Reinforcing involvement of NK cells in psoriasiform dermatitis animal model

Psoriasis (Ps) is a chronic inflammatory immune-mediated disease with skin and joint manifestations, characterized by abnormal and rapid proliferation of keratinocytes and infiltration of psoriatic lesions with immune cells. Extensive literature suggests that Ps is a T-cell mediated disease its pathogenesis being highly related to innate and adaptative immune cells. Although natural killer (NK) cells are involved in the inflammatory process of Ps through pro-inflammatory cytokine secretion (tumor necrosis factor α, interferon γ), their role in this pathology is not yet fully elucidated. In order to study the involvement of NK subpopulations in the pathogenesis of Ps we used the imiquimod-based mouse model of psoriasiform dermatitis and NK cells complex phenotype patterns from peripheral blood (PB) and spleen were investigated. Skin inflammation and the disease severity were assessed using in vivo measurements (erythema, desquamation and induration parameters, PASI modified score), splenomegaly assessment and histopathological evaluation. Phenotypic characterization of NK cells in imiquimod (IMQ)-treated mice was performed by flow cytometry, for both PB and spleen cell suspension. A large panel of surface markers was used: maturation and activation markers [cluster of differentiation (CD)49b, CD11b, CD43, CD27, KLRG1, CD335, CD69, CD28, gp49R, CD45R, CD11c] and markers for cytokine receptors (CD25, CD122, CD132). Our experimental data showed important differences in IMQ-treated mouse NK cell phenotype as compared to control group. The maturation markers (CD11b, CD43, CD27, KLRG1) were found increased on NK cells, in periphery and spleen, while CD49b⁺NK1.1⁺ was significantly lower, and the alterations correlated with the severity of the disease. Our findings reflect the immune engagement toward activatory profile of NK cells and draw attention to evaluating Ps intensity correlated with the mature profile of circulating NK cells.

Peripheral immune cell markers in children with recurrent respiratory infections in the absence of primary immunodeficiency

The immune system of a child has a degree of immaturity that is maintained until 6–7 years of age. Immaturity may be due to age-related functional disorders in the immune response. A healthy child can contract a series of infections which contribute to the maturation of the immune system during the pre-pubertal period. If repeated infections with prolonged or severe complications occur during childhood, the presence of an immunodeficiency should then be considered. Much more frequent than primary immunodeficiency are recurrent infections (frequently involving the upper respiratory tract), which are less severe and occur under the conditions of an immune system with no apparent major defects. A child can present with 4 to 8 episodes of respiratory infections within a year, during the first 5 years of its life. The average duration of infection is 8 days and up to 2 weeks; if the child presents with 3 episodes of acute infections over a period of 6 months, the respiratory infections are then considered recurrent. The aim of this study was to identify the immunological changes or deviations that cause this clinical syndrome in children. For this purpose, 30 children with recurrent respiratory infections and 10 healthy children were included. Immunoglobulin levels were examined and immunophenotyping was performed. We found that the serum immunoglobulin levels were in the normal range in 70% of the children. On the contrary, our data revealed changes in peripheral cell populations, the most important being the decrease in the T-cluster of differentiation (CD)8⁺ and total B cell percentages and the increase in the number of memory B cells. The data obtained herein indicated that the decrease in the number of total B cells was mainly due to the decrease in the number of naive IgD⁺ B cells. On the whole, the findings of this study indicate that recurrent respiratory infections may be associated with an altered cellular immune response. In such situations, the investigation of immunological parameters, such as T and B cell subtypes could complete the clinical diagnosis and guide the treatment strategy, thus increasing the quality of life of patients.

Natural killer cell monitoring in cutaneous melanoma - new dynamic biomarker

Melanoma is responsible for most skin cancer deaths in humans. The immune system plays a major role in regulating tumor cell proliferation by initiating defence responses against tumor aggression. Research on murine cancer models allow for a better understanding of immune response in malignancies, revealing specific changes of the immune status in the presence of tumors. Melanoma resistance to conventional therapies and its high immunogenicity justify the development of new therapies. These features reinforce melanoma as a suitable model for studying antitumor immunity. Recent findings on NK cell activation in cancer patients indicate that several important parameters, such as tumor capacity to modulate the function and phenotype of NK cells, require consideration for the choice of an NK-based therapy. In this study, we investigated T-CD4⁺ and T-CD8⁺ lymphocytes, B lymphocytes and NK cells in peripheral blood and spleen cells suspension from melanoma-bearing mice compared to healthy controls in order to assess the potential for tumor growth-promoting immunosuppression. Our results indicate that in a melanoma-bearing mouse model the percentage of NK cells in spleen is reduced and that their phenotype is different compared to control mouse NK cells.

Phenotypic changes of lymphocyte populations in psoriasiform dermatitis animal model

Psoriasis is a T cell mediated, chronic inflammatory autoimmune skin disease that affects up to 2-3% of the global population and leads to a decrease in quality of life. Experimental data accumulated in recent years highlighted the important role played by the immune system in the pathogenesis of this disease. Non-human psoriasis models are an important research tool that attempts to reproduce the clinical features of the disease in order to explain the pathogenesis of psoriasis and to identify possible therapeutic targets. Imiquimod-based murine model of psoriatic dermatitis is an alternative to traditional models of experimental psoriasis in mice and the induced dermatitis closely mimics the pathologic changes in human psoriasis. In order to emphasize changes in immune cell populations involved in lesion pathogenesis, we performed a murine model of psoriasiform dermatitis model by topical IMQ application. The progress and the severity of IMQ-induced skin inflammation were clinically (PASI score) and histopathologically evaluated. The immunological changes induced by IMQ treatment in lymphocyte populations from peripheral blood and spleen were evaluated by flow cytometry. The main changes observed in peripheral blood were the significantly increased T-CD8a⁺ lymphocyte and NK1.1⁺ cell percentages and the decreased T-CD4⁺ and B lymphocyte percentages in IMQ-treated mice. In spleen samples, lymphocytes showed the same tendency of variation as in peripheral blood, but without statistical significance. A significant decrease of B cells percentages was observed in spleen suspensions. Data obtained in skin samples may suggest the involvement of CD3ε⁺, CD4⁺ and CD8a⁺ cells in the lesional process. This murine model was analyzed by performing a basic cellular profile at three levels: peripheral blood, spleen and skin. The evaluation aimed to establish the immune framework of this experimental model that could further be used for etipathogenic mechanism identification and/or for studies regarding targeted therapies.