Psychoneuroimmunology

Question 1

What are the two arms that the nervous system can be considered to have?

Answer 1

The autonomic system consisting of the parasympathetic and sympathetic branches and the neuroendocrine system which is centred on the hypothalamic-pituitary-adrenal axis
These arms have extensive interconnection with the limbic system of the brain directly regulating the neurohormonal and autonomic outflow of the central nervous system

Question 2

How can perturbations of the hypothalamus affect the immune response?

Answer 2

Experimentally introducing lesions into the anterior lobe of the hypothalamus of rats depresses in vivo antibody responses
Experimentally stimulating the hypothalamus at the time of immunization enhances antibody response
Lesions in the hypothalamus and hippocampus have also been found to later natural killer activity and T cell functions

Question 3

What is the hypothalamus-pituitary-adrenal axis?

Answer 3

The neurohormonal output of the NCS is controlled through the hypothalamus-pituitary adrenal axis which can be regarded as a communication system in which the medium of information transfer is predominantly soluble hormones or other small chemical mediators

Question 4

What are the immune effects of corticosteroids?

Answer 4

Depression of in vivo responses
Depression of phagocytosis
Inhibition of macrophage activation
Inhibition of B cell and T cell activation in vitro
Alteration of lymphocyte migratory patterns
Rapid decreas in the number of cells in the thymus

Question 5

What are some non-steroid hormone immune effects?

Answer 5

Sex hormones diminish in vivo responses
Prolactin and growth hormones elevate responses
This is likely because receptors of these mediators are present on cells of the immune system it is likely that at least some of their effects are a consequence of direct binding to lymphocytes or monocytes

Question 6

What neuropeptides interact with the immune system?

Answer 6

Vasoactive Intestinal Peptide
Substance P
Oxytoxicn and vasopressin
Melatonin
Met-enkephalin

Question 7

How does the neuropeptide vasoactive intestinal peptide interact with the immune system?

Answer 7

Activates lymphocytes and modulates the migration of gut lymphocytes

Question 8

How does the neuropeptide substance P interact with the immune system?

Answer 8

This is chemotactic for neutrophils and monocytes, it is a mediator of local inflammatory responses
Enhances stimulated T cells proliferation and in vitro IgA production

Question 9

How do the neuropeptides oxytocin and vasopressin interact with the immune system?

Answer 9

They can replace IL-2 in some mitogen-activated functions

Question 10

How does the neuropeptide Melatonin interact with the immune system?

Answer 10

Enhances antibody synthesis in mixed lymphocyte reactions

Question 11

How does the neuropeptide Met-enkephalin interact with the immune system?

Answer 11

Enhances NK cell activity and affects the TH1/TH2 distribution

Question 12

What are the neurological mediators that interact with the immune system?

Answer 12

Beta-endorphin, Catecholamines and acetylcholine

Question 13

How does the nuerological mediator Beta-endorphin interact with the immune system?

Answer 13

Inhibits mitogen-activated T cell proliferation
Decreases CD4 and MHC II expression
Enhances NK cell activity
Suppresses antibody responses

Question 14

How does the nuerological mediator catecholamines interact with the immune system?

Answer 14

Suppress mitogen-induced lymphocyte proliferation

Question 15

How does the nuerological mediator acetylcholine interact with the immune system?

Answer 15

Increase cell proliferation in the bone marrow

Question 16

What are the neurohormones which interact with the immune system?

Answer 16

Prolactin
Somatostatin
Groeth hormone
ACTH
Angiotensin II
Nerve growth factor
Thyroxine

Question 17

How does the neurohomorne prolactin interact with the immune system?

Answer 17

Enhances macrophage activation and stimulates IL-2 production

Question 18

How does the neurohomorne somatostatin interact with the immune system?

Answer 18

Stimulates histamine release from mast cells
Inhibits histamine release from basophils
Inhibits T cell proliferation and IgA production

Question 19

How does the neurohomorne growth hormone interact with the immune system?

Answer 19

Enhances antibody synthesis and macrophage activation and modulates IL-2 production

Question 20

How does the neurohomorne ATCH interact with the immune system?

Answer 20

Affects macrophage activation, cytokine production, NK activity and antibody synthesis

Question 21

How does the neurohomorne angiotensin II interact with the immune system?

Answer 21

Modulates macrophage Fc receptor activity

Suppresses T cell activation by mitogens

Question 22

How does the neurohomorne nerve growth factor interact with the immune system?

Answer 22

Stimulates neutrophil chemotaxis

Question 23

How does the neurohomorne thyroxine interact with the immune system?

Answer 23

Enhances T cell activation and antibody formation

Question 24

What is the relationship between the autonomic nervous system and immune system?

Answer 24

Histochemical staining techniques for identification of small nerves have revealed extensive innervation of all lymphoid tissue
This is predominately from sympathetic nerves which use norepinephrine as transmitter
In lymph nodes these nerves appear to terminate predominately in the T cell rich regions and suggests a possible link to immunoregulatory functions
Surgical or chemical ablation of sympathetic nerves to lymph nodes or spleen augments antibody responses to these organs
Conversely ablation of parasympathetic innervation of lymphoid tissues generally depresses immune responsiveness

Question 25

What are the effects the immune system can have on the nervous system?

Answer 25

Changes in electrical activity and in neurotransmitter levels in the hypothalamus are observed to correlate with the time course of immune responses suggesting that information is passing from the immune system to the brain in some from this could be due to lymphocytes secreting neurological mediators or alternatively cytokines produced during the course of the immune response could directly affect neural tissues

Question 26

What are the neurological mediators that can be produced by immune cells?

Answer 26

Corticotrophin (ACTH), CRF-like activity, Thyroid-stimualting hormone, beta endorphinm vasoactive intestinal peptide, substance P, smoatostatins, oxytocin and neruophysin, human chorionic gonadotrophic hormone

Question 27

What immune cells can produce the neurological mediator corticotrophin?

Answer 27

Lymphocytes and monocytes

Question 28

What immune cells can produce the neurological mediator CRF-like activity?

Answer 28

Lymphocytes

Question 29

What immune cells can produce the neurological mediator Thyroid stimulating hormone?

Answer 29

Lymphocytes

Question 30

What immune cells can produce the neurological mediator beta-endorphin?

Answer 30

Lymphocytes and monocytes

Question 31

What immune cells can produce the neurological mediator vasoactive intestinal peptide?

Answer 31

Polymorphs and mast cells

Question 32

What immune cells can produce the neurological mediator substance P?

Answer 32

Basophils, mast cells and monocytes

Question 33

What immune cells can produce the neurological mediator somatostatins?

Answer 33

Basophils, mast cells and monocytes

Question 34

What immune cells can produce the neurological mediator oxytocin and neurophysin?

Answer 34

Thymus tissue

Question 35

What immune cells can produce the neurological mediator human chorionic gonadotrophin?

Answer 35

Lymphocytes

Question 36

What affect does IL-1 have on CNS activity?

Answer 36

This cytokine is secreted by astrocytes and glial cells Stimulates proliferation in astroglia and oligodendroglia Increases slow wave sleep when it is administered to the brain’s lateral ventricle IL-1Beta is a neurotransmitter in pre-optic and hypothalamic neurones Promotes illness bheaviours

Question 37

What affect does IL-1beta and IL-2 have on CNS activity?

Answer 37

Enhances the expression of POMC mRNA in pituitary cells

Question 38

What affect does IFN-alpha have on CNS activity?

Answer 38

Modulates electrical activity when introduced into the rat brain melanocyte-stimulating hormone-like activity thyroid stimulating hormone-like activity

Question 39

What affect does IL-6 have on CNS activity?

Answer 39

Stimulates ACTH production in the pituitary

Question 40

How does IL-1 provide a connection between the immune system and the central nervous system?

Answer 40

Activation of macrophages produces IL-1 and subsequently leads to altered electrical activity in the brain and metabolism of the neurotransmitters norepinephrine, serotonin and dopamine in certain brain regions These changes can also be induced by IL-1 injection and blocked by IL-1 receptor antagonists However despite the fact that neurons I nthe preoptic nucleus have receptors of IL-1 due to the size and solubility of IL-1 it may have issues moving across the blood brain barrier therefore some active transport mechanism may exist or it may cross the vascular endothelium in the regions of the brain where the barrier is weak or absent Alternatively IL-1 may stimulate peripheral nerves which then go on to stimulate the brain this was highlighted by the fact that cutting the vagus nerve dramatically reduces IL-1 effects on the brain

Question 41

What immune measures have been affected by stress?

Answer 41

Nonspecific, mitogen induced proliferative responses of lymphocytes Development of antigen specific cytotoxic T cells Generation of specific antibody responses Macrophage activation Alteration of TH1/TH2 balance Secretion of cytokines Trafficking patterns of immune cells between compartments of the immune system

Question 42

What determines the impact and direction of stress on immune behaviour?

Answer 42

The quality, quantity and duration of the stressor The temporal relationship beyween exposure to the stressor and the introduction of antigenic or pathogenic stimulation Socio-environmental conditions Various host factors such as species, strain and sex

Question 43

What are some examples of human studies on stress and immunity?

Answer 43

In a one year study a group of medical students there was a strong association between examination stress increased incidence of illness and depression of various immunological measures, at the times of examination stress those students who were chronic carriers of latent Epstein barr viruses exhibited increased antibody titres Another study looked at a group of students who were immunized with Hepatitis B virus vaccine at examination time those who seroconverted early were significantly less stressed and anxious than those who did not as well as those students with greater social support Volunteers completed questionaires assessing degrees of perceived stress and social network diversity and were intra-nasally inoculated with rhino and adenoviruses in a quarantine unit, it was found that stress correlated strongly with increased risk of infection and social diversity could relieve some of this effect Elderly people experiencing chronic stress by caring for individuals with dementia exhibit diminished cytokine responses, healed wounds slower and responded less well to influenza