A pan-influenza monoclonal antibody neutralizes H5 strains and prophylactically protects through intranasal administration.

Avian A(H5N1) influenza virus poses an elevated zoonotic threat to humans, and no pharmacological products are currently registered for fast-acting pre-exposure protection in case of spillover leading to a pandemic. Here, we show that an epitope on the stem domain of H5 hemagglutinin is highly conserved and that the human monoclonal antibody CR9114, targeting that epitope, potently neutralizes all pseudotyped H5 viruses tested, even in the rare case of substitutions in its epitope. Further, intranasal administration of CR9114 fully protects mice against A(H5N1) infection at low dosages, irrespective of pre-existing immunity conferred by the quadrivalent seasonal influenza vaccine. These data provide a proof-of-concept for broad, pre-exposure protection against a potential future pandemic using the intranasal administration route. Studies in humans should assess if autonomous administration of a broadly-neutralizing monoclonal antibody is safe and effective and can thus contribute to pandemic preparedness.

Recombinant C1 inhibitor in brain ischemic injury.

OBJECTIVE: C1 inhibitor (C1-INH) is an endogenous inhibitor of complement and kinin systems. We have explored the efficacy and the therapeutic window of the recently available human recombinant (rh) C1-INH on ischemic brain injury and investigated its mechanism of action in comparison with that of plasma-derived (pd) C1-INH. METHODS: rhC1-INH was administered intravenously to C57Bl/6 mice undergoing transient or permanent ischemia, and its protective effects were evaluated by measuring infarct volume and neurodegeneration. The binding profiles of rhC1-INH and pdC1-INH were assessed in vitro using surface plasmon resonance. Their localization in the ischemic brain tissue was determined by immunohistochemistry and confocal analysis. The functional consequences of rhC1-INH and pdC1-INH administration on complement activation were analyzed by enzyme-linked immunosorbent assay on plasma samples. RESULTS: rhC1-INH markedly reduced cerebral damage when administered up to 18 hours after transient ischemia and up to 6 hours after permanent ischemia, thus showing a surprisingly wide therapeutic window. In vitro rhC1-INH bound mannose-binding lectin (MBL), a key protein in the lectin complement pathway, with high affinity, whereas pdC1-INH, which has a different glycosylation pattern, did not. In the ischemic brain, rhC1-INH was confined to cerebral vessels, where it colocalized with MBL, whereas pdC1-INH diffused into the brain parenchyma. In addition, rhC1-INH was more active than pdC1-INH in inhibiting MBL-induced complement activation. INTERPRETATION: rhC1-INH showed a surprisingly wider time window of efficacy compared with the corresponding plasmatic protein. We propose that the superiority of rhC1-INH is due to its selective binding to MBL, which emerged as a novel target for stroke treatment.

Effect of skin barrier competence on SLS and water-induced IL-1alpha expression.

For screening of a potential irritant it is essential that an early marker for irritation should be chosen which could be detected before the physiological signs of irritation occur. Interleukin 1 alpha (IL-1alpha) is widely accepted as such a marker in both in vivo and in vitro test systems. In this study, we have determined the mRNA levels of IL-1alpha in the epidermis after topical application of sodium dodecyl sulphate (SLS) in both a commercially available epidermal kit (EpiDerm) and in excised skin. Furthermore, we have determined the effect of water, the vehicle for SLS, on IL-1alpha mRNA levels. Topical application of water to excised skin increases IL-1alpha mRNA levels sixfold in the epidermis whereas topical application of water to EpiDerm cultures did not alter IL-1alpha mRNA levels. This is explained by the finding that EpiDerm cultures have a sub-optimal barrier function when compared with excised skin - topical application of SLS was clearly toxic at much lower concentrations in EpiDerm cultures (0.2% SLS) than in excised skin (5% SLS). Also caffeine penetration was 10-fold higher through EpiDerm cultures than through the excised skin. Therefore, incubation of control EpiDerm cultures at 100% humidity effectively mimics topical exposure to water. An additional increase in IL-1alpha mRNA levels observed between topical application of water and SLS is similar (about threefold) in both experimental systems. In conclusion, in vitro reconstructed epidermis models, such as EpiDerm, can be used as a predictive model for irritancy screening. However, great care should be taken when interpreting the results due to the fact that EpiDerm cultures do not have a competent barrier function and therefore lower irritant concentrations are required than in in vivo or ex vivo studies in order to induce cytotoxic effects. Furthermore, the irritant effects of the vehicle should not be neglected. Our results show clearly that the topical application of water to excised skin results in increased levels of IL-1alpha mRNA in the epidermis. This is a cytokine that is widely used as an early marker for skin irritation.