[Pulmonary sarcoidosis: current diagnosis and treatment]

Immune Mechanisms of Pulmonary Fibrosis with Bleomycin

Fibrosis and structural remodeling of the lung tissue can significantly impair lung function, often with fatal consequences. The etiology of pulmonary fibrosis (PF) is diverse and includes different triggers such as allergens, chemicals, radiation, and environmental particles. However, the cause of idiopathic PF (IPF), one of the most common forms of PF, remains unknown. Experimental models have been developed to study the mechanisms of PF, and the murine bleomycin (BLM) model has received the most attention. Epithelial injury, inflammation, epithelial-mesenchymal transition (EMT), myofibroblast activation, and repeated tissue injury are important initiators of fibrosis. In this review, we examined the common mechanisms of lung wound-healing responses after BLM-induced lung injury as well as the pathogenesis of the most common PF. A three-stage model of wound repair involving injury, inflammation, and repair is outlined. Dysregulation of one or more of these three phases has been reported in many cases of PF. We reviewed the literature investigating PF pathogenesis, and the role of cytokines, chemokines, growth factors, and matrix feeding in an animal model of BLM-induced PF.

The Diagnosis, Differential Diagnosis, and Treatment of Sarcoidosis

BACKGROUND

Sarcoidosis is a granulomatous inflammatory disease of unknown cause. Its prevalence in Germany is approximately 46 per 100 000 persons.

METHODS

This article is based on pertinent publications retrieved by a selective search in PubMed.

RESULTS

A presumptive diagnosis of sarcoidosis is made in any patient with a granulomatous inflammation that is not explained by any other identifiable cause, such as an infection or foreign body. Non-caseating granulomas containing epithelioid cells are its histological hallmark. Recently developed diagnostic techniques, including positron emission tomography and magnetic resonance imaging, have made it easier to detect organ involvement and to assess the activity of the disease. The pattern of organ involvement varies from patient to patient. Many patients have a systemic inflammatory reaction with subfebrile or febrile temperatures, night sweats, weight loss, diminished physical reserve, and fatigue. Sarcoidosis often resolves spontaneously. Detection of organ involvement is not necessarily an indication for treatment, but treatment is clearly needed if there is symptomatic cardiac involvement or any involvement of the central nervous system. Oral corticosteroids are the first line of treatment. Their long-term use can cause serious complications.

CONCLUSION

The treatment of patients with sarcoidosis, particularly those with complicated disease courses, requires close collaboration of the primary care physician with a specialized interdisciplinary center.

Fluorofenidone attenuates pulmonary inflammation and fibrosis via inhibiting the activation of NALP3 inflammasome and IL-1β/IL-1R1/MyD88/NF-κB pathway

Interleukin (IL)‐1β plays an important role in the pathogenesis of idiopathic pulmonary fibrosis. The production of IL‐1β is dependent upon caspase‐1‐containing multiprotein complexes called inflammasomes and IL‐1R1/MyD88/NF‐κB pathway. In this study, we explored whether a potential anti‐fibrotic agent fluorofenidone (FD) exerts its anti‐inflammatory and anti‐fibrotic effects through suppressing activation of NACHT, LRR and PYD domains‐containing protein 3 (NALP3) inflammasome and the IL‐1β/IL‐1R1/MyD88/NF‐κB pathway in vivo and in vitro. Male C57BL/6J mice were intratracheally injected with Bleomycin (BLM) or saline. Fluorofenidone was administered throughout the course of the experiment. Lung tissue sections were stained with haemotoxylin and eosin and Masson's trichrome. Cytokines were measured by ELISA, and α‐smooth muscle actin (α‐SMA), fibronectin, collagen I, caspase‐1, IL‐1R1, MyD88 were measured by Western blot and/or RT‐PCR. The human actue monocytic leukaemia cell line (THP‐1) were incubated with monosodium urate (MSU), with or without FD pre‐treatment. The expression of caspase‐1, IL‐1β, NALP3, apoptosis‐associated speck‐like protein containing (ASC) and pro‐caspase‐1 were measured by Western blot, the reactive oxygen species (ROS) generation was detected using the Flow Cytometry, and the interaction of NALP3 inflammasome‐associated molecules were measured by Co‐immunoprecipitation. RLE‐6TN (rat lung epithelial‐T‐antigen negative) cells were incubated with IL‐1β, with or without FD pre‐treatment. The expression of nuclear protein p65 was measured by Western blot. Results showed that FD markedly reduced the expressions of IL‐1β, IL‐6, monocyte chemotactic protein‐1 (MCP‐1), myeloperoxidase (MPO), α‐SMA, fibronectin, collagen I, caspase‐1, IL‐1R1 and MyD88 in mice lung tissues. And FD inhibited MSU‐induced the accumulation of ROS, blocked the interaction of NALP3 inflammasome‐associated molecules, decreased the level of caspase‐1 and IL‐1β in THP‐1 cells. Besides, FD inhibited IL‐1β‐induced the expression of nuclear protein p65. This study demonstrated that FD, attenuates BLM‐induced pulmonary inflammation and fibrosis in mice via inhibiting the activation of NALP3 inflammasome and the IL‐1β/IL‐1R1/MyD88/ NF‐κB pathway.

[Sarcoidosis : Organ involvement, diagnosis, current treatment]

Sarcoidosis is characterized by the appearance of noncausating, epitheloid cell granulomas, primarily in skin and lung. Hereditary disposition is well known; additional infection-associated triggers play a role for the development of inflammation mediated by T helper (Th)1 cells. Clinically, various disease courses can be observed that are characterized by the formation of skin papules at typical sites of the body which differ in their tendency to be associated with systemic organ involvement. Systemic disease without skin affections is also possible. The diagnosis is based on the typical clinical appearance, biopsy of affected tissue (e.g. skin, lung) and laboratory investigations. Additional systemic involvement needs to be excluded. In most cases, the disease is self-limited, but can also be life threatening due to organ fibrosis. The degree of (extra-)cutaneous involvement and level of discomfort are used to select the type of treatment, which ranges from topical immune suppressive agents to systemic therapy with corticosteroids. In nonresponders, additional modern immunosuppressive/immunomodulating therapeutic options are available.

Epigenetics in immune-mediated pulmonary diseases

Immune-mediated pulmonary diseases are a group of diseases that resulted from immune imbalance initiated by allergens or of unknown causes. Inflammatory responses without restrictions cause tissue damage and remodeling, which leads to airway hyperactivity, destruction of alveolar architecture, and a resultant loss of lung function. Epigenetic mechanisms have been demonstrated to be involved in inflammation, autoimmunity, and cancer. Recent studies have identified that epigenetic changes also regulate molecular pathways in immune-mediated lung diseases. Aberrant DNA methylation status, dysregulation of histone modifications, as well as altered microRNAs expression could change transcription activity of genes involved in the development of immune-mediated pulmonary diseases, which contributes to skewed differentiation of T cells and proliferation and activation of myofibroblasts, leading to overproduction of inflammatory cytokines and excessive accumulation of extracellular matrix, respectively. Aside from this, epigenetics also explains how environmental exposure influence on gene transcription without genetic changes. It acts as a mediator of the interaction between environmental factors and genetic factors. Identification of the abnormal epigenetic marks in diseases provides novel biomarkers for prediction and diagnosis and affords novel therapeutic targets for those difficult clinical problems, such as steroid-resistance and rapidly progressing fibrosis. In this review, we summarized the latest experimental and translational epigenetic studies in immune-mediated pulmonary diseases, including asthma, idiopathic pulmonary fibrosis, tuberculosis, sarcoidosis, and silicosis.