The synthetic bacterial lipopeptide Pam3CSK4 modulates respiratory syncytial virus infection independent of TLR activation

Respiratory syncytial virus (RSV) is an important cause of acute respiratory disease in infants, immunocompromised subjects and the elderly. However, it is unclear why most primary RSV infections are associated with relatively mild symptoms, whereas some result in severe lower respiratory tract infections and bronchiolitis. Since RSV hospitalization has been associated with respiratory bacterial co-infections, we have tested if bacterial Toll-like receptor (TLR) agonists influence RSVA2- GFP infection in human primary cells or cell lines. The synthetic bacterial lipopeptide Pam3-Cys-Ser-Lys4 (Pam3CSK4), the prototype ligand for the heterodimeric TLR1/TLR2 complex, enhanced RSV infection in primary epithelial, myeloid and lymphoid cells. Surprisingly, enhancement was optimal when lipopeptides and virus were added simultaneously, whereas addition of Pam3CSK4 immediately after infection had no effect. We have identified two structurally related lipopeptides without TLR-signaling capacity that also modulate RSV infection, whereas Pam3CSK4-reminiscent TLR1/2 agonists did not, and conclude that modulation of infection is independent of TLR activation. A similar TLR-independent enhancement of infection could also be demonstrated for wild-type RSV strains, and for HIV-1, measles virus and human metapneumovirus. We show that the effect of Pam3CSK4 is primarily mediated by enhanced binding of RSV to its target cells. The Npalmitoylated cystein

Combined Treatment Strategies for Unconjugated Hyperbilirubinemia in Gunn Rats

We recently demonstrated that acceleration of the gastrointestinal transit by polyethylene glycol (PEG) treats unconjugated hyperbilirubinemia in jaundiced Gunn rats. It is unclear whether acceleration of gastrointestinal transit also (partly) underlies the therapeutic effects of established hypobilirubinemic treatments or whether PEG cotreatment might enhance these effects. We treated Gunn rats with phototherapy (17 mu W/cm(2)/nm), orlistat (200 mg/kg chow), ursodeoxycholate (5 g/kg chow), or calcium phosphate (CaP) (20 g/kg chow) either as single treatment or in combination with PEG. Three weeks of phototherapy, orlistat, ursodeoxycholic acid, or CaP treatment decreased plasma unconjugated bilirubin (UCB) levels by 47, 27, 28, and 45%, respectively (each p <0.001), without a significant impact on gastrointestinal transit time. PEG cotreatment accelerated the gastrointestinal transit in all treatment groups, which resulted in an additive hypobilirubinemic effect of -20% and -26% (final plasma UCB -67 and -53%, respectively) in phototherapy- and orlistat-treated animals. PEG cotreatment did not enhance the hypobilirubinemic effect of ursodeoxycholic acid or CaP. We conclude that phototherapy, orlistat, ursodoxycholic acid, and CaP do not exert their hypobilirubinemic effect via acceleration of the gastrointestinal transit. PEG cotreatment enhanced the hypobilirubinemic effects of phototherapy and of orlistat treatment. Current results support a clinical trial to evaluate PEG cotreatment during phototherapy. (Pediatr Res 70: 560-565, 2011