{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,25]],"date-time":"2026-01-25T00:33:05Z","timestamp":1769301185915,"version":"3.49.0"},"reference-count":33,"publisher":"American Veterinary Medical Association (AVMA)","issue":"11","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ajvr"],"published-print":{"date-parts":[[2006,11]]},"abstract":"<jats:title>Abstract<\/jats:title>\n<jats:p><jats:bold>Objective<\/jats:bold>\u2014To investigate the effects of short-chain fatty acids (SCFAs) and pH on neutrophil oxidative burst, phagocytosis, and morphology after exposure to acetate, propionate, butyrate, or succinate at pH 5.5 and 6.7.<\/jats:p>\n<jats:p><jats:bold>Sample Population<\/jats:bold>\u2014Neutrophils isolated from bovine blood samples and <jats:italic>Porphyromonas levii<\/jats:italic>, <jats:italic>Prevotella<\/jats:italic> spp, and <jats:italic>Bacteroides fragilis<\/jats:italic> isolated from lesions of cattle with acute interdigital phlegmon (foot rot).<\/jats:p>\n<jats:p><jats:bold>Procedures<\/jats:bold>\u2014Bacteria were cultured in strictly anaerobic conditions. Bacterial SCFA production was measured with high-performance liquid chromatography. Neutrophils were isolated, stimulated with phorbol 12-myristate 13-acetate (PMA) or opsonized zymosan (OZ), and incubated with dihydroethidium or dichlorofluorescein diacetate to measure production of O<jats:sup>2\u2212<\/jats:sup>and H<jats:sub>2<\/jats:sub>O<jats:sub>2<\/jats:sub>, respectively. Phagocytosis was assessed after exposure to serum-opsonized bacteria. Cellular morphology was assessed with differential staining.<\/jats:p>\n<jats:p><jats:bold>Results<\/jats:bold>\u2014All bacteria produced at least 3 of the 4 SCFAs. Production of both O<jats:sup>2\u2212<\/jats:sup> and H<jats:sub>2<\/jats:sub>O<jats:sub>2<\/jats:sub> was markedly curtailed in PMA-stimulated neutrophils exposed to SCFA at pH 5.5, compared with production at pH 6.7. Succinate caused a significant dose-dependent decrease in O<jats:sup>2\u2212<\/jats:sup> production at pH 6.7 in OZ-stimulated neutrophils. Monoprotic SCFAs elicited a significant increase in H<jats:sub>2<\/jats:sub>O<jats:sub>2<\/jats:sub> production in OZ-stimulated neutrophils at pH 6.7 but a significant decrease at pH 5.5. Monoprotic SCFAs significantly increased phagocytosis at pH 6.7 but decreased phagocytic activity at pH 5.5. Cellular necrosis was observed in cells exposed to SCFAs at pH 5.5.<\/jats:p>\n<jats:p><jats:bold>Conclusions and Clinical Relevance<\/jats:bold>\u2014Establishment and persistence of anaerobic bacteria in cattle with foot rot infection may result in part from neutrophil dysfunction secondary to the effects of bacterially secreted SCFA in acidotic microenvironments.<\/jats:p>","DOI":"10.2460\/ajvr.67.11.1901","type":"journal-article","created":{"date-parts":[[2006,11,2]],"date-time":"2006-11-02T17:22:32Z","timestamp":1162488152000},"page":"1901-1907","source":"Crossref","is-referenced-by-count":22,"title":["Evaluation of the effects of short-chain fatty acids and extracellular pH on bovine neutrophil function in vitro"],"prefix":"10.2460","volume":"67","author":[{"given":"Steven W.","family":"Mills","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shaylyn H.","family":"Montgomery","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Douglas W.","family":"Morck","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1272","reference":[{"key":"ref1","series-title":"Am J Vet Res","first-page":"1115","article-title":"Fusobacterium necrophorum and Bacteroides melaninogenicus as etiologic agents of foot rot in cattle","volume":"36","author":"Berg","year":"1975"},{"key":"ref2","series-title":"Cornell Vet","first-page":"66","article-title":"Study of etiology of foot-rot in cattle","volume":"54","author":"Gupta","year":"1964"},{"key":"ref3","series-title":"J Am Vet Med Assoc","first-page":"254","article-title":"Comparison of ceftiofur sodium and oxytetracycline for treatment of acute interdigital phlegmon (foot rot) in feedlot cattle","volume":"212","author":"Morck","year":"1998"},{"issue":"(suppl 2)","key":"ref4","series-title":"Clin Infect 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