The SKG Mutation in ZAP-70 also Confers Arthritis Susceptibility in C57 Black Mouse Strains.

Various rodent models of arthritis are essential to dissect the full complexity of human rheumatoid arthritis (RA), a common autoimmune disease affecting joints. The SKG model of arthritis originates from a spontaneous mutation in ZAP-70 found in a BALB/c colony. This mutation affects T cell selection due to reduced TCR signalling, which allows leakage of self-reactive T cells from the thymus. To further expand the practical applicability of this unique model in arthritis research, we investigated the arthritogenicity of the SKG mutation in two common black mouse strains C57BL/6.Q and C57BL/10.Q and compared to BALB/c.Q. Mice retained the reduced TCR signalling characteristic of SKG.BALB/c mice, which leads to similar alteration in thymic selection. Importantly, mice also retained susceptibility to chronic arthritis after a single injection of mannan from Saccharomyces cerevisiae, with comparable prevalence and severity regardless of the genetic background. Further characterization of CD4(+) T cells revealed a similar bias towards IL-17 production and activated T cell phenotype in all SKG strains compared to respective wild type controls. Finally, transfer of SKG thymocytes conferred susceptibility to recipients, which confirm the intrinsic defect and pathogenicity of T cells. Overall, these results underline the strong impact that the W163C ZAP-70 mutation has on T cell-driven arthritis, and they support the use of the SKG model in black mice, which is useful for further investigations of this distinctive arthritis model to better understand autoimmunity.

Lineal energy and radiation quality in radiation therapy: model calculations and comparison with experiment.

Microdosimetry is a recommended method for characterizing radiation quality in situations when the biological effectiveness under test is not well known. In such situations, the radiation beams are described by their lineal energy probability distributions. Results from radiobiological investigations in the beams are then used to establish response functions that relate the lineal energy to the relative biological effectiveness (RBE). In this paper we present the influence of the size of the simulated volume on the relation to the clinical RBE values (or weighting factors). A single event probability distribution of the lineal energy is approximated by its dose average lineal energy (y[overline](D)) which can be measured or calculated for volumes from a few micrometres down to a few nanometres. The clinical RBE values were approximated as the ratio of the α-values derived from the LQ-relation. Model calculations are presented and discussed for the SOBP of a (12)C ion (290 MeV u(-1)) and the reference (60)Co γ therapy beam. Results were compared with those for a conventional x-ray therapy beam, a 290 MeV proton beam and a neutron therapy beam. It is concluded that for a simulated volume of about 10 nm, the α-ratio increases approximately linearly with the y[overline](D)-ratio for all the investigated beams. The correlation between y and α provides the evidence to characterize a radiation therapy beam by the lineal energy when, for instance, weighting factors are to be estimated.

NADPH oxidase elevations in pyramidal neurons drive psychosocial stress-induced neuropathology.

Oxidative stress is thought to be involved in the development of behavioral and histopathological alterations in animal models of psychosis. Here we investigate the causal contribution of reactive oxygen species generation by the phagocyte NADPH oxidase NOX2 to neuropathological alterations in a rat model of chronic psychosocial stress. In rats exposed to social isolation, the earliest neuropathological alterations were signs of oxidative stress and appearance of NOX2. Alterations in behavior, increase in glutamate levels and loss of parvalbumin were detectable after 4 weeks of social isolation. The expression of the NOX2 subunit p47(phox) was markedly increased in pyramidal neurons of isolated rats, but below detection threshold in GABAergic neurons, astrocytes and microglia. Rats with a loss of function mutation in the NOX2 subunit p47(phox) were protected from behavioral and neuropathological alterations induced by social isolation. To test reversibility, we applied the antioxidant/NOX inhibitor apocynin after initiation of social isolation for a time period of 3 weeks. Apocynin reversed behavioral alterations fully when applied after 4 weeks of social isolation, but only partially after 7 weeks. Our results demonstrate that social isolation induces rapid elevations of the NOX2 complex in the brain. Expression of the enzyme complex was strongest in pyramidal neurons and a loss of function mutation prevented neuropathology induced by social isolation. Finally, at least at early stages, pharmacological targeting of NOX2 activity might reverse behavioral alterations.

The novel small molecule drug Rabeximod is effective in reducing disease severity of mouse models of autoimmune disorders.

OBJECTIVES: Autoimmune diseases such as rheumatoid arthritis (RA) and multiple sclerosis (MS) affect a relatively large portion of the population, leading to severe disability if left untreated. Even though pharmaceutics targeting the immune system have revolutionised the therapy of these diseases, there is still a need for novel, more effective therapeutic substances. One such substance is the new chemical entity 9-chloro-2,3 dimethyl-6-(N,N-dimthylamino-2-oxoethyl)-6H-indolo [2,3-b] quionoxaline, Rabeximod, currently being investigated for efficiency in treatment of human RA. In this study we aimed to evaluate Rabeximod as a treatment for autoimmune diseases, using animal models. METHODS: In the present investigation we have evaluated Rabeximod as a treatment for autoimmune diseases using mouse models of RA and MS, ie, collagen-induced arthritis, collagen antibody induced arthritis and experimental autoimmune encephalomyelitis. RESULTS: Rabeximod efficiently prevented arthritis and encephalomyelitis in mice. In addition, this effect correlated to the timepoint when cells migrate into the joints. CONCLUSIONS: We conclude that Rabeximod reduces disease severity in animal models of autoimmunity and should be considered as a new therapeutic substance for MS and RA.

Genetics of autoimmune diseases: a multistep process.

It has so far been difficult to identify genes behind polygenic autoimmune diseases such as rheumatoid arthritis (RA), multiple sclerosis (MS), and type I diabetes (T1D). With proper animal models, some of the complexity behind these diseases can be reduced. The use of linkage analysis and positional cloning of genes in animal models for RA resulted in the identification of one of the genes regulating severity of arthritis in rats and mice, the Ncf1 gene. The Ncf1 gene encodes for the Ncf1 protein that is involved in production of free oxygen radicals through the NADPH oxidase complex, which opens up a new pathway for therapeutic treatment of inflammatory diseases. In most cases, however, a quantitative trait locus (QTL) is the sum effect of several genes within and outside the QTL, which make positional cloning difficult. Here we will discuss the possibilities and difficulties of gene identification in animal models of autoimmune disorders.

Plasma concentrations of vitamin C, vitamin E and/or malondialdehyde as markers of oxygen free radical production during hemodialysis.

To investigate the effects of neutrophil activation during hemodialysis (HD), blood markers of oxygen free radical (OFR) activity were studied. Two groups of HD patients on standard cuprophane treatment were investigated after an overnight fast. In the first group (mean age 68 +/- 8 years; n = 6) vitamin supplementation was withdrawn two weeks prior to the study, whereas the second group (mean age 73 +/- 3 years; n = 7) continued their normal vitamin intake. The two control groups, one consisting of age-matched subjects (mean age 72 +/- 2 years; n = 21), the other of younger subjects (mean age 36 +/- 7 years; n = 11), were asked to cease vitamin supplementation two weeks before the study and to fast overnight before blood sampling. Serial blood and dialysate samples were collected during HD in the vitamin-deprived patient group, and a single blood sample was collected in the other three groups. Plasma concentrations of vitamin C (total and reduced form), vitamin E (alpha-tocopherol) and malondialdehyde (MDA) were determined with newly adopted and validated HPLC methods. Basal plasma vitamin C concentrations were lower among vitamin-deprived HD patients than among age-matched controls or vitamin-supplemented HD patients (22 +/- 6 microM versus 39 +/- 19 microM and 34 +/- 10 microM, respectively). During a 3-hour HD session, the mean decrease in total vitamin C was 40%. Basal alpha-tocopherol concentrations did not differ significantly between vitamin-deprived HD patients and vitamin-supplemented HD patients or age-matched controls (39 +/- 5 microM versus 40 +/- 11 microM and 38 +/- 6 microM, respectively), but were lower in younger controls (33 +/- 4 microM). No alpha-tocopherol was detected in the dialysate, and its plasma concentration did not change significantly during a single HD session. Basal plasma MDA concentrations were higher in vitamin-supplemented HD patients than in vitamin-deprived HD patients or age-matched controls (1.5 +/- 0.2 microM versus 0.9 +/- 0.2 microM and 1.1 +/- 0.2 microM, respectively). No MDA was detected in the dialysate, and its plasma concentration did not change significantly during a single HD session. Our results indicate an increased need of vitamin C supplementation in HD patients. The concentration of oxidized vitamin C seems to peak early during HD and may be of value as a marker of OFR production. alpha-tocopherol concentrations do not change during HD and do not differ from those in control subjects. MDA may increase over a longer period of time on dialysis, but does not change during a single HD treatment.

Toxicity of effluent peritoneal dialysis fluid.

Commercial heat-sterilized fluids for peritoneal dialysis (PD) are unphysiological due to low pH, high osmolality, and the presence of several toxic glucose degradation products, formed during heat sterilization. These properties are all believed to negatively affect host defense in patients. Both the low pH and the high osmolality are known to equilibrate after being introduced into the abdominal cavity of patients. Cytotoxicity due to glucose degradation products has, however, not yet been studied in this respect. Effluent peritoneal dialysates were collected from patients after dwell times of 0, 5, 15, 30, 120, and 240 minutes. Cytotoxicity, measured as the inhibition of cell growth of a cultured fibroblast cell line (L929), osmolality, and pH were determined. PD fluids, due to the presence of degradation products, were found to remain cytotoxic after a dwell time of more than 30 minutes. However, after 4 hours no cytotoxicity could be observed in the effluent fluids. Osmolality slowly decreased during the entire dialysis period, while pH rapidly increased and was close to neutral within 5 minutes following instillation. It is concluded that the presence of glucose degradation in PD fluids may be as important as low pH and high osmolality for clinical complications.