1 / 40

The Effects of Spaceflight on the Immune System

The Effects of Spaceflight on the Immune System. Crash course on the immune system Space Flight-related factors to immunosuppression Current knowledge STS-107 experiments BioMEMS sensor. What is the Immune System?.

Télécharger la présentation

The Effects of Spaceflight on the Immune System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.


Presentation Transcript

  1. The Effects of Spaceflight on the Immune System • Crash course on the immune system • Space Flight-related factors to immunosuppression • Current knowledge • STS-107 experiments • BioMEMS sensor

  2. What is the Immune System? • It is a complex network of organs, chemicals and specialized cells that work together to protect the body from foreign or local damaging material.

  3. How the Immune System Works:Cell recognition • One of the primary functions of the immune system is to distinguish between self and non-self cells. • Problem in organ transplant. http://press2.nci.nih.gov/sciencebehind/immune/immune00.htm

  4. Substance Recognition • Antigens are substances that are capable of triggering an immune response. • Foreign molecules carry distinctive markers that differentiate them. http://press2.nci.nih.gov/sciencebehind/immune/immune00.htm

  5. Two types of Immunity: Innate and Acquired

  6. Innate Immunity • We are born with it. • Physical barriers: skin, mucous membranes • Protective chemicals: acid pH, surface lipids • Enzymes: saliva, digestive tract enzymes • Macrophages and complement • Non-specific to antigens

  7. Acquired Immunity • Antigen-specific: recognizes antigens, which can be proteins, carbohydrates, lipids and nucleic acids. • Memory: results in increased reactivity upon repeated exposures to the antigen or infectious agent (i.e. vaccines). • Regulation: discriminates between self and non-self, prevents autoimmune reactions in most individuals.

  8. Cells of the Immune System • T-cells: • Helper T-cells (CD4+) • Coordinators of immune regulation (cytokines) • Augment or tone down immune responses • Cytotoxic Killer Cells (CD8+) • Deal with tumor and virus infected cells • Natural Killer Cells (CD8+) • Also deal with tumor cells, but do not need to pass through the lymphoid organs.

  9. Cells of the Immune System • B-cells: • Plasma cells • Antibody production. • Antibodies initiate the ‘complement’ destroying cascade (chemically punctures antigens). • Macrophages: • T-cell and B-cell stimulation

  10. Macrophages and their role with respect to T cells and B cells: Antibody Production

  11. The Organs of the Immune System: The Bone Marrow • Spongy tissue found in the center of most large bones • All cells in the IS initially derive from it • Produces RBCs and platelets http://press2.nci.nih.gov/sciencebehind/immune/immune00.htm

  12. The Organs of the Immune System: The Bone Marrow • Stem cells, reside within the BM (unspecialized cells) • Most radiation sensitive tissue of the human body!!

  13. Bone marrow Stem cells Differentiation • T-cells • Helper T-cells • Cytotoxic T-cells • Natural Killer Cells • B-cells • Turn into plasma cells • Secrete antibodies

  14. Thymus • Two functions: • BM T-cell maturation • Release of mature T-cells into bloodstream BM = bone marrow

  15. Spleen • Immunological filter of the blood. • Antigens are brought by macrophages or carried by the blood itself. B and T-cells are activated. • Old RBCs are destroyed.

  16. Lymph Nodes • Immunological filters of the body fluid called lymph. • Lymph is drained from most of our tissues. • Antigens are filtered before returning to circulation. http://www.innerbody.com/image/lympov.html

  17. Reviewing Article in Time Life Magazine: http://www.westom.com/coolsite/life_imm.htm

  18. Space Flight-related Factors Affecting Immunity • Launch/Landing • Weightlessness? • Cephalic fluid shift • Affects lymphatic system (lymph nodes) • Loss of body fluid affects plasma protein concentration and osmolality • Bone loss?

  19. Space Flight-related Factors Affecting Immunity • Nutrition / SMS • Circadian rhythm and sleep patterns • Radiation? • Stress? • Other effects?

  20. Current Studies • Factors that can influence physiologic functions*: • Microgravity • Isolation • Radiation • Microbial contamination • Sleep disruption • Insufficient nutrition • Interaction with other body systems (pituitary gland) *Sonnenfeld et. al, 2002

  21. Current Studies • Stress-related immunosuppression • Stressors: • Pre-flight physical training • Discomfort of lift-off and landing • Heavy in-flight work and exercise schedules • Forced adaptation to the confined environment of the spacecraft

  22. Current Studies • Observed changes: • Reduction in T-cell counts (cell-mediated immunity) • Natural killer cells: decrease in functionality and concentration. • Constant immunoglobulin levels (antibodies) • Immune cells mediators: Interleukin-2 decreases.

  23. Radiation effects • Radiation effects : cumulative and long-term exposure promotes the formation of cancer and tumors • Low-level ionizing radiation stimulates the immune system • could reduce cancer frequency • increase growth and longevity (factors that will be crucial to humans in interplanetary voyages ) • Bone marrow stem cell production impaired.

  24. Diet • Astronauts are bound to the same recommended daily allowances (RDA) with regard to micronutrients as people on Earth. • A decrease in the intake of necessary minerals and vitamins will certainly affect the immune system.

  25. Exercise • Moderate exercise has been shown to enhance immune activity • However, an increased load in exercise can also lead to an overall depression in certain immune responses: • augments chances for viral and bacterial attacks • makes astronauts more susceptible to infection

  26. Exercise • Effects such as protein aberrations were observed during the first Apollo flights that were not seen in the Skylab missions* • Major difference between the two programs: an increased exercise load for the Skylab crews compared to their predecessors *(Criswell-Hudak, 1991)

  27. Analogous environments on Earth • Submarines • Polar stations • Oil platforms • Stressors: • Confinement • Sociological dynamics of isolation

  28. Analogous environments on Earth • Deep sea labs • In case of emergency, immediate return to Earth’s surface is not viable • Astronauts, just like deep sea divers, experience the confinement of a decompression chamber before an EVA

  29. Analogous environments on Earth • On deep sea diving: • Neutrophil granulocyte (allergens) activity has been shown to increase* • Results in decreased resistance to skin and other infections. • During early spaceflights astronauts frequently suffered from otitis and skin infections** *(Benestad et al., 1990) **(Schmitt and Schaffar, 1993)

  30. STS-107 Experiments • Stress and the immune system • Two experiments: • Impairment of system’s ability to fight infections? (innate immunity) • Stress-related reactivation of latent viruses? (acquired immunity)

  31. STS-107 Experiments Stress compromises the immune system by releasing hormones that make the body prone to infection and viral reactivation.

  32. STS-107 Experiments Some viruses remain latent within the body and are never expressed until sufficient immunosuppression occurs (i.e. Herpes)

  33. STS-107 Experiments Astronauts have reported a reduced ability to recover from cuts and abrasions in microgravity.

  34. Immunological Analysis • Collecting immunological data during flight is very difficult… • Blood samples degrade with time and do not represent current state. • Traditional lab equipment is too big to fly and a hassle to operate.

  35. BioMEMS Sensor • Monitor astronaut immune response • Measure immune markers (i.e. Cytokines) • Minimally invasive • MEMS technology

  36. What are MEMS? • Microelectromechanical Systems • Integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through microfabrication technology. • Lab-on-a-chip • In vitro (Ph.D. work) • In vivo (ultimate goal) Raiteri et. al, 2001

  37. Take home lessons • The immune system’s main functions: • Self vs. Non-self • Foreign or domestic damaging cells • It is composed of engulfing cells (Macrophages), coordinators (Helper T-cells), destroyers (Killer T-cells) and antibody producers (B-cells).

  38. Take home lessons • There are several factors that may influence immunosuppression in space flight (stress, malnutrition, confinement, microgravity?), but up to now, the data is inconclusive due to the low frequency of experimentation. • Better analytical techniques are needed to assess immune system status real-time (BioMEMS).

  39. Good Sources • National Cancer Institute http://press2.nci.nih.gov/sciencebehind/immune/immune00.htm • The On-line Medical Dictionary • http://cancerweb.ncl.ac.uk/cgi-bin/omd?action=Home&query= • How Stuff Works http://www.howstuffworks.com/immune-system.htm • The Inner Body http://www.innerbody.com/image/lympov.html

  40. Questions?

More Related