Systemic Effects of Inflammation Quiz

Systemic Effects of Inflammation

• Inflammation, even localized, triggers systemic reactions called the acute-phase response, mediated by cytokines.
• TNF-α, IL-1, and IL-6 are key cytokines in the acute-phase response.
• Cytokines are produced by leukocytes in response to infectious agents or immunologic reactions and are released into the circulatory system.
• The acute-phase response involves several clinical and pathological changes.

Local Signs of Inflammation

• Heat (Calor): A localized increase in temperature.
• Redness (Rubor): Reddening of the affected area.
• Edema (Tumor): Swelling due to fluid accumulation.
• Pain (Dolor): Feeling of discomfort in the affected area.
• Loss of Function (Functio Laesa): Impairment of the affected area's normal function.

Fever (Clinical Hallmark of Inflammation)**

• Fever is a common sign of inflammation, characterized by an elevated body temperature (typically 1°C to 4°C).
• The hypothalamus plays a crucial role in regulating temperature.
• Cytokines (IL-1, TNF-α) stimulate prostaglandin production in the hypothalamus, which resets the temperature set point to a higher level.
• Pyrogens (external factors stimulating fever) include bacterial products (e.g., LPS) and cytokines.

Elevated Levels of Acute Phase Proteins

• Acute-phase proteins, mainly produced by the liver, increase significantly during inflammation.
• Notable examples include C-reactive protein (CRP), fibrinogen, and serum amyloid A (SAA).
• Cytokines (e.g., IL-6 for CRP and fibrinogen, IL-1 or TNF for SAA) stimulate the synthesis of these proteins in hepatocytes.
• The ESR (Erythrocyte Sedimentation Rate) test measures the rate at which erythrocytes settle in a test tube. Elevated ESR is linked to most cases of chronic inflammation.

Leukocytosis

• Leukocytosis is an increase in the total white blood cell count.
• Normal WBC counts in adults vary from 4000 - 11,000 cells/cu mm.
• A common feature of inflammation, especially bacterial infections, is leukocytosis.
• Accelerated release of cells from bone marrow pools due to cytokines causes leukocytosis.
• Both mature and immature white blood cells may be detected in peripheral blood samples in cases of leukocytosis.

Eosinophilia

• In certain allergic reactions or helminth (parasitic worm) infestations, there's an elevation in eosinophils known as eosinophilia.
• Asthma and hay fever are examples of conditions where eosinophilia is observed.

Leucopenia

• A decreased number of circulating white blood cells is called leucopenia.
• Typhoid fever and infections by some viruses/rickettsias/protozoa can lead to leucopenia.

Other Manifestations of Inflammation

• Anemia: Chronic inflammation is often associated with varying degrees of anemia.
• Changes in vital signs: Inflammation may cause elevated heart rate and blood pressure, and reduced sweating.
• Other systemic symptoms: Chills, rigors (shivering), anorexia (loss of appetite), somnolence (sleepiness), and malaise (general feeling of discomfort).

Septic Shock

• In severe bacterial infections (sepsis), bacterial products stimulate cytokines (like IL-1 and TNF).
• This leads to disseminated intravascular coagulation (DIC), metabolic disturbances (acidosis), and hypotensive shock.
• This combined clinical effect is termed septic shock.
• Systemic inflammatory response syndrome (SIRS) is a severe form of septic shock.