Apoptosis is a physiological response in development and homeostasis of metazoans. Apoptosis is triggered during pathological events as a means to renew affected tissues and eliminate cancer cells. The immune system regulates the extrinsic pathway of apoptosis, where signals such as TNFα or displayed ligands on the surface of immune cells trigger signal cascades by death receptors present on targeted cells. Therapeutics, like Doxorubicin, lead to apoptosis successfully.

During the last few decades, immunotherapy is considered to be an important approach to help our immune system to fight various kinds of diseases, such as tumor. Sometimes, it works very well for some types of cancers, for example: bladder cancer, colorectal cancer, breast cancer and lymphoma.

The gut microbiome or gut flora is a vast community of microorganisms such as bacteria, viruses, protozoa, and fungi that inhabit the digestive tract of the human and other animals. In the human body, bacterial species colonize into the oral cavity, skin, vagina, and placenta, however, the largest population of microorganisms resides in the intestine. The majority of gut microbiota belong to the phyla Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria.

When immune cells are activated, they undergo metabolic change in order to have sufficient energy to function effectively. The Krebs cycle is one of the most important pathways involved in this response and citrate, a critical component of this pathway, regulates carbohydrate and lipid metabolism.

The important immune cells in the brain are called microglia acting as the central junction between neuroinflammation and neurodegenerative diseases. In patients of cognitive disorders and Alzheimer’s disease (AD) animal models, amoebic morphology and inflammatory pathways are activated to release numerous cells in the inflammatory factors by active microglia.