Increased expression of the secretory leukocyte proteinase inhibitor in Wegener's granulomatosis

Serum alarm antiproteases in systemic sclerosis patients

Alarm antiproteases, i.e. secretory leukocyte protease inhibitor ad elafin, are key mediators in innate immune response and integrate innate and adaptive immunity systems. The aim of the study was to assess clinical significance of serum levels of alarm antiproteases, elafin and secretory leukocyte protease inhibitor (SLPI) in patients with systemic sclerosis (SSc). Twenty-eight patients with SSc, 25 patients with rheumatoid arthritis (RA) and 22 healthy controls were recruited. Serum elafin and SLPI levels were examined using enzyme-linked immunosorbent assay (ELISA). The patients with SSc had significantly increased serum levels of SLPI in comparison with the RA patients and the healthy controls (p<0.01), and the RA patients presented significantly higher serum levels of elafin in comparison with the controls (p=0.003). In the SSc subgroup serum SLPI level negatively correlated with diffusing capacity of the lung for carbon monoxide (DLCO) (r=-0.41, p=0.03) and total lung capacity (r=-0.42, p=0.03). Both alarm antiproteases, elafin and SLPI could be potentially implicated in the pathogenesis of SSc and SLPI may be considered a candidate for serum biomarker of lung involvement in SSc.

The role of antigen cross-presentation from leukemia blasts on immunity to the leukemia-associated antigen PR1

Cross-presentation is an important mechanism by which exogenous tumor antigens are presented to elicit immunity. Because neutrophil elastase (NE) and proteinase-3 (P3) expression is increased in myeloid leukemia, we investigated whether NE and P3 are cross-presented by dendritic cells (DC) and B cells, and whether the NE and P3 source determines immune outcomes. We show that NE and P3 are elevated in leukemia patient serum and that levels correlate with remission status. We demonstrate cellular uptake of NE and P3 into lysosomes, ubiquitination, and proteasome processing for cross-presentation. Using anti-PR1/human leukocyte antigen-A2 monoclonal antibody, we provide direct evidence that B-cells cross-present soluble and leukemia-associated NE and P3, whereas DCs cross-present only leukemia-associated NE and P3. Cross-presentation occurred at early time points but was not associated with DC or B-cell activation, suggesting that NE and P3 cross-presentation may favor tolerance. Furthermore, we show aberrant subcellular localization of NE and P3 in leukemia blasts to compartments that share common elements of the classic major histocompatibility class I antigen-presenting pathway, which may facilitate cross-presentation. Our data demonstrate distinct mechanisms for cross-presentation of soluble and cell-associated NE and P3, which may be valuable in understanding immunity to PR1 in leukemia.

Mucosal Progranulin expression is induced by H. pylori, but independent of Secretory Leukocyte Protease Inhibitor (SLPI) expression

Background

Mucosal levels of Secretory Leukocyte Protease Inhibitor (SLPI) are specifically reduced in relation to H. pylori-induced gastritis. Progranulin is an epithelial growth factor that is proteolytically degraded into fragments by elastase (the main target of SLPI). Considering the role of SLPI for regulating the activity of elastase, we studied whether the H. pylori-induced reduction of SLPI and the resulting increase of elastase-derived activity would reduce the Progranulin protein levels both ex vivo and in vitro.

Methods

The expression of Progranulin was studied in biopsies of H. pylori-positive, -negative and -eradicated subjects as well as in the gastric tumor cell line AGS by ELISA, immunohistochemistry and real-time RT-PCR.

Results

H. pylori-infected subjects had about 2-fold increased antral Progranulin expression compared to H. pylori-negative and -eradicated subjects (P < 0.05). Overall, no correlations between mucosal Progranulin and SLPI levels were identified. Immunohistochemical analysis confirmed the upregulation of Progranulin in relation to H. pylori infection; both epithelial and infiltrating immune cells contributed to the higher Progranulin expression levels. The H. pylori-induced upregulation of Progranulin was verified in AGS cells infected by H. pylori. The down-regulation of endogenous SLPI expression in AGS cells by siRNA methodology did not affect the Progranulin expression independent of the infection by H. pylori.

Conclusions

Taken together, Progranulin was identified as novel molecule that is upregulated in context to H. pylori infection. In contrast to other diseases, SLPI seems not to have a regulatory role for Progranulin in H. pylori-mediated gastritis.

Delayed cutaneous wound healing in mice lacking solute carrier 11a1 (formerly Nramp1): correlation with decreased expression of secretory leukocyte protease inhibitor

Control of macrophage functions by natural resistance-associated macrophage protein 1 (NRAMP1) has proven to be important for murine resistance to several intracellular pathogens, including Mycobacterium bovis BCG and Salmonella typhimurium, although the exact molecular mechanism of its action remains unknown. We identified secretory leukocyte protease inhibitor (SLPI) as a novel candidate gene whose expression is dependent on Nramp1 gene expression using B10A.Nramp1+/+ and B10A.Nramp1-/- macrophage cell lines in vitro, as well as mice bearing the resistance alleles (wild type (WT)) of the Nramp1 and mice with an ablated Nramp1 gene (knockout (KO)). We established that B10A.Nramp1+/+ cells spontaneously expressed a 10-fold higher level of SLPI messenger RNA (mRNA) compared to B10A.Nramp1-/- expression. Similarly, protein secretion was detected only in supernatants from B10A.Nramp1+/+ macrophages. Induction of SLPI in excisional cutaneous wounds and, most importantly, in macrophages infiltrating these wounds was significantly higher in Nramp1 WT mice compared to KO mice. These differences in SLPI expression in vivo correlated with a significant delay in the kinetics of wound healing in Nramp1 KO mice compared to WT controls. Taken together, these results suggest for the first time that Nramp1 controls macrophage SLPI mRNA and protein expression, and can also have an important effect on the kinetics of wound healing.