Overexpression of transforming growth factor (TGF)-β1 and TGF-β3 genes in lung of toxic-inhaled patients

ABSTRACT

Iraq frequently used toxic inhalants during the war with Iran, exposing over 100,000 people to chemical reagents. Bronchiolitis obliterans (BO) is a major pulmonary disease caused by exposure to harmful gases. Recently defect in clearance of apoptotic cells (efferocytosis) has been suggested as a mechanism that leads to several lung diseases. Transforming growth factor (TGF)-β, a cytokine produced by efferocytotic macrophages, suppresses the inflammation and enhances the regeneration of tissue. In this study, the authors compared the expression of these 3 isoforms of TGF-β at mRNA level in lung biopsies of Iranian victims of chemical gases with lung biopsies of control healthy volunteers. Semiquantitative reverse transcriptase–polymerase chain reaction (RT-PCR) technique was used to examine the expression level of TGF-β isoforms using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene as an internal control. The results indicated that that levels of TGF-β1 and TGF-β3 mRNAs were significantly higher in chemical gas–injured patients than noninjured group (P < .05). Therefore, the authors speculate that TGF-β1 and TGFβ3, but not TGF-β2, secretion is a result of efficient efferocytosis in chemically injured patients, playing a protective role by improving airway remodeling and lung homeostasis in this group. These properties of TGF-β are consistent with long-time survival of chemical-injured people suffering from BO.

KEYWORDS:

• bronchiolitis obliterans (BO)
• efferocytosis
• toxic inhalants
• transforming growth factor β (TGF-β)