Juvenile play experience does not affect nicotine sensitization and voluntary consumption of nicotine in adult rats.

Juvenile play experiences promote behavioral flexibility in rats. If other early positive experiences, such as tactile stimulation, are given prior to exposure to psychostimulants, the behavioral response to the drug is attenuated. The objective of the present study was to determine if the experience of juvenile play behavior would attenuate the response to nicotine. Two experiments were conducted: (1) behavioral sensitization to nicotine exposure, and (2) voluntary consumption of nicotine. For both experiments, rats were reared either with three same-sex peers (play group) or one adult (no play group) during their juvenile period. Then, as adults, half of each group was exposed to repeated injections of nicotine and the other half to saline. Prior play experience had no effect on behavioral sensitization or on voluntary consumption of nicotine. It remains to be determined whether juvenile experience with play influences the rewarding properties of nicotine in social contexts as adults.

IL-17 induces expression of vascular cell adhesion molecule through signalling pathway of NF-κB, but not Akt1 and TAK1 in vascular smooth muscle cells.

Interleukin-17 (IL-17) plays an important role in several autoimmune diseases. IL-17 can induce the expression of vascular cell adhesion molecule (VCAM-1) in aortic vascular smooth muscle cells (SMCs), which is important for the development of atherosclerosis. However, the signalling pathway of IL-17-induced VCAM-1 expression remains unclear. In this study, we reported that IL-17-induced expression of VCAM-1 in SMCs is dependent on NF-κB, but independent of Akt1 and TAK1. This is because knocking down Akt1 or TAK1 by siRNA did not reduce IL-17-induced activation of NF-κB and expression of VCAM-1, whereas knocking down NF-κB by siRNA markedly inhibited IL-17-mediated upregulation of VCAM-1 expression. In addition, IL-17-induced expression of VCAM-1 is partially dependent on activation of ERK1/2. Therefore, these signalling pathways of IL-17-mediated upregulation of VCAM-1 expression might be therapeutic targets for treatment of IL-17-mediated inflammation.

Defective lymphoid development in mice lacking Jak3.

The Janus tyrosine kinases (Jaks) play a central role in signaling through cytokine receptors. Although Jak1, Jak2, and Tyk2 are widely expressed, Jak3 is predominantly expressed in hematopoietic cells and is known to associate only with the common gamma (gamma c) chain of the interleukin (IL)-2, IL-4, IL-7, IL-9, and IL-15 receptors. Homozygous mutant mice in which the Jak3 gene had been disrupted were generated by gene targeting. Jak3-deficient mice had profound reductions in thymocytes and severe B cell and T cell lymphopenia similar to severe combined immunodeficiency disease (SCID), and the residual T cells and B cells were functionally deficient. Thus, Jak3 plays a critical role in gamma c signaling and lymphoid development.

Recruitment and proliferation of CD8+ T cells in respiratory virus infections.

The dramatic increase in the cellularity of the mediastinal lymph nodes (MLN) of mice infected intranasally (i.n.) with influenza viruses is a consequence of both recruitment and proliferation. As many as 20% of the CD8+ subset in the MLN can be shown to be in S or G2 + M phase at 6 days after i.n. challenge with the HKx31 influenza A virus, the percentage of of cycling cells being approximately five times greater for the activated/memory substantial evidence of apoptosis was found for CD8+ T cells recovered from the MLN and lung, particularly at 5 and 7 days after infection. Less than 1/100 of the proliferating T cells could be shown, by limiting dilution analysis (LDA), to be influenza virus-specific CD8+ cytotoxic T lymphocyte precursors (CTLp). A single, low dose (20 mg/kg) of the DNA-targeted drug cyclophosphamide (Cy) caused a massive decrease in frequency for the responding CD8+ CTLp, though the mice survived infection with the HKx31 virus and there was no long-term exhaustion of the CTLp pool in the MLN, spleen, or lung. The Cy treatment was also followed by a smaller reduction in the prevalence of memory CTLp (specific for Sendai virus) that were present concurrently in the regional lymph node, indicating that a measure of bystander activation is occurring. The experiments show that respiratory virus infections have no negative impact on established T cell memory, and that there is no phase of transient exhaustion in the acute virus-specific CTLp response in this localized infection.

Functional analysis of the TCR alpha- beta+ cells that accumulate in the pneumonic lung of influenza virus-infected TCR-alpha-/- mice.

In mice homozygous (-/-) for a targeted TCR-alpha gene disruption, some thymocytes express a cell-surface TCR-beta chain on the cell surface in the absence of a TCR-alpha chain, and a few CD4+CD8- TCR-alpha-beta+ cells accumulate in the peripheral lymphoid organs. We have infected these mutant mice with an influenza A virus to show that large numbers of TCR-beta+ cells (most of which are CD4+) can be retrieved from the pneumonic lung. Both freshly isolated TCR-alpha-beta+ cells and TCR-alpha-beta+ hybridoma cell lines derived from influenza virus-infected mutant mice respond appropriately to stimulation with anti-CD3 epsilon or the Mls-1 superantigen. It thus seems that CD4+ TCR-alpha-beta+ cells in the peripheral lymphoid organs of TCR-alpha mutant mice can signal through their TCR surface complex. However, there are no indications that CD4+ TCR-alpha-beta+ lymphocytes can either recognize a complex between MHC and influenza virus peptide or act as effector or Th cells. The existence and function of such cells in wild-type mice remains to be established.

Prominent usage of V beta 8.3 T cells in the H-2Db-restricted response to an influenza A virus nucleoprotein epitope.

The spectrum of TCR usage has been analyzed for virus-specific CD8+ T cells isolated from the regional mediastinal lymph modes and from the lung by bronchoalveolar lavage (BAL) of C57BL/6 (B6) mice with influenza pneumonia. Lymphocytes were recovered during the acute phase of the primary response in mice infected with an H3N2 (A/HKx31) virus, or in immune animals that were secondarily challenged with an H1N1 virus (A/PR8). Cells taken directly from the BAL of infected mice exhibited an increase in the frequency of V beta 8.3+/CD8+ T cells. In addition, 20 to 50% of proliferating CD8+ T cells in the mediastinal lymph nodes and BAL populations stimulated in vitro with A/HKx31 were V beta 8.3 TCR+. These observations indicated that the V beta 8.3+/CD8+ T cells were specifically involved in the inflammatory process during influenza infection. However, in vivo depletion of V beta 8+ T cells in CD4-depleted mice did not adversely affect viral clearance, suggesting that other CD8+ T cells can compensate for the absence of these cells. The spectrum of TCR usage was also analyzed for influenza-specific T cell hybridomas derived from freshly isolated BAL of mice with pneumonia. Many of these T cell hybridomas were V beta 8.3+, although other TCR V beta elements were used. All of the V beta 8.3+ hybridomas recognized the H-2Db-restricted NP epitope, 365-380. Although the V beta 8.3 TCR contain similar TCR D beta and J beta elements, V alpha usage was surprisingly variable. Therefore, recognition of this particular epitope was dominated by the beta-chain of the TCR. We conclude that the murine CD8+ response to influenza A virus infection of B6 mice is limited in terms of the diversity of the responding T cells. However, there is significant plasticity in the CD8+ response, which readily compensates for the absence of the dominant T cell population.

Cytokine profiles of bronchoalveolar lavage cells from mice with influenza pneumonia: consequences of CD4+ and CD8+ T cell depletion.

Cytokine production and mRNA profiles have been analyzed at the single cell level for bronchoalveolar lavage (BAL) populations from mice infected with an influenza A virus in the presence or absence of the CD4+ and CD8+ T cell subsets. Phagocytes were identified by their capacity to engulf latex particles, but the cellular elements of this inflammatory process were otherwise not characterized. BAL preparations from undepleted mice contained numerous IL-2, IL-4 and IFN-gamma-producing cells, with many fewer secreting TNF or IL-10. The frequency of mRNA+ cells detected by in situ hybridization was, in general, much higher than that for protein-secreting cells determined by ELISPOT analysis. In addition to IL-2, IL-4, and IFN-gamma, large numbers of cells were found to contain IL-10 and TNF-beta transcripts. Depletion of CD4+ and CD8+ cells caused significant reduction in the frequency of IL-2 and IL-4-producing cells, but even simultaneous elimination of both T cell subsets failed to totally remove all cells producing these cytokines. Similarly, a residual population of IFN-gamma-producing cells remained after depletion of the CD4+ and CD8+ subsets. Likely sources of these cytokines (apart from NK cells) are the CD4-8- alpha beta and gamma delta T cells found previously in BAL populations from doubly-depleted mice infected with this virus. Somewhat surprisingly, mRNA for IFN-gamma, IL-5, and TNF beta was prevalent in cells that had engulfed latex particles, though mRNA for IL-2 and IL-4 was never detected in macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of cytokine genes in T cells during primary and secondary murine influenza pneumonia.

The patterns of cytokine mRNA expression in mice with primary or secondary influenza pneumonia have been assessed by in situ hybridization analysis of cells from both the mediastinal lymph node (MLN) and the virus-infected lung. Evidence of substantial transcriptional activity was found in all lymphocyte subsets recovered from both anatomical sites. The kinetics of cytokine mRNA expression after primary infection with an H3N2 virus were in accord with the idea that the initial response occurs in regional lymphoid tissue, with the effector T cells later moving to the lung. This temporal separation was much less apparent for the more rapid secondary response resulting from challenge of H3N2-primed mice with an H1N1 virus. Among the T cell receptor alpha/beta+ subsets, transcripts for interferon (IFN) gamma and tumor necrosis factor beta were most commonly found in the CD8+ population whereas mRNA for interleukin (IL) 4 and IL-10 was much more prevalent in CD4+ T cells. The gamma/delta T cells expressed mRNA for all cytokines tested, with IL-2, IL-4, and IFN-gamma predominating among those recovered from the inflammatory exudate. At particular time points, especially early in the MLN and late in the infected lung, the frequency of mRNA+ lymphocytes was much higher than would be expected from current understanding of the prevalence of virus-specific precursors and effectors. If this response is typical, induction of cytokine gene expression for T cells that are not responding directly to the invading pathogen may be a prominent feature of acute virus infections.