lactoferrin and Pneumonia--Pneumococcal

Streptococcus pneumoniae (pneumococcus), the major pathogen for pneumonia, commonly colonizes the lung, but the mechanism underlying the coordination of virulence factors during invasion via the host protein remains poorly understood. Bacterial lysis releases the components of the cell wall, and triggers innate immunity and the subsequent secretion of pro-inflammatory cytokines. Previously, the virulence of the pep27 mutant was shown to be attenuated as a feasible candidate for vaccine development. However, the role of pep27 gene, belonging to the vancomycin-resistance locus (vncRS operon), in virulence, is largely unknown. This study demonstrates that transferrin in the host serum reduces the survival of the host during S. pneumoniae infections in mice. The exposure of the pneumococcal D39 strain to lactoferrin induced the vncRS operon, lysis, and subsequent in vivo cytokine production, resulting in lung inflammation. However, these responses were significantly attenuated in pneumococci harboring a mutation in pep27. Mechanistically, the VncS ligand, identified as lactoferrin, induced the vncRS operon and increased the in vivo mortality rates. Thus, serum-induced activation of vncRS plays an essential role in inducing pneumonia.

Topics: A549 Cells; Animals; Bacterial Proteins; Cytokines; Humans; Immunity, Innate; Inflammation; Lactoferrin; Lung; Male; Mice, Nude; Mutation; Operon; Pneumonia, Pneumococcal; Streptococcus pneumoniae; Transferrin; Vancomycin; Virulence

Most clinical isolates of Streptococcus pneumoniae consist of heterogeneous populations of at least two colony phenotypes, opaque and transparent, selected for in the bloodstream and nasopharynx, respectively. Microarray analysis revealed 24 orfs that demonstrated differences in expression greater than twofold between variants of independent strains. Twenty-one of these showed increased expression in the transparent variants, including 11 predicted to be involved in sugar metabolism. A single genomic region contains seven of these loci including the gene that encodes the neuraminidase, NanA. In contrast to previous studies, there was no contribution of NanA to adherence of S. pneumoniae to epithelial cells or colonization in an animal model. However, we observed NanA-dependent desialylation of human airway components that bind to the organism and may mediate bacterial clearance. Targets of desialylation included human lactoferrin, secretory component, and IgA2 that were shown to be present on the surface of the pneumococcus in vivo during pneumococcal pneumonia. The efficiency of desialylation was increased in the transparent variants and enhanced for host proteins binding to the surface of S. pneumoniae. Because deglycosylation affects the function of many host proteins, NanA may contribute to a protease-independent mechanism to modify bound targets and facilitate enhanced survival of the bacterium.

Topics: Animals; Bacterial Proteins; Blood; Humans; Immunoglobulin A; Lactoferrin; N-Acetylneuraminic Acid; Nasopharynx; Neuraminidase; Oligonucleotide Array Sequence Analysis; Pneumonia, Pneumococcal; Rats; Secretory Component; Streptococcus pneumoniae

The role of cytokines in the pathogenesis of pneumonia is still poorly understood. In a previous study the diagnostic value of measuring blood concentrations of interleukin 6 and interferon gamma was established. In the present study the value of blood concentrations of interleukin 8, granulocyte-colony stimulating factor, and lactoferrin as markers of bacteraemic pneumonia is evaluated.. The circulating concentrations of interleukin 8 (IL-8), granulocyte-colony stimulating factor (G-CSF), and lactoferrin were measured in 14 patients with bacteraemic pneumococcal pneumonia and 49 patients with atypical pneumonia or influenza A infection using enzyme immunoassays.. Serum G-CSF concentrations were higher in the group with bacteraemic pneumococcal pneumonia, and G-CSF values correlated with the white blood cell count and levels of C-reactive protein (CRP). The levels of IL-8 were higher in the group with bacteraemic pneumococcal pneumonia than the groups with Chlamydia pneumonia, Legionella pneumonia, or influenza A infection, but there was no difference when compared with the group with Mycoplasma pneumonia. A white blood cell count of > 15 x 10(9)/l was highly suggestive of bacteraemic pneumonia. The concentrations of lactoferrin were raised in all groups except those with influenza A infection, but no difference was found between the different aetiological groups. A correlation was found between lactoferrin and white blood cell counts.. Serum G-CSF and IL-8 concentrations are potential markers of bacteraemic pneumonia.

Topics: Acute Disease; Adult; Aged; Aged, 80 and over; Biomarkers; Chlamydia Infections; Cytokines; Female; Granulocyte Colony-Stimulating Factor; Humans; Influenza A virus; Influenza, Human; Interleukin-8; Lactoferrin; Legionnaires' Disease; Leukocyte Count; Male; Middle Aged; Pneumonia, Bacterial; Pneumonia, Mycoplasma; Pneumonia, Pneumococcal

Highly purified lactoferrin was obtained from human breast milk by sequential use of affinity chromatography and isoelectric focusing. IgG antibody to purified lactoferrin was used to develop a sensitive and reproducible enzyme linked immunosorbent assay. Characteristics of the assay included linearity over a wide range of lactoferrin concentration (3.125-200 micrograms/l) and sensitivity (lower range less than 1 microgram/l). The assay can be adapted for use on tissue cytosol as well as plasma. Healthy subjects showed plasma lactoferrin levels ranging from 187.5-450.1 micrograms/l. Pulmonary tuberculosis and acute pneumonia are associated with a 2-3-fold increase in plasma lactoferrin content while neutropenic subjects have markedly depressed lactoferrin concentrations. The assay will be useful for further delineation of lactoferrin and neutrophil function and turnover.

Topics: Antibodies; Arthritis, Rheumatoid; Breast Neoplasms; Cytosol; Edetic Acid; Enzyme-Linked Immunosorbent Assay; Female; Humans; Lactoferrin; Lactoglobulins; Leukopenia; Male; Milk, Human; Pneumonia, Pneumococcal; Tuberculosis, Pulmonary