title: Dysregulation of the immune system caused by silica and asbestos.
abstract: Silica and asbestos cause pneumoconioses known as silicosis and asbestosis, respectively, that are each characterized by progressive pulmonary fibrosis. While local effects of inhaled silica particles alter the function of alveolar macrophages and sequential cellular and molecular biological events, general systemic immunological effects may also evolve. One well-known health outcome associated with silica exposure/silicosis is an increase in the incidence of autoimmune disorders. In addition, while exposure to silica--in the crystalline form--has also been seen to be associated with the development of lung cancers, it remains unclear as to whether or not silicosis is a necessary condition for the elevation of silica-associated lung cancer risks. Since asbestos is a mineral silicate, it would be expected to also possess generalized immunotoxicological effects similar to those associated with silica particles. However, asbestos-exposed patients are far better known than silicotic patients for development of malignant diseases such as lung cancer and mesothelioma, and less so for the development of autoimmune disorders. With both asbestos and crystalline silica, one important dysregulatory outcome that needs to be considered is an alteration in tumor immunity that allows for silica- or asbestos- (or asbestos-associated agent)-induced tumors to survive and thrive in situ. In this review, the immunotoxicological effects of both silica and asbestos are presented and contrasted in terms of their abilities to induce immune system dysregulation that then are manifest by the onset of autoimmunity or by alterations in host-tumor immunity.
authors.affiliation: Department of Hygiene, Kawasaki Medical School, Kurashiki, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Maeda
authors.forename: Yasumitsu
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Naoko
authors.initials: N
authors.lastname: Kumagai
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hayashi
authors.forename: Tamayo
authors.initials: T
authors.lastname: Hatayama
authors.forename: Minako
authors.initials: M
authors.lastname: Katoh
authors.forename: Naomi
authors.initials: N
authors.lastname: Miyahara
authors.forename: Shoko
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Junichi
authors.initials: J
authors.lastname: Hirastuka
authors.forename: Takemi
authors.initials: T
authors.lastname: Otsuki
mesh_terms: D000818:Animals; D001194:Asbestos / Q000009:adverse effects / Q000276:immunology*; D015551:Autoimmunity; D006801:Humans; D007107:Immune System / Q000378:metabolism; D007157:Immunologic Surveillance; D056747:Immunomodulation; D008175:Lung Neoplasms / Q000139:chemically induced / Q000276:immunology* / Q000473:pathology; D008654:Mesothelioma / Q000139:chemically induced / Q000276:immunology* / Q000473:pathology; D011009:Pneumoconiosis / Q000276:immunology* / Q000503:physiopathology; D012822:Silicon Dioxide / Q000009:adverse effects / Q000276:immunology*
chemical_list: D001194:Asbestos; D012822:Silicon Dioxide