Nasal IgA secretion in a murine model of acute stress. The possible role of catecholamines.
Stress stimuli affect the immune system of the mucosa, and in particular IgA secretion. It is well documented that intense psychological and physical stress can increase susceptibility to infection by diverse pathogens in the upper respiratory tract. Our workgroup reported that chronic stress caused by immobilization elicits a decrease in nasal IgA levels in mice. Here, we explore how acute stress (caused by 4h of immobilization) affects IgA secretion in the nasal mucosa, and the possible role of the sympathetic nervous system in this effect. Nine-week-old male CD1 mice were divided into four groups: control, chemical sympathectomy (with 6-OHDA) and treatment with nadolol (5mg/kg) or phentolamine (15mg/kg). All these groups were subdivided into stressed and unstressed animals. The parameters evaluated included plasma corticosterone and epinephrine (only in control groups), SIgA levels (by ELISA) and SIgA expression (by Western Blot) in nasal fluid, percentage of IgA+ plasma cells, and mRNA expression of heavy alpha chain, pIgR, TNFα and TGFβ in nasal mucosa. Acute stress reduced the percentage of IgA+ cells while increasing the levels of IgA, the two hormones, and the mRNA expression of heavy alpha chain, pIgR, TNFα and TGFβ, which resulted in greater synthesis and transport of IgA. The treatments with 6-OHDA and α- and β-adrenergic receptor blockers suggest that sympathetic innervation by both types of adrenergic receptors is important for the control of SIgA secretion in nasal mucosa during acute stress. The increase in this parameter depended on the cytokines involved in IgA synthesis and transport.