Clinical isolates of Bilophila wadsworthia grew rapidly (1–3 days) in the liquid taurine-minimal-salts medium developed for B. wadsworthia RZATAU, whereas growth on Bacteroides Bile Esculin Agar ...takes up to 1 week. Though rapid growth of B. wadsworthia was achieved, and no other pure cultures grew, the medium was not selective for the organism in human faeces or in intra-abdominal specimens. We hope, however, that our understanding of the physiological and biochemical characteristics of the organism supplies a tool for further research.
Inducible (1
R,2
S)-1,2-dihydroxy-3,5-cyclohexadiene-l,4-dicarboxylate (diene-diol) dehydrogenase was found in extracts of
Comamonas testosteroni T-2 grown in
p-toluate-or terephthalate-salts medium ...and it was purified using anion exchange, hydrophobic interaction and gel filtration chromatography. The enzyme is a homodimer with subunit
Mr 39000. It had a specific activity of 500 mkat/kg of protein and was activated by the addition of Fe
2+. The dehydrogenase converted 1 mol diene-diol and 1 mol NAD
+ to 1 mol protocatechuic acid, 1 mol NADH and 1 mol CO
2. Apparent
K
m-values of 43 μM (NAD
+) and about 90 μM (diene-diol) were determined. The hydride ion was transferred to the
si face of NAD
+.
Inducible (1R,2S)‐1,2‐dihydroxy‐3,5‐cyclohexadiene‐l,4‐dicarboxylate (diene‐diol) dehydrogenase was found in extracts of Comamonas testosteroni T‐2 grown in p‐toluate‐or terephthalate‐salts medium ...and it was purified using anion exchange, hydrophobic interaction and gel filtration chromatography. The enzyme is a homodimer with subunit Mr 39000. It had a specific activity of 500 mkat/kg of protein and was activated by the addition of Fe2+. The dehydrogenase converted 1 mol diene‐diol and 1 mol NAD+ to 1 mol protocatechuic acid, 1 mol NADH and 1 mol CO2. Apparent Km‐values of 43 μM (NAD+) and about 90 μM (diene‐diol) were determined. The hydride ion was transferred to the si face of NAD+.
A new sulfate-reducing bacterium was isolated from marine sediment with phosphite as sole electron donor and CO2 as the only carbon source. Strain FiPS-3 grew slowly, with doubling times of 3 4 days, ...and oxidized phosphite, hydrogen, formate, acetate, fumarate, pyruvate, glycine, glutamate, and other substrates nearly completely, with concomitant reduction of sulfate to sulfide. Acetate was formed as a side product to a small extent. Glucose, arabinose, and proline were partly oxidized and partly fermented to acetate plus propionate. Growth with phosphite, hydrogen, or formate was autotrophic. Also, in the presence of sulfate, CO dehydrogenase was present, and added acetate did not increase growth rates or growth yields. In the absence of sulfate, phosphite oxidation was coupled to homoacetogenic acetate formation, with growth yields similar to those in the presence of sulfate. Cells were small rods, 0.6 0.8×2 4 μm in size, and gram-negative, with a G+C content of 53.9 mol%. They contained desulforubidin, but no desulfoviridin. Based on sequence analysis of the 16S rRNA gene and the sulfite reductase genes dsrAB, strain FiPS-3 was found to be closely related to Desulfotignum balticum. However, physiological properties differed in many points from those of D. balticum. These findings justify the establishment of a new species, Desulfotignum phosphitoxidans.
A new sulfate-reducing bacterium was isolated from marine sediment with phosphite as sole electron donor and CO2 as the only carbon source. Strain FiPS-3 grew slowly, with doubling times of 34 days, ...and oxidized phosphite, hydrogen, formate, acetate, fumarate, pyruvate, glycine, glutamate, and other substrates nearly completely, with concomitant reduction of sulfate to sulfide. Acetate was formed as a side product to a small extent. Glucose, arabinose, and proline were partly oxidized and partly fermented to acetate plus propionate. Growth with phosphite, hydrogen, or formate was autotrophic. Also, in the presence of sulfate, CO dehydrogenase was present, and added acetate did not increase growth rates or growth yields. In the absence of sulfate, phosphite oxidation was coupled to homoacetogenic acetate formation, with growth yields similar to those in the presence of sulfate. Cells were small rods, 0.60.8×24 μm in size, and gram-negative, with a G+C content of 53.9 mol%. They contained desulforubidin, but no desulfoviridin. Based on sequence analysis of the 16S rRNA gene and the sulfite reductase genes dsrAB, strain FiPS-3 was found to be closely related to Desulfotignum balticum. However, physiological properties differed in many points from those of D. balticum. These findings justify the establishment of a new species, Desulfotignum phosphitoxidans.
Epidemiological studies have indicated that obesity is associated with a higher risk for certain cancers caused by elevated levels of adipocyte-derived hormones. Leptin, one such hormone produced by ...adipocytes, is a major regulator of metabolism and has also been shown to modulate immunity. However, its role in regulating human natural killer (NK) cell functions is largely unknown. Here, we show that the leptin receptor (Ob-R) is expressed on 5% of NK cells isolated from blood donors, as measured with flow cytometry, and expression of the signal-transducing long form of the leptin receptor Ob-Rb was confirmed with quantitative PCR. The Ob-R+ subpopulation displayed a lower expression of CD16, a cell surface receptor mediating antibody-dependent activation. Short-term stimulation with leptin increased IFNγ secretion, CD69 activation marker expression, and cytotoxic lysis of tumor cells; this was mediated by an improved conjugate forming between NK cells and tumor cells as well as higher expression of tumor necrosis factor-related apoptosis-inducing ligand. On the contrary, long-term incubation with leptin significantly impaired these NK cell immune functions and decreased cell proliferation. In addition, phosphorylation of Jak-2 after leptin stimulation was reduced in peripheral mononuclear blood cells from obese humans compared with normal-weight controls. NK cells represent an immune cell population that is crucial for an effective antitumor response. Here, we show that long-term exposure to leptin, similarly to the situation in obese individuals with elevated serum leptin levels, significantly impairs integral parts of NK cell immune functions, possibly linking leptin to increased cancer susceptibility in obesity.
Obesity is a risk factor for various types of infectious diseases and cancer. The increase in adipose tissue causes alterations in both adipogenesis and the production of adipocyte-secreted proteins ...(adipokines). Since natural killer (NK) cells are the host's primary defense against virus-infected and tumor cells, we investigated how adipocyte-conditioned medium (ACM) affects functions of two distinct human NK cell subsets.
Isolated human peripheral blood mononuclear cells (PBMCs) were cultured with various concentrations of human and murine ACM harvested on two different days during adipogenesis and analyzed by fluorescent-activated cell sorting (FACS).
FACS analyses showed that the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), granzyme A (GzmA) and interferon (IFN)-γ in NK cells was regulated in a subset-specific manner. ACM treatment altered IFN-γ expression in CD56(dim) NK cells. The production of GzmA in CD56(bright) NK cells was differentially affected by the distinct adipokine compositions harvested at different states of adipogenesis. Comparison of the treatment with either human or murine ACM revealed that adipokine-induced effects on NK cell expression of the leptin receptor (Ob-R), TRAIL and IFN-γ were species-specific.
Considering the growing prevalence of obesity and the various disorders related to it, the present study provides further insights into the roles human NK cell subsets play in the obesity-associated state of chronic low-grade inflammation.
Obesity is associated with an elevated risk for several types of cancer and thus a major health hazard. However, the mechanism between overweight and cancer susceptibility is still elusive. Leptin, ...mainly produced by adipocytes links food intake and energy expenditure. In addition, recent studies have shown an immunomodulatory impact of leptin on NK cells. The purpose of the present study was to investigate whether leptin stimulation of NK cells from obese humans leads to altered functions as compared to NK cells from lean subjects. On the basis of body mass index 20 healthy individuals were classified in two groups: normal weight (<25 kg/m(2)) and obese (>30 kg/m(2)). Peripheral blood mononuclear cells (PBMC) were isolated from blood samples. We used flow cytometry to assess differences in phenotype and activity markers (CD107a, CD178 and TRAIL) of PBMCs between both groups. Furthermore, we determined after short-term in vitro leptin stimulation the phosphorylation of JAK2, downstream target of the intracellular signaling cascade of the leptin receptor, by Western Blotting and numbers of NK-cell-tumor-cell-conjugates as well as Granzyme(+) and IFN-γ(+) NK cells by flow cytometry. Finally, the proliferative capacity of control and long-term (7 days) leptin-stimulated NK cells was examined.
As opposed to similar NK cell counts, the number of CD3(+)CD56(+) cells was significantly lower in obese compared to lean subjects. Human NK cells express the leptin receptor (Ob-R). For further determination of Ob-R, intracellular target proteins of PBMCs were investigated by Western Blotting. Phosphorylation of JAK2 was lower in obese as compared to normal weight subjects. Furthermore, significantly lower levels of TNF-related apoptosis-inducing ligand (TRAIL) as an NK cell functional marker in obese subjects were found. In vitro leptin stimulation resulted in a higher production of interferon-γ in NK cells of normal weight subjects. Interestingly, long-term leptin stimulation had no significant influence on numbers of proliferating NK cells.
NK cells from obese healthy humans show functional deficits and altered responses after in vitro leptin challenge.
Background Obesity is a risk factor for various types of infectious diseases and cancer. The increase in adipose tissue causes alterations in both adipogenesis and the production of ...adipocyte-secreted proteins (adipokines). Since natural killer (NK) cells are the host's primary defense against virus-infected and tumor cells, we investigated how adipocyte-conditioned medium (ACM) affects functions of two distinct human NK cell subsets. Methods Isolated human peripheral blood mononuclear cells (PBMCs) were cultured with various concentrations of human and murine ACM harvested on two different days during adipogenesis and analyzed by fluorescent-activated cell sorting (FACS). Results FACS analyses showed that the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), granzyme A (GzmA) and interferon (IFN)- gamma in NK cells was regulated in a subset-specific manner. ACM treatment altered IFN- gamma expression in CD56dim NK cells. The production of GzmA in CD56bright NK cells was differentially affected by the distinct adipokine compositions harvested at different states of adipogenesis. Comparison of the treatment with either human or murine ACM revealed that adipokine-induced effects on NK cell expression of the leptin receptor (Ob-R), TRAIL and IFN- gamma were species-specific. Conclusion Considering the growing prevalence of obesity and the various disorders related to it, the present study provides further insights into the roles human NK cell subsets play in the obesity-associated state of chronic low-grade inflammation.
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