Lactoferrin, all roads lead to Rome

New insights into the systemic effects of oral lactoferrin: transcriptome profiling

The immunomodulatory nature of lactoferrin (LF) derives from its ability to bridge innate and adaptive immunity in obtaining physiological equilibrium. LF is an attractive molecule for treatment of diseases that compromise immune homeostasis. Oral delivery is a preferable method for LF administration; however, its bioavailability is affected by protein degradation and absorption. The aim of this study was to evaluate the systemic effects of orally and intravenously (IV) administered recombinant human LF (rhLF) on blood cell transcriptome profiling. Rats were administered a single dose of rhLF by gavage or IV. The transcriptome profiles from the control and the rhLF-treated rats after 3, 6, and 24 h were analyzed using a Clariom D microarray. The results showed differentially expressed genes in response to IV as well as oral administered rhLF including coding and noncoding RNAs. Moreover, a comparison of the differentially expressed genes between oral and IV administration of LF, after 6 h, revealed that the majority (72.8%) of the genes altered in response to oral administration of rhLF were the same as for the IV treatment. The pathway profiles showed similarities in up-regulation of specific genes involved in oxidative stress and inflammatory responses for both routes of treatments. These findings provide evidence of the systemic signal transduction effects of orally administered rhLF.

Lactoferrin deficiency induces a pro-metastatic tumor microenvironment through recruiting myeloid-derived suppressor cells in mice

Lactoferrin, an innate immunity molecule, is involved in anti-inflammatory, anti-microbial, and anti-tumor activities. We previously reported that lactoferrin is downregulated in specimens of nasopharyngeal carcinoma and negatively associated with tumor progression and metastasis of patients with nasopharyngeal carcinoma. However, the relationship between lactoferrin and the pro-metastatic microenvironment has not been reported yet. Here, by using the lactoferrin knockout mouse, we found that lactoferrin deficiency facilitated melanoma cells metastasizing to lungs, through recruiting myeloid-derived suppressor cells (MDSCs) in the lungs. Mechanistic studies showed that in the lung microenvironment of the lactoferrin knockout mice, the TLR9 signaling was the most repressed signaling. Lactoferrin can induce MDSCs differentiation and apoptosis, as well as upregulate TLR9 expression. TLR9 agonist or lactoferrin treatment can rescue this phenotype in the tumor metastasis mouse model. Our results suggest a protective role of lactoferrin in cancer metastasis, along with a deficiency in certain components of the innate immune system, may lead to a pro-metastatic tumor microenvironment.