Nuclear factor kappa-B signaling is integral to ocular neovascularization in ischemia-independent microenvironment
Authors: Michael DeNiro
Futwan A Al-Mohanna
Journal: PLoS ONE (2014)
Discipline: Multidisciplinary
Keywords: Retinal ischemia; VEGF expression; retinal neovascularization; molecular mechanisms; NFκB
Affiliations: Dept. of Cell Biology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia., Dept. of Cell Biology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia; Al-Faisal University, Riyadh, Saudi Arabia.

Abstract:  Retinal ischemia promotes the upregulation of VEGF expression and accounts for most pathological features of retinal neovascularization (NV). Paradoxically, VEGF remains the pivotal stimulator of ocular NV, despite the absence of ischemia. Therefore, the central question arises as to how the various molecular mechanisms interplay in ischemia-independent NV. It's been suggested that NFκB plays a crucial role in the pathogenesis of diabetic vasculopathies. Here, we dissected the molecular mechanism of ocular NV in the rho/VEGF transgenic mouse model, which develops subretinal NV in ischemia-independent microenvironment. Furthermore, we examined whether intravitreal administration of YC-1, a HIF-1 inhibitor, can modulate the activation of NFκB and its downstream angiogenic signaling in the mouse retina. We demonstrated that YC-1 inhibited retinal NFκB/p65 DNA binding activity and downregulated NFκB/p65, FAK, α5β1, EPO, ET-1, and MMP-9 expression at the message and the protein levels. In addition, YC-1 significantly inhibited subretinal NV by reducing the number of neovascular lesions, the area of each lesion and the total area of NV per retina. We further investigated the influence of VEGF signaling pathway on HIF-1α transcriptional activity to substantiate that this mouse model develops subretinal NV in an ischemia-independent microenvironment. Our data demonstrated that VEGF overexpression didn't have any impact on HIF-1α transcriptional activity, whereas treatment with YC-1 significantly inhibited endogenous HIF-1 activity. Our study suggests that retinal NFκB transcriptional activity is pivotal to ischemia-independent mechanisms, which lead to the local activation of angiogenic cascades. Our data also indicate that the nexus between VEGF and NFκB is implicated in triggering the angiogenic cascade that promotes retinal NV. Hence, targeting the VEGF/NFκB axis may act in a negative feedback loop to suppress ocular NV. This study suggests that inhibition of NFκB activation may be a means of turning off a "master switch" responsible for initiating and perpetuating these ocular pathologies. 

Retracted: Yes

PubPeer comments:
 Concern about Figure 2. This is a complex figure, and there are several issues, so let s start by posting the unmarked, complete figure. ![file] * Figure 2 - Concern 1. The top left panel, with the blue border, appears to contain several repetitive areas. Marked in orange, bright pink, and light pink boxes. ![file] , 
 * Figure 2 - Concern 2. The lower Blue-Border image should be a zoomed-in version of the top Blue-Border. But rather, it appears a zoomed-in version of the image with the Green Border, which represents a differently treated mouse. ![file] , 
 * Figure 2 - Concern 3. The zoomed-in Red, Orange, and Green panels appear to show repetitive features. I have marked those with boxes of the same color. Note that the red arrows are not mine; those are part of the original figure. ![file] , 
 Moving on to Figure 7. The differently colored borders reflect differently treated groups of mice, and 2 different immunostainings are shown. Unexpectedly, the orange CXCR4 panel looks very similar to the red FAK panel, while the orange FAK panel shared similarities to the red CXCR4 panel. Despite the similarities, there are unexpected differences too, and several areas appear to be visible multiple times within the same photo. Could the authors please explain what happened here? ![file] , 
 There are several issues in Figures 6, 8, and 9 as well, but I will leave that as an exercise for the reader. , 
 An update for Figure 2 - Concern #3. ![file] , 
 Coming back here to show the artistry of Figure 6. Here are the bottom four panels, each marked to highlight the unexpected similarities within each of these panels. ![file] , 
 Let us also admire the masterpiece that is Figure 8 - showing some of the panels here to appreciate the amount of detail. ![file] , 
 Finally, Figure 9 can also be appreciated best when zoomed in and decorated with colorful boxes. Here are four panels for you to enjoy. ![file] , 
 2019 retraction. https: journals.plos.org plosone article?id=10.1371 journal.pone.0227327 After this article [1] was published, concerns were raised about several of the reported results. Specifically: In the upper left panel of Fig 2, there are several regions that appear similar to one another. In Fig 2 the image in row 2, column 1 is reported as a high magnification view of the Control C57BL 6 Mice image in row 1, column 1, but it appears instead to be a higher magnification view of the YC-1-Treated rho VEGF Mice image (row 3, column 3). In Fig 2, there are several elements that appear similar within and across the high magnification images of the Non-Treated rho VEGF Mice, DMSO-Treated Rho VEGF Mice, and YC-1-Treated rho VEGF Mice. In Fig 6 (SDF-1 panels), Fig 8 (column 1, rows 1 and 4; column 2, rows 2, 3, 4), and Fig 9 (column 1, rows 2, 3, 4; column 2, row 4), several areas within layers appear similar. In Fig 7, similarities were noted between the following image pairs. In each case there are differences between the images in question as well as unexpected repetitions of image details: u25cb. column 1, row 2 and column 2, row 3 u25cb. column 1, row 4 and column 2 row 1 In Fig 7, similarities were noted within the images shown in column 1, row 4 and column 2, row 3. The authors were unable to resolve these issues or provide the original data underlying the results in response to journal queries. Without the original data we cannot resolve the above concerns which call into question the integrity of the images and the validity of the reported results. In light of these concerns, the PLOS ONE Editors retract this article. Per FAAM, the underlying data for this study were held by MD, for whom current contact information is not available. The journal has not received confirmation that MD received communications about this case. FAAM replied to our notification but did not specify agreement or disagreement with the retraction. MD either could not be reached or did not reply. Reference 1.DeNiro M, Al-Mohanna FA (2014) Nuclear Factor Kappa-B Signaling Is Integral to Ocular Neovascularization in Ischemia-Independent Microenvironment. PLoS ONE 9(7): e101602. https: doi.org 10.1371 journal.pone.0101602 ,