IL-6 is constitutively expressed during lung morphogenesis and enhances fetal lung explant branching

Previous studies have shown that chorioamnionitis, with increased IL-6, promotes fetal lung maturation and decreases the incidence of respiratory distress syndrome in premature neonates. However, the expression pattern and the effects of IL-6 on fetal lung growth mechanisms remain unknown. IL-6 expression was assessed by in situ hybridization and by real-time PCR between 14.5 and 21.5 d postconception. Normal and nitrofen-induced hypoplastic lung explants were cultured with increasing IL-6 doses or IL-6 neutralizing antibodies. Branching, cellular proliferation (Ki-67) and MAPK phosphorylation in fetal lung explants were analyzed. Pulmonary primitive epithelium expressed IL-6 constitutively throughout all gestational ages, displaying highest levels during earliest stages. In normal and hypoplastic lung explants, IL-6 neutralizing antibodies significantly reduced, whereas IL-6 supplementation induced a biphasic effect (lower doses increased, while the highest dose did not accomplish additional effect) on branching and cellular proliferation. IL-6 enhanced p38-MAPK phosphorylation without changing MEK1/2 and JNK pathways. The present study suggests a physiological role for IL-6 on pulmonary branching mechanisms most likely involving p38-MAPK intracellular signalling pathway

Crew/Robot Coordinated Planetary EVA Operations at a Lunar Base Analog Site

Under the direction of NASA's Exploration Technology Development Program, robots and space suited subjects from several NASA centers recently completed a very successful demonstration of coordinated activities indicative of base camp operations on the lunar surface. For these activities, NASA chose a site near Meteor Crater, Arizona close to where Apollo Astronauts previously trained. The main scenario demonstrated crew returning from a planetary EVA (extra-vehicular activity) to a temporary base camp and entering a pressurized rover compartment while robots performed tasks in preparation for the next EVA. Scenario tasks included: rover operations under direct human control and autonomous modes, crew ingress and egress activities, autonomous robotic payload removal and stowage operations under both local control and remote control from Houston, and autonomous robotic navigation and inspection. In addition to the main scenario, participants had an opportunity to explore additional robotic operations: hill climbing, maneuvering heaving loads, gathering geo-logical samples, drilling, and tether operations. In this analog environment, the suited subjects and robots experienced high levels of dust, rough terrain, and harsh lighting

Aplastic anemia rescued by exhaustion of cytokine-secreting CD8+ T cells in persistent infection with lymphocytic choriomeningitis virus

Aplastic anemia may be associated with persistent viral infections that result from failure of the immune system to control virus. To evaluate the effects on hematopoiesis exerted by sustained viral replication in the presence of activated T cells, blood values and bone marrow (BM) function were analyzed in chronic infection with lymphocytic choriomeningitis virus (LCMV) in perforin-deficient (P0/0) mice. These mice exhibit a vigorous T cell response, but are unable to eliminate the virus. Within 14 d after infection, a progressive pancytopenia developed that eventually was lethal due to agranulocytosis and thrombocytopenia correlating with an increasing loss of morphologically differentiated, pluripotent, and committed progenitors in the BM. This hematopoietic disease caused by a noncytopathic chronic virus infection was prevented by depletion of CD8+, but not of CD4+, T cells and accelerated by increasing the frequency of LCMV-specific CD8+ T cells in T cell receptor (TCR) transgenic (tg) mice. LCMV and CD8+ T cells were found only transiently in the BM of infected wild-type mice. In contrast, increased numbers of CD8+ T cells and LCMV persisted at high levels in antigen-presenting cells of infected P0/0 and P0/0 x TCR tg mice. No cognate interaction between the TCR and hematopoietic progenitors presenting either LCMV-derived or self-antigens on the major histocompatibility complex was found, but damage to hematopoiesis was due to excessive secretion and action of tumor necrosis factor (TNF)/lymphotoxin (LT)-alpha and interferon (IFN)-gamma produced by CD8+ T cells. This was studied in double-knockout mice that were genetically deficient in perforin and TNF receptor type 1. Compared with P0/0 mice, these mice had identical T cell compartments and T cell responses to LCMV, yet they survived LCMV infection and became life-long virus carriers. The numbers of hematopoietic precursors in the BM were increased compared with P0/0 mice after LCMV infection, although transient blood disease was still noticed. This residual disease activity was found to depend on IFN-gamma-producing LCMV-specific T cells and the time point of hematopoietic recovery paralleled disappearance of these virus-specific, IFN-gamma-producing CD8+ T cells. Thus, in the absence of IFN-gamma and/or TNF/LT-alpha, exhaustion of virus-specific T cells was not hampered

T-independent activation of B cells by vesicular stomatitis virus: no evidence for the need of a second signal.

Vesicular stomatitis virus (VSV) induces a T helper cell-independent IgM antibody response, whereas the IgG response is strictly T helper cell dependent. Since VSV induces B cells in complete absence of T helper cells, the question arises as to whether this induction occurs in the absence of a second signal or whether it depends upon an alternative or replacing signal 2. We therefore asked whether VSV has polyclonal B cell stimulator activity and/or whether B cell induction by VSV needs costimulation via complement or tumor necrosis factor (TNF) receptor or by natural killer (NK) cell activity. In vitro B cell proliferation assays and analysis of the in vivo antibody response in CD40-deficient mice excluded that VSV has properties of a polyclonal B cell stimulator. C3 depletion by cobra venom factor and application of anti-complement receptor antibodies showed that the T-independent IgM response was largely C3-independent except under very limiting antigen doses. Immunization of TNF receptor-deficient mice showed a normal anti-VSV IgM response, and in a cytotoxicity assay on YAC target cells there was no evidence of NK cell activation by VSV. Thus, VSV seems to induce B cells without polyclonal activation and/or C3, TNF, or NK cells functioning as a replacing second signal

Cd40 Ligand Has Potent Antiviral Activity

For B cells to make antibodies against most antigens, they require help from T cells. T cell help is delivered as two signals to the B cell, one of which is via CD40 and the other can be through receptors for any of a variety of soluble cytokines. We have constructed recombinant vaccinia viruses that express the ligand for CD40 and have shown that the growth of these viruses is dramatically controlled in vivo, even in mice that lack T or B cells. In this paper, we also describe our attempts to analyse the CD40 ligand-mediated antiviral activity by studying the clearance of these viruses in mice that are deficient in important antiviral mechanisms. Thus, the antiviral activity of CD40L may represent a surprising and potent effector mechanism of T cells activated during a virus infection

The role of IL-4 in adult acquired and congenital toxoplasmosis

The course of Toxoplasma gondii infection was studied in IL-4-deficient mice from three genetic backgrounds and their wild-type counterparts following peroral inoculation of tissue cysts. Survival rates were significantly reduced in disease-susceptible C57 BL6 mice and F1 (C57BL6× 129Sv) mice deficient in IL-4 compared with wild-type controls. In contrast, this difference was not observed in T. gondii-resistant BALBc mice. However, brain tissue cyst burdens in IL-4-deficient mice were either equivalent to (C57BL6 and BALBc mice) or significantly less (B6129 mice) than similarly infected wild-type mice. Thus strain-specific differences in the course of T. gondii were demonstrated in the absence of IL-4. The course of T. gondii infection was also compared between B6129 IL-4-deficient mice and their wild-type counterparts following peroral challenge with 20 tissue cysts on day 12 of pregnancy. Age-matched non-pregnant IL-4−/− and IL-4+/+ mice were also infected to assess the role of IL-4 on T. gondii infection during pregnancy. Disease phenotypes, as measured by mortality, were reversed if infections were initiated during pregnancy compared with non-pregnant infection. Thus significant mortality occurred immediately post partum in IL-4+/+ mothers, while all IL-4−/− mothers survived. Cyst burdens 28 days p.i. were significantly lower in IL-4−/− mothers than IL-4+/+ mothers and both IL-4−/− and IL-4+/+ non-pregnant mice. Congenital disease transmission as measured by foetal death or vertical disease transmission was independent of the presence or absence of IL-4. These studies demonstrate a role for IL-4 in pregnancy-induced immunosuppression and the associated increased susceptibility to T. gondii infection