Patterns of neutrophil serine protease-dependent cleavage of surfactant protein D in inflammatory lung disease

Abstract

The manuscript presents definitive studies of surfactant protein D (SP-D) in the context of inflammatory lung fluids. The extent of SP-D depletion in bronchoalveolar lavage fluid (BALF) of children affected with cystic fibrosis (CF) is demonstrated to correlate best with the presence of the active neutrophil serine protease (NSP) elastase. Novel C-terminal SP-D fragments of 27 kDa and 11 kDa were identified in patient lavage fluid in addition to the previously described N-terminal, 35-kDa fragment by the use of isoelectrofocusing, modified blotting conditions, and region-specific antibodies. SP-D cleavage sites were identified. In vitro treatment of recombinant human SP-D dodecamers with NSPs replicated the fragmentation, but unexpectedly, the pattern of SP-D fragments generated by NSPs was dependent on calcium concentration. Whereas the 35-and 11-kDa fragments were generated when incubations were performed in low calcium (200 M CaCl 2 ), incubations in physiological calcium (2 mM) with higher amounts of elastase or proteinase-3 generated C-terminal 27, 21, and 14 kDa fragments, representing cleavage within the collagen and neck regions. Studies in which recombinant SP-D cleavage by individual NSPs was quantitatively evaluated under low and high calcium conditions showed that the most potent NSP for cleaving SP-D is elastase, followed by proteinase-3, followed by cathepsin G. These relative potency findings were considered in the context of other studies that showed that active NSPs in CF BALF are in the order: elastase, followed by cathepsin G, followed by proteinase-3. The findings support a pre-eminent role for neutrophil elastase as the critical protease responsible for SP-D depletion in inflammatory lung disease. J. Leukoc. Biol. 83: 946 -955; 2008.

Acyl-CoA:Lysophosphatidylcholine Acyltransferase I (Lpcat1) Catalyzes Histone Protein O-Palmitoylation to Regulate mRNA Synthesis

“…At 1.5 mM, exogenous Ca 2ϩ triggered a shift of Lpcat1 from the cytosol into the nucleus. A substantial portion of cytosolic Lpcat1 moved into the nucleus when Ca 2ϩ concentrations reached 2 mM, which approximates the levels in normal epithelial lining fluid (24). To confirm these observations, we fractionated the cytosolic and the nuclear portions of cells and analyzed the fractions by immunoblotting.…”

Airway Surfactant Protein D Deficiency in Adults With Severe Asthma

“…Neutrophil serine proteinases can cleave SP-D within its carbohydrate recognition domain region and render it functionally inactive. 18,19 Furthermore, bacterial proteases have been shown to cleave SP-D, rendering the molecule incapable of binding and aggregating lung pathogens. 20 Thus, in severe asthma, neutrophilic airway inflammation, and possibly alterations in bacterial colonization, may both contribute to SP-D degradation and impaired function.…”

Glycoprotein analysis of porcine bronchoalveolar lavage fluid reveals potential biomarkers corresponding to resistance toActinobacillus pleuropneumoniaeinfection

“…However, degradation of the interstitial barrier may also lead to a stronger infiltration of pathogens, possibly resulting in an increased immune response of the host [31]. Polymorphic neutrophil (PMN)-derived secretions of antibacterial enzymes such as serine proteases could cause the strong decline in the level of the elastase-sensitive protein SP-D which results in a decrease of the anti-inflammatory impact it has on the course of disease [9,48]. In the chronic stage of infection, the expression of hyaluronidase was still increased in animals of the Germany Landrace and Piétrain breeding lines, indicating an ongoing convalescence and tissue repair process in the lung.…”