The danger model approach to the pathogenesis of the rheumatic diseases

Fostering tissue engineering and regenerative medicine to treat musculoskeletal disorders in bone and muscle

The musculoskeletal system, which is vital for movement, support, and protection, can be impaired by disorders such as osteoporosis, osteoarthritis, and muscular dystrophy. This review focuses on the advances in tissue engineering and regenerative medicine, specifically aimed at alleviating these disorders. It explores the roles of cell therapy, particularly Mesenchymal Stem Cells (MSCs) and Adipose-Derived Stem Cells (ADSCs), biomaterials, and biomolecules/external stimulations in fostering bone and muscle regeneration. The current research underscores the potential of MSCs and ADSCs despite the persistent challenges of cell scarcity, inconsistent outcomes, and safety concerns. Moreover, integrating exogenous materials such as scaffolds and external stimuli like electrical stimulation and growth factors shows promise in enhancing musculoskeletal regeneration. This review emphasizes the need for comprehensive studies and adopting innovative techniques together to refine and advance these multi-therapeutic strategies, ultimately benefiting patients with musculoskeletal disorders.

Levofloxacin induces differential effects in the transcriptome between the gut, peripheral and axial joints in the Spondyloarthritis DBA/1 mice: Improvement of intestinal dysbiosis and the overall inflammatory process

To analyze the effect of levofloxacin-induced intestinal microbiota modifications on intestinal, joint, and systemic inflammation in the DBA/1 mice with spontaneous arthritis. The study included two groups of mice, one of which received levofloxacin. The composition and structure of the microbiota were determined in the mice's stool using 16S rRNA sequencing; the differential taxa and metabolic pathway between mice treated with levofloxacin and control mice were also defied. The effect of levofloxacin was evaluated in the intestines, hind paws, and spines of mice through DNA microarray transcriptome and histopathological analyses; systemic inflammation was measured by flow cytometry. Levofloxacin decreased the pro-inflammatory bacteria, including Prevotellaceae, Odoribacter, and Blautia, and increased the anti-inflammatory Muribaculaceae in mice's stool. Histological analysis confirmed the intestinal inflammation in control mice, while in levofloxacin-treated mice, inflammation was reduced; in the hind paws and spines, levofloxacin also decreased the inflammation. Microarray showed the downregulation of genes and signaling pathways relevant in spondyloarthritis, including several cytokines and chemokines. Levofloxacin-treated mice showed differential transcriptomic profiles between peripheral and axial joints and intestines. Levofloxacin decreased the expression of TNF-α, IL-23a, and JAK3 in the three tissues, but IL-17 behaved differently in the intestine and the joints. Serum TNF-α was also reduced in levofloxacin-treated mice. Our results suggest that the microbiota modification aimed at reducing pro-inflammatory and increasing anti-inflammatory bacteria could potentially be a coadjuvant in treating inflammatory arthropathies.

Dynamics of DNA damage response markers, RAD51 and XRCC1, throughout the menstrual cycle and pregnancy in healthy women. Increment during pregnancy and relation to a low titer of antinuclear antibodies

PROBLEM

Antinuclear antibodies (ANA) potentially play a role in the pathogenesis of connective tissue diseases (CTDs); however, they are also detected in healthy individuals. Our understanding of the physiological and pathological origin of ANA is incomplete. Both; female reproductive processes and deficiencies in DNA damage response (DDR) have been independently associated with ANA production. However, the link between these two factors and the presence of ANA is unclear METHOD OF STUDY: A cohort study was conducted on 87 non-pregnant and 51 healthy pregnant women. ANA and the DDR markers X-ray repair cross-complementing 1 (XRCC1) and recombinase (RAD51) were quantified in sera by enzyme-linked immunosorbent assay. Additionally, ANA was detected by indirect immunofluorescence in HEp-2 cells in 1:40 diluted sera during the three phases of the menstrual cycle in non-pregnant women and every trimester in pregnant women RESULTS: The prevalence of ANA+ in healthy women was 26.1%, with no significant differences between pregnant and non-pregnant women. ANA and DDR marker levels did not vary among the three phases of the menstrual cycle or the three trimesters of pregnancy. However, DDR marker levels were higher in pregnant women than in non-pregnant women (p<0.001) and were found to be higher in ANA+ women (XRCC1, p = 0.025; RAD51, p = 0.006) CONCLUSIONS: The menstrual cycle and pregnancy did not influence the levels of DDR markers or ANA in healthy women; however, the DDR was higher in pregnancy and ANA+ women. The results suggest a potential role of DDR in the pathophysiology of ANA. This article is protected by copyright. All rights reserved.

Polyphenols Targeting MAPK Mediated Oxidative Stress and Inflammation in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, systemic, autoimmune disorder, predominantly symmetric, which causes joint inflammation, cartilage degeneration and bone erosion, resulting in deformity and the loss of physical function. Although the management of RA has steadily improved, the pathophysiological mechanism is incompletely elucidated, and therapeutic options are still limited. Due to shortcomings in the efficacy or safety profiles of conventional RA therapies, therapeutic alternatives have been considered. Therefore, natural extracts containing polyphenolic compounds can become promising adjuvant agents for RA global management, due to their antioxidant, anti-inflammatory and apoptotic properties. Polyphenols can regulate intracellular signaling pathways in RA and can generate different immune responses through some key factors (i.e., MAPK, interleukins (ILs 1 and 6), tumor necrosis factor (TNF), nuclear factor light k chain promoter of activated receptor (NF-κB), and c-Jun N-terminal kinases (JNK)). The critical function of the Toll like-receptor (TLR)-dependent mitogen-activating protein kinase (MAPK) signaling pathway in mediating the pathogenic characteristics of RA has been briefly discussed. Oxidative stress can trigger a change in transcription factors, which leads to the different expression of some genes involved in the inflammatory process. This review aims to provide a comprehensive perspective on the efficacy of polyphenols in mitigating RA by inhibiting signaling pathways, suggesting future research perspectives in order to validate their use.

Neuroinflammation: An Integrating Overview of Reactive-Neuroimmune Cell Interactions in Health and Disease

The concept of central nervous system (CNS) inflammation has evolved over the last decades. Neuroinflammation is the response of reactive CNS components to altered homeostasis, regardless of the cause to be endogenous or exogenous. Neurological diseases, whether traumatic, neoplastic, ischemic, metabolic, toxic, infectious, autoimmune, developmental, or degenerative, involve direct and indirect immune-related neuroinflammation. Brain infiltrates of the innate and adaptive immune system cells appear in response to an infective or otherwise noxious agent and produce inflammatory mediators. Mediators of inflammation include local and recruited cells and signals. Processes derived from extrinsic and intrinsic CNS diseases also elicit the CNS inflammatory response. A deeper understanding of immune-related inflammation in health and disease is necessary to find potential therapeutic targets for preventing or reducing CNS damage. This review is aimed at discussing the innate and adaptive immune system functions and their roles in regulating brain cell responses in disease and homeostasis maintenance.

Living in a Hostile World: Inflammation, New Drug Development, and Coronavirus

We present a brief history of the immune response and show that Metchnikoff's theory of inflammation and phagocytotic defense was largely ignored in the 20th century. For decades, the immune response was believed to be triggered centrally, until Lafferty and Cunningham proposed the initiating signal came from the tissues. This shift opened the way for Janeway's pattern recognition receptor theory, and Matzinger's danger model. All models failed to appreciate that without inflammation, there can be no immune response. The situation changed in the 1990s when cytokine biology was rapidly advancing, and the immune system's role expanded from host defense, to the maintenance of host health. An inflammatory environment, produced by immune cells themselves, was now recognized as mandatory for their attack, removal and repair functions after an infection or injury. We explore the cellular programs of the immune response, and the role played by cytokines and other mediators to tailor the right response, at the right time. Normally, the immune response is robust, self-limiting and restorative. However, when the antigen load or trauma exceeds the body's internal tolerances, as witnessed in some COVID-19 patients, excessive inflammation can lead to increased sympathetic outflows, cardiac dysfunction, coagulopathy, endothelial and metabolic dysfunction, multiple organ failure and death. Currently, there are few drug therapies to reduce excessive inflammation and immune dysfunction. We have been developing an intravenous (IV) fluid therapy comprising adenosine, lidocaine and Mg2+ (ALM) that confers a survival advantage by preventing excessive inflammation initiated by sepsis, endotoxemia and sterile trauma. The multi-pronged protection appears to be unique and may provide a tool to examine the intersection points in the immune response to infection or injury, and possible ways to prevent secondary tissue damage, such as that reported in patients with COVID-19.

DNA Damage and Deficiencies in the Mechanisms of Its Repair: Implications in the Pathogenesis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a perplexing and potentially severe disease, the pathogenesis of which is yet to be understood. SLE is considered to be a multifactorial disease, in which genetic factors, immune dysregulation, and environmental factors, such as ultraviolet radiation, are involved. Recently, the description of novel genes conferring susceptibility to develop SLE even in their own (monogenic lupus) has raised the interest in DNA dynamics since many of these genes are linked to DNA repair. Damage to DNA induces an inflammatory response and eventually triggers an immune response, including those targeting self-antigens. We review the evidence that indicates that patients with SLE present higher levels of DNA damage than normal subjects do and that several proteins involved in the preservation of the genomic stability show polymorphisms, some of which increase the risk for SLE development. Also, the experience from animal models reinforces the connection between DNA damage and defective repair in the development of SLE-like disease including characteristic features such as anti-DNA antibodies and nephritis. Defining the role of DNA damage response in SLE pathogenesis might be strategic in the quest for novel therapies.

High prevalence of autoimmune disease in the rare inflammatory bone disorder sternocostoclavicular hyperostosis: survey of a Dutch cohort

BACKGROUND

Sternocostoclavicular hyperostosis (SCCH; ORPHA178311) is a rare inflammatory disorder of the axial skeleton, the precise pathophysiology of which remains to be established. We addressed the potential association of SCCH with autoimmune processes by evaluating the lifetime prevalence of autoimmune disease in 70 patients with adult-onset SCCH and 518 SCCH-unaffected first-degree relatives (parents, siblings and children). Danish hospital registry data for autoimmune diseases were used as reference data.

RESULTS

The mean age of interviewed patients was 56.3 years (range 26-80 years) and 86% were female. Interviewed patients belonged to 63 families, with four families having clusters of 2-3 patients. A diagnosis of at least one autoimmune disease was reported in 20 SCCH patients (29%) and in 47 relatives (9.1%), compared to an estimated 3.9% prevalence of autoimmune disease in the Danish reference population. A diversity of autoimmune diseases was reported in SCCH patients and relatives, most frequently psoriasis vulgaris (14%). Palmoplantar pustulosis was reported by 28 patients (40%). In SCCH patients, inclusion of palmoplantar pustulosis as putative autoimmune disease increased the overall prevalence to 54%.

CONCLUSIONS

The high prevalence of autoimmune disease in patients with sternocostoclavicular hyperostosis and their first-degree relatives suggests that autoimmunity may play a role in the still elusive pathophysiology of the intriguing osteogenic response to inflammation observed in this rare bone disorder.

Hypoxia and its implications in rheumatoid arthritis

Alterations in tissue oxygen pressure contribute to a number of diseases, including rheumatoid arthritis (RA). Low partial pressure of oxygen, a condition known as hypoxia, is a relevant feature in RA since it is involved in angiogenesis, inflammation, apoptosis, cartilage degradation, energy metabolism, and oxidative damage. Therefore, alterations in hypoxia-related signaling pathways are considered potential mechanisms of disease pathogenesis. The objective of this review is to highlight and update our current knowledge of the role of hypoxia in the pathogenesis of RA. We describe the experimental evidence that RA synovial tissue exists in a hypoxic state, as well as the origin and involvement of synovial hypoxia in different aspects of the pathogenic process.

Serum levels of HSP70 and other DAMP proteins can aid in patient diagnosis after traumatic injury

Danger-associated molecular patterns (DAMPs) are activated by endogenous signals that originate from stressed, injured, or necrotic cells, signifying "danger" to the host. In this study, we evaluated the expression of the DAMP heat shock protein 70 (HSP70) in trauma patients with and without secondary infections. Levels of glucose (GLU), procalcitonin (PCT), total cholesterol (T-Chol), and white blood cell (WBC) counts were also evaluated at three time stages after trauma. Our analysis showed that the levels of serum HSP70 in patients with minor, moderate, and severe injuries were significantly higher than in healthy patients at each time point post-injury (P < 0.01), and levels of serum HSP70 in the severe injury group were significantly higher than in the minor injury group at 1-6 h after trauma (P = 0.047). HSP70 was correlated with GLU and was negatively correlated with T-Chol in the period 1-6 h after injury (P = 0.008/0.032). WBC and GLU were elevated after trauma, with mutual positive correlation (P < 0.001). PCT levels increased later than WBC counts and GLU levels; these levels were correlated at the two later time periods, 24-48 h and 60-90 h (P = 0.008/0.041). PCT continued to rise in patients with secondary infection, but PCT dropped at the third time period in patients without secondary infection. In summary, our results suggest that danger and stress theory can be used to predict severity of trauma.

Oxidative Stress Relevance in the Pathogenesis of the Rheumatoid Arthritis: A Systematic Review

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease whose pathogenic mechanisms remain to be elucidated. The oxidative stress and antioxidants play an important role in the disease process of RA. The study of oxidants and antioxidants biomarkers in RA patients could improve our understanding of disease pathogenesis; likely determining the oxidative stress levels in these patients could prove helpful in assessing disease activity and might also have prognostic implications. To date, the usefulness of oxidative stress biomarkers in RA patients is unclear and the evidence supporting them is heterogeneous. In order to resume and update the information in the status of oxidants and antioxidants and their connection as biomarkers in RA, we performed a systematic literature search in the PubMed database, including clinical trials published in the last five years using the word combination "rheumatoid arthritis oxidative stress". In conclusion, this review supports the fact that the oxidative stress is an active process in RA pathogenesis interrelated to other better known pathogenic elements. However, some controversial results preclude a definite conclusion.