State of the Art. Potential Etiologic Agents in Sarcoidosis

Abstract

The etiology of sarcoidosis remains uncertain. The hallmark of sarcoidosis is the epithelioid granuloma, which serves as a necessary starting point for considering disease etiology. Any etiologic agent of sarcoidosis must also explain the typical clinical behaviors and characteristic immunopathologic features of the disease. One clinical observation that serves as a bridge to the etiology of sarcoidosis is the Kveim reaction. In this reaction, local epithelioid granulomas develop several weeks after the intradermal injection of homogenates of sarcoidosis tissue. Our group capitalized on the known properties of the Kveim reagent to search for candidate pathogenic tissue antigens in sarcoidosis without other a priori hypotheses regarding possible microbial or autoimmune etiologies. Using a limited proteomics approach based on the physicochemical properties of Kveim reagent, we detected a limited number of poorly soluble antigenic proteins in sarcoidosis tissues by protein immunoblotting, using sarcoidosis sera. Matrix-associated laser desorption/ ionization-time of flight mass spectrometry identified one of these antigens to be the Mycobacterium tuberculosis catalase-peroxidase protein (mKatG). We found IgG responses to recombinant mKatG in more than 50% of patients with sarcoidosis but rarely in purified protein derivative (PPD)-negative control subjects. These findings support the conclusion that mKatG is a tissue antigen and target of the adaptive immune response in sarcoidosis, providing further evidence of a mycobacterial etiology in a subset of sarcoidosis. More generally, the approach used in these studies might be employed to discover and validate other candidate pathogenic antigens in sarcoidosis or other granulomatous disorders.

Systemic oxidative stress in patients with pulmonary sarcoidosis

“…Although the aetiology of sarcoidosis remains uncertain [17], extensively conducted research has revealed several of the histopathologic and immunopathogenic events which occur during the development of noncaseating granulomas and might interpret the aforementioned redox imbalance [18,19].…”

Características epidemiológicas de pacientes com sarcoidose na cidade do Rio de Janeiro

“…(1,2) Although the disease is of unknown etiology, it is believed that there is an environmental agent, whether infectious or not, that is responsible for triggering the inflammatory response in genetically susceptible hosts. (1)(2)(3)(4)(5) The lung is the most commonly affected organ. (3,4,6) Although there is remission in 50% of cases, some patients live with chronic disease for decades.…”

“…(1)(2)(3)(4)(5) The lung is the most commonly affected organ. (3,4,6) Although there is remission in 50% of cases, some patients live with chronic disease for decades. (1,4) Sarcoidosis affects all ethnic and age groups, being more common before the age of 50 years and being predominant in females.…”

Sarcoidosis of the spleen – rare indications for splenectomy. Own experience

“…Sarcoidosis belongs to the group of diseases characterized by non-caseating epithelioid granulomas [1][2][3]. They consist of epithelial cells (activated macrophages) and Langhans' cells, occasionally containing Schaumann conchoid bodies and asteroid bodies [3,4].…”

“…At its origin might lie infections, allergy, some medicines, chemicals, or autoimmune or genetic disorders [2,[5][6][7]. A predisposition towards sarcoidosis development was observed in subjects with HLA-B8 as well as HLA-B27 genotype [4,7].…”