Immune cells fight pathogens, destroy infected/malignant cells, and contribute to the healing of traumatic tissue damage. To become fully competent cells, immune cells must be activated and induced to differentiate into effector cells in the immune niche. Immune niches are provided by secondary lymphoid organs. They also include sites of inflammation as well as tumor microenvironments.

Microenvironments in the immune niche play an important role in the immune cell activation and are critical for the occurrence and dissolution of the immune response. Immune cells interplay with local stromal cells and shape the immune niches, via cell-cell interaction or the cell-matrix interaction. Therefore, the effect of inflammation is usually tissue-specific, especially in many cases related to the immune status. To better understand the interplay between immune cells and their microenvironments, more comprehensive investigations are required. This would extend our knowledge in tissue environment homeostasis and improve therapeutic strategies in infectious diseases, inflammatory diseases, malignant diseases, and wound healing.

The aim of this Special Issue is to attract original research and review articles that clarify related fundamental knowledge and underlying mechanisms of the interplay between immune cells and their microenvironments. We hope that this Special Issue also highlights new therapeutic strategies and improvements in clinical efficacy.

Potential topics include but are not limited to the following:

• Current perspectives in tissue-specific immune niches
• Tissue-specific infiltration of immune cells
• Immune cell-stromal cell interaction or immune cell-matrix interaction
• Immune response in the maintenance of tissue homeostasis
• Immune response in tissue repair and regeneration
• Therapeutic strategies that modulate the immune niche and the immune response