Oxidative stress induces protein and DNA radical formation in follicular dendritic cells of the germinal center and modulates its cell death patterns in late sepsis

National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Free Radical Biology and Medicine (Impact Factor: 5.74). 04/2011; 50(8):988-99. DOI: 10.1016/j.freeradbiomed.2010.12.037
Source: PubMed


Profound depletion of follicular dendritic cells (FDCs) is a hallmark of sepsis-like syndrome, but the exact causes of the ensuing cell death are unknown. The cell death-driven depletion contributes to immunoparalysis and is responsible for most of the morbidity and mortality in sepsis. Here we have utilized immuno-spin trapping, a method for detection of free radical formation, to detect oxidative stress-induced protein and DNA radical adducts in FDCs isolated from the spleens of septic mice and from human tonsil-derived HK cells, a subtype of germinal center FDCs, to study their role in FDC depletion. At 24h post-lipopolysaccharide administration, protein radical formation and oxidation were significantly elevated in vivo and in HK cells as shown by ELISA and confocal microscopy. The xanthine oxidase inhibitor allopurinol and the iron chelator desferrioxamine significantly decreased the formation of protein radicals, suggesting the role of xanthine oxidase and Fenton-like chemistry in radical formation. Protein and DNA radical formation correlated mostly with apoptotic features at 24h and necrotic morphology of all the cell types studied at 48h with concomitant inhibition of caspase-3. The cytotoxicity of FDCs resulted in decreased CD45R/CD138-positive plasma cell numbers, indicating a possible defect in B cell differentiation. In one such mechanism, radical formation initiated by xanthine oxidase formed protein and DNA radicals, which may lead to cell death of germinal center FDCs.

Download full-text


Available from: Ronald P Mason
  • Source
    • "There has been some proof to suggest that free radicals and some reactive nitrogen species trigger and increase cell death mechanisms such as apoptosis and in extreme cases necrosis [12] [13] . Scientists recommend that antioxidant can reduce the activity of free radicals including their so called side effects and thus increase the cell survival times effectively [14] . "
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective: To study the phytochemical and biological properties (antioxidant, and thrombolytic) of methanolic extracts of Enhydra fluctuans Lour, a plant bel oanngtihnegl mtoi ntthiec Asteraceae family. Methods: The phytochemical evaluation was carried out by qualitative analysis. In vitro raendtuiocxtiidona,n tt oataclt ipvihteyn oofl eaxntdr atcott awl aflsa vstoundoiiedd c uonsitneng tsfr edee treardmiicnaalt isocna vaesnsagyins.g Tahses aayn, thabelimlitiyn toicf athcrtoivmitbyo lwyatisc daectteivrimtyi nbeyd c ulosti ndgis rpuapratiloyns iass saanyd. death time of phertima posthuma (earthworm) and Results: The phytochemical evaluation showed significant presence of flavonoids, triterpenes, caacrtibvoihtyy dwraast ef,o urenddu sciignngi fsiucgaanrts [,I Csaponins, phenols, diterpenes, protein and tannin. The antioxidant 50=(135.20依0.56) μg/mL] as compared to ascorbic acid [(130.00±0.76) μg/mL]. The reducing power was increased with concentration. Total phenol and total flavonoid dcoenatthe nttims ew eorf ee a(1r5th3w.0o8r依m0s.3 f8o) rm dgif/fmerLe natn cdo n(1c7e2n.t0r4a依ti0o.n5s6 ) omf egx/mtraLc tr ewsepreec tdievteelrym. iTnhede apnadra clyosmisp aarnedd awlibthen adlabzeonldea. zAodled.i tTiohnea rlelys,u tlhtse schrouwdeed e txhtraat c1t0 s mhogw/medL ao fc tohnec ecnrutrdaeti oenx tdraecpte hnadde ds irmelialatiro nefsfheicpt wwiitthh isttsr eapntothkeinlmasine’tsic c lporto lpyesritsy (.4 0T.h13e clot lysis activity of crude extract was compared to the standard %) activity and found significant (31%). Conclusions: The study proves that the crude methanolic extract of Enhydra fluctuans Lour hphasy tosicghneimfiiccaanlst .antioxidant
    Full-text · Article · Apr 2014 · Asian Pacific Journal of Tropical Biomedicine
  • Source
    • "Free radical damage within cells has been linked to a range of disorders including cancer, arthritis, atherosclerosis, Alzheimer's disease, and diabetes [2] [3] . There has been some evidence to suggest that free radicals and some reactive nitrogen species trigger and increase cell death mechanisms within the body such as apoptosis and in extreme cases necrosis [4] . Targeted antioxidants may lead to better medicinal effects such as mitochondria-targeted ubiquinone, for example, may prevent damage to the liver caused by excessive alcohol [5] . "
    [Show abstract] [Hide abstract]
    ABSTRACT: To study the leaves of Adiantum philippense L. for their antioxidant, cytotoxicity and thrombolytic activities and to perform phytochemical evaluation. In-vitro antioxidant activity of extract was studied using DPPH radical scavenging, reducing power, total phenol and total flavonoid content determination assays. The cytotoxic activity was determined using brine shrimp lethality bioassay, thrombolytic activity by clot disruption and phytochemical potential by qualitative analysis. The antioxidant activity of the extracts was found promising. The reducing power of this crude extract increase with the increase of concentration; IC50 values of DPPH scavenging activity was (140.00±0.86) µg/mL as compared to ascorbic acid [IC50 (130.00±0.76) µg/mL]; Total phenol and total flavonoids content were (148.26±0.24) mg/mL and (163.06±0.56) mg/mL respectively. In cytotoxicity assay the LC50 values of the sample was (106.41±0.78) µg/mL where as for standard vincristin sulphate was (08.50±0.24) µg/mL as a positive control and the extract shows (12.86±1.02)% clot lytic whereas standard streptokinase shows (30.86±0.44% clot lytic activity in thrombolytic assay. The phytochemical evaluation indicates the presence of chemical constituents including carbohydrates, alkaloids, saponins, glycosides, flavonoids. This study shows that the methanol extract of leaves of Adiantum philippense L. has bioactivity but further compound isolation is necessary to confirm the activities of individual compounds.
    Preview · Article · Jun 2013 · Asian Pacific Journal of Tropical Biomedicine
  • Source
    • "Statistical significance was tested using ANOVA, with Bonferroni posthoc correction. *(P b 0.05). of 20–40 μM, has been found to act as a scavenger of free radicals (Chatterjee et al., 2011). Excess DMPO (100 mM) was thus used to scavenge free radicals in this experiment. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Today's developed world faces a major public health challenge in the rise in the obese population and the increased incidence in fatty liver disease. There is a strong association among diet induced obesity, fatty liver disease and development of nonalcoholic steatohepatitis but the environmental link to disease progression remains unclear. Here we demonstrate that in obesity, early steatohepatitic lesions induced by the water disinfection byproduct bromodichloromethane are mediated by increased oxidative stress and leptin which act in synchrony to potentiate disease progression. Low acute exposure to bromodichloromethane (BDCM), in diet-induced obesity produced oxidative stress as shown by increased lipid peroxidation, protein free radical and nitrotyrosine formation and elevated leptin levels. Exposed obese mice showed histopathological signs of early steatohepatitic injury and necrosis. Spontaneous knockout mice for leptin or systemic leptin receptor knockout mice had significantly decreased oxidative stress and TNF-α levels. Co-incubation of leptin and BDCM caused Kupffer cell activation as shown by increased MCP-1 release and NADPH oxidase membrane assembly, a phenomenon that was decreased in Kupffer cells isolated from leptin receptor knockout mice. In obese mice that were BDCM-exposed, livers showed a significant increase in Kupffer cell activation marker CD68 and, increased necrosis as assessed by levels of isocitrate dehydrogenase, events that were decreased in the absence of leptin or its receptor. In conclusion, our results show that exposure to the disinfection byproduct BDCM in diet-induced obesity augments steatohepatitic injury by potentiating the effects of leptin on oxidative stress, Kupffer cell activation and cell death in the liver.
    Full-text · Article · Feb 2013 · Toxicology and Applied Pharmacology
Show more