Understanding Asthma: Types, Triggers, and Clinical Features | Asthma and Bronchiectasis

1. f. The disease is triggered by environmental antigens, such as dusts, pollen, animal dander, and foods. g- Infections can also trigger atopic asthma. h- A skin test with the offending antigen results in an immediate wheal-and-flare reaction i- Atopic asthma also can be diagnosed based on serum radioallergosorbent tests (RASTs) that identify the presence of IgE specific for a panel of allergens.

2. 2. Non-Atopic Asthma a. No evidence of allergen sensitization, b. and skin test results usually are negative. c. A positive family history of asthma is less common. d. Respiratory infections due to viruses (e.g., rhinovirus, parainfluenza virus) and inhaled air pollutants (e.g., sulfur dioxide, ozone, nitrogen dioxide) are common triggers.

3. -It is thought that virus-induced inflammation of therespiratory mucosa lowers the threshold of the subepithelial vagal receptors to irritants. Note: -Although the connections are not well understood, the ultimate humoral and cellular mediators of airway obstruction (e.g., eosinophils) are common to both atopic and nonatopic variants of asthma, so they are treated in a similar way.

4. 3. Drug-Induced Asthma - Several pharmacologic agents provoke asthma, aspirin being the most striking example - Patients with aspirin sensitivity present with recurrent rhinitis and nasal polyps, urticaria, and bronchospasm. - The precise mechanism remains unknown, but it is presumed that aspirin inhibits the cyclooxygenase pathway of arachidonic acid metabolism without affecting the lipoxygenase route, thereby shifting the balance of production toward leukotrienes that cause bronchial spasm.

5. 4. Occupational Asthma - This form of asthma is stimulated by fumes (epoxy resins, plastics), organic and chemical dusts (wood, cotton, platinum), gases (toluene), and other chemicals. - Asthma attacks usually develop after repeated exposure to the inciting antigen(s

6. MORPHOLOGY - The morphologic changes in asthma have been described in persons who die of prolonged severe attacks (status asthmaticus) and in mucosal biopsies of persons challenged with allergens Gross: The most striking macroscopic finding is occlusion of bronchi and bronchioles by thick, tenacious mucous plugs. Histologically, a. The mucous plugs contain whorls of shed epithelium (Curschmann spirals). b. Numerous eosinophils c. Charcot-Leyden crystals (collections of crystalloids made up of eosinophil proteins) in the mucus.

7. Asthma

8. airway remodeling," include a. Thickening of airway wall Sub-basement membrane fibrosis b. Increased vascularity in submucosa c. An increase in size of the submucosal glands and goblet cell metaplasia of the airway epithelium d. Hypertrophy and/or hyperplasia of the bronchial muscle (this is the basis for the novel therapy of bronchial thermoplasty, which involves controlled delivery of thermal energy during bronchoscopy; this reduces the mass of smooth muscles which in turn reduces airway hyperresponsiveness)

9. Clinical Features - An attack of asthma is characterized by severe dyspnea with wheezing; the chief difficulty lies in expiration. - The victim labors to get air into the lungs and then cannot get it out, so that there is progressive hyperinflation of the lungs with air trapped distal to the bronchi, which are constricted and filled with mucus and debris. - In the usual case, attacks last from 1 to several hours and subside either spontaneously or with therapy, usually bronchodilators and corticosteroids

10. - Intervals between attacks are characteristically free from overt respiratory difficulties, but persistent, subtle deficits can be detected by spirometry. - Occasionally a severe paroxysm occurs that does not respond to therapy and persists for days and even weeks (status asthmaticus). - The associated hypercapnia, acidosis, and severe hypoxia may be fatal, although in most cases the condition is more disabling than lethal

11. 4.Bronchiectasis - Is the permanent dilation of bronchi and bronchioles caused by destruction of the muscle and the elastic tissue, resulting from or associated with chronic necrotizing infections. - It is not a primary disease but secondary to persisting infection or obstruction caused by a variety of conditions. - Once developed, it gives rise to a characteristic symptom complex dominated by cough and expectoration of copious amounts of purulent sputum.

12. - Diagnosis depends on an appropriate history along with radiographic demonstration of bronchial dilation. The Predisposing conditions include: 1. Bronchial obstruction and common causes are : a- Tumors, foreign bodies, and impaction of mucus. - With these conditions, the bronchiectasis is localized to the obstructed lung segment. b- Bronchiectasis can also complicate atopic asthma and chronic bronchitis. 2. Congenital or hereditary conditions

13. a. In cystic fibrosis, widespread severe bronchiectasis results from obstruction secretion of abnormally viscid mucus so predisposing to infections of the bronchi. b. In immunodeficiency states- immunoglobulin deficiencies, localized or diffuse bronchiectasis develop due to increased susceptibility to bacterial infections. c. Kartagener syndrome is an autosomal recessive disorder associated with bronchiectasis and sterility in males due to structural abnormalities of the cilia that impair mucociliary clearance in the airways, leading to persistent infections, and reduce the mobility of sperms

14. 3.Necrotizing, or suppurative, pneumonia, particularly with Staphylococcus aureus or Klebsiella spp., may predispose affected patients to development of bronchiectasis. Note: Posttuberculosis bronchiectasis continues to be a significant cause of morbidity in endemic areas. PATHOGENESIS of bronchiectasis: - Two processes are crucial in pathogenesis : obstruction and chronic infection and either of these may come first. - Normal clearance mechanisms are hampered by obstruction, so secondary infection soon follows conversely, chronic infection over time causes damage to

15. ; bronchial walls, leading to weakening and dilation. 1- For example, obstruction caused by a primary lung cancer or a foreign body impairs clearance of secretions, providing substrate for superimposed infection and the resultant inflammatory damage to the bronchial wall and the accumulating exudate further distend the airways, leading to irreversible dilation. 2- Conversely, a persistent necrotizing inflammation in the bronchi or bronchioles may cause obstructive secretions, inflammation in the wall (with peribronchial fibrosis and traction on the walls), and eventually the train of events .

16. Bronchiectasis

17. MORPHOLOGY - Bronchiectasis usually affects the lower lobes bilaterally, - When caused by tumors or foreign bodies the involvement may be localized to a single segment and the most severe involvement is in the more distal bronchi and bronchioles. Gross:The airways may be dilated to as much as four times their usual diameter and on gross examination of the lung can be followed almost to the pleural surfaces - By contrast, in normal lungs, the bronchioles cannot be followed by ordinary gross examination beyond a point 2 to 3 cm from the pleural surfaces

18. Histologic findings 1. In the full-blown active case a. An intense acute and chronic inflammatory exudate within the walls of the bronchi and bronchioles b. Desquamation and ulceration of lining epithelium. c. a mixed flora can be cultured from the involved bronchi,

19. - When healing occurs, a. The lining epithelium may regenerate completely; however,usually so much injury has occurred that abnormal dilation and scarring persist. b- Fibrosis of the bronchial and bronchiolar walls and peribronchiolar fibrosis develop in more chronic cases. c. In some instances, the necrosis destroys the bronchial or bronchiolar walls resulting in the formation of an abscess c avity within which a fungus ball may develop.

20. Clinical Features - Consist of severe, persistent cough with expectoration of mucopurulent, sometimes fetid, sputum. - The sputum may contain flecks of blood; frank hemoptysis can occur. - Symptoms often are episodic and are precipitated by upper respiratory tract infections or the introduction of new pathogenic agents. - Clubbing of the fingers may develop.

21. Complications of bronchiectasis 1- In cases of severe, widespread bronchiectasis, significant obstructive ventilatory defects are usual, with hypoxemia, hypercapnia, pulmonary hypertension, and (rarely) cor pulmonale. 2- Metastatic brain abscesses 3- Reactive amyloidosis

22. CHRONIC INTERSTITIAL (RESTRICTIVE, INFILTRATIVE) LUNG DISEASES

23. - Are a group of disorders characterized by bilateral, patchy, chronic involvement of the lung connective tissue, mainly the most peripheral and interstitium in the alveolar walls. - The interstitium is composed of basement membrane of the endothelial and epithelial cells (fused in the thinnest portions), collagen and fibers and, fibroblasts, - Many of the entities are of unknown cause , some have an intra-alveolar as well as an interstitial component, - The similarity in clinical signs, symptoms, radiographic alterations, and pathophysiologic changes justifies their consideration as a group.

24. - The hallmark feature of these disorders is reduced compliance (i.e., more pressure is required to expand the lungs because they are stiff), which in turn necessitates increased effort of breathing (dyspnea). - Chest radiographs show diffuse infiltration by small nodules, irregular lines, or "ground-glass shadows - With progression, patients can develop respiratory failure, and pulmonary hypertension and cor pulmonale - Advanced forms of these diseases may be difficult to differentiate because they result in scarring and gross destruction of the lung, referred to as "honeycomb" lung.

25. I. Fibrosing diseases

26. 1. Idiopathic pulmonary fibrosis (IPF), - Also known as cryptogenic fibrosing alveolitis, refers to a pulmonary disorder of unknown etiology. - It is characterized by patchy but progressive bilateral interstitial fibrosis, which in advanced cases results in severe hypoxemia and cyanosis. - Males are affected more often than females, - Two thirds of patients are older than 60 years of age at presentation. - The radiologic and histologic pattern of fibrosis is referred

27. to as usual interstitial pneumonia (UIP), which is required for the diagnosis of IPF. - However, similar pathologic changes in the lung may be present in well-defined entities such as asbestosis and the collagen vascular diseases. - Therefore, known causes must be ruled out before the term of idiopathic is used

28. PATHOGENESIS - IPF is caused by "repeated cycles" of epithelial activation/injury by unidentified agent - Histopathologic features include inflammation and induction of TH2 type T cell response with eosinophils, mast cells, IL-4, and IL-13 in the lesions. - Alternatively activated macrophages are important in its pathogenesis - Abnormal epithelial repair at the sites of damage and inflammation gives rise to exuberant fibroblastic or myofibroblastic proliferation leading to the characteristic

29. fibroblastic foci. a.- TGF-β1, which is released from injured type I pneumocytes induces transformation of fibroblasts into myofibroblasts leading to excessive and continuing deposition of collagen and ECM . b.- Some patients with familial IPF have mutations that shorten telomeres leading to apoptosis of pneumocytes. c.- TGF-β1 also downregulates fibroblast caveolin-1, which acts as an endogenous inhibitor of pulmonary fibrosis

30. MORPHOLOGY - The pattern of fibrosis in IPF is referred to as usual interstitial pneumonia (UIP) -The histologic hallmark of UIP is patchy interstitial fibrosis, which varies in intensity and worsens with time. - The earliest lesions demonstrate exuberant fibroblastic proliferation and appear as fibroblastic Foci - Over time these areas become more collagenous and less cellular. - Quite typical is the existence of both early and late lesions (temporal heterogeneity)

31. Usual interstitial pneumonia

32. Usual interstitial pneumonia

33. - The dense fibrosis causes collapse of alveolar walls and formation of cystic spaces lined by hyperplastic type II pneumocytes or bronchiolar epithelium (honeycomb fibrosis). - The interstitial inflammation usually is patchy and consists of an alveolar septal infiltrate of mostly lymphocytes and occasional plasma cells, mast cells, and eosinophils. - Secondary pulmonary hypertensive changes (intimal fibrosis and medial thickening of pulmonary arteries) are often present.

34. 2. Cryptogenic organizing pneumonia - Is synonymous with the previously popular designation bronchiolitis obliterans organizing pneumonia ("BOOP"); - Patients present with cough and dyspnea, and chest radiographs demonstrate subpleural or peribronchial patchy areas of air space consolidation. On histologic examination, 1 -Presence of polypoid plugs of loose organizing connective tissue within alveolar ducts, alveoli, and often bronchioles). 2.The connective tissue is all of the same age 3. The underlying lung architecture is normal.

35. Clinical Course: Some patients recover spontaneously, but most require treatment with oral steroids for 6 months or longer. Note: Organizing pneumonia with intra-alveolar fibrosis also can be seen as: a. A response to infection (pneumonia) or b. Collagen vascular disease, c. Transplantation injury - In such cases, the etiology obviously is not "cryptogenic," and the outcome is determined by the underlying disease.

36. Cryptogenic organizing pneumonia

37. 3.Pneumoconioses - Is a term originally coined to describe the non-neoplastic lung reaction to inhalation of mineral dusts. - The term has been broadened to include diseases induced by organic as well as inorganic particulates - The mineral dust pneumoconioses-the three most common of which result from exposure to : a. Coal dust, b. Silica, c. Asbestos.

38. PATHOGENESIS :The reaction of the lung to mineral dusts depends on their size shape, solubility, and reactivity -Effect of size a. 5 to 10 μm Particles are unlikely to reach distal airways, b. Particles smaller than 0.5 μm move into and out of alveoli, often without substantial deposition and injury. c. 1 to 5 μm particles are the most dangerous, because they get lodged at bifurcation of the distal airways. Reactivity 1- Coal dust is relatively inert, and large amounts must be deposited before lung disease is clinically detectable. .

39. 2. Silica, asbestos, and beryllium are more reactive than coal dust, resulting in fibrotic reactions at lower concentrations. Note: Most inhaled dust is entrapped in the mucus blanket and rapidly removed from the lung by ciliary movement,- However, some of the particles become impacted at alveolar duct bifurcations, where macrophages accumulate and engulf the trapped particulates - The alveolar macrophage is a key cellular element in the initiation and perpetuation of lung injury and fibrosis. a. Many particles activate the inflammasome and induce IL-1 b. The more reactive particles trigger the macrophages to

40. release a number of products that mediate inflammation and initiate fibroblast proliferation and collagen deposition. c. Some of the inhaled particles may reach the lymphatics either by direct drainage or within migrating macrophages and thereby initiate an immune response to components of the particulates and/or to self-proteins that are modified by the particles and This then leads to an amplification and extension of the local reaction. Note: - Tobacco smoking worsens the effects of all inhaled mineral dusts, more with asbestos than other particles.

41. A. Coal Worker's Pneumoconiosis -The spectrum of lung findings in coal workers : 1. Pulmonary anthracosis - Is the most innocuous coal-induced pulmonary lesion in coal miners and also is commonly seen in all urban dwellers and tobacco smokers. - Inhaled carbon pigment is engulfed by alveolar or interstitial macrophages, which then accumulate in the connective tissue along the lymphatics, including the pleural lymphatics, or in lymph nodes

42. - The pigment accumulates without cellular reaction 2. Simple coal worker's pneumoconiosis (CWP), - In which accumulations of macrophages occur with little to no pulmonary dysfunction, a. Coal macules :- Consists of dust-laden macrophages; b. Coal Nodules:- In addition, it contains small amounts of collagen fibers arrayed in a delicate network Note: Although these lesions are scattered throughout the lung, the upper lobes and upper zones of the lower lobes are more heavily involved.

43. 3. Complicated CWP or (PMF) : • progressive massive fibrosis (PMF), in which fibrosis is extensive and lung function is compromised and occurs on a background of simple CWP by coalescence of coal nodules and generally requires many years to develop. - Characterized by usually multiple, blackened scars larger than 2 cm, sometimes up to 10 cm in diameter. - On microscopic examination the lesions are seen to consist of dense collagen and pigment - Less than 10% of cases of simple CWP progress to PMF.

44. CWP

45. Note: - PMF is a generic term that applies to a confluent fibrosing reaction in the lung; this can be a complication of any one of the pneumoconioses Clinical Features - CWP is usually a benign disease that produces little decrement in lung function. - In those in whom PMF develops, there is increasing pulmonary dysfunction, pulmonary hypertension, and cor pulmonale.

46. - Progression from CWP to PMF has been linked to a variety of conditions including coal dust exposure level and total dust burden. - Unfortunately, PMF has a tendency to progress even in the absence of further exposure. Note: - Once smoking-related risk has been taken into account, there is no increased frequency of lung carcinoma in coal miners, a feature that distinguishes CWP from both silica and asbestos exposures .

47. B. Silicosis - Silicosis is currently the most prevalent chronic occupational disease in the world and caused by inhalation of crystalline silica, mostly in occupational settings. - Workers in sandblasting and hard-rock mining are at particular risk. Silica Forms a. Crystalline (including quartz, cristobalite, and tridymite) are by far the most toxic and fibrogenic. - Of these, quartz is most commonly implicated in silicosis b. amorphous forms

48. Pathogenesis - After inhalation the particles interact with epithelial cells and macrophages and Ingested silica particles cause release of mediators by macrophages, including IL-1, TNF, lipid mediators, ROS and fibrogenic cytokines. • anti-TNF monoclonal antibodies can block lung fibrosis in mice that are given silica intratracheally. - When mixed with other minerals, quartz has been observed to have a reduced fibrogenic effect. This phenomenon is of practical importance, because quartz in the workplace is rarely pure

49. MORPHOLOGY Silicotic nodules :Characterized grossly in early stages by barely palpable, discrete, pale-to-blackened (if coal dust is also present) nodules in the upper zones of the lungs. Microscopically, - The silicotic nodule shows concentrically arranged hyalinized collagen fibers surrounding amorphous center. - The "whorled" appearance of the collagen fibers is quite distinctive for silicosis - Polarized microscopy reveals weakly birefringent silica particles, primarily in the center of the nodules

50. silicosis