Toward a health-associated core keystone index for the human gut microbiome

A robust index of gut microbiome taxa encompassing their association with host health and microbiome resilience would be valuable for development and optimization of microbiome-based therapeutics. Here we present a single ranked order for 201 taxa, the Health-Associated Core Keystone (HACK) index, derived using their association strengths with prevalence/community association in non-diseased subjects, longitudinal stability, and host health. The index was derived based on 127 discovery cohorts and 14 validation datasets (cumulatively encompassing 45,424 gut microbiomes, subject age >18 years, representing 42 countries, 28 disease categories, and 10,021 longitudinal samples). We show that this index is reproducible regardless of microbiome profiling strategies and cohort lifestyle. Specific consortia of high HACK index taxa respond positively to Mediterranean diet interventions and reflect immune checkpoint inhibitor responsiveness and associated with specific functional profiles at the genome level. The availability of HACK indices provides a rational basis for comparing microbiomes and facilitating selection and design of microbiome-based therapeutics.