AUTHOR=Saghari Mahdi , Gal Pim , Grievink Hendrika W. , Klaassen Erica S. , Itano Andrea , McHale Duncan , Moerland Matthijs 

TITLE=Impact of oral administration of single strain Lactococcus lactis spp. cremoris on immune responses to keyhole limpet hemocyanin immunization and gut microbiota: A randomized placebo-controlled trial in healthy volunteers

JOURNAL=Frontiers in Immunology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.1009304

DOI=10.3389/fimmu.2022.1009304

ISSN=1664-3224

ABSTRACT=<sec><title>Introduction</title><p><italic>Lactococcus lactis</italic> spp. <italic>cremoris</italic> has been associated with promising immunomodulatory results in preclinical trials. The aim of this study was to investigate the pharmacodynamic (PD) effects of three monoclonal microbial formulations of <italic>L. lactis</italic> spp. <italic>cremoris</italic> (EDP1066) on the immune response to keyhole limpet hemocyanin (KLH). Potential effects on the gut microbiota were also investigated.</p></sec><sec><title>Methods</title><p>The trial was registered on Netherlands Trial Register (trial ID NL7519, <uri xlink:href="https://trialsearch.who.int" xmlns:xlink="http://www.w3.org/1999/xlink">https://trialsearch.who.int</uri>). Eighty-one healthy subjects (median 28, range 18–59 years) were randomized to 28 days of enteric-coated capsules at five doses (n = 13) (1.5 * 10<sup>12</sup> total cells daily), freeze-dried powder at one dose (n = 12) (3.0 * 10<sup>11</sup> total cells daily) or five doses (n = 12), minitablets at one dose (n = 12) or five doses (n = 12), or placebo (n = 20) prior to KLH immunization. Antibody responses and circulating regulatory T cells (Tregs) were measured after KLH immunization, and skin responses were evaluated after a KLH rechallenge by laser speckle contrast imaging and multispectral imaging. <italic>Ex vivo</italic> lymphocyte (phytohemagglutinin) and monocyte (lipopolysaccharide (LPS)) cytokine release assays were explored in the minitablet-treated groups only. The prevalence of <italic>L. lactis</italic> spp. <italic>cremoris</italic> in the gastrointestinal tract and the impact on the fecal microbiota were assessed by qPCR and 16S rRNA sequencing, respectively.</p></sec><sec><title>Results</title><p>Repeated-measures analysis of covariances revealed no significant treatment effects on the antibody responses to KLH, number of Tregs, or KLH skin rechallenge outcomes. <italic>Ex vivo</italic> LPS-driven cytokine responses in whole blood were lower in the low dose minitablet group compared to placebo: tumor necrosis factor (estimated difference (ED) from placebo: −44.2%, 95% confidence interval (CI) −65.3% to −10.3%), interleukin (IL)-1β (ED −41.4%, 95% CI −63.5% to −5.8%), and IL-6 (ED −39.2%, 95% CI −56.8% to −14.5%). The fecal presence of <italic>L. lactis</italic> spp. <italic>cremoris</italic> increased during treatment by all EDP1066 formulations and normalized 5 days after the last dose. Microbiome α-diversity did not change by the treatments compared to placebo.</p></sec><sec><title>Discussion</title><p>The EDP1066 formulations did not affect the immune response to KLH immunization in healthy individuals. However, exposure to <italic>L. lactis</italic> spp. <italic>cremoris</italic> in minitablet formulation impacted <italic>ex vivo</italic> whole blood LPS cytokine response. The clinical impact of these effects awaits further investigations.</p></sec><sec><title>Netherlands Trial Register</title><p><uri xlink:href="https://www.trialsearch.who.int/" xmlns:xlink="http://www.w3.org/1999/xlink">trialsearch.who.int</uri>, trial ID NL7519.</p></sec>