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Fischer Sigel LK, Sánchez DS, Sacerdoti F, Zotta E, Silberstein C. Progression of renal damage and tubular regeneration in pregnant and non-pregnant adult female rats inoculated with a sublethal dose of Shiga toxin 2. Microb Pathog 2024; 186:106482. [PMID: 38086442 DOI: 10.1016/j.micpath.2023.106482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 11/13/2023] [Accepted: 11/29/2023] [Indexed: 12/17/2023]
Abstract
BACKGROUND Shiga toxin-producing Escherichia coli is the main cause of post-diarrheal hemolytic uremic syndrome (HUS) which produces acute kidney injury mainly in children, although it can also affect adults. The kidneys are the organs most affected by Shiga toxin type 2 (Stx2) in patients with HUS. However, previous studies in pregnant rats showed that a sublethal dose of Stx2 causes severe damage in the uteroplacental unit and induces abortion, whereas produces mild to moderate renal damage. The aim of the present work was to study the progression of renal injury caused by a sublethal dose of Stx2, as well as renal recovery, in pregnant and non-pregnant rats, and to investigate whether pregnancy physiology may affect renal damage progression mediated by Stx2. METHODS Renal function and histopathology was evaluated in pregnant rats intraperitoneally injected with a sublethal dose of Stx2 (0.5 ng/g bwt) at the early stage of gestation (day 8 of gestation), and results in these rats were compared over time with those observed in non-pregnant female rats injected with the same Stx2 dose. Hence, progression of cell proliferation and dedifferentiation in renal tubular epithelia was also investigated. RESULTS The sublethal dose of Stx2 induced abortion in pregnant rats as well as a significant more extended functional and histological renal injury in non-pregnant rats than in pregnant rats. Stx2 also caused decreased ability to concentrate urine in non-pregnant rats compared to their controls. However, renal water handling in pregnant rats was not altered by Stx2, and was significantly different than in non-pregnant rats. The greatest renal injury in both pregnant and non-pregnant rats was observed at 4 days post-Stx2 injection, and coincided with a significant increase in tubular epithelial proliferation. Expression of mesenchymal marker vimentin in tubular epithelia was consistent with the level of tubular damage, being higher in non-pregnant rats than in pregnant rats. Recovery from Stx2-induced kidney injury was faster in pregnant rats than in non-pregnant rats. CONCLUSIONS Adaptive mechanisms developed during pregnancy such as changes in water handle and renal hemodynamic may contribute to lessen the Stx2-induced renal injury, perhaps at the expense of fetal loss.
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Affiliation(s)
- Lilian K Fischer Sigel
- Universidad de Buenos Aires (UBA), Facultad de Ciencias Médicas, Departamento de Ciencias Fisiológicas, Laboratorio de Fisiología Renal, Buenos Aires, Argentina; Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Buenos Aires, Argentina
| | - Daiana S Sánchez
- Universidad de Buenos Aires (UBA), Facultad de Ciencias Médicas, Departamento de Ciencias Fisiológicas, Laboratorio de Fisiología Renal, Buenos Aires, Argentina; Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Buenos Aires, Argentina
| | - Flavia Sacerdoti
- Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Ciencias Médicas, Departamento de Ciencias Fisiológicas, Laboratorio de Fisiopatogenia, Buenos Aires, Argentina
| | - Elsa Zotta
- Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Ciencias Médicas, Departamento de Ciencias Fisiológicas, Laboratorio de Fisiopatogenia, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Ciencias Médicas, Departamento de Ciencias Fisiológicas. Laboratorio de Patología, and Facultad de Farmacia y Bioquímica, Cátedra de Fisiopatología, Buenos Aires, Argentina
| | - Claudia Silberstein
- Universidad de Buenos Aires (UBA), Facultad de Ciencias Médicas, Departamento de Ciencias Fisiológicas, Laboratorio de Fisiología Renal, Buenos Aires, Argentina; Universidad de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Buenos Aires, Argentina.
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Scalise ML, Garimano N, Sanz M, Padola NL, Leonino P, Pereyra A, Casale R, Amaral MM, Sacerdoti F, Ibarra C. Detection of Shiga Toxin-Producing Escherichia coli (STEC) in the Endocervix of Asymptomatic Pregnant Women. Can STEC Be a Risk Factor for Adverse Pregnancy Outcomes? Front Endocrinol (Lausanne) 2022; 13:945736. [PMID: 35957815 PMCID: PMC9358589 DOI: 10.3389/fendo.2022.945736] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/14/2022] [Indexed: 11/13/2022] Open
Abstract
The presence of Escherichia coli in the vaginal microbiome has been associated with pregnancy complications. In previous works, we demonstrated that Shiga toxin-producing Escherichia coli (STEC) can produce abortion and premature delivery in rats and that Shiga toxin type 2 (Stx2) can impair human trophoblast cell lines. The hypothesis of this work was that STEC may colonize the lower female reproductive tract and be responsible for adverse pregnancy outcomes. Thus, the aim of this work was to evaluate the presence and prevalence of virulence factor genes from STEC in the endocervix of asymptomatic pregnant women. For that purpose, endocervical swabs were collected from pregnant women during their prenatal examination. Swab samples were enriched in a differential medium to select Enterobacteria. Then, positive samples were analyzed by PCR to detect genes characteristic of Escherichia sp. (such as uidA and yaiO), genes specific for portions of the rfb (O-antigen-encoding) regions of STEC O157 (rfbO157), and STEC virulence factor genes (such as stx1, stx2, eae, lpfAO113, hcpA, iha, sab, subAB). The cytotoxic effects of stx2-positive supernatants from E. coli recovered from the endocervix were evaluated in Vero cells. Our results showed that 11.7% of the endocervical samples were positive for E. coli. Additionally, we found samples positive for stx2 and other virulence factors for STEC. The bacterial supernatant from an isolate identified as E. coli O113:NT, carrying the stx2 gene, exhibited cytotoxic activity in Vero, Swan 71 and Hela cells. Our results open a new perspective regarding the presence of STEC during pregnancy.
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Affiliation(s)
- María Luján Scalise
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica, IFIBIO-Houssay (UBA-CONICET), Departamento de Ciencias Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Nicolás Garimano
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica, IFIBIO-Houssay (UBA-CONICET), Departamento de Ciencias Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marcelo Sanz
- CIVETAN-Centro de Investigación Veterinaria Tandil (CONICET, CICPBA), Facultad de Ciencias Veterinarias, Tandil, Argentina
| | - Nora Lia Padola
- CIVETAN-Centro de Investigación Veterinaria Tandil (CONICET, CICPBA), Facultad de Ciencias Veterinarias, Tandil, Argentina
| | - Patricia Leonino
- Departamento de Obstetricia, Hospital Nacional “Prof. A. Posadas”, Buenos Aires, Argentina
| | - Adriana Pereyra
- Departamento de Obstetricia, Hospital Nacional “Prof. A. Posadas”, Buenos Aires, Argentina
| | - Roberto Casale
- Departamento de Obstetricia, Hospital Nacional “Prof. A. Posadas”, Buenos Aires, Argentina
| | - María Marta Amaral
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica, IFIBIO-Houssay (UBA-CONICET), Departamento de Ciencias Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Flavia Sacerdoti
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica, IFIBIO-Houssay (UBA-CONICET), Departamento de Ciencias Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
- *Correspondence: Cristina Ibarra, ; Flavia Sacerdoti,
| | - Cristina Ibarra
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica, IFIBIO-Houssay (UBA-CONICET), Departamento de Ciencias Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
- *Correspondence: Cristina Ibarra, ; Flavia Sacerdoti,
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Sacerdoti F, Scalise ML, Burdet J, Amaral MM, Franchi AM, Ibarra C. Shiga Toxin-Producing Escherichia coli Infections during Pregnancy. Microorganisms 2018; 6:E111. [PMID: 30360505 PMCID: PMC6313425 DOI: 10.3390/microorganisms6040111] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 10/17/2018] [Accepted: 10/19/2018] [Indexed: 01/08/2023] Open
Abstract
Gastrointestinal infection with Shiga toxin-producing Escherichia coli (STEC) causes diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS), characterized by hemolytic anemia, thrombocytopenia and acute renal failure. The main virulence factor of STEC is Shiga toxin (Stx), which is responsible for HUS development. STEC can produce Stx type 1 and/or 2 (Stx1, Stx2) and their variants, Stx2 being more frequently associated with severe cases of HUS. This pathology occurs in 5⁻15% of cases with STEC infection when Stx gain access to the bloodstream and causes damage in the target organs such as the kidney and brain. STEC infections affect mainly young children, although the large HUS outbreak with a new Stx2-producing STEC O104:H4 in Europe in 2011 involved more adults than children, and women were over-represented. Maternal infections during pregnancy are associated with adverse pregnancy outcomes. Studies in rats showed that Stx2 binds to the utero-placental unit and causes adverse pregnancy outcomes. In this article, we provide a brief overview of Stx2 action on placental tissues and discuss whether they might cause pregnancy loss or preterm birth.
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Affiliation(s)
- Flavia Sacerdoti
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Buenos Aires 1121, Argentina.
| | - María Luján Scalise
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Buenos Aires 1121, Argentina.
| | - Juliana Burdet
- Laboratorio de Hematología, Hospital Universitario Austral, Pilar, Buenos Aires 1629, Argentina.
| | - María Marta Amaral
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Buenos Aires 1121, Argentina.
| | - Ana María Franchi
- CEFYBO-CONICET, Universidad de Buenos Aires, Buenos Aires 1121, Argentina.
| | - Cristina Ibarra
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, Buenos Aires 1121, Argentina.
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Sacerdoti F, Mejías MP, Bruballa AC, Alvarez RS, Amaral MM, Palermo MS, Ibarra C. Immunization with BLS-Stx2B chimera totally protects dams from early pregnancy loss induced by Shiga toxin type 2 (Stx2) and confers anti-Stx2 immunity to the offspring. Vaccine 2016; 34:4732-4737. [PMID: 27527816 DOI: 10.1016/j.vaccine.2016.07.049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 06/22/2016] [Accepted: 07/25/2016] [Indexed: 11/16/2022]
Abstract
Shiga toxin producing Escherichia coli (STEC) are bacterial pathogens involved in food-borne diseases. Shiga toxin (Stx) is the main virulence factor of STEC and is responsible for systemic complications including Hemolytic Uremic Syndrome (HUS). It has been previously demonstrated that Shiga toxin type 2 (Stx2) induces pregnancy loss in rats in early stage of pregnancy. The main purpose of this study was to determine if an active immunization prevents Stx2 mediated pregnancy loss and confers passive protective immunity to the offspring. For that purpose Sprague Dawley female rats were immunized with the chimera based on the enzyme lumazine synthase from Brucella spp. (BLS) and the B subunit of Shiga toxin 2 (Stx2B) named BLS-Stx2B. After immunization females were mated with males. At day 8 of gestation, dams were challenged intraperitoneally with a sublethal and abortifacient dose of Stx2. The immunization induced high anti-Stx2B-specific antibody titers in sera and most important, prevented pregnancy loss. Pups born and breastfeed by immunized dams had high anti-Stx2B-specific antibody titers in sera. Cross-fostering experiments indicated that passive protective immunity against Stx2 was transmitted through lactation. These results indicate that immunization of adult female rats with BLS-Stx2B prevents Stx2-induced pregnancy loss and confers anti Stx2 protective immunity to the offspring.
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Affiliation(s)
- Flavia Sacerdoti
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María P Mejías
- Laboratorio de Patogénesis e Inmunología de Procesos Infecciosos, Instituto de Medicina Experimental, (IMEX-CONICET), Academia Nacional de Medicina, Buenos Aires, Argentina
| | - Andrea C Bruballa
- Laboratorio de Patogénesis e Inmunología de Procesos Infecciosos, Instituto de Medicina Experimental, (IMEX-CONICET), Academia Nacional de Medicina, Buenos Aires, Argentina
| | - Romina Soledad Alvarez
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María M Amaral
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marina S Palermo
- Laboratorio de Patogénesis e Inmunología de Procesos Infecciosos, Instituto de Medicina Experimental, (IMEX-CONICET), Academia Nacional de Medicina, Buenos Aires, Argentina
| | - Cristina Ibarra
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
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Sacerdoti F, Amaral M, Aisemberg J, Cymeryng C, Franchi A, Ibarra C. Involvement of hypoxia and inflammation in early pregnancy loss mediated by Shiga toxin type 2. Placenta 2015; 36:674-80. [DOI: 10.1016/j.placenta.2015.03.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 03/04/2015] [Accepted: 03/06/2015] [Indexed: 10/23/2022]
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Effects of Shiga toxin type 2 on maternal and fetal status in rats in the early stage of pregnancy. BIOMED RESEARCH INTERNATIONAL 2014; 2014:384645. [PMID: 25157355 PMCID: PMC4026949 DOI: 10.1155/2014/384645] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Accepted: 04/03/2014] [Indexed: 12/03/2022]
Abstract
Shiga toxin type 2 (Stx2), a toxin secreted by Shiga toxin-producing Escherichia coli (STEC), could be one of the causes of maternal and fetal morbimortality not yet investigated. In this study, we examined the effects of Stx2 in rats in the early stage of pregnancy. Sprague-Dawley pregnant rats were intraperitoneally (i.p.) injected with sublethal doses of Stx2, 0.25 and 0.5 ng Stx2/g of body weight (bwt), at day 8 of gestation (early postimplantation period of gestation). Maternal weight loss and food and water intake were analyzed after Stx2 injection. Another group of rats were euthanized and uteri were collected at different times to evaluate fetal status. Immunolocalization of Stx2 in uterus and maternal kidneys was analyzed by immunohistochemistry. The presence of Stx2 receptor (globotriaosylceramide, Gb3) in the uteroplacental unit was observed by thin layer chromatography (TLC). Sublethal doses of Stx2 in rats caused maternal weight loss and pregnancy loss. Stx2 and Gb3 receptor were localized in decidual tissues. Stx2 was also immunolocalized in renal tissues. Our results demonstrate that Stx2 leads to pregnancy loss and maternal morbidity in rats in the early stage of pregnancy. This study highlights the possibility of human pregnancy loss and maternal morbidity mediated by Stx2.
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Burdet J, Sacerdoti F, Cella M, Franchi AM, Ibarra C. Role of TNF-α in the mechanisms responsible for preterm delivery induced by Stx2 in rats. Br J Pharmacol 2013; 168:946-53. [PMID: 23043728 PMCID: PMC3631382 DOI: 10.1111/j.1476-5381.2012.02239.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 08/22/2012] [Accepted: 09/06/2012] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Infections with a strain of Escherichia coli producing Shiga toxins could be one of the causes of fetal morbidity and mortality in pregnant women. We have previously reported that Shiga toxin type 2 (Stx2) induces preterm delivery in pregnant rats. In this study, we evaluate the role of TNF-α, PGs and NO in the Stx2-induced preterm delivery. EXPERIMENTAL APPROACH Pregnant rats were treated with Stx2 (0.7 ng g(-1)) and killed at different times after treatment. Placenta and decidua were used to analyse NOS activity by the conversion of L-[(14)C]arginine into L-[(14)C]citrulline, levels of PGE(2) and PGF(2α) assessed by radioimmunoassay, and cyclooxygenase (COX) proteins by Western blot. TNF-α level was analysed in serum by ELISA and by cytotoxicity in L929 cells. The inhibitor of inducible NOS, aminoguanidine, the COX-2 inhibitor, meloxicam, and the competitive inhibitor of TNF-α, etanercept, were used alone or combined to inhibit NO, PGs and TNF-α production respectively, to prevent Stx2-induced preterm delivery. KEY RESULTS Stx2 increased placental PGE(2) and decidual PGF(2α) levels as well as COX-2 expression in both tissues. Aminoguanidine and meloxicam delayed the preterm delivery time but did not prevent it. Etanercept blocked the TNF-α increase after Stx2 treatment and reduced the preterm delivery by approximately 30%. The combined action of aminoguanidine and etanercept prevented Stx2-induced preterm delivery by roughly 70%. CONCLUSION AND IMPLICATIONS Our results demonstrate that the increased TNF-α and NO induced by Stx2 were the predominant factors responsible for preterm delivery in rats.
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Affiliation(s)
- Juliana Burdet
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos AiresBuenos Aires, Argentina
| | - Flavia Sacerdoti
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos AiresBuenos Aires, Argentina
| | - Maximiliano Cella
- Centro de Estudios Farmacológicos y Botánicos (CEFYBO-CONICET), Universidad de Buenos AiresBuenos Aires, Argentina
| | - Ana M Franchi
- Centro de Estudios Farmacológicos y Botánicos (CEFYBO-CONICET), Universidad de Buenos AiresBuenos Aires, Argentina
| | - Cristina Ibarra
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos AiresBuenos Aires, Argentina
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Shiga toxin type 2 (Stx2), a potential agent of bioterrorism, has a short distribution and a long elimination half-life, and induces kidney and thymus lesions in rats. Arch Toxicol 2011; 85:1133-40. [DOI: 10.1007/s00204-010-0639-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 12/16/2010] [Indexed: 10/18/2022]
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Role of nitric oxide in shiga toxin-2-induced premature delivery of dead fetuses in rats. PLoS One 2010; 5:e15127. [PMID: 21206910 PMCID: PMC3012062 DOI: 10.1371/journal.pone.0015127] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 10/25/2010] [Indexed: 12/05/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) infections could be one of the causes of fetal morbimortality in pregnant women. The main virulence factors of STEC are Shiga toxin type 1 and/or 2 (Stx1, Stx2). We previously reported that intraperitoneal (i.p.) injection of rats in the late stage of pregnancy with culture supernatant from recombinant E. coli expressing Stx2 and containing lipopolysaccharide (LPS) induces premature delivery of dead fetuses. It has been reported that LPS may combine with Stx2 to facilitate vascular injury, which may in turn lead to an overproduction of nitric oxide (NO). The aim of this study was to evaluate whether NO is involved in the effects of Stx2 on pregnancy. Pregnant rats were i.p. injected with culture supernatant from recombinant E. coli containing Stx2 and LPS (sStx2) on day 15 of gestation. In addition, some rats were injected with aminoguanidine (AG), an inducible isoform inhibitor of NO synthase (iNOS), 24 h before and 4 h after sStx2 injection. NO production was measured by NOS activity and iNOS expression by Western blot analysis. A significant increase in NO production and a high iNOS expression was observed in placental tissues from rats injected with sStx2 containing 0.7 ng and 2 ng Stx2/g body weight and killed 12 h after injection. AG caused a significant reduction of sStx2 effects on the feto-maternal unit, but did not prevent premature delivery. Placental tissues from rats treated with AG and sStx2 presented normal histology that was indistinguishable from the controls. Our results reveal that Stx2-induced placental damage and fetus mortality is mediated by an increase in NO production and that AG is able to completely reverse the Stx2 damages in placental tissues, but not to prevent premature delivery, thus suggesting other mechanisms not yet determined could be involved.
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