Nucleic acid sensing activates the innate cytosolic surveillance pathway and promotes parasite survival in visceral leishmaniasis
Authors: Sushmita Das
Kumar Abhishek
Ajay Kumar
Pradeep Das
Abhishek Mandal
Sudha Verma
Ashish Kumar
Journal: Scientific Reports (2019)
Discipline: Multidisciplinary
Keywords: Microbial pattern recognition; innate response; cytosolic surveillance pathway (CSP); Leishmania donovani infection; L.donovani DNA (Ld-DNA)
Affiliations: Department of Microbiology, All-India Institute of Medical Sciences (AIIMS), Patna, India. ., Department of Biochemistry, ICMR-Rajendra Memorial Research Institute of Medical Sciences, Patna, India., Department of Molecular biology, ICMR-Rajendra Memorial Research Institute of Medical Sciences, Patna, India.

Abstract:  Microbial pattern recognition critically contributes to innate response, both at extracellular and intracellular cytosolic surveillance pathway (CSP) interface. However, the role of pattern recognition by host innate receptors in CSP is poorly understood in Leishmania donovani infection. Here, we have demonstrated that cytosolic targeting of L.donovani DNA (Ld-DNA) inhibits macrophage responsiveness to IFNɣ, through decreased MHC-II expression and lowered pSTAT1 (Y701) levels, involving host three-prime repair exonuclease-1 (TREX-1). The Ld-DNA potently induced type-1 IFNs, i.e. significant over-production of IFNβ through activation of the IRF pathway. Interestingly, knockdown of TRIF or MyD88 expression in macrophages had no effect on cytosolic Ld-DNA transfection-mediated IFN-β production, indicating involvement of a TLR independent pathway. Contrastingly, Ld-DNA failed to induce IFNβ in both TBK-1 and IRF3KO knockout macrophages. Although IFNβ was not induced by Ld-DNA in STING- knockout macrophages, STING alone was not enough for the induction. Evidently, besides STING, Ld-DNA recognition for induction of IFNβ critically required cytosolic cyclic GMP-AMP synthase (cGAS). Furthermore, the cGAS dependent targeting of Ld-DNA induced IFNβ over-production that contributed to antimony resistance in L.donovani infection. We provide the first evidence that enhanced cytosolic sensing of Ld-DNA in infection by antimony resistant (SBR-LD), but not antimony sensitive L.donovani strains (SBS-LD), was critically regulated by host MDRs, multi drug resistant associated protein 1 (MRP 1) and permeability glycoprotein (P-gp) in macrophages. Collectively, our results disclose Ld-DNA as a vital pathogen associated molecular pattern (PAMP) driving host Type-I IFN responses and antimony resistance. The findings may help in future development of policies for novel anti-leishmanial therapeutics. 

Retracted: Yes

PubPeer comments:
 Concern about Figure 3G. * all four panels appear to overlap with each other, and thus appear to all be derived from the same sample * Green and pink ellipses highlight cells that appear to be visible twice within the same photo ![file] , 
 Retraction, March 22, 2022: https: www.nature.com articles s41598-022-09098-9  The Editors have retracted this Article. After publication, concerns were raised regarding a number of figures in the Article. Specifically: * Western blot images presented in Figures 1E and 2C appear to show the same result; * in Figure 3G, the DAPI panels appear to originate from the same image, as the Mock, Ld-DNA treated and Ld-DNA+DOTAP panels all appear to partially overlap with the Ld-DNA+Lipo2000 panel (rotated); * the DAPI Mock and Ld-DNA+DOTAP panels appear to contain some duplicated cells; * the p-TBK1 Mock, Ld-DNA treated and Ld-DNA+DOTAP images do not appear to contain any signal; * Figure 5F appears to contain inconsistencies in the background of the tubulin bands. The Authors were not able to provide the original data requested by the Editors. The Editors therefore no longer have confidence in the presented data. Pradeep Das and Kumar Abhishek disagree with this retraction. None of the other Authors responded to correspondence from the Editors about this retraction. I am not sure about the statement  Western blot images presented in Figures 1E and 2C appear to show the same result - Figure 1E does not show a Western blot image. Maybe some other figure panel is meant. ,