Outer membrane protein A (OmpA) of Shigella flexneri 2a links innate and adaptive immunity in a TLR2-dependent manner and involvement of IL-12 and nitric oxide
Authors: Nibedita Mahata
Debasis Pore
Manoj K Chakrabarti
Journal: Journal of Biological Chemistry (2012)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: OmpA; TLR2; proinflammatory cytokines; NF-Œ∫B; RAW macrophages
Affiliations: Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road, Scheme-XM, Beliaghata, Kolkata 700010, West Bengal, India.

Abstract:  We determine that OmpA of Shigella flexneri 2a is recognized by TLR2 and consequently mediates the release of proinflammatory cytokines and activates NF-Œ∫B in HEK 293 cells transfected with TLR2. We also observe that in RAW macrophages TLR2 is essential to instigate the early immune response to OmpA via NF-Œ∫B activation and secretion of cytokines and NO. Consistent with these results, TLR2 knockdown using siRNA abolishes the initiation of immune responses. Processing and presentation of OmpA depend on TLR2; MHCII presentation of the processed antigen and expression of CD80 significantly attenuated in TLR2 knockdown macrophages. The optimum production of IFN-Œ≥ by the macrophages:CD4(+) T cells co-culture depends on both TLR2 activation and antigen presentation. So, TLR2 is clearly recognized as a decisive factor in initiating host innate immune response to OmpA for the development of CD4(+) T cell adaptive response. Furthermore, we demonstrate in vivo that intranasal immunization of mice with OmpA selectively enhances the release of IFN-Œ≥ and IL-2 by CD4(+) T cells. Importantly, OmpA increases the level of IFN-Œ≥ production in Ag-primed splenocytes. The addition of neutralizing anti-IL-12p70 mAb to cell cultures results in the decreased release of OmpA-enhanced IFN-Œ≥ by Ag-primed splenocytes. Moreover, coincubation with OmpA-pretreated macrophages enhances the production of IFN-Œ≥ by OmpA-primed CD4(+) T cells, representing that OmpA may enhance IFN-Œ≥ expression in CD4(+) T cells through the induction of IL-12 production in macrophages. These results demonstrate that S. flexneri 2a OmpA may play a critical role in the development of Th1 skewed adaptive immune response. 

Retracted: Yes

PubPeer comments:
  Concern with Figure 2A (First image) GAPDH bands look very similar but inverted in case of red and yellow box.  Concern with Figure 3 (second image) Actin bands look very similar (purple box) but inverted in case of red box. , 
  Concern with Figure 2A, 3 Image duplication , 
  Image duplication , 
 Figure 2A: I am deeply disturbed to see your comment of image duplication inversion and your comment that the bands look very similar. I reexamined the Figure 2A closely, because of your comment and could not find any similarity. However, we did a densitometric analysis of GAPDH bands and the values are embedded in the figure. You may see that the densitometric values are different for the individual band, which you have stated to be duplicated inverted. This indicates that all bands are having separate entity. Figure 3: I am deeply disturbed to see your comment of image duplication inversion and your comments that the bands look very similar. I reexamined the Figure 3 closely because of your comment and could not find any similarity. However, we did a densitometric analysis of beta-actin bands and the values are embedded in the figure. You may see that the densitometric values are different for the individual band, which you have stated to be duplicated inverted. This indicates that all bands are having separate entity.  Figure 4B: I am deeply disturbed to see your comment as we did not do any image duplication. However, after receiving your comments we examined the Figure 4B closely and did a densitometric analysis of beta-actin bands and the values are embedded in the figure. You may see that the densitometric values are different for the individual band, which you have stated to be duplicated, indicating that each band has separate entity. Figure 8A: I am deeply disturbed to see your comment as we did not do any image duplication. However, after receiving your comments we examined the Figure 8A closely and did a densitometric analysis of GAPDH bands and the values are embedded in the figure. You may kindly see that the densitometric values are different for the individual band, which you have stated to be duplicated, indicating that each band has separate entity.  , 
 #1  , 
 There are additional problems in figure 2, in addition to the duplications noted in earlier posts. There is a patch in lane 3 on the top row that may covering something. Lane 3 in row 3 has essentially no (or a different) background compared to lanes 1 and 2. Lane 6 in row 3 has a band that seems to have been excised from a land far away (note the difference in the surrounding background). The actin band in lane 6 on the bottom row is the same as that in lanes 1 and 3; one can make out the splice.  , 
 #6 Indeed, in a contrast-enhanced version, the similarities between two beta-actin control slices (after a 180-deg rotation) extends from the blots into the background.  , 
 https: www.jbc.org content 295 8 2543.full?sid=7a1afbd0-4238-4a9f-8334-1f493c78e23a Withdrawal: Outer membrane protein A (OmpA) of Shigella flexneri 2a links innate and adaptive immunity in a TLR2-dependent manner and involvement of IL-12 and nitric oxide. Debasis Pore, Nibedita Mahata and Manoj K. Chakrabarti VOLUME 287 (2012) PAGES 12589u201312601 This article has been withdrawn by the authors. Several concerns were raised. In Fig. 2A, the first two lanes of the GAPDH panel from BALB c macrophages were rotated 180u00b0 and used in the last two lanes. Additionally, the first two lanes of the GAPDH panel from RAW macrophages were reused in the last two lanes. Finally, the iNOS panel from RAW macrophages was spliced. In Fig. 3, the first lane from the PKC-u03b1 panel from BALB c macrophages was rotated 180u00b0 and reused in lanes 2 and 6. The first three lanes of the actin panel from BALB c macrophages were rotated and used in the last three lanes. The first lane of the PKC-u03b1 panel from RAW macrophages was rotated and used in the fourth lane. Also, there were no data in lane 3, and the band in lane 6 was pasted in. The first lane of the actin panel from RAW macrophages was reused in lanes 4 and 6. The second lane of the same panel was reused in lane 5. In Fig. 4B, lanes 1 and 3 of the PKC-u03b1 panel were the same. The first lane of the actin panel was reused in lanes 3, 5, and 7; the second lane was reused in lanes 4 and 6. Fig. 8A contained undeclared gel splices. Additionally, the GAPDH bands were duplicated. The authors were unable to provide the original data. In light of the above concerns and the unavailability of the underlying data required to support the published results, the authors are withdrawing this article. u00a9 2020 by The American Society for Biochemistry and Molecular Biology, Inc. ,