Leptin and the Immune Response

Leptin Regulated ILC2 Cell through the PI3K/AKT Pathway in Allergic Rhinitis

Background

Recent studies suggest that leptin is involved in Th2 response in allergic rhinitis (AR). However, the effect of leptin on type II innate lymphoid cells (ILC2s) in AR is not well characterized.

Methods

Twenty-six AR patients and 20 healthy controls were enrolled. Serum leptin levels were measured, and their correlation with ILC2 and type II cytokines were analyzed using enzyme-linked immunosorbent assay (ELISA) and flow cytometry. ILC2 differentiation and cytokine production stimulated by human recombinant leptin were analyzed by real-time polymerase chain reaction (PCR) and ELISA. AR mouse models were also established to verify the effect of leptin on ILC2 cell regulation.

Results

Our results showed that elevated serum leptin in AR patients was correlated with the percentage of ILC2 and the expression of type II cytokines. The recombinant leptin enhanced the expression of ILC2 cell transcription factors and type II cytokine through the PI3K/AKT pathway. The AR mice treated with leptin showed as stronger ILC2 inflammation and symptoms compared with control mice.

Conclusions

Our data provide evidence that upregulation of leptin promotes ILC2 responses in AR and this process was achieved through the PI3K/AKT pathway.

Gene expression profiling in peripheral blood mononuclear cells of patients with common variable immunodeficiency: modulation of adaptive immune response following intravenous immunoglobulin therapy

Background

Regular intravenous immunoglobulin treatment is used to replace antibody deficiency in primary immunodeficiency diseases; however the therapeutic effect seems to be related not only to antibody replacement but also to an active role in the modulation of the immune response. Common variable immunodeficiency is the most frequent primary immunodeficiency seen in clinical practice.

Methods

We have studied the effect of intravenous immunoglobulin replacement in patients with common variable immunodeficiency by evaluating the gene-expression profiles from Affimetrix HG-U133A. Some of the gene array results were validated by real time RT-PCR and by the measurement of circulating cytokines and chemokines by ELISA. Moreover we performed FACS analysis of blood mononuclear cells from the patients enrolled in the study.

Results

A series of genes involved in innate and acquired immune responses were markedly up- or down-modulated before therapy. Such genes included CD14, CD36, LEPR, IRF-5, RGS-1, CD38, TNFRSF25, IL-4, CXCR4, CCR3, IL-8. Most of these modulated genes showed an expression similar to that of normal controls after immunoglobulin replacement. Real time RT-PCR of selected genes and serum levels of IL-4, CXCR4 before and after therapy changed accordingly to gene array results. Interestingly, serum levels of IL-8 remained unchanged, as the corresponding gene, before and after treatment. FACS analysis showed a marked decrease of CD8+T cells and an increase of CD4+T cells following treatment. Moreover we observed a marked increase of CD23⁻CD27⁻IgM⁻IgG⁻ B cells (centrocytes).

Conclusions

Our results are in accordance with previous reports and provide further support to the hypothesis that the benefits of intravenous immunoglobulin therapy are not only related to antibody replacement but also to its ability to modulate the immune response in common variable immunodeficiency.

Analysis of blood flow and local expression of angiogenesis‑associated growth factors in infected wounds treated with negative pressure wound therapy

Angiogenesis is involved in the wound healing process. Increased angiogenesis and blood flow constitute a major mechanism of negative pressure wound therapy (NPWT), which has been shown to facilitate the healing of infected wounds. However, the effect on the expression of angiogensis‑related growth factor remains unknown. The goal of the current study was to investigate the angiogenic factor levels prior to and following NPWT in infected wounds. A total of 20 patients with infected wounds treated with NPWT were included in the study. Patients acted as their own control; the postoperative measurements of patients were considered as the experimental group, while preoperative measurements were considered as the controlled group. Blood flow was recorded prior to and during NPWT. A total of 10 angiogensis‑related growth factors were detected using a protein biochip array to analyze the change in protein levels prior to NPWT, and on the third day during NPWT. All wounds were successfully reconstructed by skin grafting or using local flaps following NPWT. NPWT resulted in significantly increased blood flow in the wound. There was a significant increase in vascular endothelial growth factor (VEGF), EGF, platelet‑derived growth factor and angiotesin‑2 following NPWT, while basic fibroblast growth factor decreased significantly. NPWT affects the local expression of angiogenesis‑associated growth factors, which represents another mechanism to explain how NPWT accelerates wound healing.

Leptin enhances survival and induces migration, degranulation, and cytokine synthesis of human basophils

Basophils are the rarest leukocytes in human blood, but they are now recognized as one of the most important immunomodulatory as well as effector cells in allergic inflammation. Leptin, a member of the IL-6 cytokine family, has metabolic effects as an adipokine, and it is also known to participate in the pathogenesis of inflammatory reactions. Because there is an epidemiologic relationship between obesity and allergy, we examined whether basophil functions are modified by leptin. We found that human basophils express leptin receptor (LepR) at both the mRNA and surface protein levels, which were upregulated by IL-33. Leptin exerted strong effects on multiple basophil functions. It induced a strong migratory response in human basophils, similar in potency to that of basophil-active chemokines. Also, leptin enhanced survival of human basophils, although its potency was less than that of IL-3. Additionally, CD63, a basophil activation marker expressed on the cell surface, was upregulated by leptin, an effect that was neutralized by blocking of LepR. Assessments of basophil degranulation and cytokine synthesis found that leptin showed a strong priming effect on human basophil degranulation in response to FcεRI aggregation and induced Th2, but not Th1, cytokine production by the cells. In summary, the present findings indicate that leptin may be a key molecule mediating the effects of adipocytes on inflammatory cells such as basophils by binding to LepR and activating the cellular functions, presumably exacerbating allergic inflammation.