View Point: Semaphorin-3E: An Emerging Modulator of Natural Killer Cell Functions?

Semaphorin-3E (Sema-3E) is a member of a large family of proteins originally identified as axon guidance cues in neural development. It is expressed in different cell types, such as immune cells, cancer cells, neural cells, and epithelial cells. Subsequently, dys-regulation of Sema-3E expression has been reported in various biological processes that range from cancers to autoimmune and allergic diseases. Recent work in our laboratories revealed a critical immunoregulatory role of Sema-3E in experimental allergic asthma. We further speculate possible immune modulatory function(s) of Sema-3E on natural killer (NK) cells

Thymic Stromal Lymphopoietin Is Critical for Regulation of Proinflammatory Cytokine Response and Resistance to Experimental Trypanosoma congolense Infection

African trypanosomiasis (sleeping sickness) poses serious threat to human and animal health in sub-Saharan Africa. Because there is currently no vaccine for preventing this disease and available drugs are not safe, understanding the mechanisms that regulate resistance and/or susceptibility to the disease could reveal novel targets for effective disease therapy and prevention. Thymic stromal lymphopoietin (TSLP) plays a critical role in driving Th2 immune response. Although susceptibility to experimental Trypanosoma congolense infection in mice is associated with excessive proinflammatory responses due in part to impaired Th2 response, the role of TSLP in resistance to African trypanosomiasis has not been well studied. Here, we investigated whether TSLP is critical for maintaining Th2 environment necessary for survival of T. congolense-infected mice. We observed an increased TSLP level in mice after infection with T. congolense, suggesting a role for this cytokine in resistance to the infection. Indeed, TSLPR−/− mice were more susceptible to T. congolense infection and died significantly earlier than their wild-type (WT) controls. Interestingly, serum levels of IFN-γ and TNF-α and the frequency of IFN-γ- and TNF-α-producing CD4+ T cells in the spleens and liver were significantly higher in infected TSLPR−/− mice than in the WT control mice. Susceptibility was also associated with excessive M1 macrophage activation. Treatment of TSLPR−/− mice with anti-IFN-γ mAb during infection abolished their enhanced susceptibility to T. congolense infection. Collectively, our study shows that TSLP plays a critical role in resistance to T. congolense infection by dampening the production of proinflammatory cytokines and its associated M1 macrophage activation

Pentraxin 3: An Immuno-regulator in the Lungs

Pentraxin-3 (PTX3), is a soluble pattern recognition receptor (PRR) and constitutes humoral component of the innate immune system. It interacts with pathogenic moieties, infected and dying host cells and facilitates their removal through activation of appropriate innate and adaptive mechanisms. PTX3 is secreted by a diverse variety of cells, ranging from immune cells to structural cells, in response to toll like receptor (TLR) engagement, inflammatory stimuli, physical and chemical stress. Further, PTX3 plays an essential role in female fertility as it facilitates the organization of extracellular matrix in cumulus oophorus. Such activity is also implicated in post-inflammation tissue repair. Altogether, PTX3 is a multifunctional protein and plays a non-redundant role in providing immunity against potential immunological dangers. Hence, it would be noteworthy to assess its role in lung immunity, as lungs are at a constant risk of infections and tissue damage attributable to perpetual exposure to foreign agents in air

No evidence for IgE receptor FcεRI expression on bronchial epithelial cells of asthmatic patients

Immunoglobulin E (IgE) plays an important role in the pathogenesis of asthma and anti-IgE therapy was approved for treating patients with severe persistent allergic asthma. The exact target sites of anti-IgE therapy are not well characterized; however, it has been proposed that the therapeutic effects of anti-IgE come from its intervention in the airway remodeling process. To gain insights on how anti-IgE therapy improves asthma symptoms, we aimed to validate the expression of FcεRI on airway epithelial cells and demonstrate its role in airway remodeling. The expression of FcεRI was measured (1) in situ in bronchial biopsy tissues of asthmatic and control subjects using immunohistochemistry and (2) in vitro in primary bronchial epithelial cells obtained from asthmatic subjects, at baseline and after treatment with human IgE, using qPCR and flow cytometry. FcεRI expression in situ was detected only in a very small number of cells in the epithelium of bronchial biopsies of asthmatic and control subjects. In vitro measurement revealed no expression of the receptor both at baseline and after stimulation with IgE. The release of transforming growth factor—beta (TGF)-β and thymic stromal lymphopoietin (TSLP) were examined by ELISA in bronchial epithelial cells after crosslinking of IgE. No significant differences in TSLP and TGF-β protein levels were detected between stimulated and unstimulated cells. Hence, our data conclusively indicate that bronchial epithelial cells have negligible expression of functional high affinity receptor for IgE. Taken together, anti-IgE therapy is very likely to exert its therapeutic effects via other structural cell types