Glycosaminoglycans are a potential cause of rheumatoid arthritis

In silico approaches for better understanding cysteine cathepsin-glycosaminoglycan interactions

Cysteine cathepsins constitute the largest cathepsin family, with 11 proteases in human that are present primarily within acidic endosomal and lysosomal compartments. They are involved in the turnover of intracellular and extracellular proteins. They are synthesized as inactive procathepsins that are converted to mature active forms. Cathepsins play important roles in physiological and pathological processes and, therefore, receive increasing attention as potential therapeutic targets. Their maturation and activity can be regulated by glycosaminoglycans (GAGs), long linear negatively charged polysaccharides composed of recurring dimeric units. In this review, we summarize recent computational progress in the field of (pro)cathepsin-GAG complexes analyses.

Late-Onset Reactions after Hyaluronic Acid Dermal Fillers: A Consensus Recommendation on Etiology, Prevention and Management

Hyaluronic acid (HA) dermal fillers, generally considered low-risk, can lead to rare late-onset reactions (LORs) manifesting between 3 and 4 months postinjection, occasionally even as early as 24 h postinjection. The Complication Assessment and Risk Evaluation (CARE) board was established to review these reactions. In this publication, the authors aims to explore the etiological hypotheses underlying LORs, associated risk factors, prevention, and management approaches suggested by the CARE board. The CARE board identified three etiological hypotheses contributing to LORs. Firstly, the physicochemical structure of the filler, particularly low molecular weight HA, which may trigger an immune response. Secondly, infection, potentially introduced during injection or by dormant biofilm activation. Lastly, an imbalance in the host immune system, caused by factors like autoimmune diseases or viral infections, may lead to extended foreign body reactions, delayed type IV hypersensitivity, or adjuvant-based reactions. Based on these hypotheses, the board categorized various risk factors as patient-related (e.g., recent dental treatment, current medical status, active autoimmune disease), product-related (e.g., molecular weight), and procedure-related (e.g., aseptic technique and trauma). To reduce the risk of LORs, the CARE board recommends diligent patient selection, including comprehensive medical history assessment and informed consent. Practitioners should maintain an effective aseptic technique, and choose an appropriate product and injection depth for the anatomical location. Post-procedure, patients should receive education on proper filler care. Management of LORs depends on the suspected etiology, and the CARE board has proposed an algorithm to determine the most appropriate treatment. Hyaluronidase is recommended for noninflammatory reactions in the absence of active infection, while watchful waiting and/or steroid treatment may be preferred for inflammatory reactions. Hyaluronidase is not recommended as a first-line treatment for infections, which require drainage, bacterial culture, and antibiotic treatment. However, the board emphasizes the need for individualized evaluation and treatment in all cases.

Mechanistic insights into bone remodelling dysregulation by human viral pathogens

Bone-related diseases (osteopathologies) associated with human virus infections have increased around the globe. Recent findings have highlighted the intricate interplay between viral infection, the host immune system and the bone remodelling process. Viral infections can disrupt bone homeostasis, contributing to conditions such as arthritis and soft tissue calcifications. Osteopathologies can occur after arbovirus infections such as chikungunya virus, dengue virus and Zika virus, as well as respiratory viruses, such as severe acute respiratory syndrome coronavirus 2 and enteroviruses such as Coxsackievirus B. Here we explore how human viruses dysregulate bone homeostasis, detailing viral factors, molecular mechanisms, host immune response changes and bone remodelling that ultimately result in osteopathologies. We highlight model systems and technologies to advance mechanistic understanding of viral-mediated bone alterations. Finally, we propose potential prophylactic and therapeutic strategies, introduce 'osteovirology' as a research field highlighting the underestimated roles of viruses in bone-related diseases, and discuss research avenues for further investigation.

Chondroitin sulfate proteoglycan 4: An attractive target for antibody-based immunotherapy

Multifunctional molecules involved in tumor progression and metastasis have been identified as valuable targets for immunotherapy. Among these, chondroitin sulfate proteoglycan 4 (CSPG4), a significant tumor cell membrane-bound proteoglycan, has emerged as a promising target, especially in light of advances in chimeric antigen receptor (CAR) T-cell therapy. The profound bioactivity of CSPG4 and its role in pivotal processes such as tumor proliferation, migration, and neoangiogenesis underline its therapeutic potential. We reviewed the molecular intricacies of CSPG4, its functional attributes within tumor cells, and the latest clinical-translational advances targeting it. Strategies such as blocking monoclonal antibodies, conjugate therapies, bispecific antibodies, small-molecule inhibitors, CAR T-cell therapies, trispecific killer engagers, and ribonucleic acid vaccines against CSPG4 were assessed. CSPG4 overexpression in diverse tumors and its correlation with adverse prognostic outcomes emphasize its significance in cancer biology. These findings suggest that targeting CSPG4 offers a promising avenue for future cancer therapy, with potential synergistic effects when combined with existing treatments.

Gut microbiota in pre-clinical rheumatoid arthritis: From pathogenesis to preventing progression

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by progressive polyarthritis that leads to cartilage and bone damage. Pre-clinical RA is a prolonged state before clinical arthritis and RA develop, in which autoantibodies (antibodies against citrullinated proteins, rheumatoid factors) can be present due to the breakdown of immunologic self-tolerance. As early treatment initiation before the onset of polyarthritis may achieve sustained remission, optimize clinical outcomes, and even prevent RA progression, the pre-clinical RA stage is showing the prospect to be the window of opportunity for RA treatment. Growing evidence has shown the role of the gut microbiota in inducing systemic inflammation and polyarthritis via multiple mechanisms, which may involve molecular mimicry, impaired intestinal barrier function, gut microbiota-derived metabolites mediated immune regulation, modulation of the gut microbiota's effect on immune cells, intestinal epithelial cells autophagy, and the interaction between the microbiome and human leukocyte antigen alleles as well as microRNAs. Since gut microbiota alterations in pre-clinical RA have been reported, potential therapies for modifying the gut microbiota in pre-clinical RA, including natural products, antibiotic therapy, fecal microbiota transplantation, probiotics, microRNAs therapy, vitamin D supplementation, autophagy inducer-based treatment, prebiotics, and diet, holds great promise for the successful treatment and even prevention of RA via altering ongoing inflammation. In this review, we summarized current studies that include pathogenesis of gut microbiota in RA progression and promising therapeutic strategies to provide novel ideas for the management of pre-clinical RA and possibly preventing arthritis progression.

Molecular Dynamics-Based Comparative Analysis of Chondroitin and Dermatan Sulfates

Glycosaminoglycans (GAGs) are a class of linear anionic periodic polysaccharides containing disaccharide repetitive units. These molecules interact with a variety of proteins in the extracellular matrix and so participate in biochemically crucial processes such as cell signalling affecting tissue regeneration as well as the onset of cancer, Alzheimer's or Parkinson's diseases. Due to their flexibility, periodicity and chemical heterogeneity, often termed "sulfation code", GAGs are challenging molecules both for experiments and computation. One of the key questions in the GAG research is the specificity of their intermolecular interactions. In this study, we make a step forward to deciphering the "sulfation code" of chondroitin sulfates-4,6 (CS4, CS6, where the numbers correspond to the position of sulfation in NAcGal residue) and dermatan sulfate (DS), which is different from CSs by the presence of IdoA acid instead of GlcA. We rigorously investigate two sets of these GAGs in dimeric, tetrameric and hexameric forms with molecular dynamics-based descriptors. Our data clearly suggest that CS4, CS6 and DS are substantially different in terms of their structural, conformational and dynamic properties, which contributes to the understanding of how these molecules can be different when they bind proteins, which could have practical implications for the GAG-based drug design strategies in the regenerative medicine.

TNF-α Inhibitors in Combination with MTX Reduce Circulating Levels of Heparan Sulfate/Heparin and Endothelial Dysfunction Biomarkers (sVCAM-1, MCP-1, MMP-9 and ADMA) in Women with Rheumatoid Arthritis

Sulfated glycosaminoglycans (sGAGs) are likely to play an important role in the development and progression of rheumatoid arthritis (RA)-associated atherosclerosis. The present study investigated the effect of anti-tumor necrosis factor-α (anti-TNF-α) therapy in combination with methotrexate on plasma sGAG levels and serum markers of endothelial dysfunction. Among sGAG types, plasma chondroitin/dermatan sulfate (CS/DS) and heparan sulfate/heparin (HS/H) were characterized using electrophoretic fractionation. Serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase-9 (MMP-9) and asymmetric dimethylarginine (ADMA) were measured by immunoassays. The measurements were carried out four times: at baseline and after 3, 9 and 15 months of anti-TNF-α therapy. All analyzed parameters, excluding ADMA, were significantly elevated in patients with RA before the implementation of biological therapy compared to healthy subjects. Performed anti-TNF-α treatment led to a successive decrease in HS/H levels toward normal values, without any effect on CS/DS levels in female RA patients. The treatment was also effective at lowering the serum levels of sVCAM-1, MCP-1, MMP-9 and ADMA. Moreover, a significant positive correlation was found between the circulating HS/H and the 28 joint disease activity score based on the erythrocyte sedimentation rate (DAS28-ESR, r = 0.408; p <0.05), MCP-1 (r = 0.398; p <0.05) and ADMA (r = 0.396; p <0.05) in patients before the first dose of TNF-α inhibitor. In conclusion, a beneficial effect of anti-TNF-α therapy on cell-surface heparan sulfate proteoglycans (HSPGs)/HS turnover and endothelial dysfunction was observed in this study. This was manifested by a decrease in blood HS/H levels and markers of endothelial activation, respectively. Moreover, the decrease in the concentration of HS/H in the blood of patients during treatment, progressing with the decline in disease activity, indicates that the plasma HS/H profile may be useful for monitoring the efficacy of anti-TNF-α treatment in patients with RA.

An Autoantigen Atlas From Human Lung HFL1 Cells Offers Clues to Neurological and Diverse Autoimmune Manifestations of COVID-19

COVID-19 is accompanied by a myriad of both transient and long-lasting autoimmune responses. Dermatan sulfate (DS), a glycosaminoglycan crucial for wound healing, has unique affinity for autoantigens (autoAgs) from apoptotic cells. DS-autoAg complexes are capable of stimulating autoreactive B cells and autoantibody production. We used DS-affinity proteomics to define the autoantigen-ome of lung fibroblasts and bioinformatics analyses to study the relationship between autoantigenic proteins and COVID-induced alterations. Using DS-affinity, we identified an autoantigen-ome of 408 proteins from human HFL1 cells, at least 231 of which are known autoAgs. Comparing with available COVID data, 352 proteins of the autoantigen-ome have thus far been found to be altered at protein or RNA levels in SARS-CoV-2 infection, 210 of which are known autoAgs. The COVID-altered proteins are significantly associated with RNA metabolism, translation, vesicles and vesicle transport, cell death, supramolecular fibrils, cytoskeleton, extracellular matrix, and interleukin signaling. They offer clues to neurological problems, fibrosis, smooth muscle dysfunction, and thrombosis. In particular, 150 altered proteins are related to the nervous system, including axon, myelin sheath, neuron projection, neuronal cell body, and olfactory bulb. An association with the melanosome is also identified. The findings from our study illustrate a connection between COVID infection and autoimmunity. The vast number of COVID-altered proteins with high intrinsic propensity to become autoAgs offers an explanation for the diverse autoimmune complications in COVID patients. The variety of autoAgs related to mRNA metabolism, translation, and vesicles suggests a need for long-term monitoring of autoimmunity in COVID. The COVID autoantigen atlas we are establishing provides a detailed molecular map for further investigation of autoimmune sequelae of the pandemic, such as “long COVID” syndrome.

Analysis of Normal Levels of Free Glycosaminoglycans in Urine and Plasma in Adults

Plasma and urine glycosaminoglycans (GAGs) are long, linear sulfated polysaccharides that have been proposed as potential noninvasive biomarkers for several diseases. However, owing to the analytical complexity associated with the measurement of GAG concentration and disaccharide composition (the so-called GAGome), a reference study of the normal healthy GAGome is currently missing. Here, we prospectively enrolled 308 healthy adults and analyzed their free GAGomes in urine and plasma using a standardized ultra-high-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry method together with comprehensive demographic and blood chemistry biomarker data. Of 25 blood chemistry biomarkers, we mainly observed weak correlations between the free GAGome and creatinine in urine and hemoglobin or erythrocyte counts in plasma. We found a higher free GAGome concentration – but not a more diverse composition - in males. Partitioned by gender, we also established reference intervals for all detectable free GAGome features in urine and plasma. Finally, we carried out a transference analysis in healthy individuals from two distinct geographical sites, including data from the Lifelines Cohort Study, which validated the reference intervals in urine. Our study is the first large-scale determination of normal free GAGomes reference intervals in plasma and urine and represents a critical resource for future physiology and biomarker research.

Bone Biomarkers in Mucopolysaccharidoses

The accumulation of glycosaminoglycans (GAGs) in bone and cartilage leads to progressive damage in cartilage that, in turn, reduces bone growth by the destruction of the growth plate, incomplete ossification, and growth imbalance. The mechanisms of pathophysiology related to bone metabolism in mucopolysaccharidoses (MPS) include impaired chondrocyte function and the failure of endochondral ossification, which leads to the release of inflammatory cytokines via the activation of Toll-like receptors by GAGs. Although improvements in the daily living of patients with MPS have been achieved with enzyme replacement, treatment for the bone disorder is limited. There is an increasing need to identify biomarkers related to bone and cartilage to evaluate the progressive status and to monitor the treatment of MPS. Recently, new analysis methods, such as proteomic analysis, have identified new biomarkers in MPS. This review summarizes advances in clinical bone metabolism and bone biomarkers.

Inflammatory arthritis complicating galactosialidosis: a case report

BACKGROUND

Galactosialidosis (GS) is a rare inherited lysosomal storage disorder (LSD) which is characterized by a defect in the lysosomal glycoprotein catabolism. We report, for the first time, the case of a child affected by GS presenting with recurrent episodes of extensive joint inflammation in both knee joints. The aim of this case-report is to describe the clinical presentation as well as the laboratory, radiologic and microscopic features of this unique presentation of GS. Furthermore, we explore inflammatory mechanisms potentially responsible for the origination of the arthritic joint pathology observed in our patient.

CASE PRESENTATION

We describe the rare case of a 12-year-old boy diagnosed with GS (late infantile form) who presented with multiple episodes of inflammatory arthritis involving both knees; no other joints were suspected for joint inflammation. Laboratory results did not indicate an autoimmune disorder. Synovial fluid tested negative for any bacterial infection and ruled out a malignancy and crystal-induced arthritis. Microscopic examination of the synovial tissue revealed numerous foamy macrophages with extensive vacuolization, consistent with the previous diagnosis of GS. Treatment consisted of aspiration of excessive joint fluid and subsequent intra-articular injection of triamcinolonhexacetonide with excellent but transient result. Given the evidence of storage products within macrophages of the inflamed synovial tissue and the absence of other etiological clues, GS itself was considered as the primary cause for the relapsing inflammatory joint pathology. According to the restricted data on articular manifestations in GS, to date, GS cannot be linked directly to joint inflammation. Nevertheless, in several other LSDs, the accumulation of storage material has been associated with numerous osteoimmunological changes that might play a role in the pathophysiology of arthritic processes.

CONCLUSIONS

We hypothesize that the articular build-up of GS storage products triggered systemic as well as local inflammatory processes, resulting in the extensive inflammatory joint pathology as observed in our patient. Future identification of other patients with GS is required to corroborate the existence of an arthritic clinical phenotype of GS and to assess the underlying pathophysiology.

Sulforaphane-loaded hyaluronic acid-poloxamer hybrid hydrogel enhances cartilage protection in osteoarthritis models

Sulforaphane (SFN) is an isothiocyanate with anti-arthritic and immuno-regulatory activities, supported by the downregulation of NF-κB pathway, reduction on metalloproteinases expression and prevention of cytokine-induced cartilage degeneration implicated in OA progression. SFN promising pharmacological effects associated to its possible use, by intra-articular route and directly in contact to the site of action, highlight SFN as promising candidate for the development of drug-delivery systems. The association of poloxamers (PL) and hyaluronic acid (HA) supports the development of osteotrophic and chondroprotective pharmaceutical formulations. This study aims to develop PL-HA hybrid hydrogels as delivery systems for SFN intra-articular release and evaluate their biocompatibility and efficacy for osteoarthritis treatment. All formulations showed viscoelastic behavior and cubic phase organization. SFN incorporation and drug loading showed a concentration-dependent behavior following HA addition. Drug release profiles were influenced by both diffusion and relaxation of polymeric chains mechanisms. The PL407-PL338-HA-SFN hydrogel did not evoke pronounced cytotoxic effects on either osteoblast or chondrosarcoma cell lines. In vitro/ex vivo pharmacological evaluation interfered with an elevated activation of NF-κB and COX-2, increased the type II collagen expression, and inhibited proteoglycan depletion. These results highlight the biocompatibility and the pharmacological efficacy of PL-HA hybrid hydrogels as delivery systems for SFN intra-articular release for OA treatment.

Increase in molar mass distinguishes chondroitin sulfate from osteoarthritis and normal extracellular cartilage matrix

PURPOSE

To determine alterations of chondroitin sulfate (CS) that reflect cartilage damage in an experimental osteoarthritis (OA) model as well as in human OA samples.

MATERIALS AND METHODS

Rats were subjected to anterior cruciate ligament transection (ACLT; OA) or a sham procedure and sacrificed 14, 28, or 70 days after ACLT for histopathology and analysis of extracted CS. Cartilage samples from 14 patients undergoing hip or shoulder arthroplasty secondary to OA or fracture (control) were subjected to the same protocol. The CS content (µg/mg dry cartilage) after proteolysis was determined by densitometry, using agarose-gel electrophoresis. Molar mass (MM) and peak MM of CS were determined using high-performance size-exclusion chromatography (HPSEC).

RESULTS

OA and sham joints at 70 d had 24 [22-24] and 3 [1-6] median histopathology scores, respectively (p < 0.001). Relative CS content (77.7 ± 8.3 µg/mg) was significantly increased in OA samples 70 d after ACLT, as compared to sham (53.5 ± 10.0 µg/mg). Peak MM of CS was higher in OA than in sham samples (P < 0.05). Similarly, CS content and peak MM were higher in cartilage from human OA patients, as compared to fracture samples, reproducing experimental data.

CONCLUSION

Cartilage matrix from experimental and human OA samples has increased in the relative CS content. Increase in the peak MM distinguishes CS of the extracellular matrix of OA from normal cartilage.

Small leucine-rich proteoglycans in physiological and biomechanical function of bone

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Proteoglycans (PGs) and glycosaminoglycans (GAGs) play vital roles in key signaling pathways to regulate bone homeostasis.

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The highly negatively charged GAGs are crucial in retaining bound water and modulating mechanical properties of bone.

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Age-related changes of PGs, GAGs, and bound water contribute to deterioration of bone quality during aging.

Proteoglycans (PGs) contain long unbranched glycosaminoglycan (GAG) chains attached to core proteins. In the bone extracellular matrix, PGs represent a class of non-collagenous proteins, and have high affinity to minerals and collagen. Considering the highly negatively charged character of GAGs and their interfibrillar positioning interconnecting with collagen fibrils, PGs and GAGs play pivotal roles in maintaining hydrostatic and osmotic pressure in the matrix. In this review, we will discuss the role of PGs, especially the small leucine-rich proteoglycans, in regulating the bioactivity of multiple cytokines and growth factors, and the bone turnover process. In addition, we focus on the coupling effects of PGs and GAGs in the hydration status of bone extracellular matrix, thus modulating bone biomechanical properties under physiological and pathological conditions.

A Master Autoantigen-ome Links Alternative Splicing, Female Predilection, and COVID-19 to Autoimmune Diseases

Chronic and debilitating autoimmune sequelae pose a grave concern for the post-COVID-19 pandemic era. Based on our discovery that the glycosaminoglycan dermatan sulfate (DS) displays peculiar affinity to apoptotic cells and autoantigens (autoAgs) and that DS-autoAg complexes cooperatively stimulate autoreactive B1 cell responses, we compiled a database of 751 candidate autoAgs from six human cell types. At least 657 of these have been found to be affected by SARS-CoV-2 infection based on currently available multi-omic COVID data, and at least 400 are confirmed targets of autoantibodies in a wide array of autoimmune diseases and cancer. The autoantigen-ome is significantly associated with various processes in viral infections, such as translation, protein processing, and vesicle transport. Interestingly, the coding genes of autoAgs predominantly contain multiple exons with many possible alternative splicing variants, short transcripts, and short UTR lengths. These observations and the finding that numerous autoAgs involved in RNA-splicing showed altered expression in viral infections suggest that viruses exploit alternative splicing to reprogram host cell machinery to ensure viral replication and survival. While each cell type gives rise to a unique pool of autoAgs, 39 common autoAgs associated with cell stress and apoptosis were identified from all six cell types, with several being known markers of systemic autoimmune diseases. In particular, the common autoAg UBA1 that catalyzes the first step in ubiquitination is encoded by an X-chromosome escape gene. Given its essential function in apoptotic cell clearance and that X-inactivation escape tends to increase with aging, UBA1 dysfunction can therefore predispose aging women to autoimmune disorders. In summary, we propose a model of how viral infections lead to extensive molecular alterations and host cell death, autoimmune responses facilitated by autoAg-DS complexes, and ultimately autoimmune diseases. Overall, this master autoantigen-ome provides a molecular guide for investigating the myriad of autoimmune sequalae to COVID-19 and clues to the rare but reported adverse effects of the currently available COVID vaccines.

Dermatan Sulfate Is a Potential Regulator of IgH via Interactions With Pre-BCR, GTF2I, and BiP ER Complex in Pre-B Lymphoblasts

Dermatan sulfate (DS) and autoantigen (autoAg) complexes are capable of stimulating autoreactive CD5+ B1 cells. We examined the activity of DS on CD5+ pre-B lymphoblast NFS-25 cells. CD19, CD5, CD72, PI3K, and Fas possess varying degrees of DS affinity. The three pre-BCR components, Ig heavy chain mu (IgH), VpreB, and lambda 5, display differential DS affinities, with IgH having the strongest affinity. DS attaches to NFS-25 cells, gradually accumulates in the ER, and eventually localizes to the nucleus. DS and IgH co-localize on the cell surface and in the ER. DS associates strongly with 17 ER proteins (e.g., BiP/Grp78, Grp94, Hsp90ab1, Ganab, Vcp, Canx, Kpnb1, Prkcsh, Pdia3), which points to an IgH-associated multiprotein complex in the ER. In addition, DS interacts with nuclear proteins (Ncl, Xrcc6, Prmt5, Eftud2, Supt16h) and Lck. We also discovered that DS binds GTF2I, a required gene transcription factor at the IgH locus. These findings support DS as a potential regulator of IgH in pre-B cells at protein and gene levels. We propose a (DS•autoAg)-autoBCR dual signal model in which an autoBCR is engaged by both autoAg and DS, and, once internalized, DS recruits a cascade of molecules that may help avert apoptosis and steer autoreactive B cell fate. Through its affinity with autoAgs and its control of IgH, DS emerges as a potential key player in the development of autoreactive B cells and autoimmunity.

Strong Reduction of the Chain Rigidity of Hyaluronan by Selective Binding of Ca2+ Ions

The biological functions of natural polyelectrolytes are strongly influenced by the presence of ions, which bind to the polymer chains and thereby modify their properties. Although the biological impact of such modifications is well recognized, a detailed molecular picture of the binding process and of the mechanisms that drive the subsequent structural changes in the polymer is lacking. Here, we study the molecular mechanism of the condensation of calcium, a divalent cation, on hyaluronan, a ubiquitous polymer in human tissues. By combining two-dimensional infrared spectroscopy experiments with molecular dynamics simulations, we find that calcium specifically binds to hyaluronan at millimolar concentrations. Because of its large size and charge, the calcium cation can bind simultaneously to the negatively charged carboxylate group and the amide group of adjacent saccharide units. Molecular dynamics simulations and single-chain force spectroscopy measurements provide evidence that the binding of the calcium ions weakens the intramolecular hydrogen-bond network of hyaluronan, increasing the flexibility of the polymer chain. We also observe that the binding of calcium to hyaluronan saturates at a maximum binding fraction of ∼10-15 mol %. This saturation indicates that the binding of Ca2+ strongly reduces the probability of subsequent binding of Ca2+ at neighboring binding sites, possibly as a result of enhanced conformational fluctuations and/or electrostatic repulsion effects. Our findings provide a detailed molecular picture of ion condensation and reveal the severe effect of a few, selective and localized electrostatic interactions on the rigidity of a polyelectrolyte chain.

Real-Time Quantification of Cartilage Degeneration by GAG-Targeted Cationic Nanoparticles for Efficient Therapeutic Monitoring in Living Mice

One of the characterizations of degenerative cartilage disease is the progressive loss of glycosaminoglycans (GAGs). The real-time imaging method to quantify GAGs is of great significance for the biochemical analysis of cartilage and diagnosis and therapeutic monitoring of cartilage degeneration in vivo. To this end, a cationic photoacoustic (PA) contrast agent, poly-l-lysine melanin nanoparticles (PLL-MNPs), specifically targeting anionic GAGs was developed in this study to investigate whether it can image cartilage degeneration. PLL-MNP assessed GAG depletion by Chondroitinase ABC in vitro rat cartilage and intact ex vivo mouse knee joint. A papain-induced cartilage degenerative mice model was used for in vivo photoacoustic imaging (PAI). Oral cartilage supplement glucosamine sulfate was intragastrically administered for mice cartilage repair and the therapeutic efficacy was monitored by PLL-MNP-enhanced PAI. Histologic findings were used to further confirm PAI results. In vitro results revealed that the PLL-MNPs not only had a high binding ability with GAGs but also sensitively monitored GAG content changes by PAI. The PA signal was gradually weakened along with the depletion of GAGs in cartilage. Particularly, PLL-MNPs depicted the cartilage structure and the distribution of GAGs was demonstrated in PA images in ex vivo joints. Compared with the normal joint, a lower signal intensity was detected from degenerative joint at 3 weeks after papain injection, suggesting an early diagnosis of cartilage lesion by PLL-MNPs. Importantly, this PA-enhanced nanoprobe was suitable for monitoring in vivo efficacy of glucosamine sulfate, which effectively blocked cartilage degradation in a high dose manner. In vivo imaging findings correlated well with histological examinations. PLL-MNPs provided sensitive visualization of cartilage degeneration and promising monitoring of therapeutic response in living subjects.

An Autoantigen Atlas from Human Lung HFL1 Cells Offers Clues to Neurological and Diverse Autoimmune Manifestations of COVID-19

COVID-19 is accompanied by a myriad of both transient and long-lasting autoimmune responses. Dermatan sulfate (DS), a glycosaminoglycan crucial for wound healing, has unique affinity for autoantigens (autoAgs) from apoptotic cells. DS-autoAg complexes are capable of stimulating autoreactive B cells and autoantibody production. Using DS affinity, we identified an autoantigenome of 408 proteins from human fetal lung fibroblast HFL11 cells, at least 231 of which are known autoAgs. Comparing with available COVID data, 352 proteins of the autoantigenome have thus far been found to be altered at protein or RNA levels in SARS-Cov-2 infection, 210 of which are known autoAgs. The COVID-altered proteins are significantly associated with RNA metabolism, translation, vesicles and vesicle transport, cell death, supramolecular fibrils, cytoskeleton, extracellular matrix, and interleukin signaling. They offer clues to neurological problems, fibrosis, smooth muscle dysfunction, and thrombosis. In particular, 150 altered proteins are related to the nervous system, including axon, myelin sheath, neuron projection, neuronal cell body, and olfactory bulb. An association with the melanosome is also identified. The findings from our study illustrate a strong connection between viral infection and autoimmunity. The vast number of COVID-altered proteins with propensity to become autoAgs offers an explanation for the diverse autoimmune complications in COVID patients. The variety of autoAgs related to mRNA metabolism, translation, and vesicles raises concerns about potential adverse effects of mRNA vaccines. The COVID autoantigen atlas we are establishing provides a detailed molecular map for further investigation of autoimmune sequelae of the pandemic.

Biglycan and chondroitin sulfate play pivotal roles in bone toughness via retaining bound water in bone mineral matrix

Recent in vitro evidence shows that glycosaminoglycans (GAGs) and proteoglycans (PGs) in bone matrix may functionally be involved in the tissue-level toughness of bone. In this study, we showed the effect of biglycan (Bgn), a small leucine-rich proteoglycan enriched in extracellular matrix of bone and the associated GAG subtype, chondroitin sulfate (CS), on the toughness of bone in vivo, using wild-type (WT) and Bgn deficient mice. The amount of total GAGs and CS in the mineralized compartment of Bgn KO mouse bone matrix decreased significantly, associated with the reduction of the toughness of bone, in comparison with those of WT mice. However, such differences between WT and Bgn KO mice diminished once the bound water was removed from bone matrix. In addition, CS was identified as the major subtype in bone matrix. We then supplemented CS to both WT and Bgn KO mice to test whether supplemental GAGs could improve the tissue-level toughness of bone. After intradermal administration of CS, the toughness of WT bone was greatly improved, with the GAGs and bound water amount in the bone matrix increased, while such improvement was not observed in Bgn KO mice or with supplementation of dermatan sulfate (DS). Moreover, CS supplemented WT mice exhibited higher bone mineral density and reduced osteoclastogenesis. Interestingly, Bgn KO bone did not show such differences irrespective of the intradermal administration of CS. In summary, the results of this study suggest that Bgn and CS in bone matrix play a pivotal role in imparting the toughness to bone most likely via retaining bound water in bone matrix. Moreover, supplementation of CS improves the toughness of bone in mouse models.

A proteomic repertoire of autoantigens identified from the classic autoantibody clinical test substrate HEp-2 cells

BACKGROUND

Autoantibodies are a hallmark of autoimmune diseases. Autoantibody screening by indirect immunofluorescence staining of HEp-2 cells with patient sera is a current standard in clinical practice. Differential diagnosis of autoimmune disorders is based on commonly recognizable nuclear and cytoplasmic staining patterns. In this study, we attempted to identify as many autoantigens as possible from HEp-2 cells using a unique proteomic DS-affinity enrichment strategy.

METHODS

HEp-2 cells were cultured and lysed. Total proteins were extracted from cell lysate and fractionated with DS-Sepharose resins. Proteins were eluted with salt gradients, and fractions with low to high affinity were collected and sequenced by mass spectrometry. Literature text mining was conducted to verify the autoantigenicity of each protein. Protein interaction network and pathway analyses were performed on all identified proteins.

RESULTS

This study identified 107 proteins from fractions with low to high DS-affinity. Of these, 78 are verified autoantigens with previous reports as targets of autoantibodies, whereas 29 might be potential autoantigens yet to be verified. Among the 107 proteins, 82 can be located to nucleus and 15 to the mitotic cell cycle, which may correspond to the dominance of nuclear and mitotic staining patterns in HEp-2 test. There are 55 vesicle-associated proteins and 12 ribonucleoprotein granule proteins, which may contribute to the diverse speckled patterns in HEp-2 stains. There are also 32 proteins related to the cytoskeleton. Protein network analysis indicates that these proteins have significantly more interactions among themselves than would be expected of a random set, with the top 3 networks being mRNA metabolic process regulation, apoptosis, and DNA conformation change.

CONCLUSIONS

This study provides a proteomic repertoire of confirmed and potential autoantigens for future studies, and the findings are consistent with a mechanism for autoantigenicity: how self-molecules may form molecular complexes with DS to elicit autoimmunity. Our data contribute to the molecular etiology of autoimmunity and may deepen our understanding of autoimmune diseases.

Rheumatoid meningitis and infection in absence of rheumatoid arthritis history: review of 31 cases

A 62-year-old healthy male presents with leg weakness and fever. Imaging revealed leptomeningeal enhancement (LE). After cerebrospinal fluid (CSF) cultures were negative, he was discharged with a diagnosis of aseptic meningitis, but was readmitted due to worsening symptoms. Brain biopsy suggested rheumatoid leptomeningitis associated with elevated serum rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibodies (ACPA). Following discharge, the New York State Department of Health (NYSDOH) reported a polymerase chain reaction (PCR) on CSF and brain DNA consistent with Naegleria fowleri (NF). After dramatic improvement on steroids, the patient declined antimicrobial treatment. Upon prednisone taper, symptoms recurred which responded to rituximab (RTX). This case highlights a possible association between rheumatoid leptomeningitis (RM) onset and infection, in a patient without a history of rheumatoid arthritis (RA). Our goal is to assess whether this association is present in 69 RM cases reported since 2000. We also describe diagnosis and treatment of 31 new cases (January 2017 to March 2020). We did not identify evidence of active/latent infection in patients with RM and previous RA; however, patients without RA history appeared to have a significantly higher rate. This finding could demonstrate the necessity of evaluating for infection in de novo RM cases without antecedent RA history. We also describe characteristic clinical patterns for each group. More studies are needed to corroborate these results and expand into a possible distinct natural history of RM in each group, which might have an impact upon the clinical outcome.

The Secretome Derived From 3D-Cultured Umbilical Cord Tissue MSCs Counteracts Manifestations Typifying Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disorder whose treatment is mostly restricted to pain and symptom management and to the delay of joint destruction. Mesenchymal stem/stromal cells from the umbilical cord tissue (UC-MSCs) have previously been proven to be immunomodulatory and more efficient than bone marrow-derived MSCs in causing remission of local and systemic arthritic manifestations in vivo. Given the paracrine nature of UC-MSC activity, their application as active substances can be replaced by their secretome, thus avoiding allogeneic rejection and safety issues related to unwanted grafting. In this work, we aimed at demonstrating the viability of applying the 3D-primed UC-MSC secretome for the amelioration of arthritic signs. A proteomic analysis was performed to both, media conditioned by UC-MSC monolayer (CM2D) and 3D cultures (CM3D). The analysis of relevant trophic factors confirmed secretome profiles with very significant differences in terms of therapeutic potential. Whereas, CM3D was characterised by a prevailing expression of anti-inflammatory cytokines such as IL-10 and LIF, along with trophic factors involved in different mechanisms leading to tissue regeneration, such as PDGF-BB, FGF-2, I-309, SCF, and GM-CSF; CM2D presented relatively higher levels of IL-6, MCP-1, and IL-21, with recognised pro-inflammatory roles in joint disease and pleiotropic effects in the progression of rheumatoid arthritis (RA). Accordingly, different motogenic effects over mouse chondrocytes and distinct capacities of inducing glycosaminoglycan synthesis in vitro were observed between CM3D and CM2D. Finally, the evaluation of arthritic manifestations in vivo, using an adjuvant-induced model for arthritis (AIA), suggested a significantly higher therapeutic potential of CM3D over CM2D and even UC-MSCs. Histological analysis confirmed a faster remission of local and systemic arthritic manifestations of CM3D-treated animals. Overall, the results show that the use of UC-MSC CM3D is a viable and better strategy than direct UC-MSC administration for counteracting AIA-related signs. This strategy represents a novel MSC-based but nonetheless cell-free treatment for arthritic conditions such as those characterising RA.

The role of innate immunity in mucopolysaccharide diseases

Mucopolysaccharidoses are lysosomal storage disorders characterised by accumulation of abnormal pathological glycosaminoglycans, cellular dysfunction and widespread inflammation, resulting in progressive cognitive and motor decline. Lysosomes are important mediators of immune cell function, and therefore accumulation of glycosaminoglycans (GAGs) and other abnormal substrates could affect immune function and directly impact on disease pathogenesis. This review summarises current knowledge with regard to inflammation in mucopolysaccharidosis, with an emphasis on the brain and outlines a potential role for GAGs in induction of inflammation. We propose a model by which the accumulation of GAGs and other factors may impact on innate immune signalling with particular focus on the Toll‐like receptor 4 pathway. Innate immunity appears to have a dominating role in mucopolysaccharidosis; however, furthering understanding of innate immune signalling would have significant impact on highlighting novel anti‐inflammatory therapeutics for use in mucopolysaccharide diseases.

This article is part of the Special Issue “Lysosomal Storage Disorders”.

Intermediate Molecular Mass Hyaluronan and CD44 Receptor Interactions Enhance Neutrophil Phagocytosis and IL-8 Production via p38- and ERK1/2-MAPK Signalling Pathways

CD44 is a common leukocyte adhesion molecule expressed on the surface of various cells. Hyaluronan (HA), the natural ligand of CD44, is a simple repeated disaccharide with variable molecular mass that is widely distributed on cell surfaces and the connective tissue matrix. The binding of small molecular mass HA (SMM-HA, MW < 80 kDa) to CD44 on immune-related cells elicits cell proliferation, differentiation, and cytokine production. However, the effects and molecular basis of intermediate molecular mass HA (IMM-HA, MW ≈ 500 kDa)-CD44 interactions on polymorphonuclear neutrophil (PMN) functions have not been elucidated. We hypothesised that IMM-HA would potentiate immune functions as well as SMM-HA. In the present study, we demonstrated IMM-HA and CD44 interactions enhanced normal PMN phagocytosis and IL-8 production compared to those with LPS or anti-CD45 treatment via F-actin cytoskeleton polymerization and subsequent ERK1/2- and p38-MAPK phosphorylation. Antibody-based inhibition of CD44 did not affect PMN function; however, F-actin aggregation was induced without MAPK phosphorylation. Enhanced PMN function via IMM-HA was determined to be CD44-dependent since this effect was abolished in DMSO-induced CD44(-) PMN-like cells obtained from HL-60 cells. In conclusion, we demonstrated that IMM-HA and CD44 interactions on PMNs potently elicit F-actin cytoskeleton polymerization and p38- and ERK1/2-MAPK phosphorylation to enhance PMN function.

Pro-inflammatory roles of chondroitin sulfate proteoglycans in disorders of the central nervous system

The extracellular matrix of the central nervous system is an interconnected network of proteins and sugars. It is crucial for homeostasis, but its remodeling in neurological diseases impacts both injury and repair. Here we introduce an extracellular matrix family member that participates in immune-matrix interactions, the chondroitin sulfate proteoglycans. Chondroitin sulfate proteoglycans integrate signals from the microenvironment to activate immune cells, and they boost inflammatory responses by binding immunological receptors including toll-like receptors, selectins, CD44, and β1 integrin. Chondroitin sulfate proteoglycans also bind signaling molecules for immune cells such as cytokines and chemokines, and they activate matrix-degrading enzymes. Chondroitin sulfate proteoglycans accumulate in the damaged CNS, including during traumatic brain/spinal cord injury and multiple sclerosis, and they help drive pathogenesis. This Review aims to give new insights into the remodeling of chondroitin sulfate proteoglycans during inflammation, and how these matrix glycoproteins are able to drive neuroinflammation.

Regulation of hyaluronan biosynthesis and clinical impact of excessive hyaluronan production

The tightly regulated biosynthesis and catabolism of the glycosaminoglycan hyaluronan, as well as its role in organizing tissues and cell signaling, is crucial for the homeostasis of tissues. Overexpression of hyaluronan plays pivotal roles in inflammation and cancer, and markedly high serum and tissue levels of hyaluronan are noted under such pathological conditions. This review focuses on the complexity of the regulation at transcriptional and posttranslational level of hyaluronan synthetic enzymes, and the outcome of their aberrant expression and accumulation of hyaluronan in clinical conditions, such as systemic B-cell cancers, aggressive breast carcinomas, metabolic diseases and virus infection.

Chondroitin Sulfate Proteoglycan 4 and Its Potential As an Antibody Immunotherapy Target across Different Tumor Types

Overexpression of the chondroitin sulfate proteoglycan 4 (CSPG4) has been associated with the pathology of multiple types of such as melanoma, breast cancer, squamous cell carcinoma, mesothelioma, neuroblastoma, adult and pediatric sarcomas, and some hematological cancers. CSPG4 has been reported to exhibit a role in the growth and survival as well as in the spreading and metastasis of tumor cells. CSPG4 is overexpressed in several malignant diseases, while it is thought to have restricted and low expression in normal tissues. Thus, CSPG4 has become the target of numerous anticancer treatment approaches, including monoclonal antibody-based therapies. This study reviews key potential anti-CSPG4 antibody and immune-based therapies and examines their direct antiproliferative/metastatic and immune activating mechanisms of action.

Overview of immune abnormalities in lysosomal storage disorders

The critical relevance of the lysosomal compartment for normal cellular function can be proved by numbering the clinical phenotypes that arise in lysosomal storage disorders (LSDs), a group of around 70 different monogenic autosomal or X-linked syndromes, caused by specific lysosomal enzyme deficiencies: all LSDs are characterized by progressive accumulation of heterogeneous biologic materials in the lysosomes of various parts of the body such as viscera, skeleton, skin, heart, and central nervous system. At least a fraction of LSDs has been associated with mixed abnormalities involving the immune system, while some patients with LSDs may result more prone to autoimmune phenomena. A large production of proinflammatory cytokines has been observed in Gaucher and Fabry diseases, and wide different autoantibody production has been also reported in both. Many immune-mediated reactions are crucial to the pathogenesis of different inflammatory signs in mucopolysaccharidoses, and subverted heparan sulphate catabolism might dysregulate cellular homeostasis in the brain of these patients. Furthermore, an inappropriate activation of microglia is implicated in the neurodegenerative foci of Niemann-Pick disease, in which abnormal signalling pathways are activated by impaired sphingolipid metabolism. In addition, not the simple impaired catabolism of gangliosides per se, but also the production of anti-ganglioside autoantibodies contributes to the neurological disease of gangliosidoses. Even if the exact relationship between the modification of lysosomal activities and modulation of the immune system remains obscure, there is emerging evidence of different impaired immunity responses in a variety of LSDs: in this review we investigate and summarize the immune abnormalities and/or clinical data about immune system irregularities which have been described in a subset of LSDs.

Two rheumatoid arthritis-specific autoantigens correlate microbial immunity with autoimmune responses in joints

In rheumatoid arthritis (RA), immunological triggers at mucosal sites, such as the gut microbiota, may promote autoimmunity that affects joints. Here, we used discovery-based proteomics to detect HLA-DR-presented peptides in synovia or peripheral blood mononuclear cells and identified 2 autoantigens, N-acetylglucosamine-6-sulfatase (GNS) and filamin A (FLNA), as targets of T and B cell responses in 52% and 56% of RA patients, respectively. Both GNS and FLNA were highly expressed in synovia. GNS appeared to be citrullinated, and GNS antibody values correlated with anti-citrullinated protein antibody (ACPA) levels. FLNA did not show the same results. The HLA-DR-presented GNS peptide has marked sequence homology with epitopes from sulfatase proteins of the Prevotella sp. and Parabacteroides sp., whereas the HLA-DR-presented FLNA peptide has homology with epitopes from proteins of the Prevotella sp. and Butyricimonas sp., another gut commensal. Patients with T cell reactivity with each self-peptide also had responses to the corresponding microbial peptides, and the levels were directly correlated. Furthermore, HLA-DR molecules encoded by shared-epitope (SE) alleles were predicted to bind these self- and microbial peptides strongly, and these responses were more common in RA patients with SE alleles. Thus, sequence homology between T cell epitopes of 2 self-proteins and a related order of gut microbes may provide a link between mucosal and joint immunity in patients with RA.

Poly-ion Complex of Chondroitin Sulfate and Spermine and Its Effect on Oral Chondroitin Sulfate Bioavailability

Chondroitin sulfate (CS) has been accepted as an ingredient in health foods for the treatment of symptoms related to arthritis and cartilage repair. However, CS is poorly absorbed through the gastrointestinal tract because of its high negative electric charges and molecular weight (MW). In this study, poly-ion complex (PIC) formation was found in aqueous solutions through electrostatic interaction between CS and polyamines-organic molecules having two or more primary amino groups ubiquitously distributed in natural products at high concentrations. Characteristic properties of various PICs generated by mixing CS and natural polyamines, including unusual polyamines, were studied based on the turbidity for PIC formation, the dynamic light scattering for the size of PIC particles, and ζ-potential measurements for the surface charges of PIC particles. The efficiency of PIC formation between CS and spermine increased in a CS MW-dependent manner, with 15 kDa CS being critical for the formation of PIC (particle size: 3.41 µm) having nearly neutral surface charge (ζ-potential: -0.80 mV). Comparatively, mixing tetrakis(3-aminopropyl)ammonium and 15 kDa of CS afforded significant levels of PIC (particle size: 0.42±0.16 µm) despite a strongly negative surface charge (-34.67±1.15 mV). Interestingly, the oral absorption efficiency of CS was greatly improved only when PIC possessing neutral surface charges was administered to mice. High formation efficiency and electrically neutral surface charge of PIC particles are important factors for oral CS bioavailability.

Raman spectroscopy and regenerative medicine: a review

The field of regenerative medicine spans a wide area of the biomedical landscape-from single cell culture in laboratories to human whole-organ transplantation. To ensure that research is transferrable from bench to bedside, it is critical that we are able to assess regenerative processes in cells, tissues, organs and patients at a biochemical level. Regeneration relies on a large number of biological factors, which can be perturbed using conventional bioanalytical techniques. A versatile, non-invasive, non-destructive technique for biochemical analysis would be invaluable for the study of regeneration; and Raman spectroscopy is a potential solution. Raman spectroscopy is an analytical method by which chemical data are obtained through the inelastic scattering of light. Since its discovery in the 1920s, physicists and chemists have used Raman scattering to investigate the chemical composition of a vast range of both liquid and solid materials. However, only in the last two decades has this form of spectroscopy been employed in biomedical research. Particularly relevant to regenerative medicine are recent studies illustrating its ability to characterise and discriminate between healthy and disease states in cells, tissue biopsies and in patients. This review will briefly outline the principles behind Raman spectroscopy and its variants, describe key examples of its applications to biomedicine, and consider areas of regenerative medicine that would benefit from this non-invasive bioanalytical tool.

Glycosaminoglycans detection methods: Applications of mass spectrometry

Glycosaminoglycans (GAGs) are long blocks of negatively charged polysaccharides. They are one of the major components of the extracellular matrix and play multiple roles in different tissues and organs. The accumulation of undegraded GAGs causes mucopolysaccharidoses (MPS). GAGs are associated with other pathological conditions such as osteoarthritis, inflammation, diabetes mellitus, spinal cord injury, and cancer. The need for further understanding of GAG functions and mechanisms of action boosted the development of qualitative and quantitative (alcian blue, toluidine blue, paper and thin layer chromatography, gas chromatography, high pressure liquid chromatography, capillary electrophoresis, 1,9-dimethylmethylene blue, enzyme linked-immunosorbent assay, mass spectrometry) techniques. The availability of quantitative techniques has facilitated translational research on GAGs into the medical field for: 1) diagnosis, monitoring, and screening for MPS; 2) analysis of GAG synthetic and degradation pathways; and 3) determination of physiological and pathological roles of GAGs. This review provides a history of development of GAG assays and insights about the use of tandem mass spectrometry and its applications for GAG analysis.

Ex vivo model exhibits protective effects of sesamin against destruction of cartilage induced with a combination of tumor necrosis factor-alpha and oncostatin M

Background

Rheumatoid arthritis (RA) is an autoimmune disease associated with chronic inflammatory arthritis. TNF-α and OSM are pro-inflammatory cytokines that play a key role in RA progression. Thus, reducing the effects of both cytokines is practical in order to relieve the progression of the disease. This current study is interested in sesamin, an active compound in sesame seeds. Sesamin has been shown to be a chondroprotective agent in osteoarthritis models. Here, we have evaluated a porcine cartilage explant as a cartilage degradation model related to RA induced by TNF-α and/or OSM in order to investigate the effects of sesamin on TNF-α and OSM in the cartilage degradation model.

Methods

A porcine cartilage explant was induced with a combination of TNF-α and OSM (test group) or IL-1β and OSM (control group) followed by a co-treatment of sesamin over a long-term period (35 days). After which, the tested explants were analyzed for indications of both the remaining and the degradation aspects using glycosaminoglycan and collagen as an indicator.

Results

The combination of TNF-α and OSM promoted cartilage degradation more than either TNF-α or OSM alone and was comparable with the combination of IL-1β and OSM. Sesamin could be offering protection against cartilage degradation by reducing GAGs and collagen turnover in the generated model.

Conclusions

Sesamin might be a promising agent as an alternative treatment for RA patients. Furthermore, the generated model revealed itself to be an impressive test model for the analysis of phytochemical substances against the cartilage degradation model for RA. The model could be used to test for the prevention of cartilage degradation in other biological agents induced with TNF-α and OSM as well.

Manipulating autophagic processes in autoimmune diseases: a special focus on modulating chaperone-mediated autophagy, an emerging therapeutic target

Autophagy, a constitutive intracellular degradation pathway, displays essential role in the homeostasis of immune cells, antigen processing and presentation, and many other immune processes. Perturbation of autophagy has been shown to be related to several autoimmune syndromes, including systemic lupus erythematosus. Therefore, modulating autophagy processes appears most promising for therapy of such autoimmune diseases. Autophagy can be said non-selective or selective; it is classified into three main forms, namely macroautophagy, microautophagy, and chaperone-mediated autophagy (CMA), the former process being by far the most intensively investigated. The role of CMA remains largely underappreciated in autoimmune diseases, even though CMA has been claimed to play pivotal functions into major histocompatibility complex class II-mediated antigen processing and presentation. Therefore, hereby, we give a special focus on CMA as a therapeutic target in autoimmune diseases, based in particular on our most recent experimental results where a phosphopeptide modulates lupus disease by interacting with CMA regulators. We propose that specifically targeting lysosomes and lysosomal pathways, which are central in autophagy processes and seem to be altered in certain autoimmune diseases such as lupus, could be an innovative approach of efficient and personalized treatment.

UP3005, a Botanical Composition Containing Two Standardized Extracts of Uncaria gambir and Morus alba, Improves Pain Sensitivity and Cartilage Degradations in Monosodium Iodoacetate-Induced Rat OA Disease Model

Osteoarthritis (OA) is a multifactorial disease primarily noted by cartilage degradation in association with inflammation that causes significant morbidity, joint pain, stiffness, and limited mobility. Present-day management of OA is inadequate due to the lack of principal therapies proven to be effective in hindering disease progression where symptomatic therapy focused approach masks the actual etiology leading to irreversible damage. Here, we describe the effect of UP3005, a composition containing a proprietary blend of two standardized extracts from the leaf of Uncaria gambir and the root bark of Morus alba, in maintaining joint structural integrity and alleviating OA associated symptoms in monosodium-iodoacetate- (MIA-) induced rat OA disease model. Pain sensitivity, micro-CT, histopathology, and glycosaminoglycans (GAGs) level analysis were conducted. Diclofenac at 10 mg/kg was used as a reference compound. UP3005 resulted in almost a complete inhibition in proteoglycans degradation, reductions of 16.6% (week 4), 40.5% (week 5), and 22.0% (week 6) in pain sensitivity, statistically significant improvements in articular cartilage matrix integrity, minimal visual subchondral bone damage, and statistically significant increase in bone mineral density when compared to the vehicle control with MIA. Therefore, UP3005 could potentially be considered as an alternative therapy from natural sources for the treatment of OA and/or its associated symptoms.

Chondroitin sulfate activates B cells in vitro, expands CD138+ cells in vivo, and interferes with established humoral immune responses

Glycosaminoglycans have anti-inflammatory properties and interact with a variety of soluble and membrane-bound molecules. Little is known about their effects on B cells and humoral immune responses. We show that CS but not dextran or other glycosaminoglycans induces a pronounced proliferation of B cells in vitro compared with TLR4 or TLR9 ligands. With the use of inhibitors and KO mice, we demonstrate that this proliferation is mediated by the tyrosine kinases BTK and Syk but independent of CD44. Antibodies against Ig-α or Ig-β completely block CS-induced B cell proliferation. Injection of CS in mice for 4-5 days expands B cells in the spleen and results in a marked increase of CD138(+) cells in the spleen that is dependent on BTK but independent of CD4(+) T cells. Long-term treatment with CS for 14 days also increases CD138(+) cells in the bone marrow. When mice were immunized with APC or collagen and treated with CS for up to 14 days during primary or after secondary immune responses, antigen-specific humoral immune responses and antigen-specific CD138(+) plasma cells in the bone marrow were reduced significantly. These data show that CD138(+) cells, induced by treatment with CS, migrate into the bone marrow and may displace other antigen-specific plasma cells. Overall, CS is able to interfere markedly with primary and fully established humoral immune responses in mice.

Anti-inflammatory Effect of Isaria sinclairii Glycosaminoglycan in an Adjuvant-treated Arthritis Rat Model

The anti-inflammatory effects of glycosaminoglycan (GAG) derived from Isaria sinclairii (IS) and of IS extracts were investigated in a complete Freund’s adjuvant (CFA)-treated chronic arthritis rat model. Groups of rats were treated orally with 30 mg/kg one of the following: [1] saline control, extracts of [2] water-IS, [3] methanol-IS, [4] butanol-IS, [5] ethyl acetate-IS, or [6] Indomethacin® as the positive control for a period of two weeks. The anti-paw edema effects of the individual extracts were in the following order: water-IS ex. > methanol ex. > butanol ex. > ethyl acetate ex. The water/methanol extract from I. sinclairii remarkably inhibited UV-mediated upregulation of NF-κB activity in transfected HaCaT cells. GAG as a water-soluble alcohol precipitated fraction also produced a noticeable anti-edema effect. This GAG also inhibited the pro-inflammatory cytokine levels of prostaglandin E₂-stimulated lipopolysaccharide in LAW 264.7 cells, cytokine TNF-α production in splenocytes, and atherogenesis cytokine levels of vascular endothelial growth factor (VEGF) production in HUVEC cells in a dose-dependent manner. In the histological analysis, the LV dorsal root ganglion, including the articular cartilage, and linked to the paw-treated IS GAG, was repaired against CFA-induced cartilage destruction. Combined treatment with Indomethacin® (5 mg/kg) and IS GAG (10 mg/kg) also more effectively inhibited CFA-induced paw edema at 3 hr, 24 hr, and 48 hr to levels comparable to the anti-inflammatory drug, indomethacin. Thus, the IS GAG described here holds great promise as an anti-inflammatory drug in the future.

Anti-inflammatory effect of glycosaminoglycan derived from Gryllus bimaculatus (a type of cricket, insect) on adjuvant-treated chronic arthritis rat model

Anti-inflammatory effects of glycosaminoglycan (GAG) derived from cricket (Gryllus bimaculatus, Gb) were investigated in a complete Freund's adjuvant (CFA)-treated chronic arthritic rat model. This GAG produced a significant anti-edema effect as evidenced by inhibition of C-reactive protein (CRP) and rheumatoid factor, and interfered with atherogenesis by reducing proinflammatory cytokine levels of (1) vascular endothelial growth factor (VEGF) production in human umbilical vein endothelial cells (HUVEC), (2) interleukin-6, (3) prostaglandin E2-stimulated lipopolysaccharide in RAW 264.7 cells, and (4) tumor necrosis factor (TNF)-α production in normal splenocytes, in a dose-dependent manner. This GAG was also found to induce nitric oxide (NO) production in HUVEC cells and elevated endothelial nitric oxide synthase (eNOS) activity levels. Histological findings demonstrated the fifth lumbar vertebrae (LV) dorsal root ganglion, which was linked to the paw treated with Gb GAG, was repaired against CFA-induced cartilage destruction. Further, combined indomethacin (5 mg/kg)-Gb GAG (10 mg/kg) inhibited more effectively CFA-induced paw edema at 3 h and 2 or 3 d after treatment to levels comparable to only the anti-inflammatory drug indomethacin. Ultraviolet (UV)-irritated skin inflammation also downregulated nuclear factor κB (NFκB) activity in transfected HaCaT cells. Data suggest that the anti-inflammatory effects of GAG obtained from cricket (Gb) may be useful for treatment of inflammatory diseases including chronic arthritis.

Osteoimmunology in mucopolysaccharidoses type I, II, VI and VII. Immunological regulation of the osteoarticular system in the course of metabolic inflammation

BACKGROUND

Mucopolysaccharidoses (MPSs) are rare genetic diseases caused by a deficient activity of one of the lysosomal enzymes involved in the glycosaminoglycan (GAG) breakdown pathway. These metabolic blocks lead to the accumulation of GAGs in various organs and tissues, resulting in a multisystemic clinical picture. The pathological GAG accumulation begins a cascade of interrelated responses: metabolic, inflammatory and immunological with systemic effects. Metabolic inflammation, secondary to GAG storage, is a significant cause of osteoarticular symptoms in MPS disorders.

OBJECTIVE AND METHOD

The aim of this review is to present recent progress in the understanding of the role of inflammatory and immune processes in the pathophysiology of osteoarticular symptoms in MPS disorders and potential therapeutic interventions based on published reports in MPS patients and studies in animal models.

RESULTS AND CONCLUSIONS

The immune and skeletal systems have a number of shared regulatory molecules and many relationships between bone disorders and aberrant immune responses in MPS can be explained by osteoimmunology. The treatment options currently available are not sufficiently effective in the prevention, inhibition and treatment of osteoarticular symptoms in MPS disease. A lot can be learnt from interactions between skeletal and immune systems in autoimmune diseases such as rheumatoid arthritis (RA) and similarities between RA and MPS point to the possibility of using the experience with RA in the treatment of MPS in the future. The use of different anti-inflammatory drugs requires further study, but it seems to be an important direction for new therapeutic options for MPS patients.

Using Small-Angle Scattering Techniques to Understand Mechanical Properties of Biopolymer-Based Biomaterials

The design and engineering of innovative biopolymer-based biomaterials for a variety of biomedical applications should be based on the understanding of the relationship between their nanoscale structure and mechanical properties. Down the road, such understanding could be fundamental to tune the properties of engineered tissues, extracellular matrices for cell delivery and proliferation/differentiation, etc. In this tutorial review, we attempt to show in what way biomaterial structural data can help to understand the bulk material properties. We begin with some background on common types of biopolymers used in biomaterials research, discuss some typical mechanical testing techniques and then review how others in the field of biomaterials have utilized small-angle scattering for material characterization. Detailed examples are then used to show the full range of possible characterization techniques available for biopolymer-based biomaterials. Future developments in the area of material characterization by small-angle scattering will undoubtedly facilitate the use of structural data to control the kinetics of assembly and final properties of prospective biomaterials.

Apoptosis-like cell death induction and aberrant fibroblast properties in human incisional hernia fascia

Incisional hernia often occurs following laparotomy and can be a source of serious problems. Although there is evidence that a biological cause may underlie its development, the mechanistic link between the local tissue microenvironment and tissue rupture is lacking. In this study, we used matched tissue-based and in vitro primary cell culture systems to examine the possible involvement of fascia fibroblasts in incisional hernia pathogenesis. Fascia biopsies were collected at surgery from incisional hernia patients and non-incisional hernia controls. Tissue samples were analyzed by histology and immunoblotting methods. Fascia primary fibroblast cultures were assessed at morphological, ultrastructural, and functional levels. We document tissue and fibroblast loss coupled to caspase-3 activation and induction of apoptosis-like cell-death mechanisms in incisional hernia fascia. Alterations in cytoskeleton organization and solubility were also observed. Incisional hernia fibroblasts showed a consistent phenotype throughout early passages in vitro, which was characterized by significantly enhanced cell proliferation and migration, reduced adhesion, and altered cytoskeleton properties, as compared to non-incisional hernia fibroblasts. Moreover, incisional hernia fibroblasts displayed morphological and ultrastructural alterations compatible with autophagic processes or lysosomal dysfunction, together with enhanced sensitivity to proapoptotic challenges. Overall, these data suggest an ongoing complex interplay of cell death induction, aberrant fibroblast function, and tissue loss in incisional hernia fascia, which may significantly contribute to altered matrix maintenance and tissue rupture in vivo.

Dermatan sulfate interacts with dead cells and regulates CD5(+) B-cell fate: implications for a key role in autoimmunity

CD5(+) (B-1a) B cells play pivotal roles in autoimmunity through expression of autoreactive B-cell receptors and production of autoantibodies. The mechanism underlying their positive selection and expansion is currently unknown. This study demonstrates that dermatan sulfate (DS) expands the B-1a cell population and augments the specific antibody response to an antigen when it is in complex with DS. DS displays preferential affinity for apoptotic and dead cells, and DS-stimulated cell cultures produce antibodies to various known autoantigens. The companion article further illustrates that autoantigens can be identified by affinity to DS, suggesting that molecules with affinity to DS have a high propensity to become autoantigens. We thus propose that the association of antigens from dead cells with DS is a possible origin of autoantigens and that autoreactive B-1a cells are positively selected and expanded by DS∙autoantigen complexes. This mechanism may also explain the clonal expansion of B-1a cells in certain B-cell malignancies.

Elevated IgG autoantibody production in oligoarticular juvenile idiopathic arthritis may predict a refractory course

OBJECTIVES

Although oligoarticular juvenile idiopathic arthritis (oJIA) is considered to carry the best prognosis among the JIA subtypes, many children evolve to a chronic course. A few studies have identified clinical risk factors for disease extension, and recent studies have evaluated synovial fluid markers. However, the only biological marker from the serum studied to date is the anti-nuclear antibody (ANA), regarding which there is mixed data regarding prognosis. No studies have evaluated whether additional autoantibodies may affect the articular prognosis of oJIA.

METHODS

Microarrays containing candidate autoantigens were printed on slides, which were used to profile 36 children with oJIA and 18 controls. Unsupervised cluster analysis was used to identify distinct subgroups of JIA patients. Response to therapy after a mean interval of 4.9 months was evaluated.

RESULTS

Cluster analysis revealed two subgroups of oJIA patients, with identical clustering observed when children with onset over age six were excluded. Cluster 1 had higher levels of multiple autoantibodies compared to both cluster 2 as well as controls, including antibodies against several extracellular matrix (ECM) and nuclear antigens. Although the two patient clusters were similar with respect to clinical features and treatment decisions, children in cluster 1 were less likely to have attained remission by the follow-up visit.

CONCLUSIONS

Antibodies against ECM and possibly other antigens may identify a sub-group of children with oJIA who will require more aggressive therapy to attain control of the arthritis.

Bioengineered hyaluronic acid elicited a nonantigenic T cell activation: implications from cosmetic medicine and surgery to nanomedicine

Hyaluronan is known to act as a filling material of extracellular matrices and as an adhesive substrate for cellular migration. Consequently, it is widely used in aesthetic medicine and surgery, and it would be expected to be used in nanomedicine. Previous clinical case reports associated hyaluronic acid implants to delayed immune-mediated adverse effects. A series of experiments to evaluate immune cell activation supported by this dermal filler and nanomedical biomaterial were performed. The study comprised a total of 12 individuals. Four healthy individuals, none with cosmetically injected dermal filler, were considered as control. Five individuals carried injections of hyaluronic acid dermal filler. Three individuals carried injections of hyaluronic acid dermal filler and presented delayed adverse effects related to the dermal filler. Hyaluronic acid-stimulated peripheral blood mononuclear cells (PBMC) produced low levels of pro-inflammatory cytokines. Phytohemagglutinine (PHA)-stimulated PBMC from patients with hyaluronic implants presenting adverse effects showed a slight increase in the production of interferon (IFN)-gamma and higher expression of CD25, CD69, or CD71. In conclusion, hyaluronic acid administration elicited a laboratory evidence of immune cell activation. Production of low levels of proinflammatory cytokines in vitro could be an observation for low-grade inflammation in vivo resulting in T cell activation.

Immune modulation by chondroitin sulfate and its degraded disaccharide product in the development of an experimental model of multiple sclerosis

Clinical symptoms in MOG-induced EAE mice significantly exacerbated following chondroitin sulfate A (CS-A) injection, whereas administration of a degraded product, CSPG-DS, caused dramatic inhibition of EAE development. Also, administration of CSPG-DS but not CS-A, after the onset of clinical symptoms of EAE, was able to suppress the disease. Further studies demonstrated that CS-A up-regulated STAT4 expression and thus, induced IFN-gamma production and Th1 CD4 T cell differentiation. CS-A also up-regulated STAT3 and IL-23 expression and thus increased IL-17 producing T cells. CSPG-DS treatment both in vivo and in vitro decreased TNFalpha production from splenocytes. In vitro and in vivo studies indicated that CSPG-DS treatment in EAE mice significantly blocked migration of lymphocytes, whereas CS-A treatment increased lymphocyte infiltration in the brain.

Mucopolysaccharidosis IIIB, a lysosomal storage disease, triggers a pathogenic CNS autoimmune response

Background

Recently, using a mouse model of mucopolysaccharidosis (MPS) IIIB, a lysosomal storage disease with severe neurological deterioration, we showed that MPS IIIB neuropathology is accompanied by a robust neuroinflammatory response of unknown consequence. This study was to assess whether MPS IIIB lymphocytes are pathogenic.

Methods

Lymphocytes from MPS IIIB mice were adoptively transferred to naïve wild-type mice. The recipient animals were then evaluated for signs of disease and inflammation in the central nervous system.

Results

Our results show for the first time, that lymphocytes isolated from MPS IIIB mice caused a mild paralytic disease when they were injected systemically into naïve wild-type mice. This disease is characterized by mild tail and lower trunk weakness with delayed weight gain. The MPS IIIB lymphocytes also trigger neuroinflammation within the CNS of recipient mice characterized by an increase in transcripts of IL2, IL4, IL5, IL17, TNFα, IFNα and Ifi30, and intraparenchymal lymphocyte infiltration.

Conclusions

Our data suggest that an autoimmune response directed at CNS components contributes to MPS IIIB neuropathology independent of lysosomal storage pathology. Adoptive transfer of purified T-cells will be needed in future studies to identify specific effector T-cells in MPS IIIB neuroimmune pathogenesis.