lactoferrin and Hypertrophy

Lactoferrin (Lf) is a multifunctional glycoprotein, which promotes the proliferation of murine C2C12 myoblasts. In the present study, it was investigated how Lf promotes myoblast proliferation and whether Lf promotes myoblast differentiation or induces myotube hypertrophy. Lf promoted the proliferation of myoblasts in a dose‑dependent manner. Myoblast proliferation increased on day 3 when myoblasts were cultured in the presence of Lf for three days and also when myoblasts were cultured in the presence of Lf for the first day and in the absence of Lf for the subsequent two days. In addition, Lf induced the phosphorylation of extracellular signal‑regulated kinase (ERK)1/2 in myoblasts. The mitogen‑activated protein kinase kinase 1/2 inhibitor U0126 inhibited Lf‑induced ERK1/2 phosphorylation and repressed Lf‑promoted myoblast proliferation. C2C12 myoblasts, myotubes and skeletal muscle expressed low‑density lipoprotein receptor‑related protein (LRP)1 mRNA and Lf‑promoted myoblast proliferation was attenuated by an LRP1 antagonist or LRP1 gene silencing. The knockdown of LRP1 repressed Lf‑induced phosphorylation of ERK1/2. Furthermore, when myoblasts were induced to differentiate, Lf increased the expression of the myotube‑specific structural protein, myosin heavy chain (MyHC) and promoted myotube formation. Knockdown of LRP1 repressed Lf‑induced MyHC expression. Lf also increased myotube size following differentiation. These results indicate that Lf promotes myoblast proliferation and differentiation, at least partially through LRP1 and also stimulates myotube hypertrophy.

Topics: Animals; Cell Differentiation; Cell Line; Cell Proliferation; Hypertrophy; Lactoferrin; Low Density Lipoprotein Receptor-Related Protein-1; Male; MAP Kinase Signaling System; Mice; Mitogen-Activated Protein Kinase 3; Muscle Fibers, Skeletal; Myoblasts; Receptors, LDL; Tumor Suppressor Proteins

Muramidase and lactoferrin are important components of the antimicrobial defense system. Muramidase has the ability of opsonization and immunopotentiation and therefore a close relation to the lymphatic tissue. Till now there are only immunohistochemical and microbiological studies on the presence of muramidase and lactoferrin in adenoid and tonsil tissue available.. We investigated the concentrations of muramidase and lactoferrin in palatine tonsils and adenoidal hypertrophies quantitatively using ELISA.. We investigated tissue of 18 palatine tonsils and 16 pharyngeal tonsils.. We found a significant difference in the concentration of muramidase but no difference in the concentration of lactoferrin between adenoids and tonsils. There was no significant difference in the concentration of lactoferrin and muramidase between the hypertrophic and chronic infected tonsils. There was no correlation between the age of the patients and the concentration of muramidase and lactoferrin. A connection between the microbial biofilm, the concentration of the proteins and the recurrent tonsillitis is discussed.. Due to the production of muramidase and lactoferrin adenoids and tonsils play an important role in the local antimicrobial defense in any age or inflammation.

Topics: Adenoids; Adolescent; Adult; Age Factors; Biofilms; Child; Child, Preschool; Chronic Disease; Data Interpretation, Statistical; Enzyme-Linked Immunosorbent Assay; Humans; Hypertrophy; Lactoferrin; Middle Aged; Muramidase; Palatine Tonsil; Tonsillectomy; Tonsillitis