HP – Psychoneuroimmunology (PNI)

Psychoneuroimmunology (PNI) root words.
Psycho: beliefs, thoughts, stress, emotions, moods, etc.;
Neuro: central and peripheral nervous system.;
Immunology: the immune system.

Psychoneuroimmunology (PNI) definition
What stress can do to the immune system.

What is the immune system’s primary job?
To defend against infectious agents like viruses, bacteria, and parasites.

What is autoimmune disease?
Parts of the body attacked by the immune system.

Innate Immunity
Inborn resistance to pathogens; acts the same way for all invaders, e.g. skin.

The role of inflammation
Occurs when white blood cells enter tissues to attack infections; many pathogens can get past this defense.

Cells of innate immunity: Natural killer cells
Cells of innate immunity: Natural killer cells
The “soldiers” that patrol around looking for invaders; they kill all invaders the same way.

Cells of innate immunity: Macrophages
Cells of innate immunity: Macrophages
The “pac” men that kill by ingesting invaders and digesting them into harmless bits.

Cells of innate immunity: Antigen presenting cells
Cells of innate immunity: Antigen presenting cells
The “tattle tales” that take a piece of antigen (the invader) with them to show it to more powerful cells.

Cells of innate immunity: The
Cells of innate immunity: The “phils” (eosinophils, basophils, and neutrophils)
The “suicide bombers” that release destructive enzymes. They die killing antigens.

Adaptive immunity
Immunity acquired from pathogens encountered during lifetime.

Cells of adaptive immunity: Helper T Cells
Cells of adaptive immunity: Helper T Cells
A type of white blood cell, different for each kind of antigen, they build an army of clones and Cytotoxic Killer T Cells

Cells of adaptive immunity: Cytotoxic Killer T Cells
Cells of adaptive immunity: Cytotoxic Killer T Cells
The “Jack the Rippers”, they directly kill or eat their victims; tears invaders to shreds

Cells of adaptive immunity: B Cells
Cells of adaptive immunity: B Cells
Are like Snow White’s evil stepmother. They are activated by Helper T Cells, and use antibodies (specially designed poison) to kill the invaders.

Cells of adaptive immunity: Memory Cells
Cells of adaptive immunity: Memory Cells
Are like the “elephant’s memory”; Different for each antigen, created from B Cells and T Cells. Ready to act fast if encountered again. Vaccines take advantage of this.

Conditioned nausea in rats.
Before conditioning: Sugar water; No response.
Before conditioning: Drug; Nausea.
During conditioning: Sugar water + Drug; Nausea.
After conditioning: Sugar water; Nausea.

Conditioned immune suppression in rats.
Before conditioning: Sugar water; No response.
Before conditioning: Drug; Immune suppression.
During conditioning: Sugar water + Drug; Immune suppression.
After conditioning: Sugar water; Immune suppression.

Ader’s study
[1] The two groups differed based on nausea. Immune response was never measured. Perhaps drug had delayed response?
[2] Rats in the conditioned group showed a suppressed immune system. So, an immune response *can* be behaviorally conditioned.
[3] *This study started the PNI field.*

Why is it hard to measure immune response?
There is no single measure of it. Some measures may show a better response, while others show a worse response; Some cells inhibit the activity of other cells; you might look for changes too early or too late.

Proinflammatory Cytokines (like Interleukin-1)
Immune substances that have many roles: in *adaptive immunity*, they *coordinate* the *function* of *other immune cells*; in *innate immunity*, they lead to *inflammation*, increased *sleep*, reduced activity and consumption, send immune sells into tissues, *tissue repair and wound healing*.

Stress and Wound healing, Study 1 (Keicolt-Glaser et al., 1995) design
[1] Find a group of stressed people (care givers) and match them to non-stressed controls.
[2] Wound subjects (biopsy punch)
[3] Measure how long it takes for the wound to heal and measure interleukin-1

Stress and Wound healing, Study 1(Keicolt-Glaser et al., 1995) results
Results: Stressed participants’ wounds healed slower compared to the wounds of the control group. Stressed participants blook produced less interleukin-1 compared to the control group.

Potential confounds: can’t randomly assign people to care-giver groups.

Stress and Wound healing, Study 2 (Marucha et al., 1998) design
[1] Find a group of dental students.
[2] Wound students during summer break.
[3] Measure time it takes for the wound to heal, and measure amount of interleukin-1 in blood.
[4] Wound students 3 days before exams and repeat [3] (each student served as his/her own control)

Stress and Wound healing, Study 2 (Marucha et al., 1998) results
Results: Dental students’ wounds healed 40% slower during finals exams compared to during summer break. Dental students interleukin-1 levels decreased during exam time compared to during the summer.

Confounds: time of year?

Stress and Wound healing, Study 3 (Broadbent et al., 2000) design
[1] Assessed wound healing in 36 adults following a hernia repair surgery.
[Method:] Pre-surgery: assess perceived stress; Post-surgery: measure wound fluid, perceived stress, pain, and recovery speed.

Stress and Wound healing, Study 3 (Broadbent et al., 2000) results
Results: Participants with higher stress pre-surgery had lower levels of interleukin-1, had more pain, and slower recovery.

Acute Stress and Immune Response (Schedlowski et al., 1993) design
[1] Participants: first time parachute jumpers.
[2] Take blood 3 times: 2 hours before jump, immediately after jump, and 1 hour after jump.
[3] Monitor HR continuously.
[4] Measure sympathetic nervous system hormones continuously.

Acute Stress and Immune Response (Schedlowski et al., 1993) results:
Results: HR shoots up during jump; epinephrine shoots up during jump; norepinephrine shoots up just after jump; natural killer cells increase right after jump; natural killer cells decrease below their starting point an hour after jump.

Short term response
(Stress and Immune Response: The Complex Picture)
Many aspects of your *immune system are activated* in response to the sudden onset of acute stressors.

Long term response
(Stress and Immune Response: The Complex Picture)
Many aspects of your *immune system are suppressed* in response to ongoing stressors.