Heat shock proteins and their immunomodulatory role in inflammatory arthritis

Moringa oleifera L. Nanosuspension Extract Administration Affects Heat Shock Protein-10 and -70 under Orthodontics Mechanical Force In Vivo

OBJECTIVE

 The mechanical stimulation known as orthodontic mechanical force (OMF) causes biological reactions in orthodontic tooth movement (OTM). Heat shock protein-70 (HSP-70) needs pro-inflammatory cytokines to trigger bone resorption in OTM; nevertheless, heat shock protein-10 (HSP-10), a "Alarmin" cytokine, should control these pro-inflammatory cytokines to get the best alveolar bone remodeling (ABR). Moringa oleifera L. nanosuspension extract (MONE) has anti-inflammatory, antioxidant, and ABR-stimulating properties. The aim of the study was to examine in vivo HSP-10 and HSP-70 expressions under OMF following MONE application in Wistar rats (Rattus norvegicus).

MATERIAL AND METHODS

 A total of 36 Wistar rats (R. norvegicus) were split up into eight groups: one for treatment (OMF + MONE) and one for control (OMF + MONE administration for days 1, 7, 14, and 21). By employing nickel-titanium coil springs and using 10 g of light force per millimeter to implant the orthodontic device, the OMF was completed. According to the day of observation, all of the samples were sacrificed. To perform an immunohistochemistry investigation, the premaxilla of the sample was isolated. Tukey's Honest Significant Different (HSD) test (p < 0.05) was performed after an Analysis of Variance (ANOVA) analysis of the data.

RESULTS

 In both the OMF and MONE groups, HSP-70 peaked on day 14 and began to fall on day 21. HSP-10 peaked on day 21, but along with MONE, it also began to progressively decline on days 14 and 21, with significant differences (p < 0.05).

CONCLUSION

 According to immunohistochemistry evidence, postadministration of MONE markedly elevated HSP-10 but lowered HSP-70 expression in the alveolar bone of Wistar rats under OMF.

Alarmins in Chronic Spontaneous Urticaria: Immunological Insights and Therapeutic Perspectives

Background: In the world, approximately 1% of the population suffers from chronic spontaneous urticaria (CSU), burdening patients' quality of life and challenging clinicians in terms of treatment. Recent scientific evidence has unveiled the potential role of a family of molecules known as "alarmins" in the pathogenesis of CSU. Methods: Papers focusing on the potential pathogenetic role of alarmins in CSU with diagnostic (as biomarkers) and therapeutic implications, in English and published in PubMed, Scopus, Web of Science, as well as clinical studies registered in ClinicalTrials.gov and the EudraCT Public website, were reviewed. Results: The epithelial-derived alarmins thymic stromal lymphopoietin and IL-33 could be suitable diagnostic and prognostic biomarkers and possible therapeutic targets in CSU. The evidence on the role of non-epithelial-derived alarmins (heat shock proteins, S-100 proteins, eosinophil-derived neurotoxin, β-defensins, and acid uric to high-density lipoproteins ratio) is more heterogeneous and complex. Conclusions: More homogeneous studies on large cohorts, preferably supported by data from international registries, will be able to elucidate the intriguing and complex pathogenetic world of CSU.

Distribution of Immunomodulation, Protection and Regeneration Factors in Cleft-Affected Bone and Cartilage

BACKGROUND

Craniofacial clefts can form a significant defect within bone and cartilage, which can negatively affect tissue homeostasis and the remodeling process. Multiple proteins can affect supportive tissue growth, while also regulating local immune response and tissue protection. Some of these factors, like galectin-10 (Gal-10), nuclear factor kappa-light-chain-enhancer of activated B cells protein 65 (NF-κB p65), heat shock protein 60 (HSP60) and 70 (HSP70) and cathelicidin (LL-37), have not been well studied in cleft-affected supportive tissue, while more known tissue regeneration regulators like type I collagen (Col-I) and bone morphogenetic proteins 2 and 4 (BMP-2/4) have not been assessed jointly with immunomodulation and protective proteins. Information about the presence and interaction of these proteins in cleft-affected supportive tissue could be helpful in developing biomaterials and improving cleft treatment.

METHODS

Two control groups and two cleft patient groups for bone tissue and cartilage, respectively, were organized with five patients in each group. Immunohistochemistry with the semiquantitative counting method was implemented to determine Gal-10-, NF-κB p65-, HSP60-, HSP70-, LL-37-, Col-I- and BMP-2/4-positive cells within the tissue.

RESULTS

Factor-positive cells were identified in each study group. Multiple statistically significant correlations were identified.

CONCLUSIONS

A significant increase in HSP70-positive chondrocytes in cleft patients could indicate that HSP70 might be reacting to stressors caused by the local tissue defect. A significant increase in Col-I-positive osteocytes in cleft patients might indicate increased bone remodeling and osteocyte activity due to the presence of a cleft. Correlations between factors indicate notable differences in molecular interactions within each group.

Autoimmunity to stromal-derived autoantigens in rheumatoid ectopic germinal centers exacerbates arthritis and affects clinical response

Ectopic lymphoid structures (ELSs) in the rheumatoid synovial joints sustain autoreactivity against locally expressed autoantigens. We recently identified recombinant monoclonal antibodies (RA-rmAbs) derived from single, locally differentiated rheumatoid arthritis (RA) synovial B cells, which specifically recognize fibroblast-like synoviocytes (FLSs). Here, we aimed to identify the specificity of FLS-derived autoantigens fueling local autoimmunity and the functional role of anti-FLS antibodies in promoting chronic inflammation. A subset of anti-FLS RA-rmAbs reacting with a 60 kDa band from FLS extracts demonstrated specificity for HSP60 and partial cross-reactivity to other stromal autoantigens (i.e., calreticulin/vimentin) but not to citrullinated fibrinogen. Anti-FLS RA-rmAbs, but not anti-neutrophil extracellular traps rmAbs, exhibited pathogenic properties in a mouse model of collagen-induced arthritis. In patients, anti-HSP60 antibodies were preferentially detected in RA versus osteoarthritis (OA) synovial fluid. Synovial HSPD1 and CALR gene expression analyzed using bulk RNA-Seq and GeoMx-DSP closely correlated with the lympho-myeloid RA pathotype, and HSP60 protein expression was predominantly observed around ELS. Moreover, we observed a significant reduction in synovial HSP60 gene expression followed B cell depletion with rituximab that was strongly associated with the treatment response. Overall, we report that synovial stromal-derived autoantigens are targeted by pathogenic autoantibodies and are associated with specific RA pathotypes, with potential value for patient stratification and as predictors of the response to B cell-depleting therapies.

Heat shock protein-related diagnostic signature and molecular subtypes in ankylosing spondylitis: new pathogenesis insights

Heat shock proteins (HSP) have been associated with a range of persistent inflammatory disorders; however, little research has been conducted on the involvement of HSP in the development of ankylosing spondylitis (AS). The research aims to identify a diagnostic signature based on HSP-related genes and determine the molecular subtypes of AS. We gathered the transcriptional data of patients with AS from the GSE73754 dataset and conducted a literature search for HSP-related genes (HRGs). The logistic regression model was utilized for the identification of hub HRGs associated with AS. Subsequently, these HRGs were employed in the construction of a nomogram prediction model. We employed a consensus clustering approach to identify novel molecular subgroups. Subsequently, we conducted functional analyses, encompassing GO, KEGG, and GSEA, to elucidate the underlying mechanisms between these subgroups. To assess the immunological landscape, we employed the xCell algorithm. Through logistic regression analysis, the four core HRGs (CCT2, HSPA6, DNAJB14, and DNAJC5) were confirmed as potential biomarkers for AS. Subsequent stratification revealed two distinct molecular phenotypes, designated as Cluster 1 and Cluster 2. Notably, Cluster 2 was characterized by the upregulation of pathways pertinent to immune response and inflammation. Our research suggests that the CCT2, HSPA6, DNAJB14, and DNAJC5 exhibit potential as effective blood-based diagnostic biomarkers for AS. These findings contribute to a deeper comprehension of the underlying mechanisms involved in the development of AS and offer potential targets for personalized therapeutic interventions.

Anti-heat shock protein 10 IgG in chronic spontaneous urticaria: Relation with miRNA-101-5p and platelet-activating factor

BACKGROUND

Anti-heat shock protein (HSP) autoantibodies are detected in autoimmune diseases. We sought to ascertain whether anti-HSP10 IgG is present in patients with CSU and to elucidate the role of HSP10 in CSU pathogenesis.

METHOD

Using a human proteome microarray, six potential autoantibodies had higher expression in 10 CSU samples compared with 10 normal controls (NCs). Among them, HSP10 IgG autoantibody was quantified by immune dot-blot assay in sera from 86 CSU patients and 44 NCs. The serum levels of HSP10 and microRNA-101-5p were measured in CSU patients and NCs. The effects of HSP10 and miR-101-5p on mast cell degranulation in response to IgE, compound 48/80, and platelet-activating factor (PAF) were investigated.

RESULTS

CSU patients had higher IgG positivity to HSP10 (40.7% vs. 11.4%, p = .001), lower serum HSP10 levels (5.8 ± 3.6 vs. 12.2 ± 6.6 pg/mL, p < .001) than in NCs, and their urticaria severity was associated with anti-HSP10 IgG positivity, while HSP10 levels were related to urticaria control status. MiR-101-5p was increased in CSU patients. PAF enhanced IL4 production in PBMCs from CSU patients. IL-4 upregulated miR-101-5p and reduced HSP10 expression in keratinocytes. Transfection of miR-101-5p reduced HSP10 expression in keratinocytes. MiR-101-5p promoted PAF-induced mast cell degranulation, while HSP10 specifically prevented it.

CONCLUSION

A new autoantibody, anti-HSP10 IgG was detected in CSU patients, which showed a significant correlation with UAS7 scores. A decreased serum HSP10 level was associated with upregulation of miR-101-5p due to increased IL-4 and PAF in CSU patients. Modulation of miR-101-5p and HSP10 may be a novel therapeutic approach for CSU.

Hepatic NLRP3-Derived Hsp70 Binding to TLR4 Mediates MASLD to MASH Progression upon Inhibition of PP2A by Harmful Algal Bloom Toxin Microcystin, a Second Hit

Harmful algal bloom toxin microcystin has been associated with metabolic dysfunction-associated steatotic liver disease (MASLD) progression and hepatocellular carcinoma, though the mechanisms remain unclear. Using an established mouse model of MASLD, we show that the NLRP3-Hsp70-TLR4 axis drives in part the inflammation of the liver lobule that results in the progression of MASLD to metabolic dysfunction-associated steatohepatitis (MASH). Results showed that mice deficient in NLRP3 exhibited decreased MASH pathology, blocked Hsp70 expression, and co-binding with NLRP3, a crucial protein component of the liver inflammasome. Hsp70, both in the liver lobule and extracellularly released in the liver vasculature, acted as a ligand to TLR4 in the liver, primarily in hepatocytes to activate the NF-κB pathway, ultimately leading to hepatic cell death and necroptosis, a crucial pathology of MASH progression. The above studies show a novel insight into an inflammasome-triggered Hsp70-mediated inflammation that may have broader implications in MASLD pathology. MASLD to MASH progression often requires multiple hits. One of the mediators of progressive MASLD is environmental toxins. In this research report, we show for the first time a novel mechanism where microcystin-LR, an environmental toxin, advances MASLD to MASH by triggering the release of Hsp70 as a DAMP to activate TLR4-induced inflammation in the liver.

Heat shock proteins in cancer - Known but always being rediscovered: Their perspectives in cancer immunotherapy

Heat shock proteins (HSPs) represent cellular chaperones that are classified into several families, including HSP27, HSP40, HSP60, HSP70, and HSP90. The role of HSPs in the cell includes the facilitation of protein folding and maintaining protein structure. Both processes play crucial roles during stress conditions in the cell such as heat shock, degradation, and hypoxia. Moreover, HSPs are important modulators of cellular proliferation and differentiation, and are strongly associated with the molecular orchestration of carcinogenesis. The expression and/or activity of HSPs in cancer cells is generally abnormally high and is associated with increased metastatic potential and activity of cancer stem cells, more pronounced angiogenesis, downregulated apoptosis, and the resistance to anticancer therapy in many patients. Based on the mentioned reasons, HSPs have strong potential as valid diagnostic, prognostic, and therapeutic biomarkers in clinical oncology. In addition, numerous papers describe the role of HSPs as chaperones in the regulation of immune responses inside and outside the cell. Importantly, highly expressed/activated HSPs may be inhibited via immunotherapeutic targets in various types of cancers. The aim of this work is to provide a comprehensive overview of the relationship between HSPs and the tumor cell with the intention of highlighting the potential use of HSPs in personalized cancer management.

Impact of Non-Invasive Physical Plasma on Heat Shock Protein Functionality in Eukaryotic Cells

Recently, biomedical research has increasingly investigated physical plasma as an innovative therapeutic approach with a number of therapeutic biomedical effects. It is known from radiation and chemotherapy that these applications can lead to the induction and activation of primarily cytoprotective heat shock proteins (HSP). HSP protect cells and tissues from physical, (bio)chemical, and physiological stress and, ultimately, along with other mechanisms, govern resistance and treatment failure. These mechanisms are well known and comparatively well studied in drug therapy. For therapies in the field of physical plasma medicine, however, extremely little data are available to date. In this review article, we provide an overview of the current studies on the interaction of physical plasma with the cellular HSP system.

Nanomedical approaches in the realm of rheumatoid arthritis

Rheumatoid arthritis (RA) is a heterogeneous autoimmune inflammatory disorder defined by the damage to the bone and cartilage in the synovium, which causes joint impairment and an increase in the mortality rate. It is associated with an incompletely elucidated pathophysiological mechanism. Even though disease-modifying antirheumatic drugs have contributed to recent improvements in the standard of care for RA, only a small fraction of patients is able to attain and maintain clinical remission without the necessity for ongoing immunosuppressive drugs. The evolution of tolerance over time as well as patients' inability to respond to currently available therapy can alter the overall management of RA. A significant increase in the research of RA nano therapies due to the possible improvements they may provide over traditional systemic treatments has been observed. New approaches to getting beyond the drawbacks of existing treatments are presented by advancements in the research of nanotherapeutic techniques, particularly drug delivery nano systems. Via passive or active targeting of systemic delivery, therapeutic drugs can be precisely transported to and concentrated in the affected sites. As a result, nanoscale drug delivery systems improve the solubility and bioavailability of certain drugs and reduce dose escalation. In the present paper, we provide a thorough overview of the possible biomedical applications of various nanostructures in the diagnostic and therapeutic management of RA, derived from the shortcomings of conventional therapies. Moreover, the paper suggests the need for improvement on the basis of research directions and properly designed clinical studies.

Mycoplasma hominis Causes DNA Damage and Cell Death in Primary Human Keratinocytes

Mycoplasma hominis can be isolated from the human urogenital tract. However, its interaction with the host remains poorly understood. In this study, we aimed to assess the effects of M. hominis infection on primary human keratinocytes (PHKs). Cells were quantified at different phases of the cell cycle. Proteins involved in cell cycle regulation and apoptosis progression were evaluated. The expression of genes encoding proteins that are associated with the DNA damage response and Toll-like receptor pathways was evaluated, and the cytokines involved in inflammatory responses were quantified. A greater number of keratinocytes were observed in the Sub-G0/G1 phase after infection with M. hominis. In the viable keratinocytes, infection resulted in G2/M-phase arrest; GADD45A expression was increased, as was the expression of proteins such as p53, p27, and p21 and others involved in apoptosis regulation and oxidative stress. In infected PHKs, the expression of genes associated with the Toll-like receptor pathways showed a change, and the production of IFN-γ, interleukin (IL) 1β, IL-18, IL-6, and tumour necrosis factor alpha increased. The infection of PHKs by M. hominis causes cellular damage that can affect the cell cycle by activating the response pathways to cellular damage, oxidative stress, and Toll-like receptors. Overall, this response culminated in the reduction of cell proliferation/viability in vitro.

Heat Shock Proteins Alterations in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory and autoimmune disease characterized by the attack of the immune system on the body's healthy joint lining and degeneration of articular structures. This disease involves an increased release of inflammatory mediators in the affected joint that sensitize sensory neurons and create a positive feedback loop to further enhance their release. Among these mediators, the cytokines and neuropeptides are responsible for the crippling pain and the persistent neurogenic inflammation associated with RA. More importantly, specific proteins released either centrally or peripherally have been shown to play opposing roles in the pathogenesis of this disease: an inflammatory role that mediates and increases the severity of inflammatory response and/or an anti-inflammatory and protective role that modulates the process of inflammation. In this review, we will shed light on the neuroimmune function of different members of the heat shock protein (HSPs) family and the complex manifold actions that they exert during the course of RA. Specifically, we will focus our discussion on the duality in the mechanism of action of Hsp27, Hsp60, Hsp70, and Hsp90.

Salivary biomarkers in children with juvenile idiopathic arthritis and healthy age-matched controls: a prospective observational study

Monitoring the immune system's regulation and signaling using saliva could be of interest for clinicians and researchers. Saliva, a biofluid with close exchange with serum, is influenced by circadian variance and oral factors such as masticatory function. This study investigated the detectability and concentration of cytokines and chemokines in saliva in children with juvenile idiopathic arthritis (JIA) as well as saliva flow and the influence of orofacial pain on saliva flow. Of the 60 participants (7-14 years old) enrolled, 30 had a diagnosis of JIA and active disease, and 30 were sex- and age-matched healthy controls. Demographic data and three validated questions regarding presence of orofacial pain and dysfunction were recorded. Stimulated whole saliva was collected and analyzed using a customized R&D bead-based immunoassay with 21 targeted biomarkers. Fourteen of these were detectable and showed similar levels in both children with JIA and controls: TNF-alpha, TNFRSF1B, MMP-2, MMP-3, IL-1alpha, IL-1beta, IL-6R alpha, IL-8, S100A8, CCL2, CCL3, IL-10, CCL11, and CXCL9. In addition, there was no difference in salivary flow rate between groups, but there was an association between orofacial pain and reduced saliva flow rate for both groups.Trial registration: ClinicalTrials.gov Protocol id: 2010/2089-31/2.

Management of Rheumatoid Arthritis: An Overview

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease of unknown etiology, primarily affecting the joints, then extra-articular manifestations can occur. Due to its complexity, which is based on an incompletely elucidated pathophysiological mechanism, good RA management requires a multidisciplinary approach. The clinical status of RA patients has improved in recent years due to medical advances in diagnosis and treatment, that have made it possible to reduce disease activity and prevent systemic complications. The most promising results were obtained by developing disease-modifying anti-rheumatic drugs (DMARDs), the class to which conventional synthetic, biologic, and targeted synthetic drugs belong. Furthermore, ongoing drug development has led to obtaining molecules with improved efficacy and safety profiles, but further research is needed until RA turns into a curable pathology. In the present work, we offer a comprehensive perspective on the management of RA, by centralizing the existing data provided by significant literature, emphasizing the importance of an early and accurate diagnosis associated with optimal personalized treatment in order to achieve better outcomes for RA patients. In addition, this study suggests future research perspectives in the treatment of RA that could lead to higher efficacy and safety profiles and lower financial costs.

Mining the capacity of human-associated microorganisms to trigger rheumatoid arthritis-A systematic immunoinformatics analysis of T cell epitopes

Autoimmune diseases, often triggered by infection, affect ~5% of the worldwide population. Rheumatoid Arthritis (RA)–a painful condition characterized by the chronic inflammation of joints—comprises up to 20% of known autoimmune pathologies, with the tendency of increasing prevalence. Molecular mimicry is recognized as the leading mechanism underlying infection-mediated autoimmunity, which assumes sequence similarity between microbial and self-peptides driving the activation of autoreactive lymphocytes. T lymphocytes are leading immune cells in the RA-development. Therefore, deeper understanding of the capacity of microorganisms (both pathogens and commensals) to trigger autoreactive T cells is needed, calling for more systematic approaches. In the present study, we address this problem through a comprehensive immunoinformatics analysis of experimentally determined RA-related T cell epitopes against the proteomes of Bacteria, Fungi, and Viruses, to identify the scope of organisms providing homologous antigenic peptide determinants. By this, initial homology screening was complemented with de novo T cell epitope prediction and another round of homology search, to enable: i) the confirmation of homologous microbial peptides as T cell epitopes based on the predicted binding affinity to RA-related HLA polymorphisms; ii) sequence similarity inference for top de novo T cell epitope predictions to the RA-related autoantigens to reveal the robustness of RA-triggering capacity for identified (micro/myco)organisms. Our study reveals a much larger repertoire of candidate RA-triggering organisms, than previously recognized, providing insights into the underestimated role of Fungi in autoimmunity and the possibility of a more direct involvement of bacterial commensals in RA-pathology. Finally, our study pinpoints Endoplasmic reticulum chaperone BiP as the most potent (most likely mimicked) RA-related autoantigen, opening an avenue for identifying the most potent autoantigens in a variety of different autoimmune pathologies, with possible implications in the design of next-generation therapeutics aiming to induce self-tolerance by affecting highly reactive autoantigens.

A case report of monoarthritis in a COVID-19 patient and literature review: Simple actions for complex times

RATIONALE

COVID-19 presentation is multifaceted and up to 44% of patients affected by COVID-19 experience musculoskeletal complaints, mostly in the form of diffuse aspecific arthromyalgias. Nevertheless, only a few cases of arthritis following SARS-CoV2 infection are reported.

PATIENT CONCERNS

A 27-year-old man affected by nail psoriasis presented with monoarthritis 2 weeks after being diagnosed with COVID-19.

DIAGNOSES

Diagnostic work-up and differential diagnosis were made difficult by patient isolation, absence of lab tests, and his visit via telemedicine, even though signs of first metacarpophalangeal joint involvement were clear.

INTERVENTIONS

Due to the inefficacy of acetaminophen and nonsteroidal anti-inflammatory drugs, the patient was prescribed oral steroids with a rapid benefit.

OUTCOMES

The patient's response to oral steroid was prompt and maintained even after therapy tapering. Even so, a formal diagnosis was not possible due to a difficult diagnostic work-up and lack of a long-term follow-up.

LESSONS

Like many other viral diseases, SARS-CoV2 can play as a causative agent or as a trigger for inflammatory arthritis development in predisposed individuals.

Physiological Functions of Heat Shock Proteins

Heat shock proteins (HSPs) are molecular chaperones involved in a variety of life activities. HSPs function in the refolding of misfolded proteins, thereby contributing to the maintenance of cellular homeostasis. Heat shock factor (HSF) is activated in response to environmental stresses and binds to heat shock elements (HSEs), promoting HSP translation and thus the production of high levels of HSPs to prevent damage to the organism. Here, we summarize the role of molecular chaperones as anti-heat stress molecules and their involvement in immune responses and the modulation of apoptosis. In addition, we review the potential application of HSPs to cancer therapy, general medicine, and the treatment of heart disease.

Beyond Heat Stress: Intestinal Integrity Disruption and Mechanism-Based Intervention Strategies

The current climate changes have increased the prevalence and intensity of heat stress (HS) conditions. One of the initial consequences of HS is the impairment of the intestinal epithelial barrier integrity due to hyperthermia and hypoxia following blood repartition, which often results in a leaky gut followed by penetration and transfer of luminal antigens, endotoxins, and pathogenic bacteria. Under extreme conditions, HS may culminate in the onset of “heat stroke”, a potential lethal condition if remaining untreated. HS-induced alterations of the gastrointestinal epithelium, which is associated with a leaky gut, are due to cellular oxidative stress, disruption of intestinal integrity, and increased production of pro-inflammatory cytokines. This review summarizes the possible resilience mechanisms based on in vitro and in vivo data and the potential interventions with a group of nutritional supplements, which may increase the resilience to HS-induced intestinal integrity disruption and maintain intestinal homeostasis.

The Functions and Therapeutic Potential of Heat Shock Proteins in Inflammatory Bowel Disease-An Update

Inflammatory bowel disease (IBD) is a multifactorial human intestinal disease that arises from numerous, yet incompletely defined, factors. Two main forms, Crohn's disease (CD) and ulcerative colitis (UC), lead to a chronic pathological form. Heat shock proteins (HSPs) are stress-responsive molecules involved in various pathophysiological processes. Several lines of evidence link the expression of HSPs to the development and prognosis of IBD. HSP90, HSP70 and HSP60 have been reported to contribute to IBD in different aspects. Moreover, induction and/or targeted inhibition of specific HSPs have been suggested to ameliorate the disease consequences. In the present review, we shed the light on the role of HSPs in IBD and their targeting to prevent further disease progression.

HSP-Target of Therapeutic Agents in Sepsis Treatment

Sepsis is a syndrome characterized by a dysregulated inflammatory response, cellular stress, and organ injury. Sepsis is the main cause of death in intensive care units worldwide, creating need for research and new therapeutic strategies. Heat shock protein (HSP) analyses have recently been developed in the context of sepsis. HSPs have a cytoprotection role in stress conditions, signal to immune cells, and activate the inflammatory response. Hence, HSP analyses have become an important focus in sepsis research, including the investigation of HSPs targeted by therapeutic agents used in sepsis treatment. Many therapeutic agents have been tested, and their HSP modulation showed promising results. Nonetheless, the heterogeneity in experimental designs and the diversity in therapeutic agents used make it difficult to understand their efficacy in sepsis treatment. Therefore, future investigations should include the analysis of parameters related to the early and late immune response in sepsis, HSP localization (intra or extracellular), and time to the onset of treatment after sepsis. They also should consider the differences in experimental sepsis models. In this review, we present the main results of studies on therapeutic agents in targeting HSPs in sepsis treatment. We also discuss limitations and possibilities for future investigations regarding HSP modulators.

The possible role of heat shock protein-70 induction in collagen-induced arthritis in rats

AIM

This study aimed to evaluate the possible role of heat shock protein-70 (HSP70) induction by 17-allylaminodemethoxygeldanamycin (17-AAG) in collagen-induced arthritis in rats.

MATERIAL AND METHODS

Male Wistar rats were divided into five groups (n = 10/group) and were treated intraperitoneally twice a week for 4 weeks, namely normal control (saline), arthritis control (AR; saline), AR + 17-AAG, AR + methotrexate (MTX), and AR + 17-AAG + MTX. At the end of the treatments, arthritic score was determined and then the animals were sacrificed. Erythrocyte sedimentation rate (ESR), serum levels of HSP70, interleukin-17 (IL-17), tumor necrosis factor-alpha (TNF-α), rheumatic factor (RF), C-reactive protein (CRP), malondialdehyde (MDA), glutathione peroxidase (GPx), and matrix metalloproteinase-9 (MMP-9) were determined.

RESULTS

In the AR group, all parameters increased significantly, except for GPx, which showed a pronounced decrease. The 17-AAG and/or MTX treatments significantly reduced arthritic score, ESR, IL-17, TNF-α, RF, CRP, MDA, and MMP-9 with significant increase in GPx compared to the AR group. The HSP70 level was significantly higher in the AR + 17-AAG and the AR + 17-AAG + MTX groups but significantly lower in the AR + MTX group as compared to the AR group. Also, it was significantly lower in the AR + MTX group as compared to the AR + 17-AAG group.

CONCLUSION

We concluded that HSP70 induction by 17-AAG attenuated the inflammatory process in a rheumatoid arthritis (RA) model induced by collagen, which suggested that HSP70 inducers can be promising agents in the treatment of RA.

Autoantibodies to heat shock proteins 60, 70, and 90 in patients with rheumatoid arthritis

Heat shock proteins (HSP) have been reported to impact immune responses and to be associated with rheumatoid arthritis (RA). Recently, we provided evidence for a role of autoantibodies to Hsp40 in patients with RA. In this study, we aimed at investigating the humoral autoimmune response to Hsp60, Hsp70, and Hsp90 in RA patients (n = 39). In comparison with healthy controls (n = 40), circulating IgG, IgM, and IgA autoantibodies against Hsp60, Hsp70, and Hsp90 were significantly increased in RA patients. Non-parametric statistical analysis, however, revealed no significant association between anti-HSP and disease activity or disease progression. On the other hand, positive correlations between serum levels of anti-Hsp60 IgG and IL-4 (Th2-like cytokine) or between serum levels of anti-Hsp90 IgG and IFN-ɣ (Th1-like cytokine) were found to be statistically significant in RA. In addition, a significant inverse correlation was found for serum levels of anti-Hsp70 IgM and TNF-α (Th1-like cytokine) in RA. Our results suggest a pronounced anti-Hsp60, anti-Hsp70, and anti-Hsp90 humoral autoimmune response in RA patients that seems not to be directly linked to RA pathophysiology, however, may have a potential modulatory impact on inflammatory status in this disease. Further investigations are needed to clarify the role of anti-HSP autoantibodies in RA.

Damage-Associated Molecular Patterns in Inflammatory Diseases

Damage-associated molecular patterns (DAMPs) are endogenous danger molecules that are released from damaged or dying cells and activate the innate immune system by interacting with pattern recognition receptors (PRRs). Although DAMPs contribute to the host's defense, they promote pathological inflammatory responses. Recent studies have suggested that various DAMPs, such as high-mobility group box 1 (HMGB1), S100 proteins, and heat shock proteins (HSPs), are increased and considered to have a pathogenic role in inflammatory diseases. Here, we review current research on the role of DAMPs in inflammatory diseases, including rheumatoid arthritis, systemic lupus erythematosus, osteoarthritis, atherosclerosis, Alzheimer's disease, Parkinson's disease, and cancer. We also discuss the possibility of DAMPs as biomarkers and therapeutic targets for these diseases.

Extracellular cell stress (heat shock) proteins-immune responses and disease: an overview

Extracellular cell stress proteins are highly conserved phylogenetically and have been shown to act as powerful signalling agonists and receptors for selected ligands in several different settings. They also act as immunostimulatory 'danger signals' for the innate and adaptive immune systems. Other studies have shown that cell stress proteins and the induction of immune reactivity to self-cell stress proteins can attenuate disease processes. Some proteins (e.g. Hsp60, Hsp70, gp96) exhibit both inflammatory and anti-inflammatory properties, depending on the context in which they encounter responding immune cells. The burgeoning literature reporting the presence of stress proteins in a range of biological fluids in healthy individuals/non-diseased settings, the association of extracellular stress protein levels with a plethora of clinical and pathological conditions and the selective expression of a membrane form of Hsp70 on cancer cells now supports the concept that extracellular cell stress proteins are involved in maintaining/regulating organismal homeostasis and in disease processes and phenotype. Cell stress proteins, therefore, form a biologically complex extracellular cell stress protein network having diverse biological, homeostatic and immunomodulatory properties, the understanding of which offers exciting opportunities for delivering novel approaches to predict, identify, diagnose, manage and treat disease.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.

Stress proteins in the pathogenesis of spondyloarthritis

Spondyloarthritis is an autoinflammatory rheumatic disease in which arthritis and osteoproliferation lead the patients who suffer from it to chronic disability. This disease is associated with the expression of class I MHC molecule HLA-B27, which tends to be misfolded in the endoplasmic reticulum and, therefore, expressed in aberrant forms. This phenomena lead to endoplasmic reticulum stress, which in time, evokes a whole response to cellular injury. Under these conditions, the molecules involved in restoring cell homeostasis play a key role. Such is the case of the "heat-shock proteins", which usually regulate protein folding, but also have important immunomodulatory functions, as well as some roles in tissue modeling. In this review, we attempt to summarize the involvement of cell stress and heat-shock proteins in the homeostatic disturbances and pathological conditions associated with this disease.

The Enigma of Heat Shock Proteins in Immune Tolerance

The fundamental problem of autoimmune diseases is the failure of the immune system to downregulate its own potentially dangerous cells, which leads to destruction of tissue expressing the relevant autoantigens. Current immunosuppressive therapies offer relief but fail to restore the basic condition of self-tolerance. They do not induce long-term physiological regulation resulting in medication-free disease remissions. Heat shock proteins (HSPs) have shown to possess the capacity of inducing lasting protective immune responses in models of experimental autoimmune diseases. Especially mycobacterial HSP60 and HSP70 were shown to induce disease inhibitory IL-10-producing regulatory T cells in many different models. This in itself may seem enigmatic, since based on earlier studies, HSPs were also coined sometimes as pro-inflammatory damage-associated molecular patterns. First clinical trials with HSPs in rheumatoid arthritis and type I diabetes have also indicated their potential to restore tolerance in autoimmune diseases. Data obtained from the models have suggested three aspects of HSP as being critical for this tolerance promoting potential: 1. evolutionary conservation, 2. most frequent cytosolic/nuclear MHC class II natural ligand source, and 3. upregulation under (inflammatory) stress. The combination of these three aspects, which are each relatively unique for HSP, may provide an explanation for the enigmatic immune tolerance promoting potential of HSP.

T Cell-Mediated Chronic Inflammatory Diseases Are Candidates for Therapeutic Tolerance Induction with Heat Shock Proteins

Failing immunological tolerance for critical self-antigens is the problem underlying most chronic inflammatory diseases of humans. Despite the success of novel immunosuppressive biological drugs, the so-called biologics, in the treatment of diseases such rheumatoid arthritis (RA) and type 1 diabetes, none of these approaches does lead to a permanent state of medicine free disease remission. Therefore, there is a need for therapies that restore physiological mechanisms of self-tolerance. Heat shock proteins (HSPs) have shown disease suppressive activities in many models of experimental autoimmune diseases through the induction of regulatory T cells (Tregs). Also in first clinical trials with HSP-based peptides in RA and diabetes, the induction of Tregs was noted. Due to their exceptionally high degree of evolutionary conservation, HSP protein sequences (peptides) are shared between the microbiota-associated bacterial species and the self-HSP in the tissues. Therefore, Treg mechanisms, such as those induced and maintained by gut mucosal tolerance for the microbiota, can play a role by targeting the more conserved HSP peptide sequences in the inflamed tissues. In addition, the stress upregulated presence of HSP in these tissues may well assist the targeting of the HSP induced Treg specifically to the sites of inflammation.

Exosomal HSP60: a potentially useful biomarker for diagnosis, assessing prognosis, and monitoring response to treatment

INTRODUCTION

Cell-to-cell communication is imperative for life and it is mediated by sending and receiving information via the secretion and subsequent receptor-mediated detection of biological molecules. Exosomes (EXs) secreted from cells to the extracellular environment play an important role in intercellular communication in normal and pathological conditions. Areas covered: New evidence indicates that tumor cells-derived EXs contribute to cancer progression through the modulation of tumor microenvironment. The exosomal heat shock protein 60 (HSP60) is very likely a key player in intercellular cross-talk, particularly during the progress of diseases, such as cancer. Many studies have focused on the extracellular roles played by HSP60 that pertain to cancer development and immune system stimulation. Our experimental data in vitro and in vivo demonstrated that HSP60 occurs on the surface of EXs secreted by tumour cells. Expert commentary: Exosomal HSP60 has great potential for clinical applications, as a 'liquid biopsy', including its use as biomarker for diagnostics, assessing prognosis, and monitoring disease progression and response to treatment, particularly in cancer.

The function of myeloid dendritic cells in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease that causes joint pain, inflammation, and loss of function. Disease pathogenesis involves activation and proliferation of autoreactive pro-inflammatory effector T cells. While the details of RA onset and progression remain controversial, dendritic cell (DC) numbers dramatically increase in the synovial joint tissues of RA patients. Based on their key functions as antigen-presenting cells and inducers of T cell differentiation, DCs may play an important role in the initiation of joint inflammation. Myeloid DC contributions are likely central to the development of RA, as they are more efficient at antigen presentation in comparison with their closely related cousins, plasmacytoid DCs. Synovial fluid in the joints of RA patients is enriched with pro-inflammatory cytokines and chemokines, which may stimulate or result from DC activation. Epidemiological evidence indicates that smoking and periodontal infection are major environmental risk factors for RA development. In this review, factors in the synovial environment that contribute to altered myeloid DC functions in RA and the effects of environmental risk factors on myeloid DCs are described.