Development of a mathematic equation for host-pathogen interaction: shifting the paradigm of the pathogen-targeted medicine to the host-based medicine

Prognosis of infectious diseases is determined by the dynamic interaction between hosts and pathogens. Over the past several decades, the control of pathogens has been the central dogma of treating infectious diseases in modern medicine, and little efforts have been devoted on regulation of hosts. However, the pathogen-directed medicine is now facing significant challenges, such as lack of effective antimicrobials for newly emerging pathogens, drug resistance of pathogens, and drug side-effects, etc. Here, a mathematic equation (termed the equation of host-pathogen interactions, HPI-Equation) is developed to dissect the key variables of host-pathogen interaction. It clearly shows that control of pathogens is neither necessary nor sufficient for host recovery. Instead, a combination of promoting the host self-healing power and balancing the host immune response provides the best benefit for the host. The HPI-Equation strongly suggests a paradigm shift of the pathogen-targeted medicine to the host-based medicine. Moreover, the HPI-Equation elucidates the scientific basis of traditional Chinese medicine (TCM), a model of the host-based medicine that treats infectious diseases by promoting the host self-healing power and balancing the immune response. The importance of the self-healing power elucidated in the HPI-Equation was confirmed by recent studies that the tolerance mechanism, which is discovered in plants and animals and conceptually equivalent to the self-healing power, improves host survival without directly attacking pathogens. In summary, the HPI-Equation describes the host-pathogen interaction with mathematic logics and precision; It translates the ancient wisdoms of TCM into apprehensible modern sciences and opens a new venue for integration of TCM and modern medicine for the future medicine.