Toxoplasma gondii isolate with genotype Chinese 1 triggers trophoblast apoptosis through oxidative stress and mitochondrial dysfunction in mice
Authors: Wen Hu
Xiucai Xu
He Chen
Qing Li
Aimei Zhang
Jian Du
Liuyuan He
Jilong Shen
Journal: Experimental Parasitology (2015)
Discipline: MICROBIOLOGY
Keywords: Apoptosis; Mitochondrial dysfunction; Oxidative stress; Toxoplasma gondii.
Affiliations: Anhui Provincial Laboratories of Pathogen Biology and Zoonoses, Department of Microbiology and Parasitology, Anhui Medical University, 81 Meishan Road, Hefei 230032, China; The Central Laboratory of Affiliated Provincial Hospital, Anhui Medical University, Hefei 230031, China. Electronic address: ., Anhui Provincial Laboratories of Pathogen Biology and Zoonoses, Department of Microbiology and Parasitology, Anhui Medical University, 81 Meishan Road, Hefei 230032, China., The Central Laboratory of Affiliated Provincial Hospital, Anhui Medical University, Hefei 230031, China., Department of Pathology of Affiliated Provincial Hospital, Anhui Medical University, Hefei, China., Department of Biochemistry and Molecular Biology, Anhui Medical University, Hefei 230032, China., Anhui Provincial Laboratories of Pathogen Biology and Zoonoses, Department of Microbiology and Parasitology, Anhui Medical University, 81 Meishan Road, Hefei 230032, China. Electronic address: .

Abstract:  Congenital toxoplasmosis may result in abortion, severe mental retardation and neurologic damage in the offspring. Placental damage is considered as the key event in this disease. Here we show that maternal infection with Toxoplasma gondii Wh3 isolate of genotype Chinese 1, which is predominantly prevalent in China, induced trophoblast apoptosis of pregnant mouse. PCR array analysis of 84 key genes in the biogenesis and functions of mouse mitochondrion revealed that ten genes were up-regulated at least 2-fold in the Wh3 infection group, compared with those in the control. The elevated levels of reactive oxygen species (ROS), malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG), as well as the decreased glutathione (GSH), were observed in the infected mice. The mRNA levels of NADPH oxidase 1 and glutathione peroxidase 6 (GPx6) were significantly increased. The production of excessive ROS was NADPH oxidase-dependent, which contributed to mitochondrial structural damage and mitochondrial dysfunction in placentas, followed by the cleavage of caspase-9 and caspase-3, and finally resulted in apoptosis of trophoblasts. All the above-mentioned phenomena were inhibited by pretreatment with the antioxidant of N-acetylcysteine (NAC). Taken together, we concluded that Wh3 infection during pregnancy may contribute to trophoblast apoptosis by oxidative stress-induced mitochondrial dysfunction and activation of the downstream signaling pathway. 

Retracted: No

PubPeer comments:
 Figure 3. * Red boxes: Panel A appears to show the same specimen as panel E, albeit rotated and shown at a different magnification. ![file] , 
 u8c22u8c22u60a8u7684u8be2u95eeu3002u7684u786euff0cu4e24u5e45u56feu7684u67d0u4e9bu90e8u5206(u56fe3uff0cAu3001E) u00a0u6709u9ad8u5ea6u7684u76f8u4f3cu6027u3002u00a0u6211u4eecu8ba4u4e3au8fd9u4e24u5f20u56feu7247u5e76u4e0du662fu5bf9u540cu4e00u5f20u56feu7247u7684u4ebau5de5u65cbu8f6cuff0cu800cu662fu6765u81eau4e8eu7535u5b50u663eu5faeu955cu7684u4e24u5f20u4e0du540cu7684u539fu59cbu7167u7247(u89c1u56feu7247u5e95u90e8u7684u6570u5b57u548cu653eu5927u500du6570)u3002u00a0u4f46u7535u5b50u663eu5faeu955cu5728u6807u672cu6807u8bb0u7684u64cdu4f5cu8fc7u7a0bu4e2du4e5fu6709u53efu80fdu51fau73b0u9519u8befu3002u00a0u6211u4eecu60f3u8bf4u7684u662fuff0cu6ca1u6709u6076u610fu7be1u6539u56feu7247u7684u5b58u5728uff0cu53e6u4e00u65b9u9762uff0cu8fd9u79cdu53efu80fdu7684u8befu7528u5373u4f7fu53d1u751fu4e5fu4e0du4f1au76f4u63a5u5f71u54cdu6587u7ae0u7684u7ed3u679cu548cu7ed3u8bbau3002 u00a0 u4f46u65e0u8bbau5982u4f55uff0cu9274u4e8eu56feu50cfu7684u76f8u4f3cu6027uff0cu5982u679cu9700u8981u548cu53efu80fdu7684u8bdduff0cu6211u4eecu5e0cu671bu52d8u8befu4e00u4e2au65b0u7684u7167u7247u4ee3u66ffu00a0(u89c1u4e0bu56fe)u3002 u00a0 Thank you for your inquiry.u00a0u00a0Indeed, some parts of the two images (Fig.3, A and E) have a high degree of similarity.u00a0We believe that these two images are not an artificial rotation of the same image but from the two different original photoes of electronic microscopy (see the numbers and magnification in the bottom of the images). But it is not impossible that error in operation process of electronic microscopy in specimen labeling might happen.u00a0We want to say that no malicious tampering of the images exists and, on the other hand, this possible misuseuff0c if any, does not directly affect the results and conclusions of the articles.u00a0 But anyway, in view of the image similarity, we would like, if needed and possible, to have a new photo instead in correct error printing. (see the photo below). ![file] , 
 Thanks for the critical comment. Indeed, there is a high degree of similarity between certain parts of the two pictures. We also carefully checked the process of manuscript preparation, in this process there is no error in the use of pictures. Here we provide the original picture (NAC-GD12, see the attachment). Firstly, the photographic markers are produced in the process of electron microscopy and are displayed in the lower center of the image with different specimen numbers and magnification. These marks were not added during the preparation of the manuscript. Therefore, it is impossible to tamper with the photos intentionally, and NAC-GD12 can not be generated by zooming in and rotating other images, such as Con-GD12. Secondly, in the process of electron microscopy, because of the difference of specimen number, the possibility of specimen mark error is very low. In addition, if two images are from the same sample, the same position can be found when shooting, and the direction of rotation shooting, this situation is also difficult to happen during the two checks. To sum up, there is no possibility of malicious tampering. However, based on the high similarity of the two images, there is still the possibility that an error in the operation of the electron microscope may lead to the misuse of the picture. Based on the support provided by another set of images, this possible misuse does not directly affect our assumptions and results. ![file] , 
 #2, #3 1.  NAC-GD12 can not be generated by zooming in and rotating other images, such as Con-GD12 See the animated comparison below [click to animate]. NAC-GD12 *can* be generated by zooming and rotating Con-GD12, using the figures from the original manuscript. ![file] 2.  if two images are from the same sample, the same position can be found when shooting, and the direction of rotation shooting, this situation is also difficult to happen during the two check . I think the author is trying to say that it is unlikely to image the same part of a TEM slice by chance, including rotation and mislabeling ( the possibility of specimen mark error is very low ). In (1) it was shown the same area **is** re-imaged at a different magnification and rotation. Can the authors please find out what happened here? 3. From the text:  NAC pretreatment remarkably prevented mitochondria of placenta from damage under the parasite infection (Fig. 3E and F). Fig. 3E turns out to be part of the control, Fig. 3A. How can we be sure that NAC treatment is really effective? , 
 #3 Curiosity question. The labeling of the SEM images was deemed important, as it was done by the SEM:  Firstly, the photographic markers are produced in the process of electron microscopy and are displayed in the lower center of the image with different specimen numbers and magnification. These marks were not added during the preparation of the manuscript. . In #3 you provide a higher resolution of the original paper s NAC-GS12 SEM image. It indeed corresponds 1:1 with the original image. Its label is, however, very different. And looks like pasted in from a scan or photograph, including dust particles, bright reflections, and text and scalebar curved and at strange angles. What happened with this label? Why is the image perfect and the label, well, not. [ from paper ] ![file] [ from #3] ![file] , 
 Usually, we try to keep the original labels in the process of submitting a paper. So, in my last answer, I took it for granted that I didnu2019t change the labels. Since this article was submitted about eight years ago, Iu2019ve forgotten some of the details. Iu2019m very sorry for this. Since one reviewer found the labels under the images to be very unclear in the PDF version during the reviewing phase, we added new labels to all of the FIG3 images and overlaid the original labels for readability, but did not change its main information. Here, we provide the original image of Fig3A. In a word, we admit that some parts of the two images have high similarity, but we do not have dishonest processing of the images in the preparation of the article. We stick to the main points we made in our last answer. ![file] , 
 #1 I agree with your comment. See my illustration of the overlap between A and E, after scaling A up and rotating it, the overlap looks like a perfect match: ![file] , 
 #6 Can you please also respond to #4 and #7? It is unfortunate that you had to relabel the images. Still, I do not see how a TEM could have computer-generated your original #3 label. Which is tilted, contains dust, etc. This is not how computer-generated labeling normally works. Another question on your TEM system. The corners of your images contain curious black features with patterns inside. The overlap between Con-GD12 and NAC-GD12 shows that these were not part of the sample, see for example the nice overlay of comment #7. What are these features that change size and shape between images? ![file] ![file] ,