Alantolactone alleviates collagen-induced arthritis and inhibits Th17 cell differentiation through modulation of STAT3 signalling

Alantolactone ameliorates graft versus host disease in mice

The anti-inflammatory and immunosuppressive drugs which are used in the treatment of Graft-versus-Host Disease (GVHD) have limited effects in controlling the severity of the disease. In this study, we aimed to investigate the prophylactic effect of Alantolactone (ALT) in a murine model of experimental GVHD. The study included 4 BALB/c groups as hosts: Naïve (n = 7), Control GVHD (n = 16), ALT-GVHD (n = 16), and Syngeneic transplantation (n = 10). Busulfan (20 mg/kg/day) for 4 days followed by cyclophosphamide (100 mg/kg/day) were administered for conditioning. Allogeneic transplantation was performed with cells collected from mismatched female C57BL/6, and GVHD development was monitored by histological and flow cytometric assays. Additionally, liver biopsies were taken from GVHD patient volunteers between ages 2-18 (n = 4) and non-GVHD patients between ages 2-50 (n = 5) and cultured ex vivo with ALT, and the supernatants were used for ELISA. ALT significantly ameliorated histopathological scores of the GVHD and improved GVHD clinical scores. CD8+ T cells were shown to be reduced after ALT treatment. More importantly, ALT treatment skewed T cells to a more naïve phenotype (CD62L+ CD44-). ALT did not alter Treg cell number or frequency. ALT treatment appears to suppress myeloid cell lineage (CD11c+). Consistent with reduced myeloid lineage, liver and small intestine levels of GM-CSF were reduced in ALT-treated mice. IL-6 gene expression was significantly reduced in the intestinal tissue. Ex vivo ALT-treated liver biopsy samples from GVHD patients showed a trend of decrease in pro-inflammatory cytokines but there was no statistical significance. Collectively, the data indicated that ALT may have immunomodulatory actions in a preclinical murine GVHD model.

The role of retinoic acid receptor-related orphan receptors in skeletal diseases

Bone homeostasis, depending on the balance between bone formation and bone resorption, is responsible for maintaining the proper structure and function of the skeletal system. As an important group of transcription factors, retinoic acid receptor-related orphan receptors (RORs) have been reported to play important roles in bone homeostasis by regulating the transcription of target genes in skeletal cells. On the other hand, the dysregulation of RORs often leads to various skeletal diseases such as osteoporosis, rheumatoid arthritis (RA), and osteoarthritis (OA). Herein, we summarized the roles and mechanisms of RORs in skeletal diseases, aiming to provide evidence for potential therapeutic strategies.

Discovery of alantolactone as a naturally occurring NLRP3 inhibitor to alleviate NLRP3-driven inflammatory diseases in mice

BACKGROUND AND PURPOSE

The NLR family pyrin domain-containing 3 (NLRP3) inflammasome is activated in many inflammatory conditions. So far, no low MW compounds inhibiting NLRP3 have entered clinical use. Identification of naturally occurring NLRP3 inhibitors may be beneficial to the design and development of compounds targeting NLRP3. Alantolactone is a phytochemical from a traditional Chinese medicinal plant with anti-inflammatory activity, but its precise target remains unclear.

EXPERIMENTAL APPROACH

A bank of phytochemicals was screened for inhibitors of NLRP3-driven production of IL-1β in cultures of bone-marrow-derived macrophages from female C57BL/6 mice. Models of gouty arthritis and acute lung injury in male C57BL/6J mice were used to determine the in vivo effects of the most potent compound.

KEY RESULTS

Among the 150 compounds screened in vitro, alantolactone exhibited the highest inhibitory activity against LPS + ATP-induced production of IL-1β in macrophages, suppressing IL-1β secretion, caspase-1 activation and pyroptosis. Alantolactone directly bound to the NACHT domain of NLRP3 to inhibit activation and assembly of NLRP3 inflammasomes. Molecular simulation analysis suggested that Arg335 in NLRP3 was a critical residue for alantolactone binding, leading to suppression of NLRP3-NEK7 interaction. In vivo studies confirmed significant alleviation by alantolactone of two NLRP3-driven inflammatory conditions, acute lung injury and gouty arthritis.

CONCLUSION AND IMPLICATIONS

The phytochemical alantolactone inhibited activity of NLRP3 inflammasomes by directly targeting the NACHT domain of NLRP3. Alantolactone shows great potential in the treatment of NLRP3-driven diseases and could lead to the development of novel NLRP3 inhibitors.

Natural Product Alantolactone Targeting AKR1C1 Suppresses Cell Proliferation and Metastasis in Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) is one of the leading causes of cancer-related deaths, characterized by high invasion and metastasis. Aldo-keto reductase family 1 member C1 (AKR1C1) plays an important role in cancer cell proliferation and metastasis, and has gained attention as an anticancer drug target. Here, we report that the natural sesquiterpene lactone alantolactone (ALA) was shown to bind directly to AKR1C1 through the Proteome Integral Solubility Alteration (PISA) analysis, a label-free target identification approach based on thermal proteome profiling. Acting as a specific inhibitor of AKR1C1, ALA selectively inhibits the activity of AKR1C1 and ALA treatment in human non-small-cell lung cancer (NSCLC) cell results in a reduction in cell proliferation and metastasis, inhibition of AKR1C1 expression, and deactivation of STAT3. Moreover, ALA inhibited tumor growth in vivo, and the inhibition of AKR1C1 and STAT3 activation were also found in the murine xenograft model. Collectively, our work not only gives mechanistic insights to explain the bioactivity of ALA in anticancer but also provides opportunities of developing novel sesquiterpene lactone-based AKR1C1 inhibitors for the treatment of NSCLC.

Anti-Inflammatory and Immunoregulatory Action of Sesquiterpene Lactones

Sesquiterpene lactones (SL), characterized by their high prevalence in the Asteraceae family, are one of the major groups of secondary metabolites found in plants. Researchers from distinct research fields, including pharmacology, medicine, and agriculture, are interested in their biological potential. With new SL discovered in the last years, new biological activities have been tested, different action mechanisms (synergistic and/or antagonistic effects), as well as molecular structure–activity relationships described. The review identifies the main sesquiterpene lactones with interconnections between immune responses and anti-inflammatory actions, within different cellular models as well in in vivo studies. Bioaccessibility and bioavailability, as well as molecular structure–activity relationships are addressed. Additionally, plant metabolic engineering, and the impact of sesquiterpene lactone extraction methodologies are presented, with the perspective of biological activity enhancement. Sesquiterpene lactones derivatives are also addressed. This review summarizes the current knowledge regarding the therapeutic potential of sesquiterpene lactones within immune and inflammatory activities, highlighting trends and opportunities for their pharmaceutical/clinical use.

Low-Dose Interleukin-2 Altered Gut Microbiota and Ameliorated Collagen-Induced Arthritis

Purpose

Low-dose interleukin-2 (ld-IL-2) has been shown to regulate the balance between effector T and regulatory T (Treg) cells and has been used in several clinical trials to treat autoimmune diseases including rheumatoid arthritis (RA). In this study, we investigated the effects of ld-IL-2 on collagen-induced arthritis (CIA) in mice.

Methods

Arthritis severity in CIA mice was measured using the arthritis index (AI), radiographs, and hematoxylin and eosin staining. Cytokines were detected using enzyme-linked immunosorbent assay. Gut microbiota alterations and short-chain fatty acid production were analyzed through 16S rRNA sequencing and gas chromatography.

Results

The AI scores of CIA mice treated with ld-IL-2 were significantly lower compared to the model group, which significantly reduced the severity of arthritis. Ld-IL-2 also altered the gut microbiota in CIA mice. The diversity, composition, and dominant species of gut microbiota were altered by ld-IL-2 treatment. Ld-IL-2 also increased short-chain fatty acid levels. There was a strong correlation between ld-IL-2 treatment and improved gut microbiota.

Conclusion

Ld-IL-2 significantly ameliorated joint inflammation and bone damage and improved gut microbial dysbiosis in CIA, indicating that it may be a promising therapy for RA patients.

Cyanidin restores Th17/Treg balance and inhibits T follicular helper cell differentiation via modulation of ROCK2 signaling in an experimental model of rheumatoid arthritis

Disturbed Th17/Treg balance is a critical pathological event in the disease progression of rheumatoid arthritis (RA). Recently, emerging studies have demonstrated that CD4 + T helper follicular (Tfh) cells exacerbates the pathogenic manifestations of RA. Contrarily, our previous report has shown that cyanidin, a flavonoid compound, attenuates disease severity of RA. Howbeit, this study investigated the therapeutic efficacy of cyanidin in relation to Th17/Treg balance and pathogenic Tfh cells in RA. Onto results, cyanidin inhibited increased Th17 cell differentiation and reciprocally improved FoxP3 + Treg cells both in-vivo and in-vitro. Concomitantly, cyanidin abated the detrimental effects of IL-17 via restoration of IL-10 secretion in adjuvant induced arthritic (AIA) rats. Furthermore, cyanidin reduced Tfh cells proportion and IgG levels in AIA rats, thus rectifying Tfh and follicular regulatory T (Tfr) cell ratio. Mechanistically, the restoring effect of cyanidin was associated with blunted activation of ROCK2/STAT3 signaling axis and reciprocal increase in the level of STAT-5 activity. Notwithstanding, cyanidin therapeutic efficacy correlated with specific oral ROCK2 inhibitor KD025 in-vitro. Collectively, these results demonstrate a dual promising therapeutic role of cyanidin via regulating Th17/Treg ratio and Tfh cell differentiation in an experimental model of RA.

Alantolactone: A sesquiterpene lactone with diverse pharmacological effects

Alantolactone (Ala) is a sesquiterpene lactone that can be isolated from many herbal plants belonging to Asteraceae. Besides the antimicrobial activities against bacteria, fungi and viruses, Ala has also demonstrated significant anti-inflammatory effects in various models by inhibiting NF-κB and MAPKs to decrease the pro-inflammatory cytokines such as IL-1β, IL-6 and TNF-α. The antitumor effects of Ala have been demonstrated in vitro and in vivo via inducing intrinsic apoptosis, oxidative stress, ER stress, cell cycle arrest and inhibiting autophagy and STAT3 phosphorylation, which are also involved in its combination or synergy with other antitumor drugs. Ala also has neuroprotective activity through attenuating oxidative stress and inflammation, besides its modulation of glucose and lipid metabolism. This review summarizes the recent advances of the pharmacological effects of Ala, including anti-inflammatory, antitumor, antimicrobial, neuroprotective activities, as well as the underlying mechanisms. Ala might be employed as a potential lead to develop drugs for multiple diseases.

Back to the Roots-An Overview of the Chemical Composition and Bioactivity of Selected Root-Essential Oils

Since ancient times, plant roots have been widely used in traditional medicine for treating various ailments and diseases due to their beneficial effects. A large number of studies have demonstrated that-besides their aromatic properties-their biological activity can often be attributed to volatile constituents. This review provides a comprehensive overview of investigations into the chemical composition of essential oils and volatile components obtained from selected aromatic roots, including Angelica archangelica, Armoracia rusticana, Carlina sp., Chrysopogon zizanioides, Coleus forskohlii, Inula helenium, Sassafras albidum, Saussurea costus, and Valeriana officinalis. Additionally, their most important associated biological impacts are reported, such as anticarcinogenic, antimicrobial, antioxidant, pesticidal, and other miscellaneous properties. Various literature and electronic databases-including PubMed, ScienceDirect, Springer, Scopus, Google Scholar, and Wiley-were screened and data was obtained accordingly. The results indicate the promising properties of root-essential oils and their potential as a source for natural biologically active products for flavor, pharmaceutical, agricultural, and fragrance industries. However, more research is required to further establish the mechanism of action mediating these bioactivities as well as essential oil standardization because the chemical composition often strongly varies depending on external factors.

Kurarinone Attenuates Collagen-Induced Arthritis in Mice by Inhibiting Th1/Th17 Cell Responses and Oxidative Stress

Kurarinone is a flavanone, extracted from Sophora flavescens Aiton, with multiple biological effects. Here, we determine the therapeutic potential of kurarinone and elucidate the interplay between kurarinone and the autoimmune disease rheumatoid arthritis (RA). Arthritis was recapitulated by induction of bovine collagen II (CII) in DBA/1 mice as a collagen-induced arthritis (CIA) model. After the establishment of the CIA, kurarinone was given orally from day 21 to 42 (100 mg/kg/day) followed by determination of the severity based on a symptom scoring scale and with histopathology. Levels of cytokines, anti-CII antibodies, and the proliferation and lineages of T cells from the draining lymph nodes were measured using ELISA and flow cytometry, respectively. The expressional changes, including STAT1, STAT3, Nrf2, KEAP-1, and heme oxygenase-1 (HO-1) changes in the paw tissues, were evaluated by Western blot assay. Oxidative stress featured with malondiadehyde (MDA) and hydrogen peroxide (H₂O₂) activities in paw tissues were also evaluated. Results showed that kurarinone treatment reduced arthritis severity of CIA mice, as well as their levels of proinflammatory cytokines, TNF-α, IL-6, IFN-γ, and IL-17A, in the serum and paw tissues. T cell proliferation was also reduced by kurarinone even under the stimulation of CII and anti-CD3 antibody. In addition, kurarinone reduced STAT1 and STAT3 phosphorylation and the proportions of Th1 and Th17 cells in lymph nodes. Moreover, kurarinone suppressed the production of MDA and H₂O_2. All while promoting enzymatic activities of key antioxidant enzymes, SOD and GSH-Px. In the paw tissues, upregulation of Nrf-2 and HO-1, and downregulation of KEAP-1 were observed. Overall, kurarinone showed an anti-inflammatory effect by inhibiting Th1 and Th17 cell differentiation and an antioxidant effect exerted in part through activating the Nrf-2/KEAP-1 pathway. These beneficial effects in CIA mice contributed to the amelioration of their arthritis, indicating that kurarinone might be an adjunct treatment option for rheumatoid arthritis.