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Cow’s Immune Response and Stray Voltage; Overview of Bovine Immunity

Lorraine M. Sordillo College of Veterinary Medicine

Michigan State University

Lameness

Ketosis Mastitis Displaced Abomasum

Milk Fever

Retained Fetal

Membranes

Metritis

Health Disorders of Dairy Cows

Disease resistance is dependent on effective immunity.

§ Several layers of defense •  Physical barriers (teat end)

•  Innate immune system

•  Adaptive immune system

Immune System Overview

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§  Innate Immunity (minutes to hours)

•  Predominant during early infection

•  Activated quickly by numerous stimuli

•  Not augmented by repeated exposure

•  Can eliminate microbes without visible changes to milk or tissues

•  Adequacy of inflammatory response


Inflammation (Essential Innate Immune Response)

n  Purposes of inflammation: •  eliminate or neutralize source of injury •  assist in repairing damaged tissues to normal function •  complex and tightly regulated response •  initiated by release of mediators from damaged tissue

� Recognition of Bacteria §  Toxin & bacterial factors (i.e. endotoxin)

§  Pathogen associated molecular patterns (PAMPs)

§  Binds receptors on host cells (Toll-like receptors, TLR)

§  Stimulates production of inflammatory mediators (cytokines & oxylipids)

Inflammatory Response

Pathogen

Endotoxin Lipoteichoic Acid

TLR

Cytokines, Leukotrienes, & Prostaglandins

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�  Macrophages & lymphocytes �  Various local cell populations

§  Endothelial cells

§  Fibroblasts

§  Epithelial Cells

Sources of Inflammatory Mediators

Migrate to Injury

White Blood Cell Recruitment

Changes in Vascular Permeability

Blood Vessel

Inflammatory mediators: Cytokines, Prostaglandins, & Leukotrienes

Neutrophils

Damaged Tissue

Macrophage

Neutrophils are Essential for Protection

•  First cells to accumulate into tissues during inflammation

•  Up to 97% of cells found in mastitic milk •  Key role in eliminating bacteria

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Leukocyte Removal of Bacteria

� Neutrophil Antimicrobial Functions •  Phagocytosis

•  Releases toxic oxidizing agents (H2O2, O., &

HOCl) called ROS •  Antibacterial peptides (proteases and

lysozyme) •  Neutrophil extracellular traps (NET)

formation

ROS

Vacuole Lysosome containing enzymes

Neutrophil functions dictate the outcome of infection.

Pathogen

Resolution of Inflammation � Return tissues to normal function

•  Anti-inflammatory oxylipids and cytokines •  Vascular permeability changes •  Leukocyte infiltration stops •  Local macrophages removes damaged cells •  Growth factors help heal tissues

What if innate defenses of the cow fail to eliminate disease-causing

pathogens?

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§  Adaptive Immunity (> 96 hours) •  Important when innate defenses fail

•  Recognizes specific antigens

•  Heightened reaction upon repeated exposure

•  Ability to recognize self and non-self (MHC)

•  Basis of vaccination protocols


Adaptive Immunity (Pathogen Recognition)

§  Antigen presenting cells •  Macrophages and

Dendritic Cells

•  Important link with innate immunity

OpenStax College. 2013. Adaptive Immune Response. OpenStax_CNX, June 21, 2013. http://cnx.org/content/m44821/1.6/.

Adaptive Immunity (Effector Phase)

T Helper Cell

Antigen Presentation Cell

T cell receptor

MHC

B cell

Cytokines

Activated Helper T cell

Memory B cells

Plasma cells

Secreted Antibodies

Humoral Immune Response

Pearson Education, Inc., 2011

+

Plasma Cells

Memory

B cell

Recognition of same antigen

T helper cell

Cytokines IFN & IL2

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OpenStax College. 2013. Adaptive Immune Response. OpenStax_CNX, June 21, 2013. http://cnx.org/content/m44821/1.6/.

§  Re-exposure to pathogen •  Circulating memory cells

differentiate

•  Response is faster and more robust

•  Plasma cells produce 10-100 fold more antibodies

Opsonization Neutralization

Antibody

Pathogen

Pathogen

Neutrophil

Activation of Complement System Complement proteins

Formation of membrane attack complex

Flow of water and ions

Pore

Antigen


Antibody-Mediated Removal of Pathogens

Pearson Education, Inc., 2011

Effective Immune System highly interactive & coordinated

Adaptive Immunity (Later Response)

Innate Immunity (Early Response)

Disease Resistance

Immunity is Important!

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•  Physiological transition from late gestation to early lactation

•  Majority of all disease occurs the first weeks of lactation

•  50% of all cows experience disease

•  Major reason for culling

Increased Disease Incidence & Severity Periparturient Period

LeBlanc et al., 2006; Nordlund et al., 2006; DeVliegher et al., 2012; Pinedo et al., 2010

Transition Cow Immune Dysfunction

Uncontrolled Inflammation

Cytokines Prostaglandin

Neutrophils Macrophages

Poor Vaccine Response

Antibodies Lymphocyte Function

Innate Immunity

Adaptive Immunity

Inadequate Innate and Adaptive Immunity

Increased Disease Common linkage between metabolic and infectious diseases

Uncontrolled Inflammation in Periparturient Cows

� Inflammatory responses help disease progression ●  Inability of local defenses to detect and eliminate pathogen

(inadequate neutrophil function) ●  Uncontrolled leukocyte recruitment and activation of

inflammatory response (altered cytokine expression) ●  Delicate balance of robust initial response and inflammatory

resolution is lost ●  Bystander damage to host tissues ●  MASTITIS & METRITIS

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Sordillo et al., 1997. J. Dairy Sci. 80:1851.

Evidence of Immune Dysfunction Altered Periparturient Cytokine Expression

Impact on Neutrophils & Inflammation

Enhancement/Optimization Suppression/Dysfunction Interferon-γInterleukin-2 Colony Stimulating Factors (granulocyte/macrophage)

Tumor necrosis factor Interleukin-1 Interleukin-4 Interleukin-10

Cytokines in Milk During Mastitis Robust Initial Response

0

1

2

3

4

5

6

TN

F (U

/ml)

or IL

-1 (U

x 1

05 /ml

0

50

100

150

200

IL-8

(pg/

ml)

or IL

-6 (U

/ml)

0 12 24 36 48 60 72 Time Relative to E. coli Challenge (h)

IL-1

TNF α

IL-6

IL-8

Shuster et al, 1995

Cytokine Response in Periparturient Cows Coliform Mastitis Challenge

Sordillo et al. 1992 J. Dairy Sci.75:2119-2125.

0

5

10

15

20

25

30

35

40

0 4 8 12 24 36 48 60

TN

F (n

g/m

l)

Hours Following Challenge

Survived

Excessive cytokine response

Death

*

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Hoeben et al., 2000. J. Dairy Sci. 67:249

Evidence of Inflammatory Dysfunction Reduced Periparturient Neutrophil Function

Optimal neutrophil function is critical for inflammation

Indicator of bacterial killing capacity

Lee et al., 1998. Am. J. Vet Res. 59:37-43.

Evidence of Immune Dysfunction Reduced Periparturient Neutrophil Function

Indicator of neutrophil migration

Graph courtesy of Marcus Kehrli, USDA, NADC

Neutrophils are Essential for Uterine Health §  Retained Placenta

•  Decreased immune function contributes to placental retention (Beagley et al. 2010. J. Vet. Intern. Med. 24:261)

•  Impaired neutrophil functions leads to development of retained placenta (Gunnink, 1984. Vet Q. 6:49)

§  Metritis •  Innate immunity is needed postpartum to prevent

clinical metritis (LeBlanc et al., 2011. Theriogenol. 76:1610)

•  Reductions in neutrophil functions are associated with more clinical disease (Hammon et al., 2006. Vet. Immunol. Immunopathol. 113:21-29)

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Ramification of Immune Dysfunction Reduced Neutrophil Function

Kimura et al., 2002. J. Dairy Sci. 85:544-550.

Retained Placenta Healthy

Indicator of bacterial killing capacity


Kimura et al., 2002. J. Dairy Sci. 85:544-550.

Retained Placenta

Healthy

Indicator of migration from blood to tissue


Endometritis

Healthy

Indicator of bactericidal activity

Kim et al., 2005. J. Reprod Develop. 51:757-764.

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Neutrophils are Essential for Mastitis Resistance •  First cells to accumulate into mammary tissues

during initial stages of infection (Schalm et al., 1964. AJVR 25:90-96)

•  Represents 97% of cells found in mastitic milk (Paape et al., 1963. J. Dairy Sci. 36:1211-1216)

•  Key role in eliminating bacteria (Jain et al., 1971. AJVR 32:1929- )

Shuster et al., 1996. AJVR 57:1569-1575

Ramifications of Immune Dysfunction Bacterial Growth During Mastitis

Ramifications of Immune Dysfunction Increased Clinical Mastitis

n  Epidemiological Evidence of Coliform Mastitis l  25% cases occur by first 2 weeks lactation

l  45% cases occur by first 4 weeks lactation

l  60% cases occur by first 8 weeks lactation

Smith et al., 1985, J. Dairy Sci. 68:402 Hogan et al., 1989, J. Dairy Sci. 72:1547

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Factors that Impact Immune Dysfunction

Ø Genetic variation based on heritability estimates (Detilleux et al., J Dairy Sci. 77:2640, 1994)

Ø Stress hormones of parturition (cortisol) (Burton & Kehrli, J Leuk Biol 59:90, 1996)

Ø Nutritional Factors (Sordillo, J Dairy Sci. 99:4967, 2016)

Ø Metabolic Stress (Sordillo & Raphael, Vet Clinics North Am Food Anim 29:267, 2013)

CSIRO PUBLISHING

Animal Production Science, 2014, 54, 1204–1214 Review http://dx.doi.org/10.1071/AN14503 !

The nexus between nutrient metabolism, oxidative stress and inflammation in transition cow

!L. M. Sordillo A,B and V. Mavangira A

Destructive feedback loops that enhance disease susceptibility.

Dysfunctional Inflammation

Oxidative Stress

Altered Nutrient Metabolism

Metabolic Stress Triad

§  Transition from late lactation to dry period §  Transition from late gestation to early lactation §  Fetal demands §  Onset of copious milk production §  Linked to changes in nutrient requirements

Increased Need: ü  Energy ü  Proteins ü Glucose ü Minerals ü Vitamins


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Dry Matter Intake

Nutrient Requirements

Altered Nutrient Metabolism in Periparturient Cows (Negative Energy Balance)

Negative Energy Balance

Ene

rgy

(M

cal N

EI/

day)

24

20

16

12

28

60 120 140 168 196 224 252 280 0 30 Days from Calving

Energy Ingested

Energy Required

Babcock Institute


•  Lipid and protein mobilization •  Alterations in blood lipids •  Increased nonesterified fatty

acids (NEFA) •  Increased beta-hydroxybutyrate

(BHB)

Metabolic Adaptations to NEB

Suriyasathaporn et al., 2000


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Observed Effect Periparturient Period

●  Reduces antibody formation ( van Knegsel , 2007) & neutrophil functions (Hammon et al., 2006)

●  Compromised lymphocyte functions (Lacetera et al 2004), impaired cytokine production (Scalia et al 2006), reduced neutrophil function (Ster et al 2012)

●  Impairs neutrophil function (Grinberg et al., 2008)

●  Alters cytokine production (O’Boyle et al., 2006) and reduces lymphocyte functions (Lacetera et al., 2005)

●  Increases disease susceptibility and affects innate and acquired immune parameters (Sordillo & Aitken, 2008)

Elevated NEFA

Body Condition Score

Micronutrient Deficiencies (Vitamins & Minerals)

Negative Energy Balance

Ketosis (BHB levels)

Consequences of Altered Nutrient Metabolism Compromised immunity increases disease susceptibility

Goff and Stabel. 1990 J. Dairy Sci. 73:3195

Decline in Antioxidant Micronutrients During the Periparturient Period

Plasma Vitamin A Plasma Vitamin E

Calving Calving

Observed Effect

Micronutrients and Bovine Immunity Micronutrient

Selenium l  improves neutrophil function; decreases severity of mastitis

l  increase neutrophil killing; decrease clinical mastitis

l  increases killing by phagocytes; increase lymphocyte proliferation

l  improves lymphocyte functions; increased antibody responses

l  deficiency decreases neutrophil functions & increases susceptibility to disease

Copper & Zinc

β-carotene

Chromium

Vitamin E

Sordillo, J Dairy Sci. 99:4967, 2016; Spears & Weiss, Vet. J. 176:70.

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Metabolic Adaptations During the Transition Period

NE

FA

Glu

cose

NEFA Release#

Lipase Activity

Blood Insulin

NEFA Release

Lipase Activity

Blood Insulin

NEFA Release

Lipase Activity

Insulin Resistance

Inflammation Metabolic Homeostasis

Sordillo & Raphael (2013) Vet Clin Food Anim 29:267.

Balance is Essential

Practical Considerations •  Reduce intense lipid mobilization during the transition period

•  Minimize reductions in dry matter intake (DMI) •  Design diets to increase energy without affecting DMI •  Prevent over-conditioning in the dry period

•  Optimize inflammatory responses and oxidant balance •  Reduces sources of stress (heat stress, exposure to pathogens) •  Micronutrient supplementation (Se, Vitamin E, etc.) •  Immunomodulators (vaccines, supplements, etc.)

•  Comprehensive Approach to Reduce Metabolic Stress •  Monitoring Programs •  Inclusive of entire dry period and early lactation •  Early intervention

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