WAT Inflammation Flashcards
What determines the mass of WAT?
- Hypertrophy: swelling of existing adipocytes to accommodate excess nutrients such as triglycerides
- Hyperplasia/Adipogenesis: an increase in adipose stem cell proliferation with subsequent adipogenesis
- It can also change from both
Why is adipocyte hypertrophy bad?
- Increasing the size of an adipocyte
- desensitizes it to insulin
- Promotes lipid storage/biogenesis problems
How does having less oxygen at the cellular level a problem?
- ER stress
- Mitochondria dysfunction
- Adipocyte death
- Lack of oxygen for cellular process
Two types of Hypoxia
- Acute hypertrophy hypoxic response:
- Chronic hypertrophy response:
Acute hypertrophy hypoxic response:
- Adipocytes quickly expand in size and reach the diffusional limit of oxygen
- It is mild but induces a stress signal that drives new blood vessel formation to facilitate further expansion of WAT and reduce hypoxia. (It can be seen as healthy)
- Angiogenesis: blood vessel forming
- If it continues it will become chronic
Chronic hypertrophy response:
- Adipocytes keep expanding in size and exhaust the ability of WAT to produce new blood vessels
- Hypoxia is greater and induces stress signals resulting in adipocyte cell death
How does hypoxia alter WAT:
- Tissue stress: nutrient deprivation
- Stimulate inflammatory signals
- Force adipocyte cell death and necrosis: stimulating lipid release
Could we target hypoxia be a potential for obesity:
- No, because you might grow vascularization in areas you don’t want
- Increases vascularity(growing blood vessels ) in all tissues
- Increase the risk of cancer
- Only promotes healthier WAT expansion short-term
Fibrotic Tissue Is Made:
- Fibroblasts within the tissue/organ control the amount of collagen fiber and other extracellular matrix deposition
- Normal process but if not regenerated properly it can cause healing effects like scar
- Severe fibrosis for Obese
4 Phases of fibrogenesis:
- Initiation of the response (poor diet, adipocyte hypertrophy, hypoxia)
- Activation of effector cells (fibroblast)
- Elaboration of extracellular matrix( production of collagen and fiber in between adipocytes)
- Full progression of fibrosis and organ failure
Initiation of WAT Fibrosis:
Hypoxic conditions and adipocyte hypertrophy stimulate the secretion of pro-fibrotic that stimulate cells within WAT to expand themselves and to produce collagen and other matrix materials
What does fibrosis mean for adipose tissue?
-Increase tissue stiffness
- Disruption of tissue organization and architecture
- Interfere with cell-cell communication
- adipocyte -blood vessel communication
- Activated fibroblast will secret hormones and factors that disrupt WAT biology
Adipocytes signal to the immune system:
- Hypertrophy adipocytes secret cytokines that attract
- immune cells to the WAT
- Immune cells and macrophages elicit/mount a pro-inflammatory response
- Encircle and engulf adipocyte
Macrophages
- phagocytic cells. Sentinels of the immune system that fight off infections
- Largest pop of immune cells in visceral AT
-First line defense
-10% of lean states but 50% of Obese state
Crown-like structure:
formed from macrophage engulfment, signals cell death
