Pulmonary lymphatic vessel morphology: a review

Our understanding of lymphatic vessels has been advanced by the recent identification of relatively specific lymphatic endothelium markers, including Prox-1, VEGFR3, podoplanin and LYVE-1. The use of lymphatic markers has led to the observation that, contrary to previous assumptions, human lymphatic vessels extend deep inside the pulmonary lobule, either in association with bronchioles, intralobular arterioles or small pulmonary veins. Pulmonary lymphatic vessels may thus be classified into pleural, interlobular (in interlobular septa) and intralobular. Intralobular lymphatic vessels may be further subdivided in: bronchovascular (associated with a bronchovascular bundle), perivascular (associated with a blood vessel), peribronchiolar (associated with a bronchiole), and interalveolar (in interalveolar septa). Most of the intralobular lymphatic vessels are in close contact with a blood vessel, either alone or within a bronchovascular bundle. A minority is associated with a bronchiole, and small lymphatics are occasionally present even in interalveolar septa, seemingly independent of blood vessels or bronchioles. The lymphatics of the interlobular septa often contain valves, are usually associated with the pulmonary veins, and connect with the pleural lymphatics. The large lymphatics associated with bronchovascular bundles have similar characteristics to pleural and interlobular lymphatics and may be considered conducting vessels. The numerous small perivascular lymphatics and the few peribronchiolar ones that are found inside the lobule are probably the absorbing compartment of the lung responsible for maintaining the alveolar interstitium relatively dry in order to provide a minimal thickness of the air-blood barrier and thus optimize gas diffusion. These lymphatic populations could be differentially involved in the pathogenesis of diseases preferentially involving distinct lung compartments.

Elevated nocturnal desaturation index predicts mortality in interstitial lung disease

BACKGROUND

Nocturnal desaturation may contribute to long-term pulmonary vascular stress in interstitial lung disease (ILD). We study the prevalence, severity and prognostic utility of nocturnal desaturation across ILD.

METHODS

ILD patients with overnight oximetry (June 2006-August 2008) were reviewed (n = 134). Significant nocturnal desaturation was considered as > 10% of sleep with SpO2 < 90%. Desaturation index (DI) was defined as the number of desaturation events > 4%/hr. Covariates, including indices of nocturnal desaturation, were evaluated against mortality.

RESULTS

Nocturnal desaturation was present in 49 (37%) patients. 31% of patients had pulmonary hypertension (PH) on echocardiography. Increased DI was associated with higher mortality independent of age, gender and BMI (HR 1.04; 95% CI 1.00, 1.06; p = 0.009). In separate models, DI and a) elevated brain natriuretic peptide (BNP; HR 1.04; 95% CI 1.00, 1.08; p = 0.04); b) moderate-severe PH on echocardiography (HR 3.15; 95% CI 1.24, 8.00; p = 0.02); and c) daytime resting SpO2 (HR 0.92; 95% CI 0.85, 0.99; p = 0.04) independently predicted mortality following adjustment for age, gender and BMI.

CONCLUSION

Nocturnal desaturation is common and may be severe in ILD. Elevated nocturnal DI predicts higher mortality across ILD, independent of other vascular parameters. This finding may have important implications for the pathogenesis of PH in IPF.

Significance of connective tissue disease features in idiopathic interstitial pneumonia

In idiopathic interstitial pneumonia (IIP), the significance of connective tissue disease (CTD) features in the absence of a specific CTD diagnosis remains unclear. We studied the clinical and prognostic utility of a diagnosis of undifferentiated CTD (UCTD) in patients with biopsy-proven IIP. IIP patients undergoing surgical lung biopsy (1979-2005) were studied (nonspecific interstitial pneumonia (NSIP), n = 45; idiopathic pulmonary fibrosis, n = 56). UCTD was considered present when serum autoantibodies were present and symptoms or signs suggested CTD. The relationship between UCTD and NSIP histology was evaluated. A clinical algorithm that best predicted NSIP histology was constructed using a priori variables. The prognostic utility of UCTD, and of this algorithm, was evaluated. UCTD was present in 14 (31%) NSIP and seven (13%) IPF patients. UCTD was not associated with a survival benefit. The algorithm predictive of NSIP (OR 10.4, 95% CI 3.21-33.67; p<0.0001) consisted of the absence of typical high-resolution computed tomography (HRCT) features for IPF and 1) a compatible demographic profile (females aged <50 yrs) or 2) Raynaud's phenomenon. In patients with an HRCT scan not typical for IPF, this algorithm predicted improved survival (hazard ratio 0.35, 95% CI 0.14-0.85; p = 0.02) independent of IIP severity. UCTD is associated with NSIP histology. However, the diagnostic and prognostic significance of UCTD in IIP patients remains unclear.

Genetic mutations in surfactant protein C are a rare cause of sporadic cases of IPF

BACKGROUND

While idiopathic pulmonary fibrosis (IPF) is one of the most common forms of interstitial lung disease, the aetiology of IPF is poorly understood. Familial cases of pulmonary fibrosis suggest a genetic basis for some forms of the disease. Recent reports have linked genetic mutations in surfactant protein C (SFTPC) with familial forms of pulmonary fibrosis, including one large family in which a number of family members were diagnosed with usual interstitial pneumonitis (UIP), the pathological correlate to IPF. Because of this finding in familial cases of pulmonary fibrosis, we searched for SFTPC mutations in a cohort of sporadic cases of UIP and non-specific interstitial pneumonitis (NSIP).

METHODS

The gene for SFTPC was sequenced in 89 patients diagnosed with UIP, 46 patients with NSIP, and 104 normal controls.

RESULTS

Ten single nucleotide polymorphisms in the SFTPC sequence were found in IPF patients and not in controls. Only one of these created an exonic change resulting in a change in amino acid sequence. In this case, a T to C substitution resulted in a change in amino acid 73 of the precursor protein from isoleucine to threonine. Of the remaining polymorphisms, one was in the 5' UTR, two were exonic without predicted amino acid sequence changes, and six were intronic. One intronic mutation suggested a potential enhancement of a splicing site.

CONCLUSIONS

Mutations in SFTPC are identified infrequently in this patient population. These findings indicate that SFTPC mutations do not contribute to the pathogenesis of IPF in the majority of sporadic cases.

Distribution of novel polymorphisms of the interleukin-8 and CXC receptor 1 and 2 genes in systemic sclerosis and cryptogenic fibrosing alveolitis

OBJECTIVE

To search for single-nucleotide polymorphisms in the interleukin-8 (IL-8) and IL-8 receptor CXCR-1 and CXCR-2 genes, and to compare their distribution among patients with systemic sclerosis (SSc) with fibrosing alveolitis (FASSc) or without fibrosing alveolitis (NFASSc), or patients with cryptogenic fibrosing alveolitis (CFA), and normal healthy subjects.

METHODS

Fifty control subjects were screened for potential polymorphisms by using polymerase chain reaction in association with sequence-specific primers incorporating mismatches at the 3' end. The novel polymorphisms were subsequently examined in British Caucasian subjects, including 194 healthy controls, 71 patients with CFA, and 128 patients with SSc who were further subdivided into 78 FASSc patients and 50 NFASSc patients.

RESULTS

Three novel biallelic polymorphisms were identified in the IL-8 gene (all in noncoding areas of the gene), 1 was found in the CXCR-1 gene (resulting in a conservative amino acid change), and 3 were observed in the CXCR-2 gene, of which the first resulted in a silent codon change and the others were in the 3' untranslated area of exon 3. Compared with controls, a significant increase in the frequency of the CXCR-2 +785 CC homozygote and of the CXCR-2 +1208 TT homozygote was found in the SSc patients (37% versus 22% [P = 0.01] and 33% versus 17% [P = 0.003], respectively). A subgroup analysis revealed this association to be significant both in the FASSc patients and in the NFASSc patients.

CONCLUSION

This report describes an association between SSc and 2 polymorphisms occurring close to each other in the CXCR-2 gene. This finding and its functional significance need to be confirmed and analyzed in future studies.

Distribution of novel polymorphisms of the interleukin-8 and CXC receptor 1 and 2 genes in systemic sclerosis and cryptogenic fibrosing alveolitis

OBJECTIVE

To search for single-nucleotide polymorphisms in the interleukin-8 (IL-8) and IL-8 receptor CXCR-1 and CXCR-2 genes, and to compare their distribution among patients with systemic sclerosis (SSc) with fibrosing alveolitis (FASSc) or without fibrosing alveolitis (NFASSc), or patients with cryptogenic fibrosing alveolitis (CFA), and normal healthy subjects.

METHODS

Fifty control subjects were screened for potential polymorphisms by using polymerase chain reaction in association with sequence-specific primers incorporating mismatches at the 3' end. The novel polymorphisms were subsequently examined in British Caucasian subjects, including 194 healthy controls, 71 patients with CFA, and 128 patients with SSc who were further subdivided into 78 FASSc patients and 50 NFASSc patients.

RESULTS

Three novel biallelic polymorphisms were identified in the IL-8 gene (all in noncoding areas of the gene), 1 was found in the CXCR-1 gene (resulting in a conservative amino acid change), and 3 were observed in the CXCR-2 gene, of which the first resulted in a silent codon change and the others were in the 3' untranslated area of exon 3. Compared with controls, a significant increase in the frequency of the CXCR-2 +785 CC homozygote and of the CXCR-2 +1208 TT homozygote was found in the SSc patients (37% versus 22% [P = 0.01] and 33% versus 17% [P = 0.003], respectively). A subgroup analysis revealed this association to be significant both in the FASSc patients and in the NFASSc patients.

CONCLUSION

This report describes an association between SSc and 2 polymorphisms occurring close to each other in the CXCR-2 gene. This finding and its functional significance need to be confirmed and analyzed in future studies.

Consumption of fresh fruit rich in vitamin C and wheezing symptoms in children. SIDRIA Collaborative Group, Italy (Italian Studies on Respiratory Disorders in Children and the Environment)

BACKGROUND

A beneficial effect of fresh fruit consumption on lung function has been observed in several studies. The epidemiological evidence of the effect on respiratory symptoms and asthma is limited. The consumption of fruit rich in vitamin C was examined in relation to wheezing and other respiratory symptoms in cross sectional and follow up studies of Italian children.

METHODS

Standardised respiratory questionnaires were filled in by parents of 18 737 children aged 6-7 years living in eight areas of Northern and Central Italy. The winter intake of citrus fruit and kiwi fruit by the children was categorised as less than once per week, 1-2 per week, 3-4 per week, and 5-7 per week. A subset of 4104 children from two areas was reinvestigated after one year using a second parental questionnaire to record the occurrence of wheezing symptoms over the intervening period.

RESULTS

In the cross sectional analysis, after controlling for several confounders (sex, study area, paternal education, household density, maternal smoking, paternal smoking, dampness or mould in the child's bedroom, parental asthma), intake of citrus fruit or kiwi fruit was a highly significant protective factor for wheeze in the last 12 months (odds ratio (OR) = 0.66, 95% confidence intervals (CI) 0.55 to 0.78, for those eating fruit 5-7 times per week compared with less than once per week), shortness of breath with wheeze (OR = 0.68, 95% CI 0.56 to 0.84), severe wheeze (OR = 0.59, 95% CI 0.40 to 0.85), nocturnal cough (OR = 0.73, 95% CI 0.65 to 0.83), chronic cough (OR = 0.75, 95% CI 0.65 to 0.88), and non-coryzal rhinitis (OR = 0.72, 95% CI 0.63 to 0.83). In the follow up study fruit intake recorded at baseline was a strong and independent predictor of all symptoms investigated except non-coryzal rhinitis. In most cases the protective effect was evident even among children whose intake of fruit was only 1-2 times per week and no clear dose-response relationship was found. The effect was stronger (although not significantly so (p = 0.13)) in subjects with a history of asthma; those eating fresh fruit at least once a week experienced a lower one year occurrence of wheeze (29. 3%) than those eating fruit less than once per week (47.1%) (OR = 0. 46, 95% CI 0.27 to 0.81).

CONCLUSIONS

Although the effect of other dietary components cannot be excluded, it is concluded that the consumption of fruit rich in vitamin C, even at a low level of intake, may reduce wheezing symptoms in childhood, especially among already susceptible individuals.

The impact of parental smoking on asthma and wheezing. SIDRIA Collaborative Group. Studi Italiani sui Disturbi Respiratori nell'Infanzia e l'Ambiente

To evaluate the impact of parental smoking on childhood asthma and wheezing, we studied two random samples of subjects ages 6-7 and 13-14 years in ten areas of northern and central Italy. Standardized questionnaires were completed by parents of 18,737 children and 21,068 adolescents (response rates, 92.8% and 96.3%, respectively) about their smoking habits and the respiratory health of their children. Adolescents were asked about their respiratory health and personal smoking. We compared two groups of cases with healthy subjects: (1) "current asthma" (children, 5.2%; adolescents, 6.2%) and (2) "current wheezing" not labeled as asthma (children = 4.5%, adolescents = 8.5%). Exposure to smoke of at least one parent increased the relative risk of current asthma among children [odds ratio (OR) = 1.34; 95% confidence interval (CI) = 1.11-1.62] and of current wheezing among adolescents (OR = 1.24; 95% CI = 1.07-1.44). Maternal smoking had a stronger effect than paternal smoking. Maternal smoking during pregnancy was associated with current asthma (OR = 1.62; 95% CI = 1.34-1.96) and current wheezing in children (OR = 1.31; 95% CI = 1.06-1.62); the effects were lower among adolescents. Among subjects with a negative history of parental asthma, maternal smoking was associated with current wheezing in both age groups, whereas among those with a positive history of parental asthma it was associated with current asthma in children, but not in adolescents. We estimated that 15% (95% CI = 12-19) of the current asthma cases among children and 11% (95% CI = 8.3-14) of the current wheezing cases among adolescents are attributable to parental smoking in Italy.

Risk factors for early, persistent, and late-onset wheezing in young children. SIDRIA Collaborative Group

Wheezing in childhood is not a single disorder and different wheezing-associated respiratory illnesses have been recently described. We investigated the association between wheezing conditions and familial, pre-, peri-, and postnatal risk factors. We studied 16,333 children, 6 to 7 yr old, enrolled in a population-based study. Standardized questionnaires were filled in by parents. A total of 1,221 children had transient early wheezing, 671 had persistent wheezing, 918 had late-onset wheezing, and 13,523 never had wheezing or asthma (control group). Maternal asthma or chronic obstructive airway disease were significantly (p < 0.0001) more associated with persistent wheezing than with transient early and late-onset wheezing. The same pattern was observed for exposure to maternal smoke during pregnancy. Having a mother > 35 yr old was protective against transient early wheezing (odds ratio [OR]: 0.68, 95% confidence intervals [95% CI]: 0.53 to 0.86). Breast feeding >/= 6 mo was slightly protective against transient early wheezing (OR: 0.82, 95% CI: 0.68 to 0.97), whereas it was a moderate risk factor for late-onset wheezing (OR: 1.22, 95% CI: 0.99 to 1.50). On the contrary, having siblings and attending a day care center were both risk factors for transient early wheezing (OR: 1.41 [95% CI: 1.21 to 1.64] and 1.70 [95% CI: 1.48 to 1.96], respectively) and protective factors against wheezing of late onset (OR: 0.83 [95% CI: 0.70 to 0.97] and 0.72 [95% CI: 0.59 to 0.88]). There was a stronger (p < 0.0001) positive association between personal history of eczema or allergic rhinitis and persistent and late-onset wheezing than transient early wheezing. Our findings suggest a different contribution of risk factors to wheezing conditions in childhood.

Differences in parental- and self-report of asthma, rhinitis and eczema among Italian adolescents. SIDRIA collaborative group. Studi Italiani sui Disordini Respiratori dell' Infanzia e l'Ambiente

Epidemiological and clinical information on respiratory and allergic disorders in adolescents has been collected from the adolescents themselves or from their parents, but little is known about the differences between these two sources of information. This study compared the responses to 10 identically worded questions from the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire on asthma, rhinitis and eczema between written self- and parent-completed questionnaires in a large sample of 21,068 adolescent Italians aged 13-14 yrs. The effects of sex, latitude of residence, urbanization, socioeconomic status, previous diagnosis of asthma, family history of allergic diseases and adolescent's smoking habits on the prevalence estimates obtained with the two questionnaires were analysed using multiple logistic regression. Prevalence of self-reported symptoms was significantly higher in self-reported for all questions except for lifetime eczema, which was higher in parental report. Agreement between the two sources of information was poor, although it was slightly better for questions relative to clinical diagnosis of asthma, hay fever or eczema than for related symptoms, and for respiratory with respect to cutaneous disorders. When compared with self-reported, parent-reported was consistently higher in males and was more affected by socioeconomic level and by a diagnosis of asthma or family history of allergic diseases, whereas self-reported was more sensitive to the effect of the adolescent's smoking habits. It is concluded that, in adolescents, parent- and self-reported respiratory and allergic symptoms differ significantly and are differently affected by several constitutional and environmental factors. Obtaining direct information from adolescents may be essential for a correct evaluation of respiratory symptoms.

Road traffic and adverse respiratory effects in children. SIDRIA Collaborative Group

OBJECTIVES

To investigate the relation between traffic indicators in the area of residence and the occurrence of chronic respiratory disorders in children.

METHODS

A population based survey was conducted in 10 areas of northern and central Italy (autumn 1994 to winter 1995) in two age groups (6-7 and 13-14 years). Information on several respiratory disorders and on traffic near residences was collected with a questionnaire given to children and to their parents. The sample analysed included 39,275 subjects (response rate 94.4%). Outcomes were: (a) early (first 2 years of life) respiratory diseases, and (b) current respiratory disorders (asthma, wheeze, cough, or phlegm in the past year). Odds ratios (ORs) and 95% confidence intervals (95% CIs), adjusted for several potential confounders, were estimated from logistic regression models. Main results were stratified by level of urbanisation (metropolitan areas, other centres).

RESULTS

In the metropolitan areas, high frequency of lorry traffic in the street of residence was associated with significantly increased risks for many adverse respiratory outcomes. Among early respiratory diseases, the strongest associations were found for recurrent bronchitis (OR 1.69, 95% CI 1.24 to 2.30), bronchiolitis (1.74, 1.09 to 2.77) and pneumonia (1.84, 1.27 to 2.65), although no association was detected for episodes of wheezing bronchitis. All the current respiratory disorders were positively and consistently associated with frequency of lorry traffic, particularly the most severe bronchitic and wheezing symptoms: persistent phelgm for > 2 months (1.68; 1.14 to 2.48), and severe wheeze limiting speech (1.86; 1.26 to 2.73). No or weaker associations with heavy vehicular traffic were detected in urban and rural areas and no increased risks were found in the whole sample with the reported traffic density in the zone of residence. After extensive evaluations, the potential of reporting bias seems unlikely.

CONCLUSION

Exposure to exhausts from heavy vehicular traffic may have several adverse effects on respiratory health of children living in metropolitan areas, increasing the occurrence of lower respiratory tract infections early in life and of wheezing and bronchitic symptoms at school age.

Clinical, laboratory and radiological findings in pulmonary fibrosis with and without connective tissue disease

Uncertainty exists over whether to consider "lone" idiopathic pulmonary fibrosis (LIPF) and pulmonary fibrosis associated with connective tissue disorders (PFCTD) as significantly different entities. We retrospectively analysed data collected at the time of first diagnosis in 17 patients with LIPF and in 14 patients with PFCTD and compared survival in the two groups. At first evaluation, the time from onset of respiratory symptoms, spirometric volumes and the diffusing capacity for carbon monoxide were not significantly different between the two groups. However, arterial oxygen tension was significantly lower in LIPF than in PFCTD (63 +/- 3 vs 88 +/- 3 mmHg, p < 0.001). The radiological profusion scores relative to the upper and middle lung fields were significantly higher in LIPF than in PFCTD (upper regions: 6.9 +/- 0.6 vs 3.4 +/- 0.6, p < 0.005 - middle regions: 7.1 +/- 0.5 vs 4.8 +/- 0.7, p < 0.025), whereas the scores relative to the lower fields were similar (7.4 +/- 0.4 in LIPF and 8.4 +/- 0.6 in PFCTD). Survival since onset of respiratory symptoms was significantly better in the PFCTD than in LIPF patients, with a hazard ratio of 4.16 (95% CI 1.12-15.58, p=0.034). Thus, in our series of patients, those with LIPF had a more severe disease than those with PFCTD as shown by the higher frequency of hypoxaemia, the more diffuse pulmonary involvement demonstrated by the chest X-ray and the decreased survival.

Multimedia presentation of lung sounds as a learning aid for medical students

New educational technologies might help to compensate for the decrease in time and emphasis dedicated to physical examination in medical training. This may, in particular, be applicable for improving the skills in auscultation of the chest. We investigated whether a multimedia presentation of acoustic and graphic characteristics of lung sounds could improve the learning of pulmonary auscultation by medical students, in comparison with conventional teaching methods. We studied 48 medical students without clinical experience, who had received conventional formal teaching on chest examination. Chest auscultation skills were evaluated using an inaccuracy score for the student's auscultation report on three patients, selected according to a standardized procedure. After a baseline evaluation, 27 students in groups of 5-10, participated in a multimedia seminar on lung sounds during which digitized lung sounds were played and the corresponding time-expanded waveform and frequency spectrum were commented on and displayed on a computer. The remaining 21 students received conventional bedside training, acting as control group. The following week, all the students underwent a second evaluation of chest auscultation skills. No differences in the inaccuracy score were observed between the two groups in the preliminary test. However, in the second postintervention assessment, the inaccuracy score of the students who had followed the seminar (11.2 +/- 1.3 points) was significantly lower than that of the controls (16.6 +/- 1.6 points). The answers to a feedback questionnaire confirmed that the great majority of the students found the association of the acoustic signals with their visual image to be useful for learning and understanding lung sounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Multimedia presentation of lung sounds as a learning aid for medical students

New educational technologies might help to compensate for the decrease in time and emphasis dedicated to physical examination in medical training. This may, in particular, be applicable for improving the skills in auscultation of the chest. We investigated whether a multimedia presentation of acoustic and graphic characteristics of lung sounds could improve the learning of pulmonary auscultation by medical students, in comparison with conventional teaching methods. We studied 48 medical students without clinical experience, who had received conventional formal teaching on chest examination. Chest auscultation skills were evaluated using an inaccuracy score for the student's auscultation report on three patients, selected according to a standardized procedure. After a baseline evaluation, 27 students in groups of 5-10, participated in a multimedia seminar on lung sounds during which digitized lung sounds were played and the corresponding time-expanded waveform and frequency spectrum were commented on and displayed on a computer. The remaining 21 students received conventional bedside training, acting as control group. The following week, all the students underwent a second evaluation of chest auscultation skills. No differences in the inaccuracy score were observed between the two groups in the preliminary test. However, in the second postintervention assessment, the inaccuracy score of the students who had followed the seminar (11.2 +/- 1.3 points) was significantly lower than that of the controls (16.6 +/- 1.6 points). The answers to a feedback questionnaire confirmed that the great majority of the students found the association of the acoustic signals with their visual image to be useful for learning and understanding lung sounds.(ABSTRACT TRUNCATED AT 250 WORDS)