Histamine: A Bacterial Signal Molecule

This work was supported by FEDER funds and the Fondo Social Europeo through grants from the CSIC to M.A.M. (PIE-202040I003), the Spanish Ministry for Science, Innovation and Universities to M.A.M. (PID2019-103972GA-I00), the Junta de Andalucia to T.K. (P18-FR-1621) and Spanish Ministry of Economy and Competitiveness (BIO2016-76779-P to T.K. and BIO2016-74875-P to J.A.G.). A.R. was supported by the Spanish Ministry of Science and Innovation, Promotion of Talent and its Employability-Ramon y Cajal R&D&i Programme (RYC2019-026481-I).Bacteria have evolved sophisticated signaling mechanisms to coordinate interactions with organisms of other domains, such as plants, animals and human hosts. Several important signal molecules have been identified that are synthesized by members of different domains and that play important roles in inter-domain communication. In this article, we review recent data supporting that histamine is a signal molecule that may play an important role in inter-domain and inter-species communication. Histamine is a key signal molecule in humans, with multiple functions, such as being a neurotransmitter or modulator of immune responses. More recent studies have shown that bacteria have evolved different mechanisms to sense histamine or histamine metabolites. Histamine sensing in the human pathogen Pseudomonas aeruginosa was found to trigger chemoattraction to histamine and to regulate the expression of many virulence-related genes. Further studies have shown that many bacteria are able to synthesize and secrete histamine. The release of histamine by bacteria in the human gut was found to modulate the host immune responses and, at higher doses, to result in host pathologies. The elucidation of the role of histamine as an inter-domain signaling molecule is an emerging field of research and future investigation is required to assess its potential general nature.European CommissionFondo Social Europeo through CSIC PIE-202040I003Spanish Ministry for Science, Innovation and Universities PID2019-103972GA-I00Junta de Andalucia P18-FR-1621Spanish Ministry of Economy and Competitiveness BIO2016-76779-P BIO2016-74875-PSpanish Ministry of Science and Innovation, Promotion of Talent and its Employability-Ramon y Cajal RDi Programme RYC2019-026481-