Role Of Alarmins Research Articles

The Role of Alarmins in the Pathogenesis of Rheumatoid Arthritis, Osteoarthritis, and Psoriasis.

Alarmins are immune-activating factors released after cellular injury or death. By secreting alarmins, cells can interact with immune cells and induce a variety of inflammatory responses. The broad family of alarmins involves several members, such as high-mobility group box 1, S100 proteins, interleukin-33, and heat shock proteins, among others. Studies have found that the concentrations and expression profiles of alarmins are altered in immune-mediated diseases. Furthermore, they are involved in the pathogenesis of inflammatory conditions. The aim of this narrative review is to present the current evidence on the role of alarmins in rheumatoid arthritis, osteoarthritis, and psoriasis. We discuss their potential involvement in mechanisms underlying the progression of these diseases and whether they could become therapeutic targets. Moreover, we summarize the impact of pharmacological agents used in the treatment of these diseases on the expression of alarmins.

The Role of Alarmins in Osteoarthritis Pathogenesis: HMGB1, S100B and IL-33.

Osteoarthritis (OA) is a multifactorial disease in which genetics, aging, obesity, and trauma are well-known risk factors. It is the most prevalent joint disease and the largest disability problem worldwide. Recent findings have described the role of damage-associated molecular patterns (DAMPs) in the course of the disease. In particular, alarmins such as HMGB1, IL-33, and S100B, appear implicated in enhancing articular inflammation and favouring a catabolic switch in OA chondrocytes. The aims of this review are to clarify the molecular signalling of these three molecules in OA pathogenesis, to identify their possible use as staging biomarkers, and, most importantly, to find out whether they could be possible therapeutic targets. Osteoarthritic cartilage expresses increased levels of all three alarmins. HMGB1, in particular, is the most studied alarmin with increased levels in cartilage, synovium, and synovial fluid of OA patients. High levels of HMGB1 in synovial fluid of OA joints are positively correlated with radiological and clinical severity. Counteracting HMGB1 strategies have revealed improving results in articular cells from OA patients and in OA animal models. Therefore, drugs against this alarmin, such as anti-HMGB1 antibodies, could be new treatment possibilities that can modify the disease course since available medications only alleviate symptoms.

791 CAN ALARMINS BECOME A THERAPEUTIC TARGET FOR A PATIENTS WITH ATRIAL FIBRILLATION?

Abstract The link between alarmins and atrial fibrillation is clear and well known in the literature. We performed a non-systematic review about role of alarmins in pathophysiological mechanism of AF, hypothesizing their role in potential novel therapeutic targets for arrhythmia. Several studies have shown a key role of HMGB1 in AF physiopathology. We have seen an almost direct correlation between HMGB1 and oxidative stress in the inflammatory process of AF. Wu et al. observed that HMGB1 is higher in patients with permanent AF, because they experienced a continuous inflammatory tissue damaging impulse. It was shown a prothrombotic and procoagulative role of HMGB1, increased in patients with AF and atrial thrombosis. Scherschel et al. showed higher concentration of S100β protein in AF patients undergoing catheter ablation. Neuronal injury by intrinsic cardiac autonomic nervous system (ICSN) upon catheter treatment released damage-associated molecular pattern proteins (DAMPs) as S100β protein. In vitro studies dealing with murine intracardiac neuros showed that S100β decreased potential action and increased neuronal cells growth. Many studies demonstrate HSP70 protective role when intracellular, at high concentrations in patients who do not develop arrhythmia after cardiac injury, such as bypass, and low concentrations preoperatively in patients who later develop arrhythmia. At the serum level, on the other hand, it becomes an important marker of cellular damage and oxidative stress, also related to increased IL-2 AND IL-4. Conclusions These results could be considered for new therapeutic strategies, as inhibition of oxidative stress, novel therapeutic targets of anticoagulant drugs and considering alarmins as predictive or prognostic biomarkers of disease.

Role of alarmins in poststroke inflammation and neuronal repair.

Severe loss of cerebral blood flow causes hypoxia and glucose deprivation in the brain tissue, resulting in necrotic cell death in the ischemic brain. Several endogenous molecules, called alarmins or damage-associated molecular patterns (DAMPs), are extracellularly released from the dead cells to activate pattern recognition receptors (PRRs) in immune cells that infiltrate into ischemic brain tissue following the disruption of the blood-brain barrier (BBB) after stroke onset. The activated immune cells produce various inflammatory cytokines and chemokines, triggering sterile cerebral inflammation in the ischemic brain that causes further neuronal cell death. Poststroke inflammation is resolved within several days after stroke onset, and neurological functions are restored to some extent as neural repair occurs around peri-infarct neurons. Clearance of DAMPs from the injured brain is necessary for the resolution of poststroke inflammation. Neurons and glial cells also express PRRs and receive DAMP signaling. Although the role of PRRs in neural cells in the ischemic brain has not yet been clarified, the signaling pathway is likely to be contribute to stroke pathology and neural repair after ischemic stroke. This review describes the molecular dynamics, signaling pathways, and functions of DAMPs in poststroke inflammation and its resolution.

Role of Alarmins in the Pathogenesis of Systemic Sclerosis

Systemic sclerosis (SSc) is a rare chronic autoimmune disease associated with significant morbidity and mortality. Two main subsets of SSc are recognized: (i) diffuse cutaneous SSc with rapidly progressive fibrosis of the skin, lungs, and other internal organs; and (ii) limited cutaneous SSc, which is dominated by vascular manifestations, with skin and organ fibrosis generally limited and slowly progressing. In spite of intense investigation, both etiology and pathogenesis of SSc are still unknown. Genetic and environmental factors, as well as abnormalities of immune functions, are strongly suggested for etiology, while microvascular abnormalities, immune system activation, and oxidative stress are suggested for the pathogenesis. Recently, it has been found that a multitude of mediators and cytokines are implicated in the fibrotic processes observed in SSc. Among these, a central role could be exerted by “alarmins”, endogenous and constitutively expressed proteins/peptides that function as an intercellular signal defense. This review describes, in a detailed manner, the role of alarmins in the pathogenesis of scleroderma.

A longitudinal study highlights shared aspects of the transcriptomic response to cardiogenic and septic shock

BackgroundSeptic shock (SS) and cardiogenic shock (CS) are two types of circulatory shock with a different etiology. Several studies have described the molecular alterations in SS patients, whereas the molecular factors involved in CS have been poorly investigated. We aimed to assess in the whole blood of CS and SS patients, using septic patients without shock (SC) as controls, transcriptomic modifications that occur over 1 week after ICU admission and are common to the two types of shock.MethodsWe performed whole blood RNA sequencing in 21 SS, 11 CS, and 5 SC. In shock patients, blood samples were collected within 16 h from ICU admission (T1), 48 h after ICU admission (T2), and at day 7 or before discharge (T3). In controls, blood samples were available at T1 and T2. Gene expression changes over time have been studied in CS, SS, and SC separately with a paired analysis. Genes with p value < 0.01 (Benjamini-Hochberg multiple test correction) were defined differentially expressed (DEGs). We used gene set enrichment analysis (GSEA) to identify the biological processes and transcriptional regulators significantly enriched in both types of shock.ResultsIn both CS and SS patients, GO terms of inflammatory response and pattern recognition receptors (PRRs) were downregulated following ICU admission, whereas gene sets of DNA replication were upregulated. At the gene level, we observed that alarmins, interleukin receptors, PRRs, inflammasome, and DNA replication genes significantly changed their expression in CS and SS, but not in SC. Analysis of transcription factor targets showed in both CS and SS patients, an enrichment of CCAAT-enhancer-binding protein beta (CEBPB) targets in genes downregulated over time and an enrichment of E2F targets in genes with an increasing expression trend.ConclusionsThis pilot study supports, within the limits of a small sample size, the role of alarmins, PRRs, DNA replication, and immunoglobulins in the pathophysiology of circulatory shock, either in the presence of infection or not. We hypothesize that these genes could be potential targets of therapeutic interventions in CS and SS.Trial registrationClinicalTrials.gov, NCT02141607. Registered 19 May 2014.

Extracellular ATP and IL-23 Form a Local Inflammatory Circuit Leading to the Development of a Neutrophil-Dependent Psoriasiform Dermatitis

Psoriasis is a chronic inflammatory skin disease dependent on the IL-23/IL-17 axis, a potent inflammatory pathway involved in pathogen clearance and autoimmunity. Several triggers have been proposed as initiators for psoriasis, including alarmins such as adenosine triphosphate. However, the role of alarmins in psoriasis pathogenesis and cutaneous inflammation has not been well addressed. Studies show that signaling through the P2X7 receptor (P2X7R) pathway underlies the development of psoriasiform inflammation. In this regard, psoriasiform dermatitis induced by IL-23 is dependent on P2X7R signaling. Furthermore, direct activation of the P2X7R is sufficient to induce a well-characterized psoriasiform dermatitis. Mechanistic studies determined that P2X7R-induced inflammation is largely dependent on the IL-1β/NLRP3 inflammasome pathway and neutrophils. In conclusion, this work provides basic mechanistic insight into local inflammatory circuits induced after purinergic P2X7R signaling that are likely involved in the pathogenesis of many inflammatory diseases, such as psoriasis.

Alarmins as biomarkers of gastrointestinal surgical injury - a pilot study.

The dysregulation of inflammatory response to surgical injury affects outcomes. Alarmins, the earliest bioactive substances from damaged cells, play a crucial role in initiating the inflammation. We analyzed serum levels of alarmins (S100A8, S100A12, high mobility group box, and heat shock protein 70) after major abdominal surgery (MAS) in surgical (S) (n=82) and nonsurgical (NS) groups (n=35). The main objective was determining a role of selected alarmins in host response to MAS. The secondary objectives were (i) evaluation of the relationship among alarmins and selected biomarkers (C-reactive protein, interleukin-6), (ii) influence of the place of gastrointestinal resection, and (iii) role of alarmins in MAS for cancer. Except for HMGB1, the levels of all alarmins were higher in the S group compared with the NS group. In the S group, positive correlations were found between S100A8 and both IL-6 and CRP. Additionally, the S100A8 level was higher (p<0.01) in patients who underwent upper gastrointestinal tract (GIT) surgery compared to middle and lower GIT resections. Alarmins levels did not differ between cancer and noncancer patients. MAS is able to elicit increase in alarmin levels. S100A8 can be considered a potential biomarker of surgical injury, especially in the upper part of the GIT.

The role of alarmins in fracture repair

Searchable abstracts of presentations at key conferences on calcified tissues ISSN 2052-1219 (online)