Essential role of macrophages in the initiation of allergic rhinitis in mice sensitized intranasally once with cedar pollen: regulation of class switching of immunoglobulin in B cells by controlling interleukin-4 production in T cells of submandibular lymph nodes.

The production of allergen-specific IgE antibodies (Abs) in allergen-sensitized patients or animals has a mutual relationship with the immunologic response leading to allergic rhinitis. We recently reported that, after an intranasal injection of cedar pollen into mice, an interleukin-4 (IL-4)-dependent increase in serum nonspecific IgE Abs was a prerequisite for the production of serum allergen-specific IgE Abs. Here, we explored which lymphoid organs were responsive to the intranasally injected allergen and how IL-4 and IgE Abs were produced in the lymphocytes. Time-dependent changes in the total cell numbers and in in vitro IgE Ab production in various lymphoid organs revealed that the submandibular lymph nodes were the main responsible organ. After treatment with allergen (for IgE production) or allergen and complete Freund's adjuvant (for IgG production), we separated submandibular lymph node cells into macrophage-, lymphocyte-, and granulocyte-rich populations by discontinuous Percoll density-gradient centrifugation. Unexpectedly, bulk cells, but not the lymphocyte- or macrophage-rich populations, produced significant amounts of IL-4, IgE, and IgG; whereas production was restored by addition of Mac-1(+) cells from the macrophage-rich to the lymphocyte-rich fraction. Furthermore, a combination of the lymphocyte-rich population (for IgG [or IgE]) production) and the macrophage-rich population (for IgE [or IgG]) production) produced a large amount of IgE (or IgG). These results indicate that, in the initiation of allergic rhinitis, macrophages in the submandibular lymph nodes are essential not only for IL-4 or immunoglobulin production, but also for class switching of immunoglobulin in lymphocytes.

Comprehensive proteomic profiling of plasma and serum phosphatidylserine-positive extracellular vesicles reveals tissue-specific proteins.

Extracellular vesicles (EVs) are ubiquitously secreted by almost all tissues and carry many cargoes, including proteins, RNAs, and lipids, which are related to various biological processes. EVs are shed from tissues into the blood and expected to be used as biomarkers for diseases. Here, we isolated EVs from EDTA plasma and serum of six healthy subjects by an affinity capture isolation method, and a total of 4,079 proteins were successfully identified by comprehensive EV proteomics. Our reliable and detailed catalog of the differential expression profiles of EV proteins in plasma and serum between healthy individuals could be useful as a reference for biomarker discovery. Furthermore, tissue-specific protein groups co-regulated between blood EVs from healthy individuals were identified. These EV proteins are expected to be used for more specific and sensitive enrichment of tissue-specific EVs and for screening and monitoring of disease without diagnostic imaging in patient blood in the future.

Automated Proteomics Sample Preparation of Phosphatidylserine-Positive Extracellular Vesicles from Human Body Fluids.

Extracellular vesicles (EVs) are ubiquitously secreted by almost every cell type and are present in all body fluids. Blood-derived EVs can be used as a promising source for biomarker monitoring in disease. EV proteomics is currently being analyzed in clinical specimens. However, their EV proteomics preparation methods are limited in throughput for human subjects. Here, we introduced a novel automated EV isolation and sample preparation method using a magnetic particle processing robot for automated 96-well processing of magnetic particles for EV proteomics analysis that can be started with a low volume of multiple clinical samples. The automation of EV purification reduced the coefficient of variation of protein quantification from 3.5 to 2.2% compared with manual purification, enabling the quantification of 1120 proteins in 1 h of MS analysis. This automated proteomics EV sample preparation is attractive for processing large cohort samples for biomarker development, validation, and routine testing.

IL-4-dependent induction of IgE basophils in peripheral blood and IgE B cells in spleen as respective indicators of allergen sensitization and a precursor of cells secreting allergen-specific IgE antibody.

It was recently reported by us that either primary i.n. or i.p. injection of cedar pollen extract into BALB/c mice, or a second s.c. injection of the allergen into i.v. or s.c. sensitized mice, causes an IL-4-dependent increase in total IgE serum antibody to produce allergen-specific IgE antibody upon further s.c. sensitization. To determine the biology of total IgE antibody, in the present study IgE+ cells in peripheral blood or lymphoid tissues of allergen-sensitized BALB/c mice have been characterized. In peripheral blood, mice sensitized one to three times with the allergen produced a 2.5- to 4-fold increase in the number of IgE+ cells, with a time-course similar to that of the concentration of total IgE antibody in serum. These IgE+ cells were basophils. On the other hand, the number of IgE+ cells in the lymphoid tissues did not change significantly after an i.n., i.p., i.v. or s.c. injection of allergen into the mice, whereas a second s.c. injection of the allergen into the i.v.-, but not into the i.n.-, i.p.- or s.c.-, sensitized mice induced a small number of IgE+/IgM+/B220+ B cells in the spleen. In contrast, IgE+ cells were not seen in the blood or spleen of IL-4 -/- mice after sensitization with the allergen. These results suggest that IgE+ basophils in the peripheral blood, and IgE+ B cells in the spleen, might be IL-4-dependently induced as an indicator of sensitization with allergen, and a precursor of cells secreting allergen-specific IgE antibody, respectively.