Isothiocyanates are detected in human synovial fluid following broccoli consumption and can affect the tissues of the knee joint

Exploring the anti-inflammatory activity of sulforaphane

Dysregulation of innate immune responses can result in chronic inflammatory conditions. Glucocorticoids, the current frontline therapy, are effective immunosuppressive drugs but come with a trade-off of cumulative and serious side effects. Therefore, alternative drug options with improved safety profiles are urgently needed. Sulforaphane, a phytochemical derived from plants of the brassica family, is a potent inducer of phase II detoxification enzymes via nuclear factor-erythroid factor 2-related factor 2 (NRF2) signaling. Moreover, a growing body of evidence suggests additional diverse anti-inflammatory properties of sulforaphane through interactions with mediators of key signaling pathways and inflammatory cytokines. Multiple studies support a role for sulforaphane as a negative regulator of nuclear factor kappa-light chain enhancer of activated B cells (NF-κB) activation and subsequent cytokine release, inflammasome activation and direct regulation of the activity of macrophage migration inhibitory factor. Significantly, studies have also highlighted potential steroid-sparing activity for sulforaphane, suggesting that it may have potential as an adjunctive therapy for some inflammatory conditions. This review discusses published research on sulforaphane, including proposed mechanisms of action, and poses questions for future studies that might help progress our understanding of the potential clinical applications of this intriguing molecule.

A literature review on plant-based foods and dietary quality in knee osteoarthritis

This literature review summarizes the role of plant-based foods and diet quality in osteoarthritis, particularly knee osteoarthritis, in observational studies and clinical trials published during 2015- 2020. The included studies have suggested favorable results on reducing the prevalence, pain, and cartilage changes related to osteoarthritis and inflammatory and oxidation markers such as inter- leukin-1, interleukin-6, tumor necrosis factor, and lipid peroxidation. Due to the lack of large lon- gitudinal cohorts to study whole foods or diets concerning knee osteoarthritis, findings from the cross-sectional studies or clinical trials require further validation, particularly in well-designed clinical trials and a more extended follow-up period. Potential mechanisms on the role of plant-based foods in body weight, inflammation, and microbiome were explored to explain their protective associations with osteoarthritis. However, most evidence examining the relationship between the microbiome and osteoarthritis joint pain is conducted in preclinical animal studies, and few observational studies show a positive association between Streptococcus species and local joint inflammation in the knee. Given the close links of plant-based foods on obesity, inflammation, and microbiome, data on the role of whole foods or diets in the change in knee osteoarthritis pain through the lens of microbial composition can provide more certainty regarding the utilization of microbiome as a potential thera- peutic target.

Dietary organosulfur compounds: Emerging players in the regulation of bone homeostasis by plant-derived molecules

The progressive decline of bone mass and the deterioration of bone microarchitecture are hallmarks of the bone aging. The resulting increase in bone fragility is the leading cause of bone fractures, a major cause of disability. As the frontline pharmacological treatments for osteoporosis suffer from low patients' adherence and occasional side effects, the importance of diet regimens for the prevention of excessive bone fragility has been increasingly recognized. Indeed, certain diet components have been already associated to a reduced fracture risk. Organosulfur compounds are a broad class of molecules containing sulfur. Among them, several molecules of potential therapeutic interest are found in edible plants belonging to the Allium and Brassica botanical genera. Polysulfides derived from Alliaceae and isothiocyanates derived from Brassicaceae hold remarkable nutraceutical potential as anti-inflammatory, antioxidants, vasorelaxant and hypolipemic. Some of these effects are linked to the ability to release the gasotrasmitter hydrogen sulfide (H₂S). Recent preclinical studies have investigated the effect of organosulfur compounds in bone wasting and metabolic bone diseases, revealing a strong potential to preserve skeletal health by exerting cytoprotection and stimulating the bone forming activity by osteoblasts and attenuating bone resorption by osteoclasts. This review is intended for revising evidence from preclinical and epidemiological studies on the skeletal effects of organosulfur molecules of dietary origin, with emphasis on the direct regulation of bone cells by plant-derived polysulfides, glucosinolates and isothiocyanates. Moreover, we highlight the potential molecular mechanisms underlying the biological role of these compounds and revise the importance of the so-called 'H₂S-system' on the regulation of bone homeostasis.

The Metabolism of Glucosinolates by Gut Microbiota

Glucosinolates (GLS) and their derivatives are secondary plant metabolites abundant in Brassicaceae. Due to the enzymatic reaction between GLS and myrosinase enzyme, characteristic compounds with a pungent taste are formed, used by plants to defend themselves against insect herbivores. These GLS derivatives have an important impact on human health, including anti-inflammation and anti-cancer effects. However, GLS derivatives' formation needs previous enzymatic reactions catalyzed by myrosinase enzyme. Many of the brassica-based foods are processed at a high temperature that inactivates enzymes, hindering its bioavailability. In the last decade, several studies showed that the human gut microbiome can provide myrosinase activity that potentially can raise the beneficial effects of consumption of vegetables rich in GLS. The variability of the human gut microbiome (HGM) in human populations and the diverse intake of GLS through the diet may lead to greater variability of the real dose of pro-healthy compounds absorbed by the human body. The exploitation of the genetic and biochemical potential of HGM and correct ecological studies of both isolated strains and mixed population are of great interest. This review focuses on the most recent advances in this field.

Effect of interleukin-6, -17, -21, -22, and -23 and STAT3 on signal transduction pathways and their inhibition in autoimmune arthritis

Rheumatic diseases are complex autoimmune diseases which include among others rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), and psoriatic arthritis (PsA). These diseases are characterized by prolonged and increased secretion of inflammatory factors, eventually leading to inflammation. This is often accompanied by persistent pain and stiffness in the joint and finally bone destruction and osteoporosis. These diseases can occur at any age, regardless of gender or origin. Autoimmune arthritis is admittedly associated with long-term treatment, and discontinuation of medication is associated with unavoidable relapse. Therefore, it is important to detect the disease at an early stage and apply appropriate preventative measures. During inflammation, pro-inflammatory factors such as interleukins (IL)-6, -17, -21, -22, and -23 are secreted, while anti-inflammatory factors including IL-10 are downregulated. Research conducted over the past several years has focused on inhibiting inflammatory pathways and activating anti-inflammatory factors to improve the quality of life of people with rheumatic diseases. The aim of this paper is to review current knowledge on stimulatory and inhibitory pathways involving the signal transducer and activator of transcription 3 (STAT3). STAT3 has been shown to be one of the crucial factors involved in inflammation and is directly linked with other pro-inflammatory factors and thus is a target of current research on rheumatoid diseases.

Study on Human Urinary Metabolic Profiles after Consumption of Kale and Daikon Radish using a High-resolution Mass Spectrometry-Based Non-targeted and Targeted Metabolomic Approach

In the present study, urine samples were collected from healthy human volunteers to determine the metabolic fates of phenolic compounds and glucosinolates after a single meal of kale and daikon radish. The major glucosinolates and phenolic compounds in kale and daikon radish were measured. The urinary metabolome after feeding at different time periods was investigated. A targeted metabolite analysis method was developed based on the known metabolic pathways for glucosinolates and phenolic compounds. Using a targeted approach, a total of 18 metabolites were found in urine: 4 from phenolic compounds and 14 from glucosinolates. Among these metabolites, 4-methylsulfinyl-3-butenyl isothiocyanate, 4-methylsulfinyl-3-butenyl isothiocyanate-cysteine, and 4-methylsulfinyl-3-butenylglucosinolate-N-acetyl cysteine were reported for the first time in human urine. The combination of non-targeted and targeted metabolomic approaches can gain a full metabolite profile for human dietary intervention studies.

Current Landscape of NRF2 Biomarkers in Clinical Trials

The transcription factor NF-E2 p45-related factor 2 (NRF2; encoded by NFE2L2) plays a critical role in the maintenance of cellular redox and metabolic homeostasis, as well as the regulation of inflammation and cellular detoxication pathways. The contribution of the NRF2 pathway to organismal homeostasis is seen in many studies using cell lines and animal models, raising intense attention towards targeting its clinical promise. Over the last three decades, an expanding number of clinical studies have examined NRF2 inducers targeting an ever-widening range of diseases. Full understanding of the pharmacokinetic and pharmacodynamic properties of drug candidates rely partly on the identification, validation, and use of biomarkers to optimize clinical applications. This review focuses on results from clinical trials with four agents known to target NRF2 signaling in preclinical studies (dimethyl fumarate, bardoxolone methyl, oltipraz, and sulforaphane), and evaluates the successes and limitations of biomarkers focused on expression of NRF2 target genes and others, inflammation and oxidative stress biomarkers, carcinogen metabolism and adduct biomarkers in unavoidably exposed populations, and targeted and untargeted metabolomics. While no biomarkers excel at defining pharmacodynamic actions in this setting, it is clear that these four lead clinical compounds do touch the NRF2 pathway in humans.

Optimization of Synovial Fluid Collection and Processing for NMR Metabolomics and LC-MS/MS Proteomics

Synovial fluid (SF) is of great interest for the investigation of orthopedic pathologies, as it is in close proximity to various tissues that are primarily altered during these disease processes and can be collected using minimally invasive protocols. Multi-"omic" approaches are commonplace, although little consideration is often given for multiple analysis techniques at sample collection. Nuclear magnetic resonance (NMR) metabolomics and liquid chromatography tandem mass spectrometry (LC-MS/MS) proteomics are two complementary techniques particularly suited to the study of SF. However, currently there are no agreed upon standard protocols that are published for SF collection and processing for use with NMR metabolomic analysis. Furthermore, the large protein concentration dynamic range present within SF can mask the detection of lower abundance proteins in proteomics. While combinational ligand libraries (ProteoMiner columns) have been developed to reduce this dynamic range, their reproducibility when used in conjunction with SF, or on-bead protein digestion protocols, has yet to be investigated. Here we employ optimized protocols for the collection, processing, and storage of SF for NMR metabolite analysis and LC-MS/MS proteome analysis, including a Lys-C endopeptidase digestion step prior to tryptic digestion, which increased the number of protein identifications and improved reproducibility for on-bead ProteoMiner digestion.

The glucosinolates and their bioactive derivatives in Brassica: a review on classification, biosynthesis and content in plant tissues, fate during and after processing, effect on the human organism and interaction with the gut microbiota

The present study is a systematic review of the scientific literature reporting content, composition and biosynthesis of glucosinolates (GLS), and their derivative compounds in Brassica family. An amended classification of brassica species, varieties and their GLS content, organized for the different plant organs and in uniformed concentration measure unit, is here reported for the first time in a harmonized and comparative manner. In the last years, the studies carried out on the effect of processing on vegetables and the potential benefits for human health has increased rapidly and consistently the knowledge on the topic. Therefore, there was the need for an updated revision of the scientific literature of pre- and post-harvest modifications of GLS content, along with the role of gut microbiota in influencing their bioavailability once they are ingested. After analyzing and standardizing over 100 articles and the related data, the highest GLS content in Brassica, was declared in B. nigra (L.) W. D. J. Koch (201.95 ± 53.36 µmol g^-1), followed by B. oleracea Alboglabra group (180.9 ± 70.3 µmol g^-1). The authors also conclude that food processing can influence significantly the final content of GLS, considering the most popular methods: boiling, blanching, steaming, the latter can be considered as the most favorable to preserve highest level of GLS and their deriviatives. Therefore, a mild-processing strategic approach for GLS or their derivatives in food is recommended, in order to minimize the loss of actual bioactive impact. Finally, the human gut microbiota is influenced by Brassica-rich diet and can contribute in certain conditions to the increasing of GLS bioavailability but further studies are needed to assess the actual role of microbiomes in the bioavailability of healthy glucosinolate derivatives.

Natural ingredients-derived antioxidants attenuate H2O2-induced oxidative stress and have chondroprotective effects on human osteoarthritic chondrocytes via Keap1/Nrf2 pathway

Osteoarthritis (OA) is the most common disabling joint disease and its pathological process is closely related to oxidative stress. Recent studies have shown that antioxidants allicin, sulforaphane, and lycopene derived from natural ingredients garlic, broccoli, and tomato can reduce the degree of oxidative stress and the expression of inflammatory markers, indicating that theses antioxidants might be helpful for OA treatment. In this study, we investigated the effects of allicin, sulforaphane, and lycopene on H₂O₂-stimulated human osteochondral samples and osteoarthritic chondrocytes. Our results revealed that allicin, sulforaphane, and lycopene effectively reduced the oxidative stress-induced cell apoptosis, and increased gene expression of antioxidant enzymes. Besides, these natural ingredients-derived antioxidants reduced the expression of inflammatory factors, enhanced the chondrogenic matrix synthesis, and reduced the hypertrophic differentiation of osteoarthritic chondrocytes. These regulations were mainly through the activation of Keap1/Nrf2 pathway. Our findings suggest that these antioxidants might be a potential therapeutic strategy for OA.

Nutraceutical Activity in Osteoarthritis Biology: A Focus on the Nutrigenomic Role

Osteoarthritis (OA) is a disease associated to age or conditions that precipitate aging of articular cartilage, a post-mitotic tissue that remains functional until the failure of major homeostatic mechanisms. OA severely impacts the national health system costs and patients' quality of life because of pain and disability. It is a whole-joint disease sustained by inflammatory and oxidative signaling pathways and marked epigenetic changes responsible for catabolism of the cartilage extracellular matrix. OA usually progresses until its severity requires joint arthroplasty. To delay this progression and to improve symptoms, a wide range of naturally derived compounds have been proposed and are summarized in this review. Preclinical in vitro and in vivo studies have provided proof of principle that many of these nutraceuticals are able to exert pleiotropic and synergistic effects and effectively counteract OA pathogenesis by exerting both anti-inflammatory and antioxidant activities and by tuning major OA-related signaling pathways. The latter are the basis for the nutrigenomic role played by some of these compounds, given the marked changes in the transcriptome, miRNome, and methylome. Ongoing and future clinical trials will hopefully confirm the disease-modifying ability of these bioactive molecules in OA patients.

Broccoli or Sulforaphane: Is It the Source or Dose That Matters?

There is robust epidemiological evidence for the beneficial effects of broccoli consumption on health, many of them clearly mediated by the isothiocyanate sulforaphane. Present in the plant as its precursor, glucoraphanin, sulforaphane is formed through the actions of myrosinase, a β-thioglucosidase present in either the plant tissue or the mammalian microbiome. Since first isolated from broccoli and demonstrated to have cancer chemoprotective properties in rats in the early 1990s, over 3000 publications have described its efficacy in rodent disease models, underlying mechanisms of action or, to date, over 50 clinical trials examining pharmacokinetics, pharmacodynamics and disease mitigation. This review evaluates the current state of knowledge regarding the relationships between formulation (e.g., plants, sprouts, beverages, supplements), bioavailability and efficacy, and the doses of glucoraphanin and/or sulforaphane that have been used in pre-clinical and clinical studies. We pay special attention to the challenges for better integration of animal model and clinical studies, particularly with regard to selection of dose and route of administration. More effort is required to elucidate underlying mechanisms of action and to develop and validate biomarkers of pharmacodynamic action in humans. A sobering lesson is that changes in approach will be required to implement a public health paradigm for dispensing benefit across all spectrums of the global population.

Kartogenin hydrolysis product 4-aminobiphenyl distributes to cartilage and mediates cartilage regeneration

Rationale The small molecule Kartogenin (KGN) promotes cartilage regeneration in osteoarthritis (OA) by activating stem cells differentiation, but its pharmacological mode-of-action remains unclear. KGN can be cleaved into 4-aminobiphenyl (4-ABP) and phthalic acid (PA) following enzymolysis of an amide bond. Therefore, this study investigated whether 4-ABP or PA exerted the same action as KGN. Methods KGN, 4-ABP and PA were analyzed in cartilage of mice after oral, intravenous or intra-articular administration of KGN by liquid chromatography-mass spectrometry method. Their effect on proliferation and chondrogenic differentiation of mesenchymal stem cells (MSC) was evaluated in vitro. Furthermore, their effect on cartilage preservation was tested in mice OA model induced by destabilization of medial meniscus. OA severity was quantified using OARSI histological scoring. Transcriptional analysis was used to find the possible targets of the chemicals, which were further validated. Results We demonstrated that while oral or intra-articular KGN delivery effectively ameliorated OA phenotypes in mice, only 4-ABP was detectable in cartilage. 4-ABP could induce chondrogenic differentiation and proliferation of MSC in vitro and promote cartilage repair in OA mouse models mainly by increasing the number of CD44⁺/CD105⁺ stem-cell and prevention of matrix loss. These effect of 4-ABP was stronger than that of KGN. Transcriptional profiling of 4-ABP-stimulated MSC suggested that RPS6KA2 and the PI3K-Akt pathway were 4-ABP targets; 4-ABP could activate the PI3K-Akt pathway to promote MSC proliferation and repair OA injury, which was blocked in RPS6KA2-knockdown MSC or RPS6KA2-deficient mice. Conclusion 4-ABP bio-distribution in cartilage promotes proliferation and chondrogenic differentiation of MSC, and repairs osteoarthritic lesions via PI3K-Akt pathway activation.

The potential use of l-sulforaphane for the treatment of chronic inflammatory diseases: A review of the clinical evidence

According to the World Health Organisation, 70% of all deaths globally can be attributed to chronic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, respiratory conditions, cardiovascular diseases, diabetes and cancer. Chronic inflammation has a significant impact on the quality of life of affected individuals with an increased risk of developing other chronic inflammatory diseases. Given the limitations of current pharmaceuticals, there is an intense research interest in identifying novel dietary interventions that can regulate and alleviate inflammation. A diet rich in cruciferous vegetables has been extensively studied for its immediate and long-term health benefits, particularly in the context of cardiovascular disease and cancer. Cruciferous vegetables contain the precursor glucoraphanin, which is hydrolysed upon consumption to form l-sulforaphane (LSF), the primary active compound that mediates potential cardio-protective and anti-carcinogenic effects. LSF has been shown to have beneficial effects in vitro and in animal studies through its classical antioxidant and anti-inflammatory properties, and more recently its chromatin modifying effects. This review discusses the clinical evidence to date in relation to the use of LSF in the context of chronic inflammatory diseases as well as provide key mechanistic insights for these effects.

Proteomic analysis of synovial fluid: current and potential uses to improve clinical outcomes

INTRODUCTION

Synovial fluid (SF) is in close proximity to tissues which are primarily altered during articular disease and has significant potential to better understand the underlying disease pathogeneses of articular pathologies and biomarker discovery. Although development of mass spectrometry-based methods has allowed faster and higher sensitivity techniques, interrogation of the SF proteome has been hindered by its large protein concentration dynamic range, impeding quantification of lower abundant proteins. Areas covered: Recent advances have developed methodologies to reduce the large protein concentration dynamic range of SF and subsequently allow deeper exploration of the SF proteome. This review concentrates on methods to overcome biofluid complexity, mass spectrometry proteomics methodologies, extracellular vesicles proteomics and the application of advances within the field in clinical disease, including osteoarthritis, rheumatoid arthritis, spondyloarthritis and juvenile arthritis. A narrative review was conducted with articles searched using PubMed, 1991-2018. Expert opinion: The SF proteomics field faces various challenges, including the requirement for rigorous and standardised methods of sample collection/storage, the sensitivity and specificity of proteomic assays, techniques to combat the large protein concentration dynamic range and comprehensive data analysis to reduce falsely identified markers. Additionally, there are challenges in developing multi 'omic' integration techniques, with computational integration enhancing analysis.

Glycation marker glucosepane increases with the progression of osteoarthritis and correlates with morphological and functional changes of cartilage in vivo

Background

Changes of serum concentrations of glycated, oxidized, and nitrated amino acids and hydroxyproline and anticyclic citrullinated peptide antibody status combined by machine learning techniques in algorithms have recently been found to provide improved diagnosis and typing of early-stage arthritis of the knee, including osteoarthritis (OA), in patients. The association of glycated, oxidized, and nitrated amino acids released from the joint with development and progression of knee OA is unknown. We studied this in an OA animal model as well as interleukin-1β-activated human chondrocytes in vitro and translated key findings to patients with OA.

Methods

Sixty male 3-week-old Dunkin-Hartley guinea pigs were studied. Separate groups of 12 animals were killed at age 4, 12, 20, 28 and 36 weeks, and histological severity of knee OA was evaluated, and cartilage rheological properties were assessed. Human chondrocytes cultured in multilayers were treated for 10 days with interleukin-1β. Human patients with early and advanced OA and healthy controls were recruited, blood samples were collected, and serum or plasma was prepared. Serum, plasma, and culture medium were analyzed for glycated, oxidized, and nitrated amino acids.

Results

Severity of OA increased progressively in guinea pigs with age. Glycated, oxidized, and nitrated amino acids were increased markedly at week 36, with glucosepane and dityrosine increasing progressively from weeks 20 and 28, respectively. Glucosepane correlated positively with OA histological severity (r = 0.58, p < 0.0001) and instantaneous modulus (r = 0.52–0.56; p < 0.0001), oxidation free adducts correlated positively with OA severity (p < 0.0009–0.0062), and hydroxyproline correlated positively with cartilage thickness (p < 0.0003–0.003). Interleukin-1β increased the release of glycated and nitrated amino acids from chondrocytes in vitro. In clinical translation, plasma glucosepane was increased 38% in early-stage OA (p < 0.05) and sixfold in patients with advanced OA (p < 0.001) compared with healthy controls.

Conclusions

These studies further advance the prospective role of glycated, oxidized, and nitrated amino acids as serum biomarkers in diagnostic algorithms for early-stage detection of OA and other arthritic disease. Plasma glucosepane, reported here for the first time to our knowledge, may improve early-stage diagnosis and progression of clinical OA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1636-6) contains supplementary material, which is available to authorized users.

The Role of MicroRNAs in the Chemopreventive Activity of Sulforaphane from Cruciferous Vegetables

Colorectal cancer is an increasingly significant cause of mortality whose risk is linked to diet and inversely correlated with cruciferous vegetable consumption. This is likely to be partly attributable to the isothiocyanates derived from eating these vegetables, such as sulforaphane, which is extensively characterised for cytoprotective and tumour-suppressing activities. However, its bioactivities are likely to extend in complexity beyond those currently known; further insight into these bioactivities could aid the development of sulforaphane-based chemopreventive or chemotherapeutic strategies. Evidence suggests that sulforaphane modulates the expression of microRNAs, many of which are known to regulate genes involved at various stages of colorectal carcinogenesis. Based upon existing knowledge, there exist many plausible mechanisms by which sulforaphane may regulate microRNAs. Thus, there is a strong case for the further investigation of the roles of microRNAs in the anti-cancer effects of sulforaphane. There are several different types of approach to the wide-scale profiling of microRNA differential expression. Array-based methods may involve the use of RT-qPCR or complementary hybridisation probe chips, and tend to be relatively fast and economical. Cloning and deep sequencing approaches are more expensive and labour-intensive, but are worth considering where viable, for their greater sensitivity and ability to detect novel microRNAs.