Immunoglobulin A proteases in gram-negative bacteria isolated from human urinary tract infections

Abstract

Several strains of gram-negative bacteria (seven genera, eight species) isolated from patients with urinary tract infections were found to hydrolyze myeloma immunoglobulin A (IgA) protein. Human IgG and IgM and colostrum IgA were not degraded by these organisms. Examination of cleavage digests showed two fragments of different electrophoretic mobilities, with antigenic reactivity and sodium dodecyl sulfate polyacrylamide gel electrophoresis profiles consistent with their identification as Fc and Fab components. The immunoelectrophoresis patterns of cleavage digests suggested that the proteases responsible for this hydrolysis may be dissimilar in the specificity of their IgA cleavage sites.

Zinc and iron regulate translation of the gene encoding Pseudomonas aeruginosa elastase

“…Furthermore, elastase can degrade a variety of compounds such as immunoglobulins IgA and IgG, human polymorphonuclear leucocytes, human plasma alpha-proteinase inhibitor, as well as transferrin (Doring etai, 1988;Fick etai, 1985;Heck et al. 1990;Milazzo and Delisle, 1984;Morihara ef a/., 1979;Morihara and Homma, 1985) thereby decreasing the host's ability to combat infection. Despite the importance of elastase in the establishment and maintenance of a P. aeruginosa infection, little is known about the environmental signals that regulate elastase biosynthesis.…”

Extraintestinal pathogenic isolates ofEscherichia colido not possess active IgA1, IgA2, sIgA or IgG proteases

“…We cannot exclude the possibility that only a limited number of E. coli that cause extraintestinal infection are capable of cleaving immunoglobulin (e.g. 14% in Milazzo et al, Milazzo & Delisle, 1984) and our assessment of 33 strains was insufficient to detect representatives from this minority subgroup, but we believe this to be unlikely. Further, of the strains studied in this report, many were isolated from sites where the possession of a immunoglobulin protease would be advantageous, such as the two strains that caused pneumonia, the one isolate that caused meningitis, and the 14 strains that were representative of homologous isolates that caused recurrent UTI in women (Table 1).…”

“…However H. influenzae supernatant and live H. influenzae, which contains/produces a secreted IgA 1 protease, degraded IgA 1 and sIgA when run in parallel with the E. coli assays, thereby minimizing the possibility that our negative results were due to a cryptic technical issue. Interestingly, the findings of the two positive studies were conflicting in that colostrum IgA was cleaved in one study (Diebel et al, 2004), but not the other (Milazzo & Delisle, 1984). Further, in the study by Milazzo & Delisle (1984), IgA was cleaved but not sIgA.…”

“…Interestingly, the findings of the two positive studies were conflicting in that colostrum IgA was cleaved in one study (Diebel et al, 2004), but not the other (Milazzo & Delisle, 1984). Further, in the study by Milazzo & Delisle (1984), IgA was cleaved but not sIgA. Many immunoglobulin proteases are capable of cleaving both of these substrates, such as the IgA 1 protease from H. influenzae (Fig.…”

“…1). Previous studies, which reported that E. coli strains isolated from patients with urinary tract infection were able to hydrolyze myeloma IgA protein (Milazzo & Delisle, 1984) or colostrum sIgA (Diebel et al, 2004) used isolates that were 'fresh'. All of our strains were minimally passaged (once or twice after isolation in the Hospital Microbiology laboratory from the patient sample).…”