Elicitation of allergic asthma by immunoglobulin free light chains

Abstract

The observation that only 50% of patients with adult asthma manifest atopy indicates that other inflammatory mechanisms are likely involved in producing the characteristic features of this disorder; namely reversible airway obstruction, hyperresponsiveness, and pulmonary inflammation. Our recent discovery that antigen-specific Ig free light chains (LCs) mediate hypersensitivity-like responses suggests that these molecules may be of import in the pathophysiology of asthma. Using a murine experimental model of nonatopic asthma, we now have shown that an LC antagonist, the 9-mer peptide F991, can abrogate the development of airway obstruction, hyperresponsiveness, and pulmonary inflammation. Further, passive immunization with antigen-specific LCs and subsequent airway challenge can elicit a mast cell-dependent reaction leading to acute bronchoconstriction. These findings, and the demonstration that the concentration of free kappa LCs in the sera of patients with adult asthma were significantly increased (as compared with age-matched nonasthmatic individuals), provide previously undescribed insight into the pathogenesis of asthma. In addition, the ability to inhibit pharmacologically LC-induced mast cell activation provides a therapeutic means to prevent or ameliorate the adverse bronchopulmonary manifestations of this incapacitating disorder.

Fig. 1.

The LC antagonist F991 inhibits antigen-induced early-phase bronchoconstriction and mast cell activation found after intra-airway DNBS challenge of mice actively immunized with DNFB. (a) DNFB- (black circle) but not vehicle- (open circle) immunized mice showed an acute bronchoconstrictive response after challenge. Intranasal application of F991 (200 μg per mouse) 30 min before challenge (black triangle) resulted in a profound reduction of bronchoconstriction in DNFB-immunized mice. Intranasal application of F991 did not influence Penh values of vehicle-immunized mice (open triangle); n = 5–6; *, P < 0.05, for the whole curve. (b) mMCP-1 levels in serum of DNFB-immunized mice (black bars) are enhanced compared with vehicle-immunized (open bars) mice 30 min after challenge. Intranasal application of F991 resulted in inhibition of DNBS-induced increase in mMCP-1 serum levels of DNFB-immunized mice; n = 6; *, P < 0.05.

Fig. 2.

The LC antagonist F991 inhibits the development of mucosal exudation, cellular infiltration, and tracheal hyperreactivity associated with the late phase of DNFB-induced pulmonary hypersensitivity reaction in mice. (a) Immunization with DNFB (black bars) results in an increase in mucosal exudation 24 h after challenge. Intraperitoneal pretreatment with F991 (50 μg per mouse, 24 h and 5 min before challenge) prevented the development of DNFB/DNBS-induced mucosal exudation in the airway lumen. F991 did not influence basal mucosal exudation found in vehicle-sensitized mice; n = 6; *, P < 0.05. (b and d) Tracheal hyperreactivity is found in DNFB-immunized mice (black circle) compared with vehicle-immunized (open circle) mice 24 and 48 h after challenge. (b and d) Injections with F991 blocked the development of tracheal hyperreactivity normally found 24 and 48 h after challenge (c and e); n = 5–6; *, P < 0.05, for the whole curve.

Fig. 3.

Antigen-specific LCs mediate acute bronchoconstriction after challenge. (a) Typical individual tracings of bronchoconstriction (Penh recordings) of (b) saline or TNP-specific LC-immunized mouse from -5 to 25 min after challenge. Arrows indicate time of challenge. (c) TNP-specific LC- (black circle) but not vehicle- (open circle) immunized mice showed an acute bronchoconstrictive response after challenge. (d) TNP-specific LC-immunized mice (black diamond) that were challenged with OXA-BSA failed to demonstrate bronchoconstriction. (e) Passive immunization with TNP-specific recombinant LC (black circle) resulted in bronchoconstriction after challenge; n = 4–7; *, P < 0.05, for the whole curve.

Fig. 4.

The TNP-specific LC-induced acute bronchoconstriction after challenge is mast cell-dependent. (a) mMCP-1 levels in serum of TNP-specific LC (black bars) are enhanced compared with vehicle-sensitized (open bars) mice 30 min after challenge; n = 6; *, P < 0.05. (b) Mast cells in tracheal sections of mice passively immunized with TNP-specific LC showed degranulation after reexposure to antigen when compared with vehicle-sensitized mice; n = 4; *, P < 0.05 (black, degranulated and white, nondegranulated mast cells). Electron microscopy reveals degranulation characterized by swelling of intracytoplamic granules and decrease of electron density of granules. (c) Tracheal mast cell from vehicle-immunized and challenged mouse. (d) Tracheal mast cell from TNP-specific LC-immunized and challenged mouse. (e) The acute bronchoconstriction found in TNP-specific LC-immunized mice is mast cell-dependent. TNP-specific LC- (black circle) but not vehicle- (open circle) immunized congenic +/+ mice showed an acute bronchoconstrictive response after challenge. (f) TNP-specific LC-injected mast cell-deficient W/W^v mice failed to demonstrate bronchoconstriction after challenge. (g) Selective reconstitution of mast cells in mast cell-deficient mice (BMMC→W/W^v) restored LC-mediated acute bronchoconstriction; n = 5–6; *, P < 0.05, for the whole curve.

Fig. 5.

The LC antagonist F991 inhibits bronchoconstriction and mast cell activation found after challenge of mice immunized with TNP-specific LCs. TNP-specific LC- (black circle) but not vehicle- (open circle) immunized mice showed an acute bronchoconstrictive response after challenge. (a) Simultaneous injection of F991 (200 μg per mouse) and TNP-specific LCs (black triangle) resulted in a profound reduction of bronchoconstriction. (b) Intranasal administration of F991 (200 μg per mouse) (black triangle) completely inhibited the TNP-specific LC-induced bronchoconstriction. i.v. or intranasal application of F991 did not influence Penh values of vehicle-immunized mice (open triangle); n = 5–6; *, P < 0.05, for the whole curve. (c) mMCP-1 levels in serum of TNP-specific LCs (black bars) are enhanced compared with vehicle-sensitized (open bars) mice 30 min after challenge. Intranasal application of F991 (200 μg per mouse) resulted in inhibition of increases in mMCP-1 serum levels of TNP-specific LC-immunized mice; n = 6; *, P < 0.05.

Fig. 6.

Concentrations of κ and λ LC in serum of nonatopic and atopic adult asthma patients and nonatopic and atopic nonasthmatic subjects. (a) κ LC serum levels in nonatopic adult asthmatics (NAA; n = 14, black bar) compared with nonatopic healthy controls (NA; n = 34, open bar); ^**, P = 0.001. (b) κ LC serum levels in atopic adult asthmatics (AA; n = 17, black bar) compared with atopic nonasthmatics (A; n = 15, hatched bar) and nonatopic healthy controls (NA; n = 34, open bar); *, P = 0.023 compared with nonatopic healthy controls. (c) Correlation of λ LC vs. κ LC of nonatopic asthma patients (black diamond). (d) Correlation of λ LC vs. κ LC of nonatopic healthy individuals (open diamond). (e) Correlation of λ LC vs. κ LC of atopic asthma patients (black triangle). (f) Correlation of λ LC vs. κ LC of atopic nonasthmatic individuals (open triangle). r², measure of goodness of fit of linear regression.