Elastase activity in granulomatous inflammation in experimental murine leprosy

Area of Science:

• Biochemistry
• Immunology
• Cell Biology

Background:

• Leprosy involves complex immune responses and tissue remodeling.
• Elastases are key enzymes in extracellular matrix degradation.
• Understanding elastase activity in granulomas is crucial for leprosy research.

Purpose of the Study:

• To characterize proteolytic and elastase-inhibitor activities in murine lepromas.
• To identify the types and origins of elastases involved in hypersensitivity-type granulomas.
• To investigate the role of membrane-bound elastases in leprosy tissue remodeling.

Main Methods:

• Extraction of bound and soluble fractions from murine lepromas.
• Enzyme activity assays using [3H]elastin, S-2484, and AAApNA substrates.
• Sephacryl S-200 and DEAE-Sepharose chromatography for enzyme purification and characterization.
• Inhibitory profiling to determine enzyme class (thiol or serine proteinase).

Main Results:

• Proteolytic activity was found in the bound fraction of hypersensitivity-type lepromas, while inhibitor activity was in the soluble fraction.
• Sephacryl S-200 chromatography revealed an elastolytic peak around 20,000 molecular weight.
• DEAE-Sepharose chromatography isolated three elastolytic fractions (E-I, E-II, E-III); E-I was a thiol proteinase, E-II and E-III were serine proteinases.
• E-II and E-III exhibited characteristics of monocyte membrane-bound elastase, differing from neutrophil or macrophage elastases.
• Lower elastolytic activity was observed in nonhypersensitivity-type lepromas.

Conclusions:

• Hypersensitivity-type murine lepromas contain distinct thiol and serine elastases.
• Serine elastases (E-II, E-III) resemble membrane-bound elastases from monocytes.
• These findings suggest a significant role for monocyte/macrophage-derived membrane-bound elastases in the tissue remodeling of hypersensitivity-type granulomas in leprosy.