Bronchoprotector properties of calcitonin gene-related peptide in guinea pig and human airways. Effect of pulmonary inflammation.

Calcitonin gene-related peptide (CGRP), a neuropeptide released from sensory nerves during axonal reflexes, has strong bronchoprotector properties in rat isolated airways. In this study, we examined this ability of CGRP to prevent agonist-induced contraction in guinea pig and human airways and determined whether inflammatory reaction affects its function. CGRP administered intravenously (0.38 to 114 microgram/kg) in anesthesized guinea pig had no effect per se on airway resistance but caused a dose-related inhibition of substance P (SP; 13.5 microgram/kg)-induced bronchoconstriction (60% at 114 microgram/kg). Similarly, CGRP (10(-)9 to 10(-)6 M) prevented in a concentration-dependent manner the contraction elicited by SP (5 x 10(-)8 M) in guinea pig isolated main bronchi and parenchymal strips, the inhibition caused by CGRP being more pronounced in distal than in proximal airways (47 and 20%, respectively, at 10(-)6 M). The breaking effect of CGRP on SP-induced constriction was however significantly reduced (p < 0.05) in guinea pig actively sensitized to ovalbumin (OA) and the loss in its potency was of similar magnitude (> 40%) whether it was administered in vivo or in vitro. A same phenomenon was observed in human isolated peripheral bronchi. CGRP (10(-)6 M) reduced by more than 75% the extent of the contraction evoked by 10(-)6 M of carbamylcholine and its protector effect was totally abolished in bronchi showing clear morphological manifestation of inflammatory reaction. It is concluded that CGRP acts as a potent bronchoprotector agent on both guinea pig and human airways but its ability to limit the extent of airway responsiveness is strongly impaired in inflammatory conditions.

Purification of antigenically intact Ro ribonucleoproteins; biochemical and immunological evidence that the 52-kD protein is not a Ro protein.

Anti-Ro sera immunoprecipitate Ro ribonucleoproteins (RNPs) from human cell extracts. Ro RNPs are biochemically heterogeneous particles whose functions are unknown and whose exact composition remains controversial. In addition to 60-kD Ro and to La proteins, a 52-kD polypeptide (p52) has been proposed to be a stable component of the Ro RNPs. To confirm the immunological studies supporting this hypothesis, we have biochemically purified Ro RNPs from HeLa cells using non-denaturing conditions. Ro RNPs segregated into three distinct populations, one of which only contained hY5 RNA (RohY5 RNPs). No p52 co-purified with Ro RNPs. Despite the absence of p52, purified Ro RNPs had biochemical and immunological properties identical to those of unfractionated Ro RNPs. Many anti-Ro sera only recognize p52 in immunoblots, and are said to be monospecific anti-p52. Preincubation with purified RohY5 RNPs (free of p52) of all human anti-Ro (including so-called monospecific anti-p52) sera abolished their capacity to immunoprecipitate Ro RNPs from unfractionated HeLa cell extracts. Conversely, preincubation of anti-Ro sera with purified p52 protein specifically inhibited recognition of p52 in immunoblots, but did not interfere with immunoprecipitation of Ro RNPs. Our data demonstrate that anti-p52 antibodies do not target intact Ro RNPs, nor do they target the native 60-kD Ro protein. Contrary to previous reports, p52 protein is not a stable component of antigenically intact Ro RNPs.