Microbiota colonization tunes the antigen threshold of microbiota-specific T cell activation in the gut

Harnessing the potential of commensal bacteria for immunomodulatory therapy in the gut requires the identification of conditions that modulate immune activation towards incoming colonizing bacteria. In this study, we used the commensal Bacteroides thetaiotaomicron (B.theta) and combined it with B.theta-specific transgenic T cells, in the context of defined colonization of gnotobiotic and immunodeficiency mouse models, to probe the factors modulating bacteria-specific T cell activation against newly colonizing bacteria. After colonizing germ-free (GF) and conventionally raised (SPF) mice with B.theta, we only observed proliferation of B.theta-specific T cells in GF mice. Using simple gnotobiotic communities we could further demonstrate that T-cell activation against newly colonizing gut bacteria is restricted by previous bacteria colonization in GF mice. However, this restriction requires a functional adaptive immune system as Rag1$^{-/-}$ allowed B.theta-specific T cell proliferation even after previous colonization. Interestingly, this phenomenon seems to be dependent on the type of TCR-transgenic model used. B.theta-specific transgenic T cells also proliferated after gut colonization with an E.coli strain carrying the B.theta-specific epitope. However, this was not the case for the SM-1 transgenic T cells as they did not proliferate after similar gut colonization with an E.coli strain expressing the cognate epitope. In summary, we found that activation of T cells towards incoming bacteria in the gut is modulated by the influence of colonizing bacteria on the adaptive immune system of the host

The relative biological effectiveness of proton irradiation in dependence of DNA damage repair

Clinical parameters and empirical evidence are the primary determinants for current treatment planning in radiation oncology. Personalized medicine in radiation oncology is only at the very beginning to take the genetic background of a tumor entity into consideration to define an individual treatment regimen, the total dose or the combination with a specific anticancer agent. Likewise, stratification of patients towards proton radiotherapy is linked to its physical advantageous energy deposition at the tumor site with minimal healthy tissue being co-irradiated distal to the target volume. Hence, the fact that photon and proton irradiation also induce different qualities of DNA damages, which require differential DNA damage repair mechanisms has been completely neglected so far. These subtle differences could be efficiently exploited in a personalized treatment approach and could be integrated into personalized treatment planning. A differential requirement of the two major DNA double-strand break repair pathways, homologous recombination and non-homologous end joining, was recently identified in response to proton and photon irradiation, respectively, and subsequently influence the mode of ionizing radiation-induced cell death and susceptibility of tumor cells with defects in DNA repair machineries to either quality of ionizing radiation. This review focuses on the differential DNA-damage responses and subsequent biological processes induced by photon and proton irradiation in dependence of the genetic background and discusses their impact on the unicellular level and in the tumor microenvironment and their implications for combined treatment modalities

Fibroblast activation protein is expressed by rheumatoid myofibroblast-like synoviocytes

Fibroblast activation protein (FAP), as described so far, is a type II cell surface serine protease expressed by fibroblastic cells in areas of active tissue remodelling such as tumour stroma or healing wounds. We investigated the expression of FAP by fibroblast-like synoviocytes (FLSs) and compared the synovial expression pattern in rheumatoid arthritis (RA) and osteoarthritis (OA) patients. Synovial tissue from diseased joints of 20 patients, 10 patients with refractory RA and 10 patients with end-stage OA, was collected during routine surgery. As a result, FLSs from intensively inflamed synovial tissues of refractory RA expressed FAP at high density. Moreover, FAP expression was co-localised with matrix metalloproteinases (MMP-1 and MMP-13) and CD44 splice variants v3 and v7/8 known to play a major role in the concert of extracellular matrix degradation. The pattern of signals appeared to constitute a characteristic feature of FLSs involved in rheumatoid arthritic joint-destructive processes. These FAP-expressing FLSs with a phenotype of smooth muscle actin-positive myofibroblasts were located in the lining layer of the synovium and differ distinctly from Thy-1-expressing and non-proliferating fibroblasts of the articular matrix. The intensity of FAP-specific staining in synovial tissue from patients with RA was found to be different when compared with end-stage OA. Because expression of FAP by RA FLSs has not been described before, the findings of this study highlight a novel element in cartilage and bone destruction of arthritic joints. Moreover, the specific expression pattern qualifies FAP as a therapeutic target for inhibiting the destructive potential of fibroblast-like synovial cells

Metabolic reconstitution of germ-free mice by a gnotobiotic microbiota varies over the circadian cycle.

The capacity of the intestinal microbiota to degrade otherwise indigestible diet components is known to greatly improve the recovery of energy from food. This has led to the hypothesis that increased digestive efficiency may underlie the contribution of the microbiota to obesity. OligoMM12-colonized gnotobiotic mice have a consistently higher fat mass than germ-free (GF) or fully colonized counterparts. We therefore investigated their food intake, digestion efficiency, energy expenditure, and respiratory quotient using a novel isolator-housed metabolic cage system, which allows long-term measurements without contamination risk. This demonstrated that microbiota-released calories are perfectly balanced by decreased food intake in fully colonized versus gnotobiotic OligoMM12 and GF mice fed a standard chow diet, i.e., microbiota-released calories can in fact be well integrated into appetite control. We also observed no significant difference in energy expenditure after normalization by lean mass between the different microbiota groups, suggesting that cumulative small differences in energy balance, or altered energy storage, must underlie fat accumulation in OligoMM12 mice. Consistent with altered energy storage, major differences were observed in the type of respiratory substrates used in metabolism over the circadian cycle: In GF mice, the respiratory exchange ratio (RER) was consistently lower than that of fully colonized mice at all times of day, indicative of more reliance on fat and less on glucose metabolism. Intriguingly, the RER of OligoMM12-colonized gnotobiotic mice phenocopied fully colonized mice during the dark (active/eating) phase but phenocopied GF mice during the light (fasting/resting) phase. Further, OligoMM12-colonized mice showed a GF-like drop in liver glycogen storage during the light phase and both liver and plasma metabolomes of OligoMM12 mice clustered closely with GF mice. This implies the existence of microbiota functions that are required to maintain normal host metabolism during the resting/fasting phase of circadian cycle and which are absent in the OligoMM12 consortium

Impact of small molecule‐mediated inhibition of ammonia detoxification on lung malignancies and liver metabolism

Metabolically induced cancer heterogeneity creates a largesourceofnovelpotentialtargetstowardsanenhancedther-apeutic window alone and in combination with classicchemo-andradiotherapy[1,2 ].Thisisofparticularinterestfor non-small cell lung cancer (NSCLC), which accountsfor more than 80% of all lung tumor types characterizedby limited responses to current treatment options [3–5].Genetically-definedKRAS/LKB1-mutant NSCLC tumorsexploit the proximal urea cycle enzyme carbamoyl phos-phate synthetase 1 (CPS1) as an intermediate step forpyrimidine biosynthesis, thereby contrasting its crucialhepatic role in ammonia detoxification [6–8]. Thus, CPS1could serve as a novel target for NSCLC susceptibility(Figure1A). In this study, we investigated the metabolicchanges observed in both NSCLC and healthy hepaticsystems following the identification, characterization andapplication of a small molecule inhibitor of ectopic CPS1functionality

Impact of small molecule‐mediated inhibition of ammonia detoxification on lung malignancies and liver metabolism

5 páginas, 1 figuraThis work was supported by the Swiss National Science Foundation, Switzerland (grant 320030_176088 to Johannes Häberle) and the Wolfermann-Nägeli-Stiftung, Switzerland (grant 2020/28 to Martin Pruschy). The highthroughput screening was supported by the Research Council of Norway (NOR-OPENSCREEN 245922/F50). The part of the work done by Vicente Rubio and Nadine Gougeard was supported by The Fundación Ramón Areces (grant CIVP20A6610). The work was also supported by a grant from European Union’s Framework Program for Research and Innovation Horizon 2020 (2014-2020) under Marie Skłodowska-Curie (Grant Agreements No.860245 (ITN THERADNET) to Marvin Kreuzer and Martin Pruschy.Peer reviewe

Metabolic reconstitution of germ-free mice by a gnotobiotic microbiota varies over the circadian cycle

The capacity of the intestinal microbiota to degrade otherwise indigestible diet components is known to greatly improve the recovery of energy from food. This has led to the hypothesis that increased digestive efficiency may underlie the contribution of the microbiota to obesity. OligoMM12-colonized gnotobiotic mice have a consistently higher fat mass than germ-free (GF) or fully colonized counterparts. We therefore investigated their food intake, digestion efficiency, energy expenditure, and respiratory quotient using a novel isolator-housed metabolic cage system, which allows long-term measurements without contamination risk. This demonstrated that microbiota-released calories are perfectly balanced by decreased food intake in fully colonized versus gnotobiotic OligoMM12 and GF mice fed a standard chow diet, i.e., microbiota-released calories can in fact be well integrated into appetite control. We also observed no significant difference in energy expenditure after normalization by lean mass between the different microbiota groups, suggesting that cumulative small differences in energy balance, or altered energy storage, must underlie fat accumulation in OligoMM12 mice. Consistent with altered energy storage, major differences were observed in the type of respiratory substrates used in metabolism over the circadian cycle: In GF mice, the respiratory exchange ratio (RER) was consistently lower than that of fully colonized mice at all times of day, indicative of more reliance on fat and less on glucose metabolism. Intriguingly, the RER of OligoMM12-colonized gnotobiotic mice phenocopied fully colonized mice during the dark (active/eating) phase but phenocopied GF mice during the light (fasting/resting) phase. Further, OligoMM12-colonized mice showed a GF-like drop in liver glycogen storage during the light phase and both liver and plasma metabolomes of OligoMM12 mice clustered closely with GF mice. This implies the existence of microbiota functions that are required to maintain normal host metabolism during the resting/fasting phase of circadian cycle and which are absent in the OligoMM12 consortium.ISSN:1544-9173ISSN:1545-788

Cecal mass interferes with normalization of energy expenditure.

(A-B) Comparison of circadian changes in energy expenditure (without normalization) among GF, OligoMM12, and SPF C57B6/J mice. (A) Circadian variation in average energy expenditure per time point and (B) overlayed curves obtained by smoothing function of data obtained every 24 min per mouse over 10 d. (C-E) Energy expenditure values obtained by “classical” ratio-based normalization methods (dividing energy expenditure values per phase by mass). (C) Area-under-curve after normalization by total mass after cecal dissection. (D) Area-under-curve after normalization by lean body mass (EchoMRI). (E) Area-under-curve after normalization by total body mass before cecal dissection. Number of mice per group in all figures unless otherwise specified: GF = 9, OligoMM12 = 8, SPF = 10. p-values obtained by Tukey’s honest significance test. Data underlying this figure are supplied in S1 Data. GF, germ-free; SPF, specific-opportunistic-pathogen-free. (TIF)</p