Antigen-specific, antibody-coated, exosome-like nanovesicles deliver suppressor T-cell microRNA-150 to effector T cells to inhibit contact sensitivity.

BACKGROUND: T-cell tolerance of allergic cutaneous contact sensitivity (CS) induced in mice by high doses of reactive hapten is mediated by suppressor cells that release antigen-specific suppressive nanovesicles. OBJECTIVE: We sought to determine the mechanism or mechanisms of immune suppression mediated by the nanovesicles. METHODS: T-cell tolerance was induced by means of intravenous injection of hapten conjugated to self-antigens of syngeneic erythrocytes and subsequent contact immunization with the same hapten. Lymph node and spleen cells from tolerized or control donors were harvested and cultured to produce a supernatant containing suppressive nanovesicles that were isolated from the tolerized mice for testing in active and adoptive cell-transfer models of CS. RESULTS: Tolerance was shown due to exosome-like nanovesicles in the supernatants of CD8(+) suppressor T cells that were not regulatory T cells. Antigen specificity of the suppressive nanovesicles was conferred by a surface coat of antibody light chains or possibly whole antibody, allowing targeted delivery of selected inhibitory microRNA (miRNA)-150 to CS effector T cells. Nanovesicles also inhibited CS in actively sensitized mice after systemic injection at the peak of the responses. The role of antibody and miRNA-150 was established by tolerizing either panimmunoglobulin-deficient JH(-/-) or miRNA-150(-/-) mice that produced nonsuppressive nanovesicles. These nanovesicles could be made suppressive by adding antigen-specific antibody light chains or miRNA-150, respectively. CONCLUSIONS: This is the first example of T-cell regulation through systemic transit of exosome-like nanovesicles delivering a chosen inhibitory miRNA to target effector T cells in an antigen-specific manner by a surface coating of antibody light chains.

Down-regulation of macrophage immune activity by natural CD8+ regulatory T cells.

To evaluate the influence of natural regulatory CD8+ T cells on macrophages we investigated in vitro production of cytokines, reactive oxygen intermediates (ROIs) and expression of CD80 surface costimulatory molecules by macrophages (MF) of wild type (WT) B10PL and syngeneic knock-out (KO) strains, TCRalpha-/-, beta2m-/- and CD1d-/- mice. MF of TCR alpha-/- (CD4- and CD8-) and beta2m-/- (CD8-) animals produced higher levels ofTNF-a, IL-6, IL-12 and ROIs and showed increased expression of CD80 costimulatory molecules in comparison to MF of WT or CD1d-/- (NKT-) mice. When MF of these strains were conjugated with TNP hapten and injected i.v. into WT mice to test either induction of contact sensitivity (CS) or tolerance, only TNP-MF of TCRalpha-/- and beta2m-/- animals induced a significant CS reaction, while cells of WT and CD1d-/- strains were tolerogenic. MF of the tested strains can be classified functionally as resembling either proinflammatory (TCRalpha-/- and beta2m-/-mice) or immunosuppressive (WT and CD1d-/-) phenotypes. We suggest the presence of an in vivo regulatory loop in which innate CD8+ Treg cells control the transition between MF phenotypes and thus adjust the magnitude of the inflammatory response to strictly local requirements.

[Immunoregulation by interference RNA (iRNA) - mechanisms, role, perspective]. / Immunoregulacja poprzez interferencyjny RNA ­ mechanizmy, rola, perspektywy.

The functioning of an organism depends on the precise control mechanisms, constantly adjusted to the actual state. Therefore, there is a need for efficient communication between both adjacent and distant cells, which may be executed by proteins such as hormones, neurotransmitters and cytokines. Recently another means of regulation has emerged - short regulatory RNAs (srRNAs). Although discovered only a couple of years ago, the mechanism of RNA interference has already become a topic of thousands of publications, defining its roles in both physiological and pathological processes, such as cancerogenesis and autoimmunization. RNAs regulating cell function may be coded in its genome (both exons and introns) or be introduced from the external environment. In mammals microRNAs (miRNAs) cooperate with proteins from the Ago/PIWI family to form effector ribonucleoprotein complexes, and owing to their complementarity to the target mRNA, control genes' expression at the posttranscriptional level, either through the suppression of mRNA translation or through mRNA degradation. SrRNAs are crucial regulators throughout the development of immune cells, starting from hematopoietic stem cells, up to the effector cells of the adaptive immune response. Moreover, some of the regulatory cells perform their function by releasing miRNAs, which are then transported to the target cells, possibly enclosed in the exosomes.

The influence of opioids on the humoral and cell-mediated immune responses in mice. The role of macrophages.

BACKGROUND: Our experiments were aimed to test the influence of treatment with different opioids (morphine, fentanyl, methadone) on the humoral and cell-mediated immune responses. METHODS: Mice were treated intraperitoneally (ip) with opioids for several days and next either immunized with sheep red blood cells (SRBC) to test the antibody production or skin-sensitized with hapten picryl chloride (PCL) to induce contact hypersensitivity (CHS). In addition, the effects of opioids on the production of reactive oxygen intermediates (ROIs) and cytokines by peritoneal macrophages (Mf) and on the expression of surface markers on these cells and blood leukocytes were estimated. RESULTS: Opioids caused an enhancement of ROIs and cytokines production when macrophages were stimulated with zymosan or lipopolysaccharide (LPS) and reduced the expression of antigen presentation markers on Mf. Numbers of anti-SRBC plaque forming cells (PFC) and antibodies titres were lower in mice treated with all tested opioids. Depending on the use of particular opioid and the phase of allergic reaction, effects of the treatment on CHS were diverse. While morphine decreased the early and late phases of induction of CHS responses, methadone increased both reactions. In case of the effector phase of CHS, morphine and fentanyl increased both its early and late stages, while methadone decreased the late reaction. Treatment of recipients with opioids had diverse influence on the passive transfer of CHS in these animals. CONCLUSIONS: Our experiments show that the action of opioids on the immune system is a complex phenomenon dependent on such variables as type of opioid, character of response (humoral versus cellular) and types of cells involved. Here Mf seem to play a significant role.