Challenges in the Immune System: Mesoscale and Mesoregime Complexity.

One of the greatest challenges in bioscience is to gain a unified view of the human immune system. This paper presents a perspective on the multilevel and multiscale complexities inherent in the immune system and discusses how these features influence the traditional research methodologies rooted in reductionism and holism. It is acknowledged that diverse complexities of the immune system are multilevel in nature, with each level showing multiscale properties, and the complexity emerging always at mesoscales in mesoregimes. Mesoscience encompasses both mesoscales, which represent the intermediate scales between the element scales and system scales at different levels, and mesoregimes, defined as transitional regimes governed by the interplay of at least two dominant mechanisms between two limiting regimes at each level. Therefore, mesoscience provides a promising paradigm to study the complexity and diversity of the immune system by bridging the gaps across multiple hierarchical levels. In particular, we focus on the mesoscience methodology to address the complexities in the immune system and offer insights into potential diagnostic, therapeutic, and theranostic strategies for immune-related diseases from a mesoscience perspective.