Broadly potent anti-SARS-CoV-2 antibody shares 93% of epitope with ACE2 and provides full protection in monkeys

OBJECTIVES

Due to the rapid evolution of SARS-CoV-2 to variants with reduced sensitivity to vaccine-induced humoral immunity and the near complete loss of protective efficacy of licensed therapeutic monoclonal antibodies, we isolated a potent, broad-spectrum neutralizing antibody that could potentially provide prophylactic protection to immunocompromised patient populations.

METHODS

Spike-specific B-cell clones isolated from a vaccinated post-infected donor were profiled for those producing potent neutralizing antibodies against a panel of SARS-CoV-2 variants. The P4J15 antibody was further characterized to define the structural binding epitope, viral resistance, and in vivo efficacy.

RESULTS

The P4J15 mAb shows <20 ng/ml neutralizing activity against all variants including the latest XBB.2.3 and EG.5.1 sub-lineages. Structural studies of P4J15 in complex with Omicron XBB.1 Spike show that the P4J15 epitope shares ∼93% of its buried surface area with the ACE2 contact region, consistent with an ACE2 mimetic antibody. In vitro selection of SARS-CoV-2 mutants escaping P4J15 neutralization showed reduced infectivity, poor ACE2 binding, and mutations are rare in public sequence databases. Using a SARS-CoV-2 XBB.1.5 monkey challenge model, P4J15-LS confers complete prophylactic protection with an exceptionally long in vivo half-life of 43 days.

CONCLUSIONS

The P4J15 mAb has potential as a broad-spectrum anti-SARS-CoV-2 drug for prophylactic protection of at-risk patient populations.

Reinforcement of barrier function and scalp homeostasis by Senkyunolide A to fight against dandruff

OBJECTIVE

Senkyunolide-A (SENKY) can be isolated from Apium graveolens seed oil obtained using supercritical CO₂ extraction. SENKY and its parent compounds, the N-butyl phthalides, have been demonstrated to protect cells from CO poisoning, to prevent diabetes mellitus and to decrease cancer cell proliferation. This study was undertaken to evaluate in vitro and in vivo the effect of SENKY on epidermal function improvement, Malassezia effect control, scalp soothing and dandruff reduction via skin protection-related pathways.

METHODS

DNA-array and proteomic studies were performed on human keratinocytes, sebocytes and skin explants to demonstrate SENKY activities. Two clinical evaluations were performed under dermatologist control on 106 volunteers, with greasy or dry scalp, experiencing dandruff, itching and redness. Volunteers tested a shampoo followed, or not, by a leave-on, containing SENKY, or their placebos. Dandruff severity and redness were scored on the scalp. Moisturization and sebum release were recorded using relevant measuring apparatus. Itching and scratching evaluations came from volunteers' self-declarations.

RESULTS

DNA-array studies on keratinocytes showed a clear regulation of skin barrier functions and epidermis defence pathways. Upregulation of epidermal differentiation complex genes was observed. These preliminary observations were reinforced by immunocytochemistry and immunohistochemistry studies showing a significant increase of involucrin, filaggrin, loricrin, SPRR, LC3B and ceramide 2 productions. Tight-junctions and corneodesmosomes were significantly reinforced both in keratinocyte cultures (corneodesmosin, claudin, ZO-1) and in skin explants (desmoglein). DNA-array studies also demonstrated upregulation of genes involved in detoxification and anti-inflammation pathways. Proteomic studies revealed that hBD2 production was increased in keratinocytes in contact with SENKY, whereas IL-8, PGE-2 and TLR-9 releases were repressed as well as sebocyte lipid production. Clinical evaluations confirmed that after 3 weeks, SENKY significantly reduced dandruff intensity, redness, itching and scalp histamine content compared to placebo and beginning of treatment.

CONCLUSION

For the first time, SENKY has been shown to promote scalp homoeostasis by reinforcing barrier and defence functions at both gene and protein levels. It reduces irritation and redness in promoting detoxification and anti-inflammation pathways while controlling the niche of Malassezia. Applied on scalp, SENKY significantly reduces the formation of dandruff and soothes the scalp.