these findings indicate that GL has a protective effect against radiation enteritis through the inhibition of the intestinal damage and the inflammatory responses, as well as the HMGB1/TLR4 signaling pathway. Thereby, GL might be a potential therapeutic agent for the treatment of radiation enteritis.