Physiological response of mammary glands to Escherichia coli infection: A conflict between glucose need for milk production and immune response

Shlomo E Blum,Yaniv Lavon,Nir Edery,Dan E Heller,Oleg Krifuks,Shamay Jacoby,Nissim Silanikove,Gabriel Leitner,Uzi Merin

doi:10.1038/s41598-020-66612-7

Abstract

The mammary immune and physiological responses to distinct mammary-pathogenic E. coli (MPEC) strains were studied. One gland in each of ten cows were challenged intra-mammary and milk composition (lactose, fat, total protein, casein), biochemical (glucose, glucose-6-phosphate (Glu6P), oxalate, malate, lactate, pyruvate and citrate, malate and lactate dehydrogenases, lactate dehydrogenase (LDH), nitrite, lactic peroxidase, catalase, albumin, lactoferrin, immunoglobulin) and clotting parameters were followed for 35 days post-challenge. Challenge lead to clinical acute mastitis, with peak bacterial counts in milk at 16–24 h post-challenge. Biochemical and clotting parameters in milk reported were partially in accord with lipopolysaccharide-induced mastitis, but increased Glu6P and LDH activity and prolonged lactate dehydrogenase and Glu6P/Glu alterations were found. Some alterations measured in milk resolved within days after challenge, while others endured for above one month, regardless of bacterial clearance, and some reflected physiological responses to mastitis such as the balance between aerobic and anaerobic metabolism (citrate to lactate ratios). The results suggest that E. coli mastitis can be divided into two stages: an acute, clinical phase, as an immediate response to bacterial infection in the mammary gland, and a chronic phase, independent of bacteria clearance, in response to tissue damage caused during the acute phase.

Highlights

The mammary immune and physiological responses to distinct mammary-pathogenic E. coli (MPEC) strains were studied
There is limited knowledge on the physiological and biochemical changes induced by live distinct mammary pathogenic E. coli and how these changes correlate to LPS-induced mastitis
E. coli bacteria were detected in milk as early as [4,5,6,7,8] h post-challenge and peak bacterial counts were observed after [16,17,18,19,20,21,22,23,24] h, reaching on the average up to ~1 × 107 colony forming units (CFU) per mL milk

Summary

Introduction

The mammary immune and physiological responses to distinct mammary-pathogenic E. coli (MPEC) strains were studied. An intra-mammary challenge experiment with MPEC strains (VL2874, VL2732 and P4) and with the non-mammary pathogenic E. coli strain K1 was conducted in order to study whether the dynamics and intensity of the immune response in bovine mammary glands is different and depends on the infecting E. coli strain[4]. These strains were chosen for representing distinct presentations of E. coli mastitis: per-acute (VL2874), persistent (VL2732) and clinical (P4), respectively[4]. The objective of the present work was to study the physiological and biochemical responses measured in the milk and mammary gland tissue of cows challenged with the above mentioned three distinct mammary-pathogenic strains of E. coli

Objectives

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Conclusion