Acid ceramidase of macrophages traps herpes simplex virus in multivesicular bodies and protects from severe disease

Abstract

Macrophages have important protective functions during infection with herpes simplex virus type 1 (HSV-1). However, molecular mechanisms that restrict viral propagation and protect from severe disease are unclear. Here we show that macrophages take up HSV-1 via endocytosis and transport the virions into multivesicular bodies (MVBs). In MVBs, acid ceramidase (aCDase) converts ceramide into sphingosine and increases the formation of sphingosine-rich intraluminal vesicles (ILVs). Once HSV-1 particles reach MVBs, sphingosine-rich ILVs bind to HSV-1 particles, which restricts fusion with the limiting endosomal membrane and prevents cellular infection. Lack of aCDase in macrophage cultures or in Asah1 −/− mice results in replication of HSV-1 and Asah1 −/− mice die soon after systemic or intravaginal inoculation. The treatment of macrophages with sphingosine enhancing compounds blocks HSV-1 propagation, suggesting a therapeutic potential of this pathway. In conclusion, aCDase loads ILVs with sphingosine, which prevents HSV-1 capsids from penetrating into the cytosol.

Click-correlative light and electron microscopy (click-AT-CLEM) for imaging and tracking azido-functionalized sphingolipids in bacteria

“…In this study we observed that beside ω-N 3 -C 6 -ceramide 16 an azido-modified sphingosine, ω-N 3 -sphingosine 22 , exhibited significant bactericidal activity. We show that an observable effect on bacteria of both modified sphingolipid analogs is distortion of the cell membrane.…”

“…The data demonstrated a potent bactericidal activity of sphingosine and the synthetic ceramide analog ω-N 3 -C 6 -ceramide against N. meningitidis 13 . Here, we now determined the MIC and MBC values for a newly synthesized sphingosine analog, ω-N 3 -sphingosine 22 , against N. meningitidis . ω-N 3 -sphingosine displayed a MIC value of 4 µg/ml and a MBC value of 8 µg/ml comparable to MIC/MBC values observed for the unmodified sphingosine for N. meningitidis (Table S1 ) 13 .…”

“…ω-N 3 -C 6 -ceramide (d18:1/6:0-ω-N 3 ) (6-azido- N -((2 S ,3 R , E )-1,3-dihydroxyoctadec-4-en-2-yl)hexanamide) was synthesized by amide coupling of sphingosine according to literature 16 . ω-N 3 -sphingosine ((2 S ,3 R , E )-2-amino-18-azidooctadec-4-ene-1,3-diol) was chemically synthesized as previously described 22 . All lipids were dissolved in pure ethanol and stored at − 20 °C.…”

“…This combination of fluorescence and electron imaging applied here to the Gram-negative bacterium N. meningitidis allowed to determine morphological and ultrastructural changes after treatment with azido-modified sphingolipid analogs as well as to visualize their subcellular localization. A dibenzocyclooctyne (DBCO)-containing fluorescent dye (Alexa Fluor 488 DIBO analog (AFDye 488 DBCO AF)) was used for fluorescent labeling of azido-tagged sphingolipid analogs 13 , 16 , 20 – 22 via Cu(I)-free strain-promoted alkyne-azide cycloaddition click chemistry reaction (SPAAC) 23 , 24 . Our data demonstrate that srAT technology in combination with click chemistry–based labeling reaction is ideally suited to visualize, track and quantify azido-modified antimicrobial sphingolipids in bacteria.…”

Elusive Roles of the Different Ceramidases in Human Health, Pathophysiology, and Tissue Regeneration

“…It was reported that the overall inhibition of ceramidase activity in host peripheral blood lymphocytes using Ceranib 1 and Ceranib 2 significantly reduces the replication of the rhinovirus and measles virus, respectively [ 110 , 111 ]. Furthermore, the inhibition of ACDase activity in macrophages significantly increases the propagation of herpes simplex virus-1, which, in turn, elevates the mortality rate in Asah1 −/− mice [ 112 ].…”