B-1 cell (CD5+/CD11b+) numbers and nIgM levels are elevated in physically active vs. sedentary rats.

Habitual, moderate exercise is associated with improved health, including reductions in illness. These benefits may stem, in part, from immune function improvements. We have previously reported that daily wheel running increases serum and peritoneal natural IgM (nIgM) in pathogen-free Sprague-Dawely rats. B-1 cells, which primarily reside in the peritoneal cavity, produce nIgM in the absence of antigen stimulation. This study examined whether physical activity would also increase B-1 cell numbers in the peritoneal cavity, mesenteric lymph nodes, and spleen. Male, pathogen-free Fischer 344 rats were sedentary (standard cages) or physically active (running wheel access) for 6-7 wk. Peritoneal cavity, mesenteric lymph nodes, and spleen cells were taken, and the number of CD5+/CD11b+ (B-1) cells were measured by using two-color flow cytometry. The results were that physically active animals had increased numbers of CD5+/CD11b+ cells in the peritoneal cavity. In addition, physically active animals had increased serum and peritoneal nIgM, thus replicating our previous observations. These results indicate that voluntary running selectively increases the B-1 cell population, which is most likely responsible for the elevated serum and peritoneal nIgM in active rats. Because B-1 cells are important in host defense, these changes may contribute to the health benefits of exercise.     

Increased plasma lipidperoxidation in vitamin B-6 deficient rats

Lipidperoxidation in plasma of rats fed with vitamin B-6 deficient diet for a period of 12 weeks was studied with pair-fed controls. Plasma pyridoxal 5'-phosphate, alanine amino transferase and aspartate amino transferase, the markers of vitamin B-6 status, were significantly low in vitamin B-6 deficient rats. Plasma malondialdehyde level, conjugated dienes and lipofuscin like pigments were increased in vitamin B-6 deficiency. Increased levels of plasma lipids, calcium, iron and copper were observed in vitamin B-6 deficiency. Plasma susceptibility to lipidperoxidation was maximal in vitamin B-6 deficiency, upon stimulation by the promotors, Fe2+, Fe3+, Cu2+, ascorbate, t-butyl hydroperoxide and hydrogen peroxide.     

Increased serum apoA-IV concentrations in experimental uremic rats.

Normal histochemical analysis localizes apoA-IV within renal proximal tubules, which suggests that the kidney is a major catabolic site. In clinical renal failure and animal models of decreased renal function, low molecular weight proteins cannot be efficiently filtered through the glomerular basement membrane, and therefore they accumulate in plasma. In normal plasma, apoA-IV exists as both lipoprotein associated and lipoprotein-free, low molecular weight forms. To examine this further, uremic serum apolipoprotein and mRNA levels were examined in surgically 5/6 nephrectomized rats. Compared to sham-operated controls, uremic serum apoA-IV was elevated twofold and was distributed to a greater extent in the lipoprotein-free subfraction. Serum triglycerides were unchanged. Despite finding no correlation between serum apoA-IV and triglyceride levels (in either the d less than 1.006 g/ml or 1.006 less than d less than 1.019 g/ml fraction), serum apoA-IV was positively correlated with the renal function parameters of blood urea nitrogen (r = 0.949, P less than 0.001), creatinine (r = 0.952, P less than 0.001), and uric acid (r = 0.903, P less than 0.001). In addition, the concentration of apoA-IV per milligram of renal homogenate protein in uremic rats was significantly higher than that of control rats, whereas there was no difference in the content of apoA-I between the two groups. ApoA-I, apoA-IV, and apoB mRNA levels in hepatic and in intestinal tissue were undistinguishable between the uremic and surgical sham rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Identification of a precursor to phosphatidyl choline-specific B-1 cells suggesting that B-1 cells differentiate from splenic conventional B cells in vivo: cyclosporin A blocks differentiation to B-1

The origin of B-1 cells is controversial. The initial paradigm posited that B-1 and B-2 cells derive from separate lineages. More recently it has been argued that B-1 cells derive from conventional B cells as a result of T-independent Ag activation. To understand B-1 cell differentiation, we have generated Ig transgenic (Tg) mice using the H and L chain genes (VH12 and Vkappa4) of anti-phosphatidyl choline (anti-PtC) B cells. In normal mice anti-PtC B cells segregate to B-1. Segregation is intact in VH12 (6-1) and VH12/Vkappa4 (double) Tg mice that develop large numbers of PtC-specific B cells. However, if B-1 cell differentiation is blocked, anti-PtC B cells in these Tg mice are B-2-like in phenotype, suggesting the existence of an Ag-driven differentiative pathway from B-2 to B-1. In this study, we show that double Tg mice have a population of anti-PtC B cells that have the phenotypic characteristics of both B-2 and B-1 cells and that have the potential to differentiate to B-1 (B-1a and B-1b). Cyclosporin A blocks this differentiation and induces a more B-2-like phenotype in these cells. These findings indicate that these cells are intermediate between B-2 and B-1, further evidence of a B-2 to B-1 differentiative pathway.     

Increased lipid peroxidation in kidney of vitamin B-6 deficient rats

Lipid peroxidation in kidney of rats fed with vitamin B-6 deficient diet for a period of 12 weeks was studied with pair-fed controls. The basal lipid peroxide level as well as the degree of susceptibility to lipid peroxidation in presence of promotors such as NADPH, ascorbate, t-butyl hydroperoxide, Fe2+, Cu2+ and oxalate, were increased in vitamin B-6 deficient kidney. The observed increased lipid peroxidation in vitamin B-6 deficient kidney was correlated with high levels of lipids, copper, iron, calcium and oxalate, low levels of antioxidants and antioxidant enzymes and increased levels of hydroperoxides and hydroxyl radicals.     

Vasoconstriction in active skeletal muscles: a potential role for P2X purinergic receptors?

There is evidence that ATP acts as a neurotransmitter in vascular smooth muscle and is coreleased with norepinephrine from sympathetic nerves. We hypothesized that P2X-receptor stimulation with the selective P2X-receptor agonist alpha,beta-methylene ATP would produce vasoconstriction in resting and exercising skeletal muscle. Six mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs and a catheter in one femoral artery. The selective P2X agonist alpha,beta-methylene ATP was infused as a bolus into the femoral artery catheter at rest and during mild, moderate, and heavy exercise. Intra-arterial infusions of alpha,beta-methylene ATP elicited reductions in vascular conductance of 54 +/- 5, 49 +/- 8, 39 +/- 8, and 30 +/- 6% at rest, 3 miles/h, 6 miles/h, and 6 miles/h at a 10% grade, respectively. The agonist infusions did not affect blood flow in the contralateral iliac artery. To examine whether nitric oxide is responsible for the attenuated vasoconstrictor response to P2X stimulation, the infusions were repeated in the presence of NG-nitro-l-arginine methyl ester. After nitric oxide synthase blockade, intra-arterial infusions of alpha,beta-methylene ATP elicited reductions in vascular conductance of 56 +/- 7, 61 +/- 8, 52 +/- 9, and 40 +/- 7% at rest, 3 miles/h, 6 miles/h, and 6 miles/h at a 10% grade, respectively. P2X-receptor responsiveness was attenuated during exercise compared with rest. Blockade of nitric oxide production did not affect the attenuation of P2X-receptor responsiveness during exercise. These data support the hypothesis that P2X purinergic receptors can produce vasoconstriction in exercising skeletal muscle.     

The H2 haplotype regulates the distribution of B cells into B-1a,B-1b and B-2 subsets

The size of B-cell subsets appears to be under genetic control, but the mechanism of this regulation is unknown. By analyzing five congenic strains of mice that differ only in their H2 haplotype, we addressed the issue of whether the MHC genes are involved in the relative proportions of B-1a, B-1b and B-2 cells. Not only were there considerable differences in the percentages of B-1 in B cells between H2s mice which were the highest [78.5+/-0.8% in the peritoneal cavity (PerC), and 26.3+/-0.5% in the spleen] and H2d mice, which were the lowest (15.2+/-0.6% in the PerC, and 10.9+/-0.6% in the spleen), but the percentages of B-1a cells varied inversely to those of B-1. Crosses between H2s and H2d strains showed that the highest B-1 frequencies occurred in F2 progeny expressing the homozygous H2s (70.8+/-2.1% in the PerC, and 30.0+/-0.5 in the spleen), and the lowest in that expressing the homozygous H2d haplotype (8.9+/-0.6% in the PerC, and 8.6+/-0.4% in the spleen). A dose effect of H2 was established in heterozygous F1 and F2 mice. As mice aged, there was a reduction of B-1 cells in the PerC, at the expense of B-1b in the H2s, but not in the H2d mice. Hence, the H2 genes appear to participate in regulating the proportions of B-1a, B-1b and B-2 cells.     

Nitrification in histosols: a potential role for the heterotrophic nitrifier.

Insufficient populations of Nitrosomonas and Nitrobacter were found in a Pahokee muck soil (Lithic medidaprit) to account for the nitrate concentration observed. To determine if heterotrophic nitrifiers could account for some of this discrepancy, a method was developed to measure the levels of heterotrophic nitrifiers in soil. A population of 4.1 X 10(5) Arthrobacter per g of dry fallow soil, capable of producing nitrite and/or nitrate from reduced nitrogenous compounds, was observed. Amendment of the much with 0.5% (wt/wt) sodium acetate and 0.1% (wt/wt) ammonium-nitrogen as ammonium sulfate (final concentrations) not only resulted in the usual increase in autotrophic nitrifiers, but also in a fourfold increase in the heterotrophic nitrifying Arrthrobacter. Amendment of like samples with N-Serve [2-chloro-6(trichloromethyl) pyridinel] prevented the increase in Nitrosomonas, but not that in the heterotrophic nitrifiers. Nitrate production in the presence of the inhibitor was diminished but not prevented. An Arthrobacter sp., isolated from the muck, produced nitrite when inoculated at high densities into sterile soil, unamended or amended with sodium acetate and/or ammomium sulfate. These data suggest that the heterotrophic population may be responsible for some of the nitrate produced in these Histosols.     

B-1a, B-1b and B-2 B cells display unique VHDJH repertoires formed at different stages of ontogeny and under different selection pressures.

Analyses of VHDJH rearrangements isolated from murine peritoneal B-1a cells (CD5+, IgMhi, B220lo), peritoneal B-1b cells (CD5-, IgMhi, B220lo), and conventional splenic B cells provide evidence that a unique repertoire of VH regions is displayed by each of these B-cell subsets. The B-1a subset is characterized by a low N-region diversity, by a high frequency of sequence homologies in the VH-D and D-JH junctions, and by a limited exonuclease nibbling of the terminals of the joining gene segments. Through expansion in ageing mice, B-1a clones with these properties are favoured. B-1b cells are similar to conventional B-2 cells with respect to N-region diversity, but are unique in terms of D gene expression. Thus, while most murine pre-B and B cells preferentially use DSP and DFL gene segments in a given reading frame (RF1), B-1b cells frequently express D genes in another reading frame (RF2). Together, these findings provide structural evidence for a model where B-1a, B-1b and B-2 cells are produced by separate progenitors that are active at different stages of ontogeny.     

Increased levels of serum myeloperoxidase in patients with active rheumatoid arthritis

Aims

The clinical significance of myeloperoxidase (MPO) has been the focus of investigation because it may contribute to the chronic, non-microbial inflammatory process in various diseases. Here, we determined serum MPO levels in rheumatoid arthritis (RA) and other autoimmune or inflammatory conditions, and investigated the associations between MPO levels and disease activity indicators in RA.

Main methods

The distribution of MPO was determined in serum samples from patients with RA, systemic lupus erythematosus (SLE), primary Sjögren's syndrome (pSS), dermatomyositis (DM), or ankylosing spondylitis (AS) and from healthy controls using commercial ELISA kits. Associations of serum MPO levels with the disease variables of RA patients were evaluated.

Key findings

All patient samples analyzed showed higher serum levels of MPO than healthy controls. Furthermore, MPO levels in RA were significantly higher than those in the other diseases with the exception of DM. Higher MPO levels were observed in RA patients with increased C-reactive protein (p = 0.005) or neutrophil percentage (p < 0.001), as well as in those with highly active disease (p < 0.001). Moderate positive correlations between MPO levels and IgM (r = 0.334, p = 0.001), C-reactive protein (r = 0.293, p = 0.003), erythrocyte sedimentation rate (r = 0.240, p = 0.016), or DAS28 (r = 0.350, p < 0.001) were also demonstrated.

Significance

The MPO concentration is likely to increase in patients with chronic inflammation. The associations between MPO and the disease variables of RA patients support a role for MPO in the inflammatory process of the disease.     

The role of B-cell-specific activator protein in the response of malignant B-1 cells to LPS

Chronic lymphocytic leukemia (CLL) results from the uncontrolled proliferation and accumulation of B-1 cells, many of which demonstrate self-reactivity. The response of B-1 cells to mitogen after undergoing malignant transformation is still unclear. Using our established malignant B-1 cell lines derived from the NZB murine model of human CLL, we investigated the response of malignant B-1 cells to the mitogen LPS. Interestingly, these malignant B-1 cells proliferated initially, but the proliferation rate decreased after a 48-h transition. Prolonged LPS treatment induced apoptosis and pathological differentiation. We studied possible underlying molecular mechanisms and found that the level of the DNA binding protein BSAP (B-cell-specific activator protein) was upregulated by LPS at the initial activation stage, followed by an increase in the apoptotic factor caspase-3 (CPP32) at 48 h and a subsequent decrease of BSAP at 72 h. The pathological differentiation induced by LPS was partially prevented by treatment with antisense BSAP. This study indicates that malignant B-1 cells could be driven to apoptosis and pathological differentiation when activated by the mitogen LPS, and BSAP may be an important factor in regulating these responses.     

Developmental potential of parthenogenetic cells: role of genotype-specific modifiers.

The developmental potential of parthenogenetic cells derived from different mouse strains was investigated by examining their distribution in various tissues of adult aggregation chimeras. Using GPI-1 allozymes as marker, no striking differences were observed between chimeras whose parthenogenetic cells were derived from activated oocytes isolated from females of different genetic backgrounds, (C57BL/6 x CBA/J) F1, CFLP, 129, and SWR. In all the combinations tested, parthenogenetic cells were consistently absent from skeletal muscle, but there were varying contributions to most other tissues. These results suggest that the maternal duplication of chromosomes containing imprinted gene(s) responsible for the systematic elimination of parthenogenetic cells from skeletal muscle, are not subject to a pronounced influence of genotype-specific modifiers. However, the contribution of parthenogenetic cells to the brain does appear to be influenced by strain background, since a marked improvement in the survival of CFLP, 129 and perhaps SWR parthenogenetic cells in chimeric brains was observed compared with F2 cells.     

B-1 cells are deficient in Lck: defective B cell receptor signal transduction in B-1 cells occurs in the absence of elevated Lck expression

B-1 cells constitute a unique B cell subset that is primarily responsible for producing nonimmune Ig. This natural Ig acts as a principal line of defense against infection. A key feature of B-1 cells is the failure of BCR-triggered signal transduction. Recently, defective BCR signaling in B-1 cells has been attributed to elevated expression of the canonical T cell src kinase, Lck. In the present study, we re-examined Lck expression in normal B-1 cells. We found that B-1 cells expressed less Lck at both the protein and RNA levels than did B-2 cells. The same B-1 cells manifested defective BCR-mediated induction of IKKbeta phosphorylation, IkappaBalpha degradation, and intracellular Ca(2+) mobilization. Thus, the failure of BCR signaling in B-1 cells does not relate to subset-specific elevation of Lck.