Elastase-producing microorganisms in horse lungs: their possible role in the pathogenesis of chronic pulmonary disease in the horse.

The research article investigates the presence of elastase-producing microorganisms in horse lungs and their potential role in chronic pulmonary disease. However, the connection between the quantity of such organisms and the condition wasn’t apparent.

Microbial Organisms in Horse Lungs

• The study examined the lungs of 21 horses and found microbial organisms in 17 of them.
• Seven of these cases had a significant number of these microorganisms.
• Elastase-producing microorganisms, largely from the Streptomyces species and to a smaller degree from the Bacillus species, made up between 22% to 99% of the total population, averaging 79%.

Characteristics of Elastase-producing Microorganisms

• A large number of these microorganisms produced elastases, enzymes that degrade elastin, a significant connective tissue protein, in vitro (outside the body).
• The veterinary researchers observed that these elastases weren’t significantly affected by horse serum, a component of blood that contains proteins and water.

Correlation Between Microorganisms and Pulmonary Disease

• The research concluded that there was no direct relation between the number of these elastase-producing microorganisms and the histopathological findings in the lung. Histopathological analysis involves examining tissues for disease at a microscopic level.
• Therefore, the researchers could not confirm these microorganisms’ relevance in the development of alveolar emphysema, a chronic pulmonary disease in horses characterized by the progressive destruction of the walls of the alveoli (the tiny air sacs in the lungs).

Interaction with Horse Serum

• The study also investigated the growth of a specific strain of Streptomyces (S. collinus/diastatochromogus) isolated from the horse lungs. The growth of this strain was suppressed by fresh horse serum, whereas decomplemented horse serum didn’t have the same effect. Decomplementing removes a portion of the immune system’s complement system, a group of proteins that enhances the immune response.
• From these findings, the researchers suggest that this interaction could lead to airway inflammation, potentially through the production of mediators, substances that transmit signals in the body and contribute to the inflammatory response.