CR1-expression and C3b-mediated phagocytosis of granulocytes in purulent maxillary secretion and peripheral blood from patients with sinusitis

Identification of Novel Genes and Biological Pathways That Overlap in Infectious and Nonallergic Diseases of the Upper and Lower Airways Using Network Analyses

Previous genetic studies on susceptibility to otitis media and airway infections have focused on immune pathways acting within the local mucosal epithelium, and outside of allergic rhinitis and asthma, limited studies exist on the overlaps at the gene, pathway or network level between the upper and lower airways. In this report, we compared [1] pathways identified from network analysis using genes derived from published genome-wide family-based and association studies for otitis media, sinusitis, and lung phenotypes, to [2] pathways identified using differentially expressed genes from RNA-sequence data from lower airway, sinus, and middle ear tissues, in particular cholesteatoma tissue compared to middle ear mucosa. For otitis media, a large number of genes (n = 1,806) were identified as differentially expressed between cholesteatoma and middle ear mucosa, which in turn led to the identification of 68 pathways that are enriched in cholesteatoma. Two differentially expressed genes CR1 and SAA1 overlap in middle ear, sinus, and lower airway samples and are potentially novel genes for otitis media susceptibility. In addition, 56 genes were differentially expressed in both tissues from the middle ear and either sinus or lower airways. Pathways that are common in upper and lower airway diseases, whether from published DNA studies or from our RNA-sequencing analyses, include chromatin organization/remodeling, endocytosis, immune system process, protein folding, and viral process. Taken together, our findings from genetic susceptibility and differential tissue expression studies support the hypothesis that the unified airway theory wherein the upper and lower respiratory tracts act as an integrated unit also applies to infectious and nonallergic airway epithelial disease. Our results may be used as reference for identification of genes or pathways that are relevant to upper and lower airways, whether common across sites, or unique to each disease.

Serum protects against azurophil granule dependent down-regulation of complement receptor type 1 (CR1) on human neutrophils

We have investigated the effect of gradual degranulation on the expression of functional receptors (CR1 and CR3) on human neutrophils. Incubation with increasing concentrations of fMLP (10(-10) - 10(-7) M) translocated CR1 and CR3 to the cell surface in a similar kinetic pattern. When reaching maximal expression of receptors (10(-7) M fMLP), 78 +/- 10% and 87 +/- 9% of the total pool of CR1 and CR3, respectively, were translocated to the cell surface. To drive the mobilization process further, cytochalasin B was introduced to increase the stimulatory effect of fMLP. No further increase in CR1 surface expression was obtained. However, we found a characteristic time course of surface appearance of CR1 and CR3 with a maximal surface expression within 1 minute, followed by a time-related down-regulation of CR1 but not CR3. In addition, the total pool of CR1 in cytochalasin B treated neutrophils was reduced after 15 minutes stimulation with fMLP measured by flow cytometry and immunoblotting, indicating degradation of CR1. The down-regulation of CR1 was concomitant with a translocation of azurophil granules, in terms of upregulation of CD63. Azurophil, but not specific nor secretory, granule fractions caused a down-regulation of CR1 on fMLP activated neutrophils. The presence of human sera and serine protease inhibitor protected CR1 from down-regulation. Together, these findings indicate that intracellular stored proteases, released in the late part of the sequential mobilization process, alters the expression of functional receptors mobilized in the early part of the mobilization process. The findings also focus on the importance of the microenvironment for the net outcome of neutrophil activation in terms of functional receptor expression.

Presence of serum modulates expression of complement receptor type 1 (CR1) on human granulocytes after quartz exposure

We have investigated the interaction between granulocytes and quartz with respect to the expression of complement receptor type 1 (CR1) and the presence of normal human serum (NHS). Quartz down-regulates selectively CR1 on activated granulocytes. This down-regulation is abolished in the presence of both NHS and heat-inactivated NHS (NHS56) but not human albumin. When quartz was preincubated with NHS (quartz-NHS) before exposure to activated granulocytes, a down-regulating effect was observed in contrast to preincubation with NHS56, which did not induce a down-regulation. Preincubation with cytochalasin B reduced the down-regulation of quartz-NHS, indicating a cytoskeleton-dependent internalization of the receptor. The serine protease inhibitor PMSF partly reduced this down-regulation. Our results indicate that the presence of NHS in the alveolar space influences the interaction between quartz and recruited granulocytes with respect to CR1 expression. Since CR1 is an important opsonin receptor and soluble CR1 can modulate the inflammatory response, this may be of importance in the inflammation and fibrosing process induced by quartz in the alveolar space and lung interstitium.

A biologic basis for altered host defenses in surgically infected abscesses

OBJECTIVE

This study determines whether there are any differences in several immunologic parameters in circulating peripheral blood leukocytes, serum, and plasma compared with pus leukocytes, and supernatant of various types of abscess.

SUMMARY BACKGROUND DATA

Although there have been reports of high lysozyme levels and low complement levels within pus, there has been no systemic comparison of concentrations of these substances and others within pus compared with those within peripheral blood.

METHODS

Peripheral blood and abscess pus were collected from 31 patients with abscesses and percent and mean channel of monocytes expressing complement receptor and major histocompatibility antigen HLA-DR, the percent and mean channel of polymorphonuclear leukocytes (PMN) expressing complement receptor, lysozyme level, and levels of total hemolytic complement, iC3b, C5b-9, and immunoglobulins were measured within both pus and peripheral blood.

RESULTS

Percent of monocytes expressing HLA-DR and percent of monocytes and PMN expressing complement receptor, total hemolytic complement, and IgM were reduced within pus compared with peripheral blood, whereas the mean channel of monocytes expressing HLA-DR and the mean channel of PMNs expressing CR3, C5b-9, and lysozyme were increased in pus.

CONCLUSIONS

There are marked differences in immunologic parameters measured within pus of abscesses versus that seen in peripheral blood.

Lability in complement receptor mobilization of granulocytes in patients with bronchial hyperreactivity

The recruitment of activated granulocytes to bronchial mucosa seems to be involved in the prolonged inflammatory response observed in asthma and probably associated with bronchial hyperresponsiveness. We studied the patients with bronchial hyperresponsiveness with respect to the expression of complement receptor type 1 (CR1), its variability and readiness to become mobilized on peripheral granulocytes from patients with bronchial hyperresponsiveness. CR1 expression and its hourly variation was significantly (P less than 0.02, P less than 0.01 respectively) higher in the patient group compared with the control group. In addition the ability to mobilize CR1 spontaneously at +37 degrees C correlated to the variation of CR1 expression that occurred during a 4 hr period. These findings indicate that granulocytes from patients with bronchial hyperresponsiveness have a higher degree of variation in CR1 expression that correlates to their ability to mobilize CR1 and may reflect a more pronounced lability.

A flow cytometric method to measure the stimulated mobilization and the intracellular pool of the adhesion promoting glucoprotein Mac-1

The receptor for complement factor C3bi (Mac-1 or CR3) belongs to a complex of leukocyte surface glucoproteins (CD11/CD18) that are essential for chemotaxis and adhesion of human polymorphonuclear leukocytes (PMN). Granulocytes can increase their surface expression of Mac-1 upon stimulation and it is proposed that this depends on a rapid mobilization of an intracellular pool of Mac-1. In the present study we describe a cell membrane permeabilization method that enables the detection of the intracellular pool of Mac-1 in granulocytes by flow cytometry. The method is based on the use of the non-ionic detergent n-octyl-beta-D-glucopyranoside (OG) to permeabilize the cell membranes of paraformaldehyde-prefixed leukocytes. It is shown that fMLP (5 x 10(-7) M)-treated cells expose 85% of the total detectable amount of Mac-1 molecules on the surfaces. The method makes it possible to measure the total detectable pool, the efficiency of Mac-1 mobilization and the in vivo expression of the receptor. This could be of value when evaluating the role of adhesion proteins in the inflammatory response.