Immunosenescence and macrophage functional plasticity: dysregulation of macrophage function by age-associated microenvironmental changes

Summary: The macrophage lineage displays extreme functional and phenotypic heterogeneity, which appears to be because, in large part, of the ability of macrophages to functionally adapt to changes in their tissue microenvironment. This functional plasticity of macrophages plays a critical role in their ability to respond to tissue damage and/or infection and to contribute to clearance of damaged tissue and invading microorganisms, to recruitment of the adaptive immune system, and to resolution of the wound and of the immune response. Evidence has accumulated that environmental influences, such as stromal function and imbalances in hormones and cytokines, contribute significantly to the dysfunction of the adaptive immune system. The innate immune system also appears to be dysfunctional in aged animals and humans. In this review, the hypothesis is presented and discussed that the observed age‐associated ‘dysfunction’ of macrophages is the result of their functional adaptation to the age‐associated changes in tissue environments. The resultant loss of orchestration of the manifold functional capabilities of macrophages would undermine the efficacy of both the innate and adaptive immune systems. The macrophages appear to maintain functional plasticity during this dysregulation, making them a prime target of cytokine therapy that could enhance both innate and adaptive immune systems.     

Vascular endothelial growth factor production by human luteinized granulosa cells in vitro

Vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) originating from the follicle or corpus luteum may be a physiological regulator of ovulation and neovascularization of luteinizing tissue, as well as a pathological factor in the development of ovarian hyperstimulation syndrome (OHSS). The objective of this study was to quantify VEGF production by human luteinized granulosa cells in vitro and to determine if gonadotrophin stimulates VEGF production directly and/or indirectly via enhanced synthesis of progesterone. In study 1, luteinized granulosa cells collected from women undergoing ovarian stimulation for in-vitro fertilization were cultured in the presence and absence of human chorionic gonadotrophin (HCG; 100 ng/ml) and/or low density lipoprotein (LDL; 100 microg protein/ml). In study 2, the progesterone synthesis inhibitor trilostane (250 ng/ml) and/or a progesterone receptor antagonist ZK137.316 (3.2 microM) were also added. Medium was harvested on days 1, 3, 5, 7 and 9 of culture and assayed for VEGF and progesterone. Results of study 1 were divided into two categories based on control concentrations of VEGF on day 1: 'low producers' (n = 6; <750 pg VEGF/ml) and 'high producers' (n = 5; >1000 pg VEGF/ml; P < 0.01). VEGF concentrations in cultures of both low and high producers increased (P < 0.01) from day 1 to maximal values on day 3, then steadily declined through to day 9. Chronic exposure to LDL or HCG increased (P < 0.05) VEGF concentrations in cultures of low producers by day 3 and day 5 respectively. In contrast, LDL did not alter VEGF concentrations in cultures of high producers and HCG did not increase VEGF concentrations until day 7. Nevertheless, acute exposure to HCG beginning on day 7 increased (P < 0.05) VEGF concentrations 3-fold in cultures of low or high producers. In study 2, trilostane treatment decreased (P < 0.05) progesterone concentrations by 91% on day 1 of culture but had no effect on VEGF concentrations on any day. ZK137.316 alone or with trilostane did not affect VEGF synthesis. These results suggest that VEGF production by luteinized granulosa cells is enhanced by gonadotrophin (HCG) independent of gonadotrophin-stimulated progesterone synthesis. These data are consistent with the hypothesis that the exacerbation of OHSS in early pregnancy is mediated by the CG stimulation of luteal VEGF production.      

Potable water as a cause of sporadic cases of community-acquired legionnaires' disease.

BACKGROUND. The environmental sources of sporadic, community-acquired legionnaires' disease are largely unknown, and culturing of water sources after identification of a case is currently not recommended. We conducted a prospective study of sporadic cases of community-acquired legionnaires' disease to determine whether the environmental reservoirs could be identified. METHODS. We cultured samples of potable water obtained from sources to which each of 20 patients with culture-confirmed, community-acquired legionnaires' disease had been exposed during the two weeks before the onset of symptoms. Monoclonal-antibody subtyping and restriction-endonuclease analysis were performed on the legionella isolates recovered from both the patients and the associated environmental cultures. RESULTS. For 8 of the 20 patients, isolates of Legionella pneumophila with identical subtypes were identified in cultures from both the patient and the potable water to which the patient had been exposed. The environmental reservoirs linked to the infections were the water supplies of two private residences, two nursing homes, two hospital outpatient clinics, and an industrial plant. CONCLUSIONS. Potable-water supplies that harbor L. pneumophila are an important source of community-acquired legionnaires' disease. Future studies should include attempts to identify the environmental sources of this infection.     

Vaccine Safety Datalink project: a new tool for improving vaccine safety monitoring in the United States. The Vaccine Safety Datalink Team

OBJECTIVE: To fill the large "gaps and limitations" in current scientific knowledge of rare vaccine adverse events identified in recent reviews of the Institute of Medicine. METHODS: Computerized information on immunization, medical outcomes, and potential confounders on more than 500 000 children 0 to 6 years of age is linked annually at several health maintenance organizations to create a large cohort for multiple epidemiologic studies of vaccine safety. RESULTS: Analysis of 3 years of follow-up data shows that 549 488 doses of diphtheria-tetanus-pertussis (DTP) and 310 618 doses of measles-mumps-rubella (MMR) vaccines have been administered to children in the study cohort. Analyses for associations between vaccines and 34 medical outcomes are underway. Screening of automated data shows that seizures are associated with receipt of DTP on the same day (relative risk [RR], 2.1; 95% confidence interval [CI], 1.1 to 4.0) and 8 to 14 days after receipt of MMR (RR, 3.0; 95% CI, 2.1 to 4.2). The diversity of vaccination exposures in this large cohort permits us to show that an apparent association of seizures 8 to 14 days after Haemophilus influenzae type b vaccine (RR, 1.6; 95% CI, 1.2 to 2.1) was attributable to confounding by simultaneous MMR vaccination; the association disappears with appropriate adjustment (RR, 1.0; 95% CI, 0.7 to 1.4). CONCLUSION: Preliminary design, data collection, and analytic capability of the Vaccine Safety Datalink project has been validated by replication of previous known associations between seizures and DTP and MMR vaccines. The diversity in vaccine administration schedules permits potential disentangling of effects of simultaneous and combined vaccinations. The project provides a model of public health-managed care collaborations in addition to an excellent infrastructure for safety and other studies of vaccines.     

Early neuromuscular recovery characteristics following administration of mivacurium plus vecuronium

Purpose

This study was designed to describe the early recovery characteristics, as well as the speed of onset of neuromuscular block, after a combination of mivacurium and vecuronium.

Methods

In this controlled, randomized study, 30 consenting ASA I–III patients were assigned to three treatment groups. The “2M2V” group received twice the dose necessary to cause 95% depression of the evoked twitch response (2 × ED₉₅) of mivacurium (0.15 mg · kg^?1) plus 2 × ED₉₅ of vecuronium (0.1 mg · kg^?1); the “2V” group received 2 × ED₉₅ of vecuronium; and the “4V” group received 4 × ED₉₅ of vecuronium. Evoked neuromuscular responses of the adductor pollicis were assessed with an adductor pollicis force transducer. The time until maximum block and times to 10% and 25% recovery (T₁₀ and T₂₅) in each group were expressed as mean ± standard deviation and compared using ANOVA.

Results

Onset of block in the 2M2V group was 27% faster than in the 2V group (2.0 ± 0.6 vs. 2.7 ± 0.8 min respectively, P < 0.05) and was similar to the 4V group (1.95 ± 0.3 min, P = NS). The times until 10% recovery were similar in the 2M2V and 4V groups (59.9 ± 12 vs 68.2 ± 25 min, P = NS) and were slower than in the 2V group (37.2 ± 9 min, P < 0.05). Between T₁₀ and T₂₅, recovery after 2M2V resembled that after 2V (6.7 ± 3 vs 5.7 ± 1 min, P = NS) and was faster than after 4V (10.9 ± 7 min, P<0.05).

Conclusions

When 2 × ED₉₅ of mivacurium is added to 2 × ED₉₅ of an intermediate or long-acting relaxant, recovery after T₁₀ will proceed as if one had administered the longeracting agent alone.     

Needle-free Biojector injection of a dengue virus type 1 DNA vaccine with human immunostimulatory sequences and the GM-CSF gene increases immunogenicity and protection from virus challenge in Aotus monkeys

A dengue-1 DNA vaccine containing sequences encoding premembrane and envelope proteins (DIME) was previously shown to elicit virus neutralizing antibodies in rhesus and Aotus monkeys, and the primates were partially protected from viremia upon challenge. To increase the neutralizing antibody levels and subsequent protection from virus challenge, four strategies were evaluated: (a) coimmunization with a plasmid expressing Aotus GM-CSF gene; (b) coimmunization with a plasmid containing human immunostimulatory sequences (ISS); (c) coimmunization with both the GM-CSF gene and ISS; and (d) delivery of vaccine using the needle-free Biojector system. Vaccination with the mixed formulation containing DIME, GM-CSF gene, and ISS, by either needle injection or Biojector, led to neutralizing antibody titers that were stable for up to 6 months after vaccination. Furthermore, 6 of 7 monkeys (85%), and 7 of 8 monkeys (87%) receiving this formulation were completely protected from viremia when challenged 1 and 6 months after vaccination, respectively. This is a significant improvement compared to our previous study in which one of three monkeys (33%) receiving just the DIME vaccine was completely protected from viremia at 6 months after immunization.     

Glutamate-induced neuron death requires mitochondrial calcium uptake

We have investigated the role of mitochondrial calcium buffering in excitotoxic cell death. Glutamate acts at NMDA receptors in cultured rat forebrain neurons to increase the intracellular free calcium concentration. Although concurrent inhibition of mitochondrial calcium uptake substantially enhanced this cytoplasmic calcium increase, it significantly reduced glutamate-stimulated neuronal cell death. Mitochondrial inhibition did not affect nitric oxide production or MAP kinase phosphorylation, which have been proposed to mediate excitotoxicity. These results indicate that very high levels of cytoplasmic calcium are not necessarily toxic to forebrain neurons, and that potential-driven uptake of calcium into mitochondria is required to trigger NMDA-receptor-stimulated neuronal death.     

Mechanomyography and oxygen consumption during incremental cycle ergometry

The purpose of this investigation was to describe and compare the relationships for mechanomyography (MMG) and oxygen consumption rate (V˙O₂) versus power output during incremental cycle ergometry. Twenty four adult males [mean (SD) age, 22.1 (2.0) years] volunteered to perform an incremental test to exhaustion on a cycle ergometer. A MMG piezoelectric recording device was placed mid-thigh over the vastus lateralis muscle and V˙O₂ was measured using standard open circuit procedures. The r ² values for the MMG and V˙O₂ versus power output relationships ranged from 0.79 to 0.99 and 0.97 to 0.99, respectively. In 20 of the 24 subjects there was no significant (P?>?0.10) difference between the slope values for the normalized MMG and V˙O₂ (expressed as a percentage of maximal values) versus power output relationships. The results of this study indicate that MMG procedures can be used to quantify muscular activity and monitor changes in exercise intensity during cycle ergometry. Furthermore, the present findings demonstrated a close association between the mechanical (MMG) and metabolic (V˙O₂) aspects of muscular contraction during incremental cycle ergometry.     

Selective expression of asialo GM1 on maturational subsets of lymphocytes in normal and athymic mice

In an attempt to clarify the restriction of asialo GM1 expression, the presence of asialo GM1 positive cells in the lymphoid tissues of normal and athymic mice was examined using affinity-purified monospecific anti-asialo GM1 antibodies and a FACS-II. The results presented herein demonstrate that a significant frequency of asialo GM1-positive cells can be detected in the primary lymphoid tissues (bone marrow and thymus) as well as in the secondary lymphoid tissues (spleen and lymph nodes). The observed expression of asialo GM1 within the T-cell lineage is, in general, consistent with the previously proposed restriction of asialo GM1 expression to mature T cells. However, the demonstration that a significant frequency of asialo GM1-positive cells is detectable in bone marrow of normal mice, as well as in spleen and bone marrow of athymic mice, establishes that a substantial number of lymphocytes not committed to the T-cell lineage and/or pre-T cells also express the asialo Gm1 antigen. These results indicate that the asialo GM1 marker may be an important tool for following T differentiation from the multipotential stem cell to the functionally mature T cell.