Increased concentrations of antibody against heat shock protein in patients with myeloperoxidase anti-neutrophil cytoplasmic autoantibody positive microscopic polyangiitis

Anti-Heat Shock Protein 70 Autoantibodies from Patients with Idiopathic Pulmonary Fibrosis Epigenetically Enhance Lung Fibroblast Apoptosis Resistance and Bcl-2 Expression

IgG autoantibodies to heat shock protein 70 (HSP70) are found in many immune-mediated clinical syndromes, and their presence among patients with idiopathic pulmonary fibrosis (IPF) portends especially poor outcomes. However, pathological effects of IPF anti-HSP70 have not been studied extensively. IPF lung fibroblasts are apoptosis resistant, and this dysregulation contributes to the accumulation of fibroblasts that characterizes the disease. During stress, HSP70 protein is exported extracellularly, where it binds to cognate cell surface receptors that mediate a variety of functional effects, including apoptosis inhibition. We hypothesized anti-HSP70 could engage HSP70-receptor complexes on fibroblasts that alter their apoptosis susceptibility. We found HSP70 is ubiquitously expressed on primary human lung fibroblasts. Treatment with anti-HSP70 isolated from patients with IPF with acute exacerbations increased Bcl-2 expression in human lung fibroblasts and reduced their susceptibility to staurosporine-induced apoptosis. Chromatin immunoprecipitation assays showed Bcl-2 gene promoter regions are enriched with the active histone mark H4 lysine 16 acetylation, and this was increased in the autoantibody-treated fibroblasts. When H4 lysine 16 acetylation was decreased by knocking down its acetyltransferase, MOF (males absent on the first), the anti-HSP70 treatments failed to upregulate Bcl-2. This study describes a heretofore unknown, to our knowledge, pathogenic consequence of autoimmunity in which autoantibodies affect the epigenetic regulation of fibroblast apoptosis. In addition to IPF, this autoimmune process could also have relevance in other immunological syndromes characterized by anti-HSP70 autoimmunity. These findings lend credence to the importance of autoimmunity in IPF and illustrate pathways that could be targeted in innovative therapies for this morbid, medically refractory lung disease.

Alarmins in autoimmune diseases

Alarmins are endogenous, constitutively expressed, chemotacting and immune activating proteins or peptides released because of non-programmed cell death (i.e. infections, trauma, etc). They are considered endogenous damage-associated molecular patterns (DAMPs), able to induce a sterile inflammation. In the last years, several studies highlighted a possible role of different alarmins in the pathogenesis of various autoimmune and immune-mediated diseases. We reviewed the relevant literature about this topic, for about 160 articles. Particularly, we focused on systemic autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, idiopathic inflammatory myopathies, ANCA-associated vasculitides, Behçet's disease) and cutaneous organ-specific autoimmune diseases (vitiligo, psoriasis, alopecia, pemphigo). Finally, we discussed about future perspectives and potential therapeutic implications of alarmins in autoimmune diseases. In fact, identification of receptors and downstream signal transducers of alarmins may lead to the identification of antagonistic inhibitors and agonists, with the capacity to modulate alarmins-related pathways and potential therapeutic applicability.

Intense immunostaining of heat shock protein 70 within renal interstitium associates with long-term renal survival in an ANCA-associated vasculitis cohort

In anti-neutrophilic cytoplasmic antibody (ANCA)-associated vasculitis (AAV) genetic predisposition, ANCA autoantibodies, neutrophil extracellular traps (NETs), complement activation, and toll-like receptor signaling are implicated in AAV pathogenesis. Heat shock proteins (HSPs), a highly conserved group of small-sized molecular chaperones, take part in protein folding during cellular stress. Although HSPs were initially observed intracellularly, it has been shown that they can be secreted in the extracellular space and modulate the immune response in various autoimmune diseases including AAV. The scope of the present study is to investigate the role of heat shock protein 60 (HSP60) and 70 (HSP70) in the long renal effects in an ANCA vasculitis cohort. In this cohort of ANCA-associated vasculitis, 29 patients were followed up over 20 years. At diagnosis, immunohistochemistry was performed for HSP60 and HSP70 within the various nephron compartments. Higher renal HSP60 expression was associated with increased interstitial inflammatory infiltrates at diagnosis, while HSP70 expression was associated with a greater extent of interstitial fibrosis at diagnosis. Notably, intense tissue expression of HSP70 at the time of biopsy was associated with a worsened kidney survival. Renal HSP70 expression was associated with poor renal outcomes during long-term follow-up. This finding may indicate a role of HSPs in renal disease progression in ANCA vasculitis. Further validating studies are needed to verify a causative association between HSP70 expression and renal outcomes in ANCA-associated vasculitis.

Infection Elicited Autoimmunity and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: An Explanatory Model

Myalgic encephalomyelitis (ME) often also called chronic fatigue syndrome (ME/CFS) is a common, debilitating, disease of unknown origin. Although a subject of controversy and a considerable scientific literature, we think that a solid understanding of ME/CFS pathogenesis is emerging. In this study, we compiled recent findings and placed them in the context of the clinical picture and natural history of the disease. A pattern emerged, giving rise to an explanatory model. ME/CFS often starts after or during an infection. A logical explanation is that the infection initiates an autoreactive process, which affects several functions, including brain and energy metabolism. According to our model for ME/CFS pathogenesis, patients with a genetic predisposition and dysbiosis experience a gradual development of B cell clones prone to autoreactivity. Under normal circumstances these B cell offsprings would have led to tolerance. Subsequent exogenous microbial exposition (triggering) can lead to comorbidities such as fibromyalgia, thyroid disorder, and orthostatic hypotension. A decisive infectious trigger may then lead to immunization against autoantigens involved in aerobic energy production and/or hormone receptors and ion channel proteins, producing postexertional malaise and ME/CFS, affecting both muscle and brain. In principle, cloning and sequencing of immunoglobulin variable domains could reveal the evolution of pathogenic clones. Although evidence consistent with the model accumulated in recent years, there are several missing links in it. Hopefully, the hypothesis generates testable propositions that can augment the understanding of the pathogenesis of ME/CFS.

Could mycobacterial Hsp70-containing fusion protein lead the way to an affordable therapeutic cancer vaccine?

Cancer vaccine development efforts have recently gained momentum, but most vaccines showing clinical impact in human trials tend to be based on technology approaches that are very costly and difficult to produce at scale. With the projected doubling of the incidence of cancer and its related cost of care in the U.S. over the next two decades, the widespread clinical use of such vaccines will prove difficult to justify. Heat shock protein-based vaccines have shown the potential to elicit clinically meaningful immunologic responses in cancer, but the predominant development approach - heat shock protein-peptide complexes derived from a patient's own tumor - face similar challenges of cost and scalability. New innovative modalities for deploying heat shock proteins in cancer vaccines may open the door to vaccines that can generate potent cytotoxic responses against multiple tumor targets and can be made in a cost-effective and scalable manner.