Mitochondrial complex I dysfunction alters the balance of soluble and membrane-bound TNF during chronic experimental colitis

[EN]Inflammatory bowel disease (IBD) is a complex, chronic, relapsing and heterogeneous disease induced by environmental, genomic, microbial and immunological factors. MCJ is a mitochondrial protein that regulates the metabolic status of macrophages and their response to translocated bacteria. Previously, an acute murine model of DSS-induced colitis showed increased disease severity due to MCJ deficiency. Unexpectedly, we now show that MCJ-deficient mice have augmented tumor necrosis factor α converting enzyme (TACE) activity in the context of chronic inflammation. This adaptative change likely affects the balance between soluble and transmembrane TNF and supports the association of the soluble form and a milder phenotype. Interestingly, the general shifts in microbial composition previously observed during acute inflammation were absent in the chronic model of inflammation in MCJ-deficient mice. However, the lack of the mitochondrial protein resulted in increased alpha diversity and the reduction in critical microbial members associated with inflammation, such as Ruminococcus gnavus, which could be associated with TACE activity. These results provide evidence of the dynamic metabolic adaptation of the colon tissue to chronic inflammatory changes mediated by the control of mitochondrial function.S

Mitochondrial complex I dysfunction alters the balance of soluble and membrane-bound TNF during chronic experimental colitis.

Inflammatory bowel disease (IBD) is a complex, chronic, relapsing and heterogeneous disease induced by environmental, genomic, microbial and immunological factors. MCJ is a mitochondrial protein that regulates the metabolic status of macrophages and their response to translocated bacteria. Previously, an acute murine model of DSS-induced colitis showed increased disease severity due to MCJ deficiency. Unexpectedly, we now show that MCJ-deficient mice have augmented tumor necrosis factor alpha converting enzyme (TACE) activity in the context of chronic inflammation. This adaptative change likely affects the balance between soluble and transmembrane TNF and supports the association of the soluble form and a milder phenotype. Interestingly, the general shifts in microbial composition previously observed during acute inflammation were absent in the chronic model of inflammation in MCJ-deficient mice. However, the lack of the mitochondrial protein resulted in increased alpha diversity and the reduction in critical microbial members associated with inflammation, such as Ruminococcus gnavus, which could be associated with TACE activity. These results provide evidence of the dynamic metabolic adaptation of the colon tissue to chronic inflammatory changes mediated by the control of mitochondrial function

Peripheral Blood Mononuclear Cells (PBMC) Microbiome is Not Affected by Colon Microbiota in Healthy Goats

BACKGROUND: The knowledge about blood circulating microbiome and its functional relevance in healthy individuals remains limited. An assessment of changes in the circulating microbiome was performed by sequencing peripheral blood mononuclear cells (PBMC) bacterial DNA from goats supplemented or not in early life with rumen liquid transplantation. RESULTS: Most of the bacterial DNA associated to PBMC was identified predominantly as Proteobacteria (55%) followed by Firmicutes (24%), Bacteroidetes (11%) and Actinobacteria (8%). The predominant genera found in PBMC samples were Pseudomonas, Prevotella, Sphingomonas, Acinetobacter, Corynebacterium and Ruminococcus. Other genera such as Butyrivibrivio, Bifidobacterium, Dorea and Coprococcus were also present in lower proportions. Several species known as blood pathogens or others involved in gut homeostasis such as Faecalibacterium prausnitzii were also identified. However, the PBMC microbiome phylum composition differed from that in the colon of goats (P≤0.001), where Firmicutes was the predominant phylum (83%). Although, rumen liquid administration in early-life altered bacterial community structure and increased Tlr5 expression (P=0.020) in colon pointing to higher bacterial translocation, less than 8% of OTUs in colon were also observed in PBMCs. CONCLUSIONS: Data suggest that in physiological conditions, PBMC microbiome differs from and is not affected by colon gut microbiota in small ruminants. Although, further studies with larger number of animals and covering other animal tissues are required, results point to a common circulating bacterial profile on mammals being phylum Proteobacteria, and genera Pseudomonas and Prevotella the most abundants. All suggest that PBMC microbiome in healthy ruminants could be implicated in homeostatic condition. This study expands our knowledge about PBMC microbiome contribution to health in farm animals.This work was supported by grants from the Spanish Ministry of Science and Innovation (MCI) co-financed with FEDER funds [AGL2017-86757- to LA, AGL2017-86938-R to DRY]. Other contributions were SAF2015-65327-R to JA and SAF2015-73549-JIN to HR. LA is a Ramón y Cajal fellow [RYC-2013-13666] from the Spanish Ministry of Science and Innovation. APC is a recipient of a fellowship from the University of the Basque Country. We thank the MCI for the Severo Ochoa Excellence accreditation (SEV-2016-0644) and the Basque Department of Industry, Tourism and Trade (Etortek and Elkartek programs

Microbioma de las células mononucleares de sangre periférica en cabras

1 página.- Trabajo presentado a las: XIX Jornadas sobre Producción Animal AIDA. On line. Zaragoza, España, 1-2 junio 2021.Financiado por los proyectos AGL2017-86757 y AGL2017-86938-R

The commensal bacterium Lactiplantibacillus plantarum imprints innate memory-like responses in mononuclear phagocytes

Gut microbiota is a constant source of antigens and stimuli to which the resident immune system has developed tolerance. However, the mechanisms by which mononuclear phagocytes, specifically monocytes/macrophages, cope with these usually pro-inflammatory signals are poorly understood. Here, we show that innate immune memory promotes anti-inflammatory homeostasis, using as model strains of the commensal bacterium Lactiplantibacillus plantarum. Priming of monocytes/macrophages with bacteria, especially in its live form, enhances bacterial intracellular survival and decreases the release of pro-inflammatory signals to the environment, with lower production of TNF and higher levels of IL-10. Analysis of the transcriptomic landscape of these cells shows downregulation of pathways associated with the production of reactive oxygen species (ROS) and the release of cytokines, chemokines and antimicrobial peptides. Indeed, the induction of ROS prevents memory-induced bacterial survival. In addition, there is a dysregulation in gene expression of several metabolic pathways leading to decreased glycolytic and respiratory rates in memory cells. These data support commensal microbe-specific metabolic changes in innate immune memory cells that might contribute to homeostasis in the gut.Supported by grants from the Spanish Ministry of Science, Innovation and Universities (MCIU) co-financed with FEDER funds (RTI2018-096494-B-100 to JA; BFU2016-76872-R to EB; AGL2017-86757-R to LA; SAF2015-73549-JIN to HR; SAF2016–77433-R and PID2019-110240RB-I00 to RPR). AP is supported by a Postdoctoral Fellowship from the Basque Government. DB and TMM are recipients of MCIU FPI fellowships. APC is a recipient of a fellowship from the University of the Basque Country. LA and RPR are supported by the Ramon y Cajal program from the Spanish Ministry of Economy and Competitiveness. We thank the MCIU for the Severo Ochoa Excellence accreditation (SEV-2016-0644), the Basque Department of Industry, Tourism and Trade (Etortek and Elkartek programs) and the Innovation Technology Department of the Bizkaia Province. This work was further supported by grants from the Jesús de Gangoiti Barrera Foundation.Peer reviewe

Akkermansia muciniphila-induced trained immune phenotype increases bacterial intracellular survival and attenuates inflammation

Abstract The initial exposure to pathogens and commensals confers innate immune cells the capacity to respond distinctively upon a second stimulus. This training capacity might play key functions in developing an adequate innate immune response to the continuous exposure to bacteria. However, the mechanisms involved in induction of trained immunity by commensals remain mostly unexplored. A. muciniphila represents an attractive candidate to study the promotion of these long-term responses. Here, we show that priming of macrophages with live A. muciniphila enhances bacterial intracellular survival and decreases the release of pro- and anti-inflammatory signals, lowering the production of TNF and IL-10. Global transcriptional analysis of macrophages after a secondary exposure to the bacteria showed the transcriptional rearrangement underpinning the phenotype observed compared to acutely exposed cells, with the increased expression of genes related to phagocytic capacity and those involved in the metabolic adjustment conducing to innate immune training. Accordingly, key genes related to bacterial killing and pro-inflammatory pathways were downregulated. These data demonstrate the importance of specific bacterial members in the modulation of local long-term innate immune responses, broadening our knowledge of the association between gut microbiome commensals and trained immunity as well as the anti-inflammatory probiotic potential of A. muciniphila

The mitochondrial negative regulator MCJ modulates the interplay between microbiota and the host during ulcerative colitis

Recent evidences indicate that mitochondrial genes and function are decreased in active ulcerative colitis (UC) patients, in particular, the activity of Complex I of the electron transport chain is heavily compromised. MCJ is a mitochondrial inner membrane protein identified as a natural inhibitor of respiratory chain Complex I. The induction of experimental colitis in MCJ-deficient mice leads to the upregulation of Timp3 expression resulting in the inhibition of TACE activity that likely inhibits Tnf and Tnfr1 shedding from the cell membrane in the colon. MCJ-deficient mice also show higher expression of Myd88 and Tlr9, proinflammatory genes and disease severity. Interestingly, the absence of MCJ resulted in distinct microbiota metabolism and composition, including a member of the gut community in UC patients, Ruminococcus gnavus. These changes provoked an effect on IgA levels. Gene expression analyses in UC patients showed decreased levels of MCJ and higher expression of TIMP3, suggesting a relevant role of mitochondrial genes and function among active UC. The MCJ deficiency disturbs the regulatory relationship between the host mitochondria and microbiota affecting disease severity. Our results indicate that mitochondria function may be an important factor in the pathogenesis. All together support the importance of MCJ regulation during UC.This work was supported by grants [AGL2017-86757-R to LA, SAF2015-65327-R to JA, AGL2017-89055-R to CS and VGC, SAF2016-77433-R to RPR] from the Spanish Ministry of Economy and Competitiveness co financed with FEDER funds, the XIII Grant from GETECCU-Otsuka (Grupo Español de Trabajo en Enfermedad de Crohn y Colitis ulcerosa to LA) and Basque Government project for health [number 2015111117 to LA]. LA and RP-R are Ramón y Cajal fellows [RYC-2013-13666] from the Spanish Ministry of Economy and Competitiveness. RP-R is supported in part by National Institute of Health [grant AI115091]. APC is a fellow of the University of the Basque Country (UPV/EHU), DB from FPI program of the Spanish Ministry of Economy and Competitiveness, and AC and AP from the Basque Government. CIC bioGUNE support was provided by the Basque Department of Industry, Tourism and Trade (Etortek and Elkartek Programs), the Innovation Technology Department of Bizkaia County, and Spanish MINECO the Severo Ochoa Excellence Accreditation [SEV-2016-0644].Peer reviewe

The immunosuppressive effect of the tick protein, Salp15, is long-lasting and persists in a murine model of hematopoietic transplant

Salp15, a salivary protein of Ixodes ticks, inhibits the activation of naïve CD4 T cells. Treatment with Salp15 results in the inhibition of early signaling events and the production of the autocrine growth factor, interleukin-2. The fate of the CD4 T cells activated in the presence of Salp15 or its long-term effects are, however, unknown. We now show that Salp15 binding to CD4 is persistent and induces a long-lasting immunomodulatory effect. The activity of Salp15 results in sustained diminished cross-antigenic antibody production even after interruption of the treatment with the protein. Transcriptionally, the salivary protein provokes an acute effect that includes known activation markers, such as Il2 or Cd44, and that fades over time. The long-term effects exerted by Salp15 do not involve the induction of either anergy traits nor increased populations of regulatory T cells. Similarly, the treatment with Salp15 does not result in B cell anergy or the generation of myeloid suppressor cells. However, Salp15 induces the increased expression of the ectoenzyme, CD73, in regulatory T cells and increased production of adenosine. Our study provides a profound characterization of the immunomodulatory activity of Salp15 and suggests that its long-term effects are due to the specific regulation of CD73. IntroductionSupported by grants from the Department of Education of the Basque Government (PI2013-49 to JA and PI2012-42 to RB). JA is funded by the European Union (Grant Agreement number 602272). AMA and JLL’s work was supported by the Basque Department of Industry, Tourism and Trade (Etortek and Elkartek Programs), the Innovation Technology Department of Bizkaia and the CIBERehd Network. The work of AC is supported by a Ramón y Cajal award, the Basque Department of Industry, Tourism and Trade (Etortek), ISCIII (PI13/00031), FERO VIII Fellowship, the BBVA foundation, MINECO (SAF2016-79381-R) and the European Research Council Starting Grant (336343). CIBERonc was co-funded with FEDER funds. AC-M was funded by a Juan de la Cierva program award and the European Union MSCA program (CIG 660191). RB was funded by MINECO grants BFU2011-25986 and BFU2014-52282-P and the Consolider Program (BFU2014-57703-REDC). FJB was funded by a MINECO grant (CTQ2014-56966-R). D.B. is funded by a MINECO FPI fellowship. We thank the MINECO for the Severo Ochoa Excellence accreditation (SEV-2016-0644).Peer reviewe

A structurally unique Fusobacterium nucleatumtannase provides detoxicant activity againstgallotannins and pathogen resistance

20 pags., 7 figs., 1 tab.Colorectal cancer pathogenesis and progression isassociated with the presence of Fusobacteriumnucleatum and the reduction of acetylated deriva-tives of spermidine, as well as dietary componentssuch as tannin-rich foods. We show that a new tan-nase orthologue of F. nucleatum (TanBFnn) has sig-nicant structural differences with its Lactobacillusplantarum counterpart affecting the ap covering theactive site and the accessibility of substrates. Crys-tallographic and molecular dynamics analysisrevealed binding of polyamines to a small cavity thatconnects the active site with the bulk solvent whichinteract with catalytically indispensable residues. Asa result, spermidine and its derivatives, particularlyN8-acetylated spermidine, inhibit the hydrolytic activ-ity of TanBFnnand increase the toxicity of gallotan-nins to F. nucleatum. Our results support a model inwhich the balance between the detoxicant activity ofTanBFnnand the presence of metabolic inhibitorscan dictate either conducive or unfavourable condi-tions for the survival of F. nucleatum.Supported by grants from the Spanish Ministry of Science and Innovation (MCI) cofinanced with FEDER funds (SAF2015‐65327‐R and RTI2018‐096494‐B‐100 to JA; AGL2017‐86757‐R to LA, SAF2015‐73549‐JIN to HR; RTI2018‐099592‐B‐C22 to GJO) and the Mizutani Foundation for Glycoscience (200077 to GJO). LA and GJO are supported by the Ramon y Cajal program (RYC‐2013‐13666 and RYC‐2013‐14706 respectively). JTC and AP are the recipients postdoctoral fellowships from the Basque Government. DB is the recipient of a MCI FPI fellowship. APC is the recipient of a fellowship from the University of the Basque Country. We thank the MCI for the Severo Ochoa Excellence accreditation (SEV‐2016‐0644) and the Basque Department of Industry, Tourism and Trade (Etortek and Elkartek programs). JMM thanks the ALBA synchrotron for providing access time to the BL‐13 XALOC beamline. This work is supported by grants from the Jesús de Gangoiti Barrera FoundationPeer reviewe