الفهرس 
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Abstract
A
sthma is a heterogenous disease, usually characterized by chronic airway inflammation. It is defined by the history of respiratory symptoms such as wheeze, shortness of breath, chest tightness and cough, that vary overtime and in intensi-ty, together with variable expiratory airflow limitation.
Asthma is typically accompanied by persistent airway inflammation and airway hyperresponsiveness to direct or indirect stimuli. Even when there are no symptoms present or lung function is normal, these characteristics typically persist; however, with treatment, they may normalize.
In various nations, asthma affects 1–18% of the popu-lation. It is a common, chronic respiratory condition. Fluc-tuating symptoms of wheezing, shortness of breath, chest tightness, and/or coughing, as well as variable expiratory airflow limitation, are characteristics of asthma. Airflow re-strictions and symptoms both typically change over time and in terms of severity.
Asthma pathophysiology can be classified into: Air-way narrowing and airway hyperresponsiveness (by edema, subepithelial fibrosis and smooth muscle hypertrophy).
Asthma can be also classified according to allergen re-sponse into: Allergic asthma (that is related to exposure to allergic food and inhalants as well as the presence of eczema or allergic rhinitis) and non-allergic asthma. Patients with non-allergic asthma frequently respond to inhaled cortico-steroids less quickly.
Asthma control is assessed by asking about the fol-lowing in the past four weeks: frequency of asthma symp-toms (days per week), any night waking due to asthma or limitation of activity and, for patients using a SABA reliev-er, frequency of its use for relief of symptoms.
Meanwhile, asthma severity is defined as : when asthma remains uncontrolled despite optimal treatment with high dose ICS-LABA, or that necessitates high dose ICS-LABA to keep it from becoming uncontrolled. Severe asth-ma must be distinguished from asthma that is difficult to treat due to insufficient or inappropriate treatment, persis-tent adherence issues, or comorbidities such as chronic rhi-nosinusitis or obesity, because the treatment implications are very different when asthma is relatively refractory to high dose ICS-LABA or even OCS.
Serum TNC is an extracellular matrix protein and a pro-inflammatory marker that is released mainly in inflammatory processes such as asthma exacerbation as well as tissue remodeling in cardiovascular events, septic conditions, and autoimmune diseases.
TNC is prototypic of the TN family and supports the migration of inflammatory cells from the interstium to the airspace. TNC expression is less prominent and more constrained in adult normal tissues, but it is noticeably enhanced in the subepithelial reticular basement membrane of the airways in asthmatic patients following allergen challenge.
Tenascin-C (TNC) was originally described as IL-4- or IL-13-induced genes in human bronchial epithelial cells. It is a glycoprotein that is secreted into the extracellular matrix.
In the bronchial mucosa of patients with atopic asthma, the density of TNC deposition significantly associated with the abundance of eosinophils, T-lymphocytes, and IL-4-positive cells.
However, serum TNC level measurement has not yet been used as an inflammatory marker for the diagnosis and severity of bronchial asthma. This study shows how serum TNC can be utilized as a marker for the diagnosis and severity of bronchial asthma by measuring serum levels of Tenascin-C in patients with bronchial asthma compared to healthy individuals and evaluating its relation to the severity of the disease.
The aim of this study is to measure serum levels of Tenascin-C in patients with bronchial asthma compared to healthy individuals and its relation to the severity of the disease.
This study is a case control study. Sixty-four known asthmatic patients were selected, aging between 18 and 60 years old, fulfilling the criteria of mild to severe asthma. Bronchial asthma was diagnosed by symptoms of airflow obstruction together with skin prick test sensitive to aeroallergens, according to GINA Main Report 2020, Severity was assessed too according to GINA Main Report 2020.
Sixty-four healthy control candidates matched with the cases according to age and sex, among hospital workers and nursing staff who are free from bronchial asthma and any other allergic diseases.
A diagnosis of COPD as well as any intercurrent pulmonary illness or fibrosis were excluded. Any intercurrent allergic disease, any end organ failure candidate was excluded as well.
Candidates were classified according to GINA latest guidelines 2022 into mild, moderate and severe cases of asthma, as well as a control group. Asthma control was also evaluated using the asthma control questionnaire.
All candidates were subjected to a complete history taking, full clinical examination and chest auscultation.
For each patient, a sample was drawn from serum to measure CBC eosinophils, CRP, total IgE. For each candidate, a pulmonary function test was done and the FEV1/FVC ratio was measured.
A skin prick test was performed for each case, at our allergy outpatient clinic in Ain Shams University hospitals. The majority of cases had atopic asthma with a sensitivity to a specific allergen, a very few number of cases had non atopic asthma with a negative skin prick test result.
Serum TNC concentrations were quantified for all candidates (patients and controls) using enzyme-linked immunosorbent assays.
Our results of the previous work revealed that: Serum TNC levels were significantly higher in patients with bronchial asthma compared to those who are non-asthmatic, with a best cut off value of 1632, above which we can consider the patient with suspicion of airflow limitation to have a confirmed bronchial asthma, with sensitivity 93.75% and specificity 60.94%, and an area under the curve of 67.9%.
Serum TNC was also higher in patients with severe asthma compared to those with mild to moderate asthma, with a statistically significant difference between the two groups, and a best cut off value of 1669, above which we can consider the patient to have a severe asthma, with sensi-tivity of 76.92% and specificity of 75%. Area under the curve being 77.7%.
Around 20% of our studied patients can be classified as having severe asthma while the rest are classified as hav-ing mild to moderate asthma. As forementioned, GINA guidelines are recently limiting the use of the word mild asthma, stressing on the fact that “mild asthma” does not guarantee the patient to be far from the possibility of serious complications.
Our study also showed that 92% of the studied pa-tients have atopic asthma, while the very small remaining portion have non atopic asthma. Also it is evident that the majority of skin test results among our patients is positive for Mites, followed by mixed pollens and mixed moulds.
Also by comparison between mild, moderate and se-vere cases regarding demographic and laboratory data; As for age, gender, blood eosinophils, lung function test, serum IgE, there was no statistically significant relation between each parameter and asthma severity.
Asthma severity, as per our results, appeared to be of no significant relation with either atopic or non atopic asthma, or with the results of skin prick tests done to patients with bronchial asthma, with an exclusion of mites and sheep wool being statistically significant present in mild cases than in severe cases of asthma.
Serum TNC level has no statistically significant relation, as per our study results, with most of the skin prick test allergens with an exception of Tobacco and Rye grass being statistically significant related to level of TNC in serum.
So mainly, our study shows that serum TNC could serve as a novel biomarker to diagnose the presence of bronchial asthma in patients with clinical suspicion of airway inflammation and obstruction. Also it shows that serum TNC can be used as a marker of severity of bronchial asthma as its level was clearly higher in patients with severe asthma compared to those with mild to moderate asthma.