Czaja, Judith M.

Substance P is a neuropeptide released by afferent neurons in the respiratory tract during inflammatory reactions. It produces effects on blood vessels, bronchial smooth muscle, nasal glands, and respiratory cilia. We studied the in vitro effect of substance P on the ciliary beat frequency of human adenoid explants and its mechanism of action. Substance P was added to cultured adenoid at concentrations of 10−10, 10−8, 10−6, and 10−4 mol/L. Ciliary beat frequency was determined with phase‐contrast microscopy and microphotometry. Substance P increased ciliary beat frequency a maximum of 11.9% ± 3.8% (p < 0.01). Diclofenac (10−6 mol/L) significantly blocked the ciliostimulatory effects of SP (p < 0.022), indicating that prostaglandin synthesis is an intermediate step in the action of substance P on ciliary beat frequency. The L‐arginine analogs, NG‐nitro‐L‐arginine methyl ester and NG‐monomethyl‐L‐arginine, inhibit nitric oxide synthesis from L‐arginine. L‐Arginine analogs (10−4 to 10−2 mol/L) inhibited the effect of substance P (p < 0.02 at the higher concentration). This inhibition was reversed by adding L‐arginine, demonstrating that nitric oxide production is a required step in substance P‐induced ciliostimulation. Substance P stimulates ciliary activity in human nasal mucosa as a result of secondary production and release of endogenous prostaglandins and nitric oxide. It is likely that inflammatory disease processes that stimulate release of substance P and subsequent prostaglandin and nitric oxide production modify mucociliary transport. Pharmacologic modification of substance P and its second messengers may eventually permit regulation of this important defense mechanism and control of neurogenic inflammation.

Abnormal mucociliary clearance in the paranasal sinuses is a significant factor in the pathogenesis of sinusitis. This study examined effects of chronic sinusitis on ciliary beat frequency (CBF), mucociliary transport (MCT) velocity, mucociliary transport patterns, and histology of sinus mucosa in rabbits. Two groups of rabbits were studied: uninfected (n = 9) and infected (n = 18). Maxillary sinus ostia in all animals were occluded, and sinuses in the infected group were inoculated with 10 8 cfu of Streptococcus pneumoniae. Chronic sinusitis developed over 6 weeks and was confirmed by histopathology and culture. Evaluation of the MCT mechanism included 1) measurement of CBF using a photometric technique, 2) direct measurement of MCT velocity, and 3) analysis of MCT patterns with inert India ink. In seven of nine (77.8%) uninfected animals, the mean CBF was 11.5 Hz (±.39 Hz) initially and 11.3 Hz (±.32 Hz) 6 weeks after occlusion (P = 0.69). MCT velocity measured 20.6 mm/min (±1.40 mm/min) initially and 16.85 mm/min (±1.96 mm/min) 6 weeks after occlusion (P = 0.16). In the infected group, there were statistically significant decreases in CBF (P < 0.05) and measured MCT velocity (P < 0.05). Examination of MCT in infected animals showed patterns of misdirected flow, pooling, and stagnation. Histopathologic changes included significant losses of ciliated epithelium and mucosal abnormalities consistent with chronic sinusitis. Chronic sinusitis secondary to long-standing bacterial infection leads to alterations in CBF, MCT velocity, and MCT patterns in the paranasal sinuses of rabbits.

Normal mucociliary clearance in the paranasal sinuses must be restored to reverse the effects of chronic sinusitis. This study examined effects of middle meatal antrostomy (MMA) on ciliary beat frequency (CBF), mucociliary transport (MCT) velocity, MCT patterns, and histology of sinus mucosa in rabbits with chronic sinusitis to determine whether objective measures of mucociliary function and histology could be reversed. Two groups of rabbits were compared: uninfected (Group A controls, n = 9) and infected (Group B, n = 11). Maxillary sinus ostia were occluded; 10 8 cfu of Streptococcus pneumoniae were inoculated into sinuses of rabbits in group B, and chronic sinusitis developed. This was confirmed by histopathology and culture 6 weeks after infection. Middle meatal antrostomies were performed in the infected group, and sinuses were studied 6 weeks later. Control animals (Group A) had mean CBF = 11.5 Hz (±.39 Hz). Animals with chronic sinusitis (Group B) had mean CBF = 8.6 Hz (±.24 Hz). This was statistically different from control (P < 0.05). Six weeks following MMA, group B had mean CBF = 12.9 Hz (±.75 Hz). This was not different from control. There were changes in MCT velocity that correlated with the CBF (r = 0.72). Examination of MCT patterns after MMA demonstrated minimal pooling and stagnation; however, small areas of misdirected flow persisted. After MMA, there were decreased numbers of inflammatory and goblet cells and increased numbers of ciliated epithelial cells. This study demonstrated that mucociliary clearance and histological changes seen in rabbits with chronic sinusitis are reversed by MMA.

Prostaglandins are ubiquitous within tissues and participate in several local regulatory functions. Previous reports have presented conflicting evidence on their role in ciliary activity in the upper airway. We studied the in vitro effects of prostaglandin E 2 (PGE 2 ) and a prostaglandin I 2 analog (Iloprost) on the ciliary beat frequency (CBF) of human adenoid explants and rabbit sinus mucosa. Tissue explants were maintained in culture at 35°C. PGE 2 or Iloprost was added to the culture media at concentrations of 10 –6 , to 10 –12 M. CBF was determined using phase contrast microscopy and microphotometry. PGE 2 increased CBF with a maximum increase of 54.6% in rabbit mucosa (P < 0.01) and 20.0% in human adenoid (P < 0.009). Iloprost increased CBF with a maximum increase of 35.2% in rabbit mucosa (P < 0.02) and 16.4% in human adenoid (P < 0.03). Induced production of endogenous prostaglandins was determined by treating specimens with a cyclooxygenase inhibitor (diclofenac) prior to addition of PGE 2 or Iloprost. Diclofenac had no effect on the ciliostimulatory effects of PGE 2 (P > 0.36), however it significantly decreased the ciliostimulatory effect of Iloprost (P < 0.037). Both PGE 2 and Iloprost stimulate ciliary motility, yet the action of PGE 2 is direct, whereas Iloprost stimulates cilia by release of endogenous prostaglandins in both the human and rabbit.

Ciliary ultrastructural abnormalities secondary to chronic sinusitis may cause abnormal mucociliary transport clearance. We examined the relationship between anatomic abnormalities of ciliary ultrastructure secondary to chronic sinusitis and ciliary beat frequency (CBF) before and after middle meatal antrostomy (MMA) in rabbits. Ultrastructural abnormalities of cilia included absence of axoneme membrane, blebs of the axoneme membrane, compound cilia, and ciliary orientation. Two groups of rabbits were studied: Uninfected (group A control, n = 3) and infected (group B, n = 10); 10 8 CFU S. pneumoniae were used to infect the animals in group B after sinus ostial occlusion and chronic sinusitis developed. After 6 weeks with infection, 6 of 10 group B animals underwent MMA and were restudied 6 weeks later. Uninfected animals had mean CBF = 11.75 Hz. Animals with chronic sinusitis had mean CBF = 8.5 Hz (p < 0.05). Six weeks after MMA, mean CBF = 11.82 Hz. This was not different from control. There were significant changes in ciliary ultrastructure when uninfected and infected rabbits were compared. These changes were reversed with MMA. Changes in ciliary ultrastructure correlated significantly with changes in CBF for all animals. Abnormalities in ciliary ultrastructure may account for the abnormal mucociliary transport clearance seen in chronic sinusitis in rabbits.