Lactate in cystic fibrosis sputum

BACKGROUND

Antibiotic therapy is thought to improve lung function in patients with cystic fibrosis (CF) by decreasing neutrophil-derived inflammation. We investigated the origin and clinical significance of lactate in the chronically inflamed CF lung.

METHODS

Lactate was measured in sputa of 18 exacerbated and 25 stable CF patients via spectrophotometry and gaschromatography. Lung function was assessed via spirometry. Seven patients with chronic obstructive pulmonary disease (COPD) and three patients with acute lung inflammation served as control groups. Neutrophil and bacterial lactate production was assessed under aerobic and anaerobic conditions.

RESULTS

In sputum specimens of patients with respiratory exacerbations lactate concentrations decreased significantly (p<0.005) from 3.4±2.3mmol/L to 1.4±1.4mmol/L after 2-3 weeks of intravenous antibiotics. Successful treatment was reflected in 16 patients (88.9%) by FVC increase associated with lactate decrease (p<0.05). In every single sputum lactate was detectable (3.0±3.1mmol/L, range 0.2-14.1mmol/L). Lactate was lower (1.6±0.8mmol/L) in sputa from seven COPD patients, and it was below the detection limit in three patients with acute lung inflammation. Neutrophil lactate production accumulated up to 10.5mmol/L after 4 days, whereas bacterial lactate production did not appear to contribute substantially to sputum lactate concentrations.

CONCLUSIONS

Successful antibiotic therapy is reflected by a decrease in lactate concentrations. Neutrophils are the most likely source for lactate in sputum of CF patients. Therefore lactate may be used to monitor responses to antibiotic therapy as an adjunct to lung function measurements.

Musculoskeletal manifestations and rheumatic symptoms in patients with cystic fibrosis (CF) no observations of CF-specific arthropathy

OBJECTIVE

To determine the character and frequency of musculoskeletal manifestations and rheumatic symptoms in patients with cystic fibrosis (CF).

METHODS

Rheumatic symptoms and signs of 70 patients with CF (age 6 to 61 yrs) were determined by interview and clinical assessment. Age and sex-matched healthy volunteers served as a control group. In CF patients, laboratory measures and bone mineral density (BMD) were investigated. The data were correlated with the CF phenotype [Shwachman Score (ShS), Chrispin-Norman Score (ChNS), and pulmonary function tests (PFT)].

RESULTS

The prevalence of joint pain in the CF patients was 12.9%, with a mean duration of 7 days. Swollen joints were found in 4 patients. None fulfilled the criteria for rheumatoid arthritis or connective tissue disease. Adult CF patients complained more often about noninflammatory back pain and myalgia, and demonstrated reduced spine mobility and impaired everyday life functions compared with the controls. Symptomatic CF patients had elevated erythrocyte sedimentation rate and C-reactive protein levels and performed worse on the ShS, ChNS, and PFT than asymptomatic patients. Antibodies against exotoxin A of Pseudomonas aeruginosa and recombinant Aspergillus fumigatus allergen f4 were found more frequently in CF patients with arthralgia. BMD was decreased in adult patients with more severe CF.

CONCLUSION

In CF patients, the prevalence of rheumatic symptoms increases with age and CF severity. Our data suggest an association of infections with P. aeruginosa and A. fumigatus with the occurrence of rheumatic symptoms. However, no association of CF with definite inflammatory joint or connective tissue diseases was observed, and no CF-specific pattern of musculoskeletal symptoms was seen.