Value of fractional exhaled nitric oxide (FE NO) for the diagnosis of pulmonary involvement due to inflammatory bowel disease

Update of gut gas metabolism in ulcerative colitis

INTRODUCTION

Ulcerative colitis (UC) is a chronic, nonspecific inflammatory disease of the intestine. The intestinal microbiota is essential in the occurrence and development of UC. Gut gases are produced via bacterial fermentation or chemical interactions, which can reveal altered intestinal microbiota, abnormal cellular metabolism, and inflammation responses. Recent studies have demonstrated that UC patients have an altered gut gas metabolism.

AREAS COVERED

In this review, we integrate gut gas metabolism advances in UC and discuss intestinal gases' clinical values as new biomarkers or therapeutic targets for UC, providing the foundation for further research. Literature regarding gut gas metabolism and its significance in UC from inception to October 2023 was searched on the MEDLINE database and references from relevant articles were investigated.

EXPERT OPINION

Depending on their type, concentration, and volume, gut gases can induce or alleviate clinical symptoms and regulate intestinal motility, inflammatory responses, immune function, and oxidative stress, significantly impacting UC. Gut gases may function as new biomarkers and provide potential diagnostic or therapeutic targets for UC.

Lung Involvement in Patients with Ulcerative Colitis: Relationship between Exhaled Nitric Oxide and Lung Function

Ulcerative colitis (UC) is characterized by immune system dysregulation with frequent extraintestinal manifestations, including airway involvement. A reduction in CO diffusing capacity and functional alterations in small airways have been described. An extended analysis of fractional exhaled nitric oxide (FeNO) may distinguish the sites of production, and the presence of small airway inflammation may be a useful, non-invasive marker for patient follow-up. The aim of our study was to compare the PFTs as well as FeNO and CANO values of UC patients with different clinical disease activities and healthy subjects to reveal lung function abnormalities and the presence of subclinical airway inflammation. We enrolled 42 adult outpatients at different clinical activity stages of UC (39 ± 13 years) and a healthy control group of 41 subjects (29 ± 3 years). C-reactive protein (CRP) and FeNO values at different flows (50,100, and 200 mL/s) were collected. All patients performed pulmonary function tests (PFTs) with static volumes and diffusing capacity (DLCO). FeNO and CANO values were significantly increased in UC patients when compared with controls (p = 0.0008 and p < 0.0001, respectively) and were proportional to disease activity (FeNO class 3: 28.1 ppb vs. classes 1-2: 7.7 ppb; CANO values class 3: 8.6 ppb vs. classes 1-2: 2.7 ppb (p < 0.0001)). TLC and DLCO were significantly reduced in severe (Mayo 3) UC patients (p = 0.010 and p = 0.003, respectively). The results of this study show significant lung functional abnormalities in UC patients and suggest the presence of airway inflammation directly correlated with disease activity, suggesting the need for an integrated approach in routine assessment.

Lung Involvement in Inflammatory Bowel Diseases: Shared Pathways and Unwanted Connections

Inflammatory bowel diseases (IBDs) are chronic, relapsing inflammatory disorders of the gastrointestinal tract, frequently associated with extraintestinal manifestations (EIMs) that can severely affect IBD patients' quality of life, sometimes even becoming life-threatening. Respiratory diseases have always been considered a rare and subsequently neglected extraintestinal manifestations of IBD. However, increasing evidence has demonstrated that respiratory involvement is frequent in IBD patients, even in the absence of respiratory symptoms. Airway inflammation is the most common milieu of IBD-related involvement, with bronchiectasis being the most common manifestation. Furthermore, significant differences in prevalence and types of involvement are present between Crohn's disease and ulcerative colitis. The same embryological origin of respiratory and gastrointestinal tissue, in addition to exposure to common antigens and cytokine networks, may all play a potential role in the respiratory involvement. Furthermore, other causes such as drug-related toxicity and infections must always be considered. This article aims at reviewing the current evidence on the association between IBD and respiratory diseases. The purpose is to raise awareness of respiratory manifestation among IBD specialists and emphasize the need for identifying respiratory diseases in early stages to promptly treat these conditions, avoid worsening morbidity, and prevent lung damage.

Pulmonary Function in Paediatric Patients with Inflammatory Bowel Disease

BACKGROUND

Among the extraintestinal manifestations of inflammatory bowel disease (IBD), those involving the lungs are relatively rare and often overlooked. There are only scarce data on the prevalence of IBD-associated lung involvement in children.

OBJECTIVES

The aim of our study was to assess pulmonary function in IBD children by different methods and to evaluate the influence of immunosuppressive therapy on disease severity.

METHODS

Seventy-two children with IBD (mean age of 14.45 ± 2.27 years) and 40 age-matched healthy controls (mean age of 14.17 ± 2.82) were included in the study. Pulmonary function tests (PFTs) were carried out by means of spirometry, oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) to assess the pulmonary involvement.

RESULTS

Certain differences were observed between the study group and the control group, regarding the spirometric and oscillometry parameters. The fractions of exhaled nitric oxide did not differ between the group with IBD patients and the control group with regards to disease activity, the duration of illness and the administered immunosuppressive treatment.

CONCLUSIONS

The mean spirometry results were significantly different in the study group compared to the controls, although they were still within the normal limits. The pulmonary function abnormalities did not depend on either the disease activity or the immunosuppressive therapy. Oscillometry could be a supplementary method to assess pulmonary resistance. In turn, FeNO does not appear to be useful either in screening IBD children for pulmonary involvement or for the evaluation of disease activity. It appears then that only general screening of asymptomatic patients is a suitable method and a necessary recommendation in this population, prompting a revision of the current diagnostic approach.

Role of pulmonary function testing in inflammatory bowel diseases (Review)

Inflammatory bowel disease (IBD) is a term used to describe chronic inflammatory entities of the gastrointestinal system with an unclear etiology. Extra-intestinal manifestations beyond the involvement of the gastrointestinal tract can also occur. Several studies have investigated the alterations of pulmonary function tests (PFTs) in patients with IBD. To the best of our knowledge, the present review article is the first to summarize all the types of PFTs that have been performed in patients with IBD. Contradictory data exist regarding the association of PFT alterations with disease activity. PFT abnormalities can develop in individuals with IBD who have no clear clinical signs or radiological evidence, suggesting that PFTs may be useful in detecting latent respiratory involvement. The most prevalent finding in the PFTs of adults and children with IBD is an impairment in the diffusing capacity for carbon monoxide, although evidence on the other tests, particularly spirometric values, and their connection with disease activity is inconsistent.

Elevated Levels of Alveolar Nitric Oxide May Indicate Presence of Small Airway Inflammation in Patients with Inflammatory Bowel Disease

INTRODUCTION

Pulmonary manifestations of inflammatory bowel disease (IBD), albeit not rare, are largely overlooked in clinical practice. The role of exhaled nitric oxide (eNO) as an established biological marker of airway inflammation compels us to use it as a tool to investigate the exact nature of these manifestations.

METHODS

Fractional eNO (FeNO) was measured in multiple flows, and with the use of a mathematical model, alveolar concentration of NO (C_ANO) and bronchial flux of NO (J_awNO) were assessed in 27 patients with IBD [17 with Crohn's disease (CD) and 10 with ulcerative colitis (UC)] and in 39 healthy controls. Carefully selected criteria were used to exclude patients or healthy controls that presented factors considered to be correlated with eNO measurements. Disease activity was measured in Crohn's patients using the CD activity index (CDAI) score and in UC using the partial Mayo score.

RESULTS

C_ANO was significantly higher in the IBD group, compared to the control group (p < 0.0001). FeNO was significantly increased in patients with IBD (p = 0.023), while there was no statistical significance found regarding levels of J_awNO in patients with IBD (p = 0.106), both compared to controls. There was no significant correlation between any eNO component and markers of disease activity.

CONCLUSIONS

Alveolar concentration of NO is elevated in patients with IBD, regardless of disease activity. This may suggest that subclinical small airway inflammation is present in patients with IBD, even those with mild or inactive disease.

Paediatric and adult bronchiectasis: Specific management with coexisting asthma, COPD, rheumatological disease and inflammatory bowel disease

Bronchiectasis, conventionally defined as irreversible dilatation of the bronchial tree, is generally suspected on a clinical basis and confirmed by means of chest high-resolution computed tomography. Clinical manifestations, including chronic productive cough and endobronchial suppuration with persistent chest infection and inflammation, may deeply affect quality of life, both in children/adolescents and adults. Despite many cases being idiopathic or post-infectious, a number of specific aetiologies have been traditionally associated with bronchiectasis, such as cystic fibrosis (CF), primary ciliary dyskinesia or immunodeficiencies. Nevertheless, bronchiectasis may also develop in patients with bronchial asthma; chronic obstructive pulmonary disease; and, less commonly, rheumatological disorders and inflammatory bowel diseases. Available literature on the development of bronchiectasis in these conditions and on its management is limited, particularly in children. However, bronchiectasis may complicate the clinical course of the underlying condition at any age, and appropriate management requires an integration of multiple skills in a team of complementary experts to provide the most appropriate care to affected children and adolescents. The present review aims at summarizing the current knowledge and available evidence on the management of bronchiectasis in the other conditions mentioned and focuses on the new therapeutic strategies that are emerging as promising tools for improving patients' quality of life.

Psoriasis and Respiratory Comorbidities: The Added Value of Fraction of Exhaled Nitric Oxide as a New Method to Detect, Evaluate, and Monitor Psoriatic Systemic Involvement and Therapeutic Efficacy

Psoriasis is a chronic inflammatory systemic disease characterized by a wide range of comorbidities. Respiratory comorbidities are currently poorly characterized and with discordant results. The systemic state of inflammation caused by psoriasis acts de novo on respiratory tissues and amplifies preexisting inflammation from asthma or chronic obstructive pulmonary disease. Because the lungs act as a gas exchanger between the internal and external environment, the impact of chronic psoriasis inflammation may be easily assessed through the analysis of exhaled breath. The fraction of exhaled nitric oxide test (FeNO) is a potential noninvasive solution that can provide quantitative and qualitative indices of respiratory airway inflammation. FeNO is routinely used to screen and manage asthmatic patients. Recent pilot studies contain encouraging data that underscore its possible use with systemic inflammatory nonpulmonary diseases, such as psoriasis. FeNO may therefore be a useful tool to evaluate underestimated airway inflammation and at the same time globally evaluate the impact of systemically antipsoriatic therapies.

Pulmonary functions in children with inflammatory bowel disease

OBJECTIVE

To investigate fractional exhaled nitric-oxide (FeNO) levels in children with Crohn's disease (CD) and ulcerative colitis (UC) and their correlation to disease activity.

MATERIALS AND METHODS

Children with CD and UC (aged 8-18 years) and age-matched healthy controls without respiratory symptoms were recruited. Disease activity was assessed using validated scores. All children performed spirometry and FeNO tests and the association between intestinal disease parameters and pulmonary functions was studied.

RESULTS

Thirty-five children with CD, nine with UC, and 24 healthy controls were enrolled. The mean FeNO level was higher in children with CD compared with the controls. Increased FeNO levels (>23 parts per billion) were more common among CD and UC compared with healthy children (46, 33, and 0%, respectively, P<0.05). Nevertheless, FeNO levels did not correlate with disease activity. There were no significant differences between CD, UC patients, and healthy controls in any of the spirometric variables.

CONCLUSION

FeNO level, a marker of airway inflammation, is elevated in children with inflammatory bowel diseases irrespective of their intestinal disease activity. Increased FeNO levels are not associated with respiratory symptoms, suggesting a latent pulmonary involvement in the systemic disease.

Measurement of Fractional Exhaled Nitric Oxide as a Marker of Disease Activity in Inflammatory Bowel Disease

BACKGROUND AND AIMS

Definitive diagnosis of IBD requires endoscopic and pathologic confirmation. These tools are also used to classify disease activity. Our aim was to determine if the fractional exhaled nitric oxide (FeNO) could be utilized to screen for IBD and assess for disease activity.

METHODS

We matched weighted IBD cases and controls from the 2009-2010 NHANES dataset. All subjects underwent measurement of FeNO using standardized techniques. We assessed for potential confounders for FeNO measurement including age, height, and asthma. For IBD subjects, we used the presence of diarrhea, fatigue, and weight loss as a proxy for IBD activity. Laboratory parameters examined to estimate disease activity included anemia (≤ 10 g/dl), iron deficiency (ferritin ≤ 20 ng/ml), hypoalbuminemia (≤ 3.2 g/dl), and CRP (≥ 1.1 mg/dl).

RESULTS

The weighted sample represented 199,414,901 subjects. The weighted prevalence of IBD was 2,084,895 (1.0%). IBD subjects had nearly the same FeNO level as those without IBD (17.0 ± 16.2 vs. 16.7 ± 14.5 ppb). The odds of a FeNO > 25 ppb was half (OR=0.501; 95% CI 0.497-0.504) for subjects with IBD compared to those without IBD after controlling for confounders. The AUROC curve for FeNO was 0.47 (0.35-0.59). FeNO levels were not higher in patients with laboratory values suggestive of active disease. FeNO levels were higher in IBD patients with diarrhea, rectal urgency, and fatigue but were lower in those with unintentional weight loss.

CONCLUSION

Measurement of FeNO does not appear to be useful to screen for IBD or assess disease activity.

Pulmonary Function Test Abnormalities in Pediatric Inflammatory Bowel Disease

BACKGROUND

Pulmonary involvement in adult patients with inflammatory bowel disease (IBD) seems more common than previously appreciated. Its prevalence and development over time in pediatric IBD patients are largely unknown.

OBJECTIVES

The aim was to study lung function including fraction of exhaled nitric oxide (FeNO) and transfer capacity for carbon monoxide (TLCO) in pediatric IBD patients and to describe the longitudinal development in a subset of patients with lung function abnormalities.

METHODS

Sixty-six measurements were made in 48 IBD patients (30 patients with Crohn's disease and 18 with ulcerative colitis) and 108 matched controls. Patients with abnormal TLCO or elevated residual volume/total lung capacity (RV/TLC) ratios were invited for a follow-up. Statistical comparisons were made by nonparametric tests and ANOVA.

RESULTS

TLCO was decreased in IBD patients [median: 88% predicted (interquartile range, IQR, 22) vs. 99% predicted (IQR 19) in controls]. RV/TLC ratios were mildly elevated in patients with ulcerative colitis [32% (IQR 9) vs. 27% (IQR 8) in controls], and maximum expiratory flows at 50 and 25% of vital capacity were mildly reduced in patients with Crohn's disease. FeNO and disease activity did not correlate with lung function abnormalities. Abnormalities did not consistently persist over a median follow-up period of 34 months.

CONCLUSIONS

This study supports evidence that variable and fluctuating pulmonary involvement also occurs in pediatric IBD patients. Its clinical significance is unclear.

Inflammatory cytokines in exhaled breath condensate in children with inflammatory bowel diseases

BACKGROUND

Although inflammatory bowel diseases (IBD) affect mainly the gastrointestinal tract, the extra-intestinal manifestations are not uncommon. Different diagnostic methods have been applied to assess pulmonary involvement in patients with IBD, but majority of these methods show significant limitations in children. The aim of our study was to evaluate the usefulness of exhaled breath condensate (EBC) measurements of pro-inflammatory cytokines in children with IBD.

MATERIAL AND METHODS

Twenty-two children with Crohn's disease (CD) (mean age 13.8 ± 3.3 years), 25 with ulcerative colitis (UC) (mean age 14.1 ± 3.3 years) and 37 healthy volunteers (mean age 13.9 ± 3.6 years) were studied. IBD activity was assessed using appropriate scoring systems. None of the patients had signs or symptoms of pulmonary disease. Exhaled breath condensate was collected and EBC concentration of interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin 8 (IL-8) was measured.

RESULTS

The concentrations of all the assessed cytokines were significantly higher in the study group as compared to controls. A negative correlation between IL-1β and CD activity index was found. There were no significant relationships between TNF-α, IL-6, or IL-8 level and CD activity index as well as between IL-1β, TNF-α, IL-6, IL-8 and UC activity index. No significant correlation between the concentration of IL-1β, TNF-α, IL-6, IL-8, and IBD duration or treatment duration was found.

CONCLUSIONS

Elevated concentration of pro-inflammatory cytokines in EBC in children with IBD may suggest the presence of asymptomatic inflammation in the lower airways.

Pulmonary manifestations of Crohn’s disease

Crohn’s disease (CD) is a systemic illness with a constellation of extraintestinal manifestations affecting various organs. Of these extraintestinal manifestations of CD, those involving the lung are relatively rare. However, there is a wide array of lung manifestations, ranging from subclinical alterations, airway diseases and lung parenchymal diseases to pleural diseases and drug-related diseases. The most frequent manifestation is bronchial inflammation and suppuration with or without bronchiectasis. Bronchoalveolar lavage findings show an increased percentage of neutrophils. Drug-related pulmonary abnormalities include disorders which are directly induced by sulfasalazine, mesalamine and methotrexate, and opportunistic lung infections due to immunosuppressive treatment. In most patients, the development of pulmonary disease parallels that of intestinal disease activity. Although infrequent, clinicians dealing with CD must be aware of these, sometimes life-threatening, conditions to avoid further impairment of health status and to alleviate patient symptoms by prompt recognition and treatment. The treatment of CD-related respiratory disorders depends on the specific pattern of involvement, and in most patients, steroids are required in the initial management.

Hand-held fractional exhaled nitric oxide measurements as a non-invasive indicator of systemic inflammation in Crohn's disease

BACKGROUND AND AIMS

Active inflammatory bowel disease (IBD) is associated with increased activity of inducible nitric oxide synthase (iNOS), which increases both mucosal and plasma nitric oxide (NO) levels. Increased fractional exhaled nitric oxide (FeNO) levels have been described in patients with IBD. Currently, hand-held FeNO measurement devices are available, enabling a fast in-office analysis of this non-invasive disease activity marker. In this pilot study, we investigated the utility of in-office FENO measurements in patients with Crohn's disease (CD).

METHODS

Fifty CD patients and 25 healthy controls (HC) were included, all of whom were free of atopic or pulmonary disorders and respiratory symptoms at the time of inclusion. The Crohn's disease activity index (CDAI) was calculated, and the inflammatory parameters and fecal calprotectin levels were assessed. FeNO was measured with a hand-held device.

RESULTS

A significant increase in FeNO (median, [interquartile range]) was observed in steroid-free CD patients with clinically active disease (CDAI>150; 22 [8] ppb) compared with CD patients in clinical remission (CDAI<150; 11 [6] ppb; P<0.001) and HC's (17 [9] ppb; P<0.05). Active CD patients treated with corticosteroids had significantly lower FeNO compared with active CD patients without steroids (12 [10] ppb vs 25 [19] ppb; P<0.05). FeNO displayed a strong correlation with the CDAI (R=0.68; P<0.001). Fair correlations were found between FeNO and several systemic inflammatory markers, but no significant correlation was found with fecal calprotectin.

CONCLUSION

This pilot study suggests that hand-held FeNO measurements could be an attractive non-invasive indicator of systemic inflammation in Crohn's disease.

Bronchial reactivity and fractional exhaled NO in Crohn's disease in the era of immunomodulating treatment

AIM

Our aim was to determine bronchial hyper-responsiveness (BHR) and fractional exhaled NO (FeNO) in a cohort followed and treated for Crohn's disease (CD) in a Pediatric Gastroenterology Unit.

METHODS

Consecutive children with CD were referred to the Pediatric Pulmonary Unit. Each patient completed a questionnaire, followed by spirometry, methacholine challenge test (MCT) and determination of FeNO. The control group included patients evaluated for functional cough who had negative MCT.

RESULTS

Twenty-three children and young adults (mean age, 17.39 ± 2.96 years) with CD were compared to 24 healthy controls. 20/23 patients received immunomodulating treatment. Forced expiratory volume in 1 sec (FEV1) was significantly lower prior to (93.74 ± 10.81%, p = 0.009) and at the end of (78.91 ± 18.39%, p = 0.001) the MCT in the CD group compared with the control group (102.2 ± 10.477% and 95.33 ± 11.075%, respectively). Bronchial hyper-responsiveness was observed in 30.4% of patients with CD. FeNO levels were 15.37 ± 24.17 in CD and 11.38 ± 5.42 in the control group (p = 0.21). Neither the response to MCT nor FeNO levels were affected by the disease duration or activity index.

CONCLUSION

In our series, BHR is less frequent than previously described in children with CD. We hypothesize that our finding could result from immunomodulating treatments or lower disease activity.

Exhaled nitric oxide (FENO) in non-pulmonary diseases

Exhaled nitric oxide (F(E)NO) represents the only exhaled biomarker that has reached clinical practice even in primary care settings, due to the non-invasiveness of its assessment and ease of repeat measurements, even in patients with severe airflow obstruction. While F(E)NO has been suggested as a readily determined biomarker that can aid in the diagnosis and management of asthma, its potential role in pathophysiology of non-pulmonary diseases is less clear and therefore remains to be established. The purpose of the present review is to highlight the current literature investigating the use of F(E)NO in the diagnosis and management of non-pulmonary diseases.

Exhaled nitric oxide as a marker of lung involvement in Crohn&#x0027;s disease

Crohn's disease is an inflammatory bowel disease associated with a variety of systemic manifestations, including large and small airway involvement. The latter is most often a subclinical one, and requires expensive and invasive diagnostic approaches. Nitric oxide (NO) can be detected non-invasively in the exhaled air (eNO) and be considered as a surrogate marker of airway inflammation. eNO tested at multiple expiratory flows can be used to distinguish the alveolar concentration of NO (CalvNO) from the total amount of fractional eNO (FeNO). The aim of our study is to compare FeNO and concentration of alveolar nitric oxide (CalvNO) levels and to assess their relationship with pulmonary involvement in Crohn's patients differing in clinical stage and therapeutic regimens versus a group of healthy subjects. Thirty Crohn's patients not showing clinical evidence of pulmonary diseases and 21 non-smoking, non-atopic healthy controls were enrolled. FeNO (14.9±10.2 ppb vs 10.1±6.3 ppb, p=0.049) and CalvNO (4.4±2.2 ppb vs 2.6±1.9; p=0.006) values were found to be significantly higher in Crohn's patients than in healthy controls. Both FeNO and CalvNO correlated positively with the Crohn's Disease Activity Index. In conclusion, our results for FeNO and CalvNO confirm the presence of subclinical pulmonary involvement in Crohn's disease. eNO measurement may be of clinical value in the follow-up of Crohn's patients.