Characterization of a neutrophil inhibitor peptide harvested from human bronchial lavage: homology to influenza A nucleoprotein

Modulating airway defenses against microbes

Prevention and treatment of respiratory infections remain an important health care challenge as the US population ages, contains more susceptible or high-risk people, and encounters new pathogens or antibiotic resistant bacteria. Reasonably protective vaccines against very common microbes are available for childhood and adult immunization, but, generally, these are underutilized. A broader definition of higher risk individuals is evolving, which will include more for immunization. Different approaches to vaccine development through design of new component vaccines are necessary. This review has updated host defense mechanisms at three levels in the human respiratory tract: naso-oropharynx (upper airways), conducting airways, and alveolar space. Examples of representative pathogenic microbes have been inserted at the respective airway segment where they may colonize or create infection (influenza, measles virus, Porphyromonas gingivalis causing periodontitis, Bordetella pertussis, Chlamydia pneumoniae, Streptococcus pneumoniae, and Bacillus anthracis ). Hopefully, microbe-host interactions will suggest new approaches for preventing these kinds of infections.

Acquired disorders of phagocyte function complicating medical and surgical illnesses

There is evidence that acquired dysfunction of neutrophils, monocytes, or macrophages is an important cause of infection in patients with diabetes mellitus, renal or hepatic failure, alcoholism, autoimmune diseases, influenza or human immunodeficiency virus infection, burns, and trauma. Distinguishable mechanisms of acquired phagocyte dysfunction include inhibitory effects of metabolic disturbances (e.g., hyperglycemia, uremia), chemical toxins (e.g., ethanol), viral proteins on phagocyte activation, and pathologic activation of phagocytes in the circulation (e.g., after hemodialysis, burns, or cardiopulmonary bypass). Although the burden of morbidity and mortality resulting from acquired phagocyte dysfunction appears to be vast, research in this area has been hampered by the complexity of the underlying illnesses and by limitations of laboratory assays and clinical study methodology. Given the advent of improved assays of phagocyte functions and treatments that can enhance these functions, there is a pressing need for more prospective studies of acquired phagocyte dysfunction.

Attenuation of interleukin 8-induced nasal inflammation by an inhibitor peptide

Polymorphonuclear neutrophils (PMNs) infiltrate tissue in response to chemoattractants, including interleukin 8 (IL-8). Infiltrating PMNs clear microorganisms but also cause tissue damage. We previously reported the presence in human bronchial lavage of a peptide that inhibits PMN functions. The current project assessed (1) effects of a synthetic analog of this peptide (synthetic neutrophil inhibitor peptide, SNIP) on IL-8-induced nasal inflammation in humans, (2) effects of SNIP on PMN apoptosis and chemotaxis, (3) specific binding of SNIP to PMNs, and (4) evidence of larger molecules with the SNIP sequence. Results show that SNIP attenuates IL-8-induced nasal inflammation, inhibits in vitro PMN chemotaxis to IL-8, and accentuates PMNs apoptosis. PMNs contain specific SNIP-binding sites and the integrin CR3 (CD11b/CD18), or a CR3-associated molecule, is one SNIP-binding molecule. Chemotaxis to IL-8 is most potently inhibited by SNIP in the presence of fibrinogen, a CR3 ligand. Antiserum against the SNIP sequence recognizes a 70-kDa protein in bronchoalveolar lavage and an anti-SNIP immunoaffinity column binds a 70-kDa protein in U937 cell culture supernatant. U937 cell mRNA contains a 1.8-kb transcript detected with degenerate oligonucleotides designed from the SNIP sequence. These studies demonstrate that a synthetic inhibitor peptide can attenuate in vivo nasal inflammation through downregulatory effects on PMNs.