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PubMed2004

Comparison of the antiproliferative properties of antiestrogenic drugs (nafoxidine and clomiphene) on glioma cells in vitro.

The antitumoral activity of nonsteroidal antiestrogens on C6 and low passage of human glioma cells was investigated. Tamoxifen and its metabolite, 4-hydroxytamoxifen, did not influence viability of the human cells, but tamoxifen had a limited antiproliferative effect on C6 cells (IC50: 49 micromol/l). The derivatives of tamoxifen, nafoxidine and clomiphene, caused reduction of living cell number in a dose-dependent manner. These two drugs showed differences in their potency following 24-hour incubation in a humidified atmosphere with 37 degrees C and 5% CO2. Obtained from a tetrazolium-formazan growth rate assay, IC50 of nafoxidine for C6 cells was calculated as 44 micromol/l and for the human cells as 16.5 micromol/l. The calculated IC50 dose of clomiphene for C6 is 16 micromol/l and for the human cells 13 micromol/l. Compared to the other drugs we used, it is clear that clomiphene is the most efficient inhibitor of C6 and the human glioma cells. These preliminary results suggest that nafoxidine and clomiphene possess antiproliferative effect on two different sources of glioma cells and therefore, instead of tamoxifen, multiple activities of these drugs may enable their use in combination therapy of glioblastoma malignancies.

Animals↗

PubMed2006

OPC-12759 increases proliferation of cultured rat conjunctival goblet cells.

PURPOSE: To determine if the gastroprotective drug OPC-12759 increased proliferation of rat conjunctival goblet cells in culture. METHODS: Cultured goblet cells were incubated with 10(-12) to 10(-8) M OPC-12759 for 1 to 7 days. Fetal bovine serum (FBS) was used as a positive control. Cell proliferation was determined by a MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] colorimetric assay and by immunohistochemical staining with anti-Ki-67, a marker of cell division. Goblet cells were identified by double-labeling with anti-Ki-67, a marker of cell division, and Ulex europaeus agglutinin I lectin, anti-MUC5AC and anticytokeratin 7. Stratified squamous cells were identified by using Griffonia (Bandeiraea) simplicifolia lectin and anticytokeratin 4 antibody. RESULTS: As determined by MTT conversion to formazan, OPC-12579 at 10(-11) M induced an almost 2-fold increase in goblet cell proliferation on Days 1 and 3 of incubation but not on Days 5 and 7. The FBS at 10% increased cell proliferation by 2- to 3-fold at each time point. Daily replenishment of OPC-12579 for 3 consecutive days induced cell proliferation at all concentrations. Proliferation as determined by the number of Ki-67 positive cells increased by 4- and 3-fold at Days 1 and 3, respectively with addition of 10(-11) M OPC-12579. The FBS at 10% induced a 10-fold increase in goblet cell proliferation on Days 1, 3, and 5. Colocalization of Ulex europaeus agglutinin I, MUC5AC and anticytokeratin 7 with Ki-67 indicated that proliferating cells were goblet cells. Proliferating cells were negative for the nongoblet cell markers Bandeiraea lectin and anticytokeratin 4. CONCLUSIONS: The OPC-12759 stimulates proliferation of conjunctival goblet cells in primary culture.

Alanine↗

PubMed1992

Tetrazolium [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction by mycoplasmas.

We investigated 22 mycoplasma and acholeplasma species for their ability to reduce tetrazolium salts by using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The test results were evaluated visually, as well as spectrophotometrically, by using an enzyme-linked immunosorbent assay reader. Our results were very similar to the results obtained when the tetrazolium salt reduction assay described by Aluotto et al. was used. However, the MTT reduction assay appeared to be better because it is faster, more objective and sensitive, easier to evaluate, and less expensive; in addition, it allows quantitative determinations. By using regression analysis a linear correlation between formazan production and the number of colony-forming units was demonstrated for all of the species investigated, indicating that the MTT assay can also be used for growth, toxicity, or chemosensitivity tests for the mycoplasma species that are capable of reducing tetrazolium salts.

Acholeplasma↗

PubMed1998

Use of a new tetrazolium-based assay to study the production of superoxide radicals by tobacco cell cultures challenged with avirulent zoospores of phytophthora parasitica var nicotianae

The relationship between the production of reactive oxygen species and the hypersensitive response (HR) of tobacco (Nicotiana tabacum L. ) toward an incompatible race of the Oomycete Phytophthora parasitica var nicotianae has been investigated. A new assay for superoxide radical (O2-) production based on reduction of the tetrazolium dye sodium,3'-(1-[phenylamino-carbonyl]-3, 4-tetrazolium)-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate (XTT) has enabled the quantitative estimation of perhydroxyl/superoxide radical acid-base pair (HO2./O2-) production during the resistant response. Tobacco suspension cells were inoculated with zoospores from compatible or incompatible races of the pathogen. Subsequent HO2./O2- production was monitored by following the formation of XTT formazan. In the incompatible interaction only, HO2./O2- was produced in a minor burst between 0 and 2 h and then in a major burst between 8 and 10 h postinoculation. During this second burst, rates of XTT reduction equivalent to a radical flux of 9.9 x 10(-15) mol min-1 cell-1 were observed. The HO2./O2- scavengers O2- dismutase and Mn(III)desferal each inhibited dye reduction. An HR was observed in challenged, resistant cells immediately following the second burst of radical production. Both scavengers inhibited the HR when added prior to the occurrence of either radical burst, indicating that O2- production is a necessary precursor to the HR.

Journal Article↗

PubMed2000

Hydrogen peroxide yields during the incompatible interaction of tobacco suspension cells inoculated with Phytophthora nicotianae.

Rates of H(2)O(2) production by tobacco suspension cells inoculated with zoospores from compatible or incompatible races of the pathogen Phytophthora nicotianae were followed by direct measurement of oxygen evolution from culture supernatants following catalase addition. Rates of HO(2)(*)/O(2)(-) production were compared by following the formation of the formazan of sodium, 3'-[1-[phenylamino-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate. In the incompatible interaction only, both reactive oxygen species (ROS) were produced by the cultured host cells in a minor burst between 0 and 2 h and then in a major burst between 8 and 12 h after inoculation. Absolute levels of H(2)O(2) could not be accurately measured due to its metabolism by host cells, but results are consistent with the majority of H(2)O(2) being formed via dismutation of HO(2)(*)/O(2)(-). The effects of inhibitors of endogenous Cu/Zn superoxide dismutase (diethyldithiocarbamate) and catalase (3-amino-1,2,4-triazole and salicylic acid) were also examined. Yields of ROS in the presence of the inhibitors diphenylene iodonium, allopurinol, and salicylhydroxamic acid suggest that ROS were generated in incompatible host responses by more than one mechanism.

Catalase↗

PubMed1996

Role of mitochondria in tributyltin-induced interleukin-1alpha production in murine keratinocytes.

Tributyltin (TBT) salts are well known skin irritants in rodents and humans. TBT induced both the intracellular production of interleukin-1alpha (IL-1alpha) and its release into culture medium in a murine keratinocyte cell line (HEL30). Here, we report that mitochondria are important for TBT-induced IL-1alpha production. Confluent cells were treated with increasing concentrations of TBT (0--2.5 microM) or dimethylsulfoxide as vehicle control. At different times thereafter (0--24 h), nuclear extracts were analyzed for nuclear factor-(kappa)B (NF-(kappa)B) binding activity by electrophoretic mobility shift assay, and the released and cell-associated IL-1alpha was measured by enzyme-linked immunosorbent assay. TBT induced a direct and concentration-related activation of NF-(kappa)B, which peaked at 2 h and was blocked by pyrrolidinedithiocarbamate, a potent NF-(kappa)B inhibitor, and rotenone, an inhibitor of the electron entry from complex I to ubiquinone. Rotenone also induced a concentration-related inhibition of IL-1alpha synthesis induced by TBT, but rotenone did not completely abrogate TBT-induced IL-1alpha production, which suggests that other transcription factors may be involved in IL-1alpha production. Prolonged treatment with ethidium bromide, an inhibitor of mitochondrial DNA and RNA synthesis, was used to partially deplete cells of functional mitochondria. After 5 d of treatment, mitochondrial conversion of tetrazolium bromide to formazan was reduced by 50%, and IL-1alpha release was decreased by 65%, whereas no induction of intracellular IL-1alpha was observed. This effect was not due to inhibition of protein synthesis, because identical incorporation of [3H]leucine into protein in control and ethidium bromide-treated cells was identical. This impairment of mitochondrial metabolism inhibited NF-(kappa)B activation by TBT. These findings indicate that mitochondria may be the source of second messenger molecules important for TBT-induced IL-1alpha production.

Animals↗

PubMed1994

Role of gene expression and protein synthesis of tyrosinase, TRP-1, lamp-1, and CD63 in UVB-induced melanogenesis in human melanomas.

Using melanotic cells (SK-MEL-23 and G361) and amelanotic cells (C32 and SK-MEL-24) of human melanoma, this study examined whether UV-B irradiation has a direct stimulatory effect on the expression of genes involved in melanogenesis. Our initial screening of methylthiazol tetrazolium (MTT)-formazan formation assay indicated a low dose of ultraviolet (UV)-B irradiation, 2.5 and 5.0 mJ/cm2, can metabolically stimulate these cells. Repeated exposure of UV-B at 5.0 mJ/cm2 for seven consecutive days resulted in increased tyrosinase activity and melanin synthesis in SK-MEL-23 and G361 cells, but not in C32 and SK-MEL-24 cells. On reverse-transcription-polymerase chain reaction and immunoprecipitation studies, the two melanotic cell lines exhibited upregulated expression of mRNA and antigenic epitopes of tyrosinase, tyrosinase-related protein (TRP-1; gp75/HMSA-5), and lysosomal membrane associated protein (Lamp-1). The amelanotic cell line, C32, expressed the tyrosinase gene and protein constitutively but revealed no active tyrosinase or melanin synthesis even after UV-B exposure. Another amelanotic cell line, SK-MEL-24, exhibited no expression of tyrosinase gene and protein before and after UV-B exposure and, therefore, no melanin synthesis. Both C32 and SK-MEL-24 showed no gene or protein expression of TRP-1 before or after UV exposure, but upregulation of the Lamp-1 gene and protein expressions after exposure. We conclude that tyrosinase is the key enzyme responsible for UVB-induced melanogenesis. Both TRP-1 and Lamp-1 act together in melanogenesis, TRP-1 being essential and necessary. There is no change in the expression of CD63 lysosomal membrane protein at either the mRNA or protein level.

Antigens, CD↗

PubMed1993

A new method for the determination of the cytotoxicity of bile acids and aqueous phase of stool: the effect of calcium.

Soluble secondary bile acids in the colon are supposed to be cytotoxic for normal colonic cells, resulting in an increased compensatory proliferation of colonic crypt cells, which is associated with an increased risk for colonic cancer. We developed a sensitive method to determine cytotoxicity of bile acids in the HT-29 colon cancer cell line, using a tetrazolium-based colorimetric assay. Only in vital cells, tetrazolium-salts are converted into formazan, which can be measured easily. Chenodeoxycholic acid and deoxycholic acid (DCA) were cytotoxic in concentrations above 100 microM, which is in the physiological range for soluble DCA in faeces. Conjugation of bile acids diminished cytotoxicity 7-10 fold. In this concentration range, no effect of calcium or calcium phosphate was demonstrated, suggesting that the effect of calcium on colonic proliferation is not mediated by a precipitation of soluble bile acids in the large bowel. Finally, we could demonstrate a significant correlation between the cytotoxicity of the aqueous phase of faeces and the soluble DCA concentration.

Bile Acids and Salts↗

PubMed2005

Secretion of prostatic specific antigen, proliferative activity and androgen response in epithelial-stromal co-cultures from human prostate carcinoma.

We investigate the proliferative activity, prostatic specific antigen (PSA) secretion, morphology and androgen response of human prostate tumour epithelial cells co-cultured with stromal cells in a bicameral system. Stromal and epithelial cells were isolated from prostate adenocarcinoma by enzyme digestion and cultured in defined media. Immunocytochemistry for prostate carcinoma tumour antigen (PCTA-1) was performed for culture purity evaluation. Also, the morphology of the epithelial cells in co-culture was evaluated by electron microscopy. PSA was determined by microparticle enzyme immunoassay (MEIA) automatized protocol and the proliferation was evaluated by a commercial spectrophotometric kit, based on formazan salt formation. Both cell cultures showed more than 90% of purity. The epithelial cell co-cultures showed marked membrane processes and cell interdigitations. The proliferative activity of the epithelial cells was increased in presence of stromal cells. Also, PSA secretion was significantly increased and maintained for at least 14 days, whereas the androgen response for PSA secretion was evidenced only in co-culture condition. Primary co-cultures of epithelial and stromal cells from human prostate carcinoma are able to maintain, for a prolonged time, proliferative and secretory properties as well hormone response, and represent a valuable tool for cellular and molecular studies on prostate cancer.

Coculture Techniques↗

PubMed1994

Production and viability of coccoid forms of Campylobacter jejuni.

Studies were conducted into the formation and physiological state of coccoid cells of a strain of the human and animal pathogen Campylobacter jejuni. It was found that growth phase and the presence of chloramphenicol did not affect the rate of shape transformation from spiral to coccoid, while nutrient limitation, aeration of the medium and the presence of free-radical scavengers had profound effects. Coccoid cells were found to reduce the tetrazolium salts INT (2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride) and CTC (5-cyano-2,3-ditolyl tetrazolium chloride) to their respective formazans and this was linked to cellular respiration. However, respiring coccoid cells could not sustain their existence in prolonged adverse conditions, and it was concluded that they represent a degenerative stage rather than a dormant state of the organism.

Campylobacter jejuni↗

PubMed1994

Comparison of the fluorescent redox dye 5-cyano-2,3-ditolyltetrazolium chloride with p-iodonitrotetrazolium violet to detect metabolic activity in heat-stressed Listeria monocytogenes cells.

The fluorogenic redox indicator 5-cyano-2,3-ditolyltetrazolium chloride (CTC) was compared with the chromogenic p-iodonitrotetrazolium violet (INT) and conventional methods to assess cellular viability. Mild heat treatment was used as well-controlled method for producing non-viable and sub-lethally injured cells. CTC gave an underestimation of the viability of Listeria monocytogenes cells when compared with classical plating methods whereas INT gave an overestimation. However, CTC proved to be a sensitive indicator of uninjured cells. The difference between the total count and the CTC count was equivalent to the injured cell population. The fluorescent formazan formed on reduction of CTC was readily detected with a charge coupled device and cells enumerated automatically using image analysis.

Bacteriological Techniques↗

PubMed2005

Expression of the virulence factor, BfpA, by enteropathogenic Escherichia coli is essential for apoptosis signalling but not for NF-kappaB activation in host cells.

Localized adherence (LA) of enteropathogenic Escherichia coli (EPEC) to epithelial cells results in attaching and effacing of the surface of these cells. LA depends on the gene bfpA, which codes for the BfpA protein. We found that EPEC-E. coli adherence factor (EAF)((+)), expressing BfpA, significantly reduced HeLa cell viability in comparison with EPEC-EAF((-)), as evaluated by the mitochondrial-dependent succinate dehydrogenase conversion of 3'-[4,5,-dimethylthiazol-2yl]2,5-diphenyltetrazolium bromide (MTT) to its formazan. Apoptosis accounts for a substantial loss of the cell viability, because the cells incubated with EPEC-EAF((+)) or with cloned BfpA (data not shown), but not with EPEC-EAF((-)), were positive for annexin-V binding, demonstrated chromatin condensation and nuclei fragmentation and exhibited a high level of caspase-3 activity. Because the blockade of bacterial cell-surface-associated BfpA by anti-BfpA immunoglobulin (Ig)Y antibody suppressed apoptotic death induced by EPEC-EAF((+)), BfpA may be the trigger for apoptosis. Both EPEC-EAF((+)) and EPEC-EAF((-)), as well as recombinant BfpA (data not shown), activated nuclear factor (NF)-kappaB in a similar manner as analysed by the electrophoretic mobility shift assay (EMSA). EMSA supershift analysis demonstrated the presence of p65/RelA in a DNA-binding complex. In contrast to DNA binding, NF-kappaB-dependent reporter gene transactivation was stimulated more strongly by EPEC B171/EAF((+)), suggesting a role for this virulence factor in the regulation of transcriptional activity of NF-kappaB. Because suppression of NF-kappaB activation by BAY11-7085, a NF-kappaB inhibitor, neither induced apoptosis by itself nor blocked apoptosis induction by EPEC-EAF((+)), it may be suggested that apoptosis is not regulated by the NF-kappaB pathway in HeLa cells.

Apoptosis↗

PubMed1975

Mitochondria and peroxisomes from the cellular slime mould Dictyostelium discoideum. Isolation techniques and urate oxidase association with peroxisomes.

The isolation of cell organelles from Dictyostelium discoideum was attempted using a variety of techniques. Cell homogenization (e.g. Potter-Elvehjem, glass beads) gave poor yields of organelles which were, in addition, exceptionally fragile and unstable in density gradients. An isolation method was developed using Triton X-100 in buffered sorbitol/Ficoll solutions at concentrations optimal for plasma membrane rupture. Immediately following cell lysis the solutions were diluted to sub-optimal Triton X-100 concentrations. Sedimentabilities of malate dehydrogenase, citrate synthetase, urate oxidase and catalase of around 55%, 40%, 35% and 55% respectively could be demonstrated using this method. The organelles were more resistant to breakage during resuspension following differential centrifugation and remained largely intact during density gradient centrifugation. The distribution of adenylate kinase activity in gradients showed that at least half the mitochondria retained an intact outer membrane. The mitochondria and peroxisomes could not be clearly separated using conventional sucrose-Ficoll density gradients. Separation was achieved by incubating the cell homogenate with succinate and a tetrazolium dye (2-p-iodophenyl-3-p-nitrophenyl-5-phenyl monotetrazolium chloride). Succinate dehydrogenase activity of mitochondria reduced the tetrazolium dye and the product (formazan) was deposited on the mitochondrial membranes ("heavy-labelling"). The mitochondria then sedimented to denser regions of the gradient while catalase distribution remained unchanged. The treatment left both organelles intact. The mitochondria (1.21 g/ml) were slightly denser than the peroxisomes (1.19 g/ml). The peroxisomes contained catalase and urate oxidase; no other hydrogen-peroxide-producing oxidases were detected. The slime mould urate oxidase resembled the mammalian enzyme. It had an apparent Km value of 12.5 muM, an optimum of activity at pH 8.5 in borate buffer and was competitively inhibited by trichloropurine.

2,6-Dichloroindophenol↗

PubMed1985

Kinetic analysis of lactate dehydrogenase in cultured chondrocytes by quantitative cytochemistry.

Kinetic analysis of lactate dehydrogenase activity in intact cultured chondrocytes was performed in situ by coupling cell culture and microcytophotometry. Cells were cultured on glass microscope slides divided into eight chambers and studied during the growth cycle in monolayer areas. Lactate dehydrogenase activity was assayed by the reduction of neotetrazolium in the presence of phenazine methosulfate. Quantification of formazan deposits within the cells was performed by scanning and integrating microdensitometry at the isosbestic wavelength of 585 nm. Results indicate the following (a) A kinetic characterization was possible: apparent constants, Km and Ks of this two-substrate enzyme were graphically determined Ks = 1.05 +/- 0.08 and 0.56 +/- 0.05 mM for lactate and NAD respectively and Km = 0.64 +/- 0.03 and 0.37 +/- 0.02 mM for lactate and NAD respectively. (b) Inhibition by lactate concentrations above 10 mM and pyruvate concentration of 1 mM, is in agreement with the well known high anaerobic glycolytic metabolism of chondrocytes. This was confirmed by electrophoresis on cellulose acetate which demonstrated a M3-H isoenzyme form in cultured chick chondrocytes. This study shows that microcytophotometric analysis of lactate dehydrogenase in cultured chondrocytes may be an interesting alternative to mass culture cells followed by classical biochemical studies.

Animals↗

PubMedDate not supplied

Selected enzyme histochemistry of Sertoli cells. 1. Immature rat Sertoli cells in vitro.

Sertoli cells were collected from the testes of 21 day old, sexually immature Wistar rats. The cells were then incubated for 10 or 14 days in culture medium with or without the addition of FSH. This time period corresponds to the time period in vivo when rat Sertoli cells undergo active differentiation with concomitant histochemical and morphological changes. Cells cultured 10 and 14 days after initial plating were processed for the histochemical detection of three esterases and four dehydrogenases by observing relative staining intensities of azo dye precipitation and formazan reaction product, respectively. Appropriate controls were established. The presence of FSH mildly increased the staining activity of LDH, SDH and G-6-PDH in both 10 and 14 day cultured cells. However, SDH staining intensity/cell did not increase to surpass LDH staining intensity/cell as it does in vivo during this period of time. Addition of FSH also slightly increased staining of non-specific esterase. Type B esterase and 3 beta-ol DH activity was not evident in 10 and 14 day cultured cells, even in the presence of FSH. Our results indicate that, based on histochemical parameters, immature Sertoli cells do not mature in culture commensurate with the cell in vivo.

Animals↗

PubMedDate not supplied

Selected enzyme histochemistry of Sertoli cells. 2. Adult rat Sertoli cells in co-culture with peritubular fibroblasts.

Sertoli cells and peritubular fibroblasts were collected from sexually mature Wistar rats and incubated by themselves (ASC) or in co-culture (AS/PC) for ten days with or without follicle stimulating hormone (FSH). Freshly collected cells and those of the ASC and AS/PC cultures were processed for histochemical detection of three esterases and four dehydrogenases. The relative staining intensities of azo dye and formazan reaction products were recorded for the cell cultures, co-cultures and appropriate controls. Freshly collected Sertoli cells stained heavily for lactic dehydrogenase (LDH), succinic dehydrogenase (SDH), glucose-6-phosphate dehydrogenase (G-6-PDH), non-specific esterase (Est.) and 3 beta-hydroxysteroid dehydrogenase (3 beta-OLDH). For Sertoli cells alone in culture (ASC) there was a marked decline of enzyme reaction product deposition/cell for LDH and Est. and absence of cellular staining for SDH, G-G-PDH, B-Est. and 3 beta-OLDH. The addition of FSH did not change this histochemical staining pattern for the adult cells in vitro. The presence of peritubular cells in adult Sertoli cell cultures (AS/PC) resulted in the maintenance of metabolic enzyme staining (i.e., LDH, SDH, G-6-PDH and Est.) in Sertoli cells, minimal staining for B-Est., but absence of detectable enzyme reaction product for 3 beta-OLDH. Sertoli cells co-cultured with other fibroblasts or in medium pre-conditioned with peritubular cells but not containing them stained minimally for LDH and Est. and did not generate reaction product for any of the other enzymes. The addition of FSH to the AS/PT co-culture as in the ASC cultures did not affect the enzyme histochemical staining profile of Sertoli cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1996

Lymphoproliferation assays in cattle naturally infected with bovine leukaemia virus (BLV) and bovine immunodeficiency-like virus (BIV).

Experiments were designed to evaluate the effect of BLV on mitogen-stimulated peripheral blood mononuclear cells (PBMC) from naturally infected cattle. BIV was also taken into consideration due to a recent report showing that in Costa Rica, most of the BLV-infected animals are also seropositive for BIV. The methodology was based on a non-radioactive technique to determine lymphoproliferation. A colorimetric assay using XTT (formazan salt) to measure cell multiplication was adapted for bovine PBMC. ELISA and Western blotting were used to determine the serologic status of the cattle. PCR was only available for BIV detection. Our results show clearly that, dually-infected cattle (BIV-BLV) have reduced lymphoproliferative responses to the mitogen Con A. Haematological abnormalities associated with viral infections were also observed, specially leukocytosis and lymphocytosis. Cows with lymphosarcomas are severely affected. The specific antibody response to different viral proteins could not be associated with the suppressive status of the animals. Due to the high rate of dual infections observed in Costa Rica, these results are not sufficient to clarify which virus is responsible for the suppressive activity, if one or both viruses are necessary, or if they act synergistically.

Animals↗

PubMed1997

All-trans retinoic acid suppresses liver injury induced by Propionibacterium acnes and lipopolysaccharide in rats.

All-trans retinoic acid (ATRA) has been reported to exert major effects on the immune system, including monocytes/macrophages. The present study was designed to determine whether ATRA would modulate macrophage-associated liver injury induced by Propionibacterium acnes and lipopolysaccharide (LPS) in rats. All-trans retinoic acid administration alleviated the liver injury and reduced the incidence of death following hepatic failure. Serum alanine aminotransferase (ALT) levels 5 h after, and survival rates within 12 h after the administration of LPS were significantly lower in the ATRA-treated group (134+/-119 IU/L and 72.7%) compared with the control group (713+/-411 IU/L and 18.2%; P< 0.05). Histological findings supported these results. These effects may be due to suppression of tumour necrosis factor-alpha (TNF-alpha) and superoxide anions produced by activated macrophages. Serum levels of TNF-alpha 1 h after LPS administration were significantly lower in the ATRA-treated group (60.5+/-7.0 ng/mL) as compared with the control group (105.2+/-39.3 ng/mL; P< 0.05). Formazan deposition that was generated by the perfusion of the liver with nitroblue tetrazolium, also suggested suppression of the release of superoxide anions from hepatic macrophages. These results suggest that ATRA acts as an immunomodulator in liver injury by suppressing the activation of liver macrophages.

Animals↗