Evaluation of serum amyloid A and haptoglobin as prognostic indicators for horses in a referral population

Acute phase protein (APP) measurement can be used to characterize and rapidly detect inflammation. Serum amyloid A (SAA) and haptoglobin (HP) may be useful for diagnostic and prognostic purposes in horses presenting for colic and other inflammatory diseases. The objective of this thesis was to evaluate the use of SAA and HP in horses presenting for colic and inflammatory diseases for prognostic application of case outcome. We examined case outcomes such as development of complications, survival outcome, duration and cost of hospitalization, and requirement for surgical intervention in horses presenting for colic. Specific laboratory values measured included total white blood cell count, neutrophil count, fibrinogen, SAA, HP, which were compared in control horses and horses admitted for colic and inflammatory diseases. Clinicopathologic values were compared in medical and surgical colic cases to test the ability of APPs to predict indication for surgical intervention. Survival outcome, development of complications, and hospitalization cost and duration were analyzed in both in horses presenting for colic and inflammatory diseases. In horses presenting for colic, SAA was significantly higher in the surgical group compared to both the control and medical colic groups. Haptoglobin concentration was not significantly different between all groups. Horses with elevated SAA were more likely to require surgical intervention than those medically managed. Euthanasia due to poor prognosis or the development of serious complications were more likely to occur in horses presenting for colic with an elevated SAA. In horses presenting for inflammatory diseases, admission SAA and HP concentrations were not significantly associated with survival or the development of complications. Increased HP concentration on admission was associated with longer duration of hospitalization in hoses with inflammatory diseases. Horses with an increasing SAA between 24-72 hours compared to admission SAA were more likely to be euthanized or develop complications. The findings of this study show that SAA and HP measurement could be a potential useful diagnostic and prognostic tool in horses presenting for colic and inflammatory diseases

The Salmonella type-3 secretion system-1 and flagellar motility influence the neutrophil respiratory burst.

Neutrophils are innate immune response cells designed to kill invading microorganisms. One of the mechanisms neutrophils use to kill bacteria is generation of damaging reactive oxygen species (ROS) via the respiratory burst. However, during enteric salmonellosis, neutrophil-derived ROS actually facilitates Salmonella expansion and survival in the gut. This seeming paradox led us to hypothesize that Salmonella may possess mechanisms to influence the neutrophil respiratory burst. In this work, we used an in vitro Salmonella-neutrophil co-culture model to examine the impact of enteric infection relevant virulence factors on the respiratory burst of human neutrophils. We report that neutrophils primed with granulocyte-macrophage colony stimulating factor and suspended in serum containing complement produce a robust respiratory burst when stimulated with viable STm. The magnitude of the respiratory burst increases when STm are grown under conditions to induce the expression of the type-3 secretion system-1. STm mutants lacking the type-3 secretion system-1 induce less neutrophil ROS than the virulent WT. In addition, we demonstrate that flagellar motility is a significant agonist of the neutrophil respiratory burst. Together our data demonstrate that both the type-3 secretion system-1 and flagellar motility, which are established virulence factors in enteric salmonellosis, also appear to directly influence the magnitude of the neutrophil respiratory burst in response to STm in vitro

MARCKS Inhibition Alters Bovine Neutrophil Responses to <i>Salmonella</i> Typhimurium

Neutrophils are innate immune cells that respond quickly to sites of bacterial infection and play an essential role in host defense. Interestingly, some bacterial pathogens benefit from exuberant neutrophil inflammation. Salmonella is one such pathogen that can utilize the toxic mediators released by neutrophils to colonize the intestine and cause enterocolitis. Because neutrophils can aid gut colonization during Salmonella infection, neutrophils represent a potential host-directed therapeutic target. Myristoylated alanine-rich C-kinase substrate (MARCKS) is an actin-binding protein that plays an essential role in many neutrophil effector responses. We hypothesized that inhibition of MARCKS protein would alter bovine neutrophil responses to Salmonella Typhimurium (STm) ex vivo. We used a MARCKS inhibitor peptide to investigate the role of MARCKS in neutrophil responses to STm. This study demonstrates that MARCKS inhibition attenuated STm-induced neutrophil adhesion and chemotaxis. Interestingly, MARCKS inhibition also enhanced neutrophil phagocytosis and respiratory burst in response to STm. This is the first report describing the role of MARCKS protein in neutrophil antibacterial responses