Asthma is a common disease that affects 300 million people worldwide. Given the large number of eosinophils in the airways of people with mild asthma, and verified by data from murine models, asthma was long considered the hallmark T helper type 2 (T(H)2) disease of the airways. It is now known that some asthmatic inflammation is neutrophilic, controlled by the T(H)17 subset of helper T cells, and that some eosinophilic inflammation is controlled by type 2 innate lymphoid cells (ILC2 cells) acting together with basophils. Here we discuss results from in-depth molecular studies of mouse models in light of the results from the first clinical trials targeting key cytokines in humans and describe the extraordinary heterogeneity of asthma.

The immunology of asthma

Asthma has been considered a T helper 2 (T(H)2) cell-associated inflammatory disease, and T(H)2-type cytokines, such as interleukin-4 (IL-4), IL-5 and IL-13, are thought to drive the disease pathology in patients. Although atopic asthma has a substantial T(H)2 cell component, the disease is notoriously heterogeneous, and recent evidence has suggested that other T cells also contribute to the development of asthma. Here, we discuss the roles of different T cell subsets in the allergic lung, consider how each subset can contribute to the development of allergic pathology and evaluate how we might manipulate these cells for new asthma therapies.

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Functions of T cells in asthma: more than just T H 2 cells

The pathogenesis of allergic diseases entails an ineffective tolerogenic immune response to allergens. Regulatory T (Treg) cells play a key role in sustaining immune tolerance to allergens, yet mechanisms by which Treg cells fail to maintain tolerance in patients with allergic diseases are not well understood. We review current concepts and established mechanisms regarding how Treg cells regulate different components of allergen-triggered immune responses to promote and maintain tolerance. We will also discuss more recent advances that emphasize the "dual" functionality of Treg cells in patients with allergic diseases: how Treg cells are essential in promoting tolerance to allergens but also how a proallergic inflammatory environment can skew Treg cells toward a pathogenic phenotype that aggravates and perpetuates disease. These advances highlight opportunities for novel therapeutic strategies that aim to re-establish tolerance in patients with chronic allergic diseases by promoting Treg cell stability and function.

Regulatory T cells in allergic diseases.

Epithelioid hemangioendothelioma is a rare vascular tumor, described for the first time in 1975 by Dail and Liebow as an aggressive bronchoalveolar cell carcinoma. The etiology is still a dilemma. Studies about suggestive hypothesis are ongoing. Most of the times it affects lung, liver and bones, although this kind of tumor may involve the head and neck area, breast, lymph nodes, mediastinum, brain and meninges, the spine, skin, abdomen and many other sites. Because of its heterogeneous presentation, as it represents less than 1% of all the vascular tumors, it is often misdiagnosed and not suitably treated, leading to a poor prognosis in some cases. Over 50-76% of the patients are asymptomatic. A small number of them complains respiratory symptoms. Bone metastases might cause pathological fractures or spine compression, if they arise in vertebrae. Imaging is necessary to determine morphological data, the involvement of surrounding tissues, and potentially the cleavage plan. It is important to recognize the expression of vascular markers (Fli-1 and CD31 are endothelial-specific markers), and the microscopic evidence of vascular differentiation to make a correct diagnosis, as many pulmonary diseases show multiple nodular lesions. Because of its rarity, there is no standard for treatment. We focused on radiotherapy as a good therapeutic option: despite the poor prognosis, evidence is in favor of radiotherapy which offers local pain control with good tolerance and better quality of life at least at a one-year follow-up in most of cases. Further studies are needed to establish the standard radiation dose to be used for locoregional control of such a complex and extremely rare disease.

https://www.oncologyreviews.org/site/article/download/259/206

Epithelioid Hemangioendothelioma: An Overview and Update on a Rare Vascular Tumor

Background Asthma is a chronic inflammatory disease involving diverse cells and mediators whose interconnectivity and relationships to asthma severity are unclear. Objective We performed a comprehensive assessment of T H 17 cells, regulatory T cells, mucosal-associated invariant T (MAIT) cells, other T-cell subsets, and granulocyte mediators in asthmatic patients. Methods Sixty patients with mild-to-severe asthma and 24 control subjects underwent detailed clinical assessment and provided induced sputum, endobronchial biopsy, bronchoalveolar lavage, and blood samples. Adaptive and invariant T-cell subsets, cytokines, mast cells, and basophil mediators were analyzed. Results Significant heterogeneity of T-cell phenotypes was observed, with levels of IL-13–secreting T cells and type 2 cytokines increased at some, but not all, asthma severities. T H 17 cells and γδ-17 cells, proposed drivers of neutrophilic inflammation, were not strongly associated with asthma, even in severe neutrophilic forms. MAIT cell frequencies were strikingly reduced in both blood and lung tissue in relation to corticosteroid therapy and vitamin D levels, especially in patients with severe asthma in whom bronchoalveolar lavage regulatory T-cell numbers were also reduced. Bayesian network analysis identified complex relationships between pathobiologic and clinical parameters. Topological data analysis identified 6 novel clusters that are associated with diverse underlying disease mechanisms, with increased mast cell mediator levels in patients with severe asthma both in its atopic (type 2 cytokine–high) and nonatopic forms. Conclusion The evidence for a role for T H 17 cells in patients with severe asthma is limited. Severe asthma is associated with a striking deficiency of MAIT cells and high mast cell mediator levels. This study provides proof of concept for disease mechanistic networks in asthmatic patients with clusters that could inform the development of new therapies.

https://www.jacionline.org/article/S0091-6749(15)00104-9/pdf

Innate and adaptive T cells in asthmatic patients: Relationship to severity and disease mechanisms

Epithelioid haemangioendotheliomas are rare tumours of endothelial origin. They can develop in any tissue but occur principally in the lung and liver. Their usual course is a slow progression, so that they can be treated by surgery. In aggressive forms, no treatment has proved efficient to date. This study, describes a case of bilateral pleural epithelioid haemangioendothelioma that extended to the peritoneum. The histological diagnosis was confirmed by both conventional examination and immunohistochemistry. After six courses of carboplatine plus etoposide, a complete response was obtained. The complete remission is still lasting at 18 months after the diagnosis and the patient is healthy.

https://erj.ersjournals.com/content/erj/14/1/237.full.pdf

Aggressive form of pleural epithelioid haemangioendothelioma : complete response after chemotherapy

Background: Asthma exacerbations represent the main source of costs and morbidity in asthma care, and drugs specifically designed to prevent exacerbations are needed. A prerequisite is to dispose of a precise knowledge of inflammatory events leading to exacerbations.



Objective:  To study T-cell activation during exacerbations from severe refractory asthmatics.



Methods:  Proportions of blood T-cell interleukin (IL)-13, interferon-γ, IL-4, IL-5, IL-10 production and of CD4+CD25+highCD62L+CD45RO+ [T regulatory (Treg)] cells were determined by flow cytometry. Blood cytokine mRNA was studied by reverse transcription-polymerase chain reaction and the respective protein levels were determined by cytokine beads array. Depletion of Treg cells was performed to study their activation. T-cell cytokines were detected in parallel in induced sputum.



Results:  At baseline, T helper 2 (Th2) cells were increased in asthmatics, whereas T helper 1 (Th1) and Treg T cells were decreased. T helper 2 cells increased before exacerbations, followed by Th1 cells, in blood and induced sputum, albeit Treg cells decreased in parallel with IL-10-producing T cells. Concordant results were found at the mRNA level. The suppressive activity of Treg cells was impaired during exacerbations compared to baseline.



Conclusions:  New insights are given into pathophysiology of asthma exacerbations: Although at baseline T-cell activation is Th2-biased, a mixed Th1/Th2 activation occurs during exacerbations. The Treg cell deficiency found at baseline in SRA increases during exacerbations.

C. Pinet

Papers

Aggressive form of pleural epithelioid haemangioendothelioma : complete response after chemotherapy

T-cell activation during exacerbations: a longitudinal study in refractory asthma.