Effects of different sources of lactoferrin on cytokine response to SARS-COV-2, respiratory syncytial virus, and rotavirus infection in vitro.

Lactoferrin (Lf) is a multifunctional iron-binding glycoprotein, involved in a wide range of bioactivities, including immunomodulatory and antiviral activities. Lf in human milk and bovine Lf added to infant formula may provide some protection against viral infections. However, functions of Lfs from different sources may differ due to varying manufacturing processes and posttranslational modifications. Here, effects of Lfs (11 commercial bovine milk Lfs, 2 recombinant Lfs, and native human/bovine milk Lf) on cytokine responses to virus infection were examined by infecting human intestinal epithelial cells (Caco-2 cells) with rotavirus (naked) or normal human bronchial epithelial cells (BEAS-2B cells) with respiratory syncytial virus (RSV, enveloped) or SARS-CoV-2 spike protein 1. Effects of Lf on viral infection were evaluated by qRT-PCR analysis of transcripts of cytokines/chemokines (TNF-α, IL-1 β, IL-6, IL-8, IL-10, IFN-β, and CXCL10). Our results show that viral infection changes transcription of these cytokines and that Lfs significantly and variously influence immune responses to rotavirus, RSV, and SARS-CoV-2 in vitro. Thus, Lf may provide protection against virus infection by down-regulating pro‑inflammatory cytokine/chemokine responses. Recombinant bovine and human Lf show similar effects as bovine milk Lfs suggesting that different posttranslational modifications do not affect the antiviral activity on cytokine response.