Francesco Borriello

Evidence of the transient nature of the Th17 phenotype of CD4+CD161+ T cells in the synovial fluid of patients with juvenile idiopathic arthritis

OBJECTIVE To investigate the phenotype and function of CD4+ T cells in synovial fluid (SF) from the affected joints of children with oligoarticular-onset juvenile idiopathic arthritis (JIA), and to establish a possible link with disease activity. METHODS CD4+ T cells were obtained from the peripheral blood (PB) and SF of 23 children with oligoarticular-onset JIA, as well as from the PB of 15 healthy children. The cells were analyzed for the expression of CXCR3, CCR6, and CD161 and for the production of interferon-γ and interleukin-17A (IL-17A). Spectratyping and clonotype analyses were performed to assess different T cell subsets. RESULTS The numbers of CD4+CD161+ cells showing either the Th1 or the Th17/Th1 phenotype were higher in the SF than in the PB of children with JIA. The few Th17 cells from JIA SF underwent a spontaneous shift to the Th1 phenotype in vitro, whereas Th17 cells from the PB of healthy children shifted only in the presence of JIA SF; this effect was neutralized by antibody blockade of IL-12 activity. Spectratyping and clonotype analyses showed a similar skewing of the T cell receptor V(β) repertoire in both CD161+ Th17 cells and CD161+ Th1 cells derived from the SF of the same JIA patient. The frequencies of CD4+CD161+ cells, particularly the Th17/Th1 cells, in the JIA SF positively correlated with the erythrocyte sedimentation rate and levels of C-reactive protein. CONCLUSION These findings suggest that a shifting of CD4+CD161+ T cells from Th17 to the Th17/Th1 or Th1 phenotype can occur in the SF of children with oligoarticular-onset JIA, and indicate that the accumulation of these cells is correlated with parameters of inflammation. Thus, the results support the hypothesis that these cells may play a role in JIA disease activity.

Interleukin-5 pathway inhibition in the treatment of eosinophilic respiratory disorders: evidence and unmet needs

Purpose of reviewHuman eosinophils were first identified and named by Paul Ehrlich in 1879 on the basis of the cells granular uptake of eosin. Although eosinophils represent approximately 1% of peripheral blood leukocytes, they have the propensity to leave the blood stream and migrate into inflamed tissues. Eosinophils and their mediators are critical effectors to asthma and eosinophilic granulomatosis with polyangiitis (EGPA). Eosinophils are equipped with a large number of cell-surface receptors and produce specific cytokines and chemokines. Recent findingsEosinophils are the major source of interleukin-5 and highly express the interleukin-5R&agr; on their surface. Clinical trials evaluating monoclonal antibodies to interleukin-5 (mepolizumab and reslizumab) and its receptor interleukin-5R&agr; (benralizumab) have been or are underway in patients with eosinophilic asthma, EGPA and chronic obstructive pulmonary disease (COPD). Overall, targeting interleukin-5/interleukin-5R&agr; is associated with a marked decrease in blood and sputum eosinophilia, the number of exacerbations and improvement of some clinical parameters in adult patients with severe eosinophilic asthma. Pilot studies suggest that mepolizumab might be a glucocorticoid-sparing treatment in patients with EGPA. A preliminary study found that benralizumab did not reduce the exacerbations and did modify lung function in patients with eosinophilic COPD. SummaryThe review examines recent advances in the biology of eosinophils and how targeting the interleukin-5 pathway might offer benefit to some patients with severe asthma, EGPA, and COPD. Interleukin-5/interleukin-5R&agr;-targeted treatments offer promises to patients with eosinophilic respiratory disorders.

Histamine Receptors and Antihistamines: From Discovery to Clinical Applications

The synthesis and the identification of histamine marked a milestone in both pharmacological and immunological research. Since Sir Henry Dale and Patrick Laidlaw described some of its physiological effects in vivo in 1910, histamine has been shown to play a key role in the control of gastric acid secretion and in allergic disorders. Using selective agonists and antagonists, as well as molecular biology tools, four histamine receptors (H1R, H2R, H3R and H4R) have been identified. The Nobel Prize in Physiology and Medicine was awarded to Daniel Bovet in 1957 for the discovery of antihistamines (anti-H1R) and to Sir James Black in 1988 for the identification of anti-H2R antagonists. Anti-H1R and anti-H2R histamine receptor antagonists have revolutionized the treatment of certain allergic disorders and gastric acid-related conditions, respectively. More recently, anti-H3R antagonists have entered early-phase clinical trials for possible application in obesity and a variety of neurologic disorders. The preferential expression of H4R by several immune cells and its involvement in the development of allergic inflammation provide the rationale for the use of anti-H4R antagonists in allergic and in other immune-related disorders.

Basophils and Skin Disorders

Since their discovery in 1879, basophils have been viewed as circulating blood granulocytes with limited immune function. New research tools for their functional analysis in vivo have revealed previously unrecognized roles for basophils in several skin disorders. Human basophils infiltrate different skin lesions and have been implicated in the pathogenesis of diseases ranging from chronic idiopathic urticaria to systemic lupus erythematosus. In mouse models, basophils participate in IgE-mediated chronic allergic inflammation of the skin and have a protective role in tick infestation. In this review, we discuss critical advances in our understanding of basophil biology and their roles in the pathophysiology of skin disorders.

Basophils: historical reflections and perspectives.

Basophils were discovered by Paul Ehrlich in 1879 and account for less than 1% of blood leukocytes, which suggests a tightly controlled regulation of basopoiesis. The conservation of basophils in a wide spectrum of the animal kingdom suggests a non-redundant role in innate and adaptive immunity. In the early 1990s, it was demonstrated that murine and human basophils synthesize interleukin (IL)-4 and IL-13, thereby suggesting that these cells are important for Th2 polarization and IgE synthesis. Human basophils also synthesize IL-3, VEGFs and other pro-angiogenic molecules. Recently, various groups have introduced the use of basophil-depleting antibodies or have developed transgenic mice that constitutively lack basophils by more than 90%. These models have highlighted previously unrecognized roles of basophils, distinct from those played by mast cells, in innate and adaptive immunity. Although the physiologic role of basophils remains unknown, there is now compelling evidence that basophils, despite their small numbers in peripheral blood and inflamed tissues, are critically involved in a wide spectrum of immunologic disorders (allergic, autoimmune and infectious diseases, immunodeficiencies and cancer). It is not inconceivable that basophils and/or their products could be promising therapeutic targets for such disorders.

Human lung-resident macrophages express CB1 and CB2 receptors whose activation inhibits the release of angiogenic and lymphangiogenic factors

Macrophages are pivotal effector cells in immune responses and tissue remodeling by producing a wide spectrum of mediators, including angiogenic and lymphangiogenic factors. Activation of cannabinoid receptor types 1 and 2 has been suggested as a new strategy to modulate angiogenesis in vitro and in vivo. We investigated whether human lung‐resident macrophages express a complete endocannabinoid system by assessing their production of endocannabinoids and expression of cannabinoid receptors. Unstimulated human lung macrophage produce 2‐arachidonoylglycerol, N‐arachidonoyl‐ethanolamine, N‐palmitoyl‐ethanolamine, and N‐oleoyl‐ethanolamine. On LPS stimulation, human lung macrophages selectively synthesize 2‐arachidonoylglycerol in a calcium‐dependent manner. Human lung macrophages express cannabinoid receptor types 1 and 2, and their activation induces ERK1/2 phosphorylation and reactive oxygen species generation. Cannabinoid receptor activation by the specific synthetic agonists ACEA and JWH‐133 (but not the endogenous agonist 2‐arachidonoylglycerol) markedly inhibits LPS‐induced production of vascular endothelial growth factor‐A, vascular endothelial growth factor‐C, and angiopoietins and modestly affects IL‐6 secretion. No significant modulation of TNF‐α or IL‐8/CXCL8 release was observed. The production of vascular endothelial growth factor‐A by human monocyte‐derived macrophages is not modulated by activation of cannabinoid receptor types 1 and 2. Given the prominent role of macrophage‐assisted vascular remodeling in many tumors, we identified the expression of cannabinoid receptors in lung cancer‐associated macrophages. Our results demonstrate that cannabinoid receptor activation selectively inhibits the release of angiogenic and lymphangiogenic factors from human lung macrophage but not from monocyte‐derived macrophages. Activation of cannabinoid receptors on tissue‐resident macrophages might be a novel strategy to modulate macrophage‐assisted vascular remodeling in cancer and chronic inflammation.

T follicular helper (Tfh ) cells in normal immune responses and in allergic disorders.

Follicular helper T cells (Tfh) are located within germinal centers of lymph nodes. Cognate interaction between Tfh, B cells, and IL‐21 drives B cells to proliferate and differentiate into plasma cells thereby leading to antibody production. Tfh cells and IL‐21 are involved in infectious and autoimmune diseases, immunodeficiencies, vaccination, and cancer. Human peripheral blood CXCR5+ CD4+ T cells comprise different subsets of Tfh‐like cells. Despite the importance of the IgE response in the pathogenesis of allergic disorders, little is known about the role of follicular and blood Tfh cells and IL‐21 in human and experimental allergic disease. Here, we review recent advances regarding the phenotypic and functional characteristics of both follicular and blood Tfh cells and of the IL‐21/IL‐21R system in the context of allergic disorders.

IL-3 synergises with basophil-derived IL-4 and IL-13 to promote the alternative activation of human monocytes

Basophil‐derived IL‐4 is involved in the alternative activation of mouse monocytes, as recently shown in vivo. Whether this applies to human basophils and monocytes has not been established yet. Here, we sought to characterise the interaction between basophils and monocytes and identify the molecular determinants. A basophil‐monocyte co‐culture model revealed that IL‐3 and basophil‐derived IL‐4 and IL‐13 induced monocyte production of CCL17, a marker of alternative activation. Critically, IL‐3 and IL‐4 acted directly on monocytes to induce CCL17 production through histone H3 acetylation, but did not increase the recruitment of STAT5 or STAT6. Although freshly isolated monocytes did not express the IL‐3 receptor α chain (CD123), and did not respond to IL‐3 (as assessed by STAT5 phosphorylation), the overnight incubation with IL‐4 (especially if associated with IL‐3) upregulated CD123 expression. IL‐3‐activated JAK2‐STAT5 pathway inhibitors reduced the CCL17 production in response to IL‐3 and IL‐4, but not to IL‐4 alone. Interestingly, monocytes isolated from allergen‐sensitised asthmatic patients exhibited a higher expression of CD123. Taken together, our data show that the JAK2‐STAT5 pathway modulates both basophil and monocyte effector responses. The coordinated activation of STAT5 and STAT6 may have a major impact on monocyte alternative activation in vitro and in vivo.

Immunopharmacological modulation of mast cells

Mast cells produce a wide spectrum of mediators and they have been implicated in several physiopathological conditions (e.g. allergic reactions and certain tumors). Pharmacologic agents that modulate the release of mediators from mast cells has helped to elucidate the biochemical mechanisms by which immunological and non-immunological stimuli activate these cells. Furthermore, the study of surface receptors and signaling pathways associated with mast cell activation revealed novel pharmacologic targets. Thus, the development of pharmacologic agents based on this new wave of knowledge holds promise for the treatment of several mast cell-mediated disorders.

Group V secreted phospholipase A2 induces the release of proangiogenic and antiangiogenic factors by human neutrophils

Secreted phospholipases A2 (sPLA2s) are extracellular enzymes that catalyze the release of free fatty acids and lysophospholipids from membrane phospholipids and also bind to different receptors (e.g., PLA2R1 or integrins). To date, 12 mammalian sPLA2s have been identified, which play a critical role in pathophysiological processes including inflammation and cancer. sPLA2s activate immune cells such as human neutrophils (PMNs) by enzymatic activity- or receptor-mediated mechanisms. In addition, human PMNs synthesize and store human group V (hGV) and human group X (hGX) sPLA2s in their granules, but only the former is released upon cellular activation. We investigated the effects of sPLA2s on the release of proangiogenic and antiangiogenic factors by PMNs. We found that exogenous hGV and hGX sPLA2s induce the release of vascular endothelial growth factor (VEGF)-A, angiopoietin 1 (Ang1), and CXCL8/IL-8. Only hGV induces the secretion of the antiangiogenic isoform of VEGF-A, namely, VEGF-A165b. While the release of VEGF-A, Ang1, and CXCL8/IL-8 was likely mediated by hGV enzymatic activity and/or binding to PLA2R1 and heparan sulfate proteoglycans, the release of VEGF-A165b requires the interaction with αVβ3 and α4β1 integrins. We also provide evidence that endogenous hGV released by N-formyl-met-leu-phe (fMLF)-activated PMNs is involved in the release of angiogenic factors. The translational relevance of these data is supported by our findings that hGV expression is increased in human samples of lung cancer which are infiltrated by PMNs. Overall, our results suggest that the hGV–neutrophil axis may play a relevant role in the modulation of cancer-related inflammation and angiogenesis.