Sulconazole inhibits PD-1 expression in immune cells and cancer cells malignant phenotype through NF-κB and calcium activity repression

The overexpression of the immunoinhibitory receptor programmed death-1 (PD1) on T-cells is involved in immune evasion in cancer. The use of anti-PD-1/PDL-1 strategy has deeply changed the therapies of cancers and patient survival. However, their efficacy diverges greatly along with tumor type and patient populations. Thereby, novel treatments are needed to interfere with the anti-tumoral immune responses and propose an adjunct therapy. In the current study, we found that the antifungal drug Sulconazole (SCZ) inhibits PD-1 expression on activated PBMCs and T cells at the RNA and protein levels. SCZ repressed NF-κB and calcium signaling, both, involved in the induction of PD-1. Further analysis revealed cancer cells treatment with SCZ inhibited their proliferation, and migration and ability to mediate tumor growth in zebrafish embryos. SCZ found also to inhibit calcium mobilization in cancer cells. These results suggest the SCZ therapeutic potential used alone or as adjunct strategy to prevent T-cell exhaustion and promotes cancer cell malignant phenotype repression in order to improve tumor eradication.

Abstract 1311: PCSK9 expression in liver sinusoidal endothelial cells during liver metastasis

PCSK9 is a serin protein kinase of the family of convertases. It has been extensively studied in hypercholesterolaemia, but has recently been shown to be involved in cancer. It is overexpressed in several types of cancer, especially during the process of metastasis. One of the most common is colon liver metastasis. In this process of dissemination, the tumor microenvironment plays a key role. Our research focuses on the function of PCSK9 in liver sinusoidal endothelial cells (LSECs) involved in angiogenesis. We have shown in a study in vitro by qPCR and western blotting (WB), that PCSK9 protein is expressed in LSECs under basal conditions. Furthermore, we activated the cells with media from SW620 tumor cells as well as from SW620-derived cancer stem cells (CSCs) during 24 hours. Thus, we have shown that activation of LSECs with CSC conditioned media significantly increases PCSK9 expression at the mRNA level. This is the first time this convertase is detected in LSECs. In addition, we performed an immunofluorescence (IF) staining of PCSK9 to determine the cellular localization of the protein in this cell type. We found PCSK9 in the nucleus of LSECs in cell culture. Furthermore, we have confirmed the nuclear location by a WB analysis of the cytoplasmatic and nuclear fraction of the cells. As far as we know, this localization of PCSK9 has never been observed which open the possibility of new function for PCSK9 in LSECs. In addition, we performed IF staining in human tissues, both adjacent and metastatic livers. Thus, LSECs were labelled with the specific marker CD31 and PCSK9 demonstrating that PSCK9 is also expressed in patient’s LSECs. Regarding cellular localization, the protein appears to be localized in the nucleus according to the observations made in vitro. In order to determine PCSK9 function, we overexpressed PCSK9 in HEK cells and we co-immunoprecipitated it to study the related proteins. Some protein of interest appeared as far as EpCAM and CDK6 which are being studied. Furthermore, we inhibited PCSK9 with siRNA and chemical inhibitor (PF-06446846). We performed a proliferation test in both conditions and we showed that LSEC proliferation significantly decrease when we inhibit PCSK9. Finally, we did a RNAseq study in LSEC cells inhibiting PCSK9 after their activation with CSC media. This result showed us a significant decrease expression of ERN1 or FAP at mRNA level when PCSK9 is inhibited. We can conclude that PCSK9 plays a key role in LSEC during Liver Colorectal Metastasis affecting significantly on proliferation and showing a particular nuclear location. Although the metabolic pathway remains undetermined, the proteomic and RNAseq studies have provided us with some molecules that seem to interact with PCSK9 and that could explain the particular function of PCSK9 in LSECs during the metastatic process

Citation Format: Ander Martin-San Sebastian, Helena García-García, Géraldine Siegfried, Abdel-Majid Khatib, Iker Badiola. PCSK9 expression in liver sinusoidal endothelial cells during liver metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1311.

Reprogramming immune cells activity by furin-like enzymes as emerging strategy for enhanced immunotherapy in cancer

Immunotherapy is becoming an advanced clinical management for various cancers. Rebuilding of aberrant immune surveillance on cancers has achieved notable progress in the past years by either in vivo or ex vivo engineering of efficient immune cells. Immune cells can be programmed with several strategies that improves their therapeutic influence and specificity. It has become noticeable that effective immunotherapy must consider the complete complexity of the immune cell function. However, today, almost all immune cells can be transiently or stably reprogrammed against various cancer cells. As a consequence, investigations have interrogated strategies to improve the efficacy of cancer immunotherapies by enhancing T-cell infiltration into tumour tissues. Here, we review the emerging role of furin-like enzymes work related to T-cell reprogramming, their tumour infiltration and cytotoxic function.

What Are the Roles of Proprotein Convertases in the Immune Escape of Tumors?

Protein convertases (PCs) play a significant role in post-translational procedures by transforming inactive precursor proteins into their active forms. The role of PCs is crucial for cellular homeostasis because they are involved in cell signaling. They have also been described in many diseases such as Alzheimer's and cancer. Cancer cells are secretory cells that send signals to the tumor microenvironment (TME), remodeling the surrounding space for their own benefits. One of the most important components of the TME is the immune system of the tumor. In this review, we describe recent discoveries that link PCs to the immune escape of tumors. Among PCs, many findings have determined the role of Furin (PC3) as a paramount enzyme causing the TME to induce tumor immune evasion. The overexpression of various cytokines and proteins, for instance, IL10 and TGF-B, moves the TME towards the presence of Tregs and, consequently, immune tolerance. Furthermore, Furin is implicated in the regulation of macrophage activity that contributes to the increased impairment of DCs (dendritic cells) and T effector cells. Moreover, Furin interferes in the MHC Class_1 proteolytic cleavage in the trans-Golgi network. In tumors, the T cytotoxic lymphocytes (CTLs) response is impeded by the PD1 receptor (PD1-R) located on CTLs and its ligand, PDL1, located on cancer cells. The inhibition of Furin is a subtle means of enhancing the antitumor response by repressing PD-1 expression in tumors or macrophage cells. The impacts of other PCs in tumor immune escape have not yet been clarified to the extent that Furin has. Accordingly, the influence of other types of PCs in tumor immune escape is a promising topic for further consideration.

Fish oil rich in eicosapentaenoic acid and docosahexaenoic acid in sow diets modifies oxylipins and immune indicators in colostrum and milk

Colostrum and milk are the first nutrient sources for newborn piglets. In addition, n-3 fatty acids (FAs) and their oxygenated derivatives (oxylipins) have the capacity to modulate immune components. The aim of the current study was to include a fish oil rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in sow diets to promote an increase of anti-inflammatory molecules in colostrum and milk to benefit piglets. Thirty-six sows were randomly assigned from insemination to the end of lactation to either a control diet with animal fat (15 g/kg in gestation and 30 g/kg in lactation) or an n-3 diet in which animal fat was totally (gestation) or half (lactation) replaced by an equivalent amount of solid fish oil. Performance of sows and piglets was monitored during the study. Colostrum and milk samples were obtained after the birth of the first piglet and at weaning, respectively. From all samples (n = 18 per treatment), FAs were quantified by gas chromatography and immunoglobulins and cytokines by ELISA. Three samples per treatment were randomly selected to analyse oxylipin composition by liquid chromatography-tandem mass spectrometry. In colostrum and in milk, the n-3 FA (P = 0.020 and P < 0.001), particularly EPA (P < 0.001 and P < 0.001) and DHA (P < 0.001 and P < 0.001), and also their oxygenated derivatives were increased in samples from sows fed n-3 diet. Fish oil had no effect on immunoglobulin concentrations, but reduced tumour necrosis factor α (TNFα) (P = 0.011) and a tendency to reduce interleukin 10 (IL10) (P = 0.059) were observed in milk. In conclusion, fish oil in sow diets increased n-3 FA, particularly EPA and DHA, and their oxygenated derivatives in colostrum and milk, reducing TNFα and IL10 in milk.

shinyCurves, a shiny web application to analyse multisource qPCR amplification data: a COVID-19 case study

BACKGROUND

Quantitative, reverse transcription PCR (qRT-PCR) is currently the gold-standard for SARS-CoV-2 detection and it is also used for detection of other virus. Manual data analysis of a small number of qRT-PCR plates per day is a relatively simple task, but automated, integrative strategies are needed if a laboratory is dealing with hundreds of plates per day, as is being the case in the COVID-19 pandemic.

RESULTS

Here we present shinyCurves, an online shiny-based, free software to analyze qRT-PCR amplification data from multi-plate and multi-platform formats. Our shiny application does not require any programming experience and is able to call samples Positive, Negative or Undetermined for viral infection according to a number of user-defined settings, apart from providing a complete set of melting and amplification curve plots for the visual inspection of results.

CONCLUSIONS

shinyCurves is a flexible, integrative and user-friendly software that speeds-up the analysis of massive qRT-PCR data from different sources, with the possibility of automatically producing and evaluating melting and amplification curve plots.

Inhibition of DDR1 reduces invasive features of human A375 melanoma, HT29 colon carcinoma and SK-HEP hepatoma cells

DDR1 is a receptor tyrosine kinases for collagen and an adverse prognostic factor in primary and metastatic tumors.Despite this, DDR1 signaling and its functional consequences in tumor development remain unclear. RT-PCR and Western blot show that A375, colon carcinoma HT29 and liver carcinoma SK-HEP human cell lines express functional DDR1 that phosphorylates in response to collagen type I. Chemical inhibition of DDR1 phosphorylation or DDR1 mRNA silencing reduced AKT and ERK phosphorylation, expression of ICAM1 and VCAM1, Ki67 and secretion of MMP9. DDR1 silenced cells showed reduced adhesion to collagen type I, MMP-dependent invasion, and chemotactic and proliferative responses to collagen type I. Our work indicates an essential role for DDR1 signaling in key prometastatic features of collagen type I in human carcinoma cells.

GeromiRs Are Downregulated in the Tumor Microenvironment during Colon Cancer Colonization of the Liver in a Murine Metastasis Model

Cancer is a phenomenon broadly related to ageing in various ways such as cell cycle deregulation, metabolic defects or telomerases dysfunction as principal processes. Although the tumor cell is the main actor in cancer progression, it is not the only element of the disease. Cells and the matrix surrounding the tumor, called the tumor microenvironment (TME), play key roles in cancer progression. Phenotypic changes of the TME are indispensable for disease progression and a few of these transformations are produced by epigenetic changes including miRNA dysregulation. In this study, we found that a specific group of miRNAs in the liver TME produced by colon cancer called geromiRs, which are miRNAs related to the ageing process, are significantly downregulated. The three principal cell types involved in the liver TME, namely, liver sinusoidal endothelial cells, hepatic stellate (Ito) cells and Kupffer cells, were isolated from a murine hepatic metastasis model, and the miRNA and gene expression profiles were studied. From the 115 geromiRs and their associated hallmarks of aging, which we compiled from the literature, 75 were represented in the used microarrays, 26 out of them were downregulated in the TME cells during colon cancer colonization of the liver, and none of them were upregulated. The histone modification hallmark of the downregulated geromiRs is significantly enriched with the geromiRs miR-15a, miR-16, miR-26a, miR-29a, miR-29b and miR-29c. We built a network of all of the geromiRs downregulated in the TME cells and their gene targets from the MirTarBase database, and we analyzed the expression of these geromiR gene targets in the TME. We found that Cercam and Spsb4, identified as prognostic markers in a few cancer types, are associated with downregulated geromiRs and are upregulated in the TME cells.

Proprotein convertases blockage up-regulates specifically metallothioneins coding genes in human colon cancer stem cells

Despite continuous exertion made, colon cancer still represents a major health problem and its incidence continues being high worldwide. There is growing evidence in support of the cancer stem cells (CSCs) being central in the initiation of this cancer, and CSCs have been the focus of various studies for the identification of new ways of treatment. Lately, the proprotein convertases (PCs) were reported to regulate the maturation and expression of various molecules involved in the malignant phenotype of colon cancer cells, however, the identity of the molecules regulated by these serine proteases in CSCs is unknown. In this study, we used the general PCs inhibitor, the Decanoyl-RVKR-chloromethylketone (Decanoyl-RVKR-CMK) that inhibits all the PCs found in the secretory pathway, and analyzed its effect on CSCs using RNA-seq analysis. Remarkably, from the only 9 up-regulated genes in the human SW620-derived sphere-forming cells, we identified 7 of the 11 human metallothioneins, all of them localized on chromosome 16, and zinc related proteins as downstream effectors of the PCs. The importance of these molecules in the regulation of cell proliferation, differentiation and chemoresistance, and their reported potential tumor suppressor role and loss in colon cancer patients associated with worse prognosis, suggests that targeting PCs in the control of the malignant phenotype of CSCs is a new potential therapeutic strategy in colon cancer.

Silencing of sinusoidal DDR1 reduces murine liver metastasis by colon carcinoma

Liver metastasis depends on the collagenous microenvironment generated by hepatic sinusoidal cells (SCs). DDR1 is an atypical collagen receptor linked to tumor progression, but whether SCs express DDR1 and its implication in liver metastasis remain unknown. Freshly isolated hepatic stellate cells (HSCs), Kupffer cells (KCs), and liver sinusoidal endothelial cells (LSECs), that conform the SCs, expressed functional DDR1. HSCs expressed the largest amounts. C26 colon carcinoma secretomes increased DDR1 phosphorylation in HSCs and KCs by collagen I. Inhibition of kinase activity by DDR1-IN-1 or mRNA silencing of DDR1 reduced HSCs secretion of MMP2/9 and chemoattractant and proliferative factors for LSECs and C26 cells. DDR1-IN-1 did not modify MMP2/9 in KCs or LSECs secretomes, but decreased the enhancement of C26 migration and proliferation induced by their secretomes. Gene array showed that DDR1 silencing downregulated HSCs genes for collagens, MMPs, interleukins and chemokines. Silencing of DDR1 before tumor inoculation reduced hepatic C26 metastasis in mice. Silenced livers bore less tumor foci than controls. Metastatic foci in DDR1 silenced mice were smaller and contained an altered stroma with fewer SCs, proliferating cells, collagen and MMPs than foci in control mice. In conclusion, hepatic DDR1 promotes C26 liver metastasis and favors the pro-metastatic response of SCs to the tumor.

An Integrative Omics Approach Reveals Involvement of BRCA1 in Hepatic Metastatic Progression of Colorectal Cancer

(1) Background & Aims: The roles of different cells in the tumor microenvironment (TME) are critical to the metastatic process. The phenotypic transformation of the liver cells is one of the most important stages of the hepatic metastasis progression of colorectal cancer (CRC). Our aim was to identify the major molecules (i.e., genes, miRNAs and proteins) involved in this process. (2) Methods: We isolated and performed whole-genome analysis of gene, miRNA, and protein expression in three types of liver cells (Ito cells, Kupffer cells, and liver sinusoidal endothelial cells) from the TME of a murine model of CRC liver metastasis. We selected the statistically significant differentially expressed molecules using the Student's t-test with Benjamini-Hochberg correction and performed functional statistically-significant enrichment analysis of differentially expressed molecules with hypergeometric distribution using the curated collection of molecular signatures, MSigDB. To build a gene-miRNA-protein network centered in Brca1, we developed a software package (miRDiana) that collects miRNA targets from the union of the TargetScan, MicroCosm, mirTarBase, and miRWalk databases. This was used to search for miRNAs targeting Brca1. We validated the most relevant miRNAs with real-time quantitative PCR. To investigate BRCA1 protein expression, we built tissue microarrays (TMAs) from hepatic metastases of 34 CRC patients. (3) Results: Using integrated omics analyses, we observed that the Brca1 gene is among the twenty transcripts simultaneously up-regulated in all three types of TME liver cells during metastasis. Further analysis revealed that Brca1 is the last BRCA1-associated genome surveillance complex (BASC) gene activated in the TME. We confirmed this finding in human reanalyzing transcriptomics datasets from 184 patients from non-tumor colorectal tissue, primary colorectal tumor and colorectal liver metastasis of the GEO database. We found that the most probable sequence of cell activation during metastasis is Endothelial→Ito→Kupffer. Immunohistochemical analysis of human liver metastases showed the BRCA1 protein was co-localized in Ito, Kupffer, and endothelial cells in 81.8% of early or synchronous metastases. However, in the greater part of the metachronous liver metastases, this protein was not expressed in any of these TME cells. (4) Conclusions: These results suggest a possible role of the co-expression of BRCA1 in Ito, Kupffer, and sinusoidal endothelial cells in the early occurrence of CRC liver metastases, and point to BRCA1 as a potential TME biomarker.

A prospective randomized open-label study of single injection versus continuous adductor canal block for postoperative analgesia after total knee arthroplasty

Aims

Adductor canal block (ACB) has emerged as an alternative to femoral nerve block (FNB) for analgesia after total knee arthroplasty (TKA). The optimal duration of maintenance of the ACB is still questionable. The purpose of this study was to compare the analgesic benefits and physiotherapy (PT) outcomes of single-shot ACB to two different regimens of infusion of the continuous ACB, 24-hour and 48-hour infusion.

Patients and Methods

This was a prospective, randomized, unblinded study. A total of 159 American Society of Anesthesiologists (ASA) physical status I to III patients scheduled for primary TKA were randomized to one of three study groups. Three patients did not complete the study, leaving 156 patients for final analysis. Group A (n = 53) was the single-shot group (16 female patients and 37 male patients with a mean age of 63.9 years (sd 9.6)), group B (n = 51) was the 24-hour infusion group (22 female patients and 29 male patients with a mean age of 66.5 years (sd 8.5)), and group C (n = 52) was the 48-hour infusion group (18 female patients and 34 male patients with a mean age of 62.2 years (sd 8.7)). Pain scores, opioid requirements, PT test results, and patient-reported outcome instruments were compared between the three groups.

Results

The proportion of patients reporting severe pain, defined as a pain score of between 7 and 10, on postoperative day number 2 (POD 2) were 21% for the single-shot group, 14% for the 24-hour block group, and 12% for the 48-hour block group (p = 0.05). Cumulative opioid requirements after 48 hours were similar between the groups. Functional outcomes were similar in all three groups in POD 1 and POD 2.

Conclusion

There was no clear benefit of the 24-hour or 48-hour infusions over the single-shot ACB for the primary endpoint of the study. Otherwise, there were marginal benefits for keeping the indwelling catheter for 48 hours in terms of reducing the number of patients with moderate pain and improving the quality of pain management. However, all three groups had similar opioid usage, length of hospital stay, and functional outcomes. Further studies with larger sample sizes are needed to confirm these findings. Cite this article: Bone Joint J 2019;101-B:340–347.

NADH dehydrogenase complex I is overexpressed in incipient metastatic murine colon cancer cells

Colon cancer is one of the most frequently occurring types of cancers in the world. Primary tumours are treated very efficiently, but the metastatic cases are known to have severe outcomes. Therefore, the aim of the present study was to obtain a greater understanding of the transformation of primary colon cancer cells into metastatic phenotypes. Small changes in protein expression provoke the metastatic phenotype transformation. More sensitive methods to detect small variations are required. A murine colon cancer cell line with metastatic characteristics in a very early phase was created in order to investigate the first steps of transformation using a murine liver metastasis model. The protein expression patterns of metastatic and non-metastatic cells were compared using the stable isotope labelling by amino acids in cell culture method in combination with mass spectrometry. Quantitative proteomics data indicated that nicotinamide adenine dinucleotide hydride (NADH) dehydrogenase complex I was overexpressed in metastatic cells with respect to non-metastatic cells. Since the NADH dehydrogenase complex catalyses the oxidation of NADH to NAD⁺, the functionality of the complex was studied by measuring the amount of NADH. The results revealed that metastatic cells accumulate more NADH and reactive oxygen species. In addition, the mitochondrial membrane potential of metastatic cells was lower than that of non-metastatic cells, indicating that the activity of NADH dehydrogenase and the mitochondrial oxidative chain were decreased in metastatic cells. During the incipient transformation of primary cancer cells, NADH dehydrogenase complex I was overexpressed but then became inactive due to the Warburg effect, which inhibits mitochondrial activity. In the first step of transformation, the high energy demand required in an adverse environment is fulfilled by overexpressing components of the respiratory chain, a fact that should be considered for future anti-metastatic therapies.

Targeting liver sinusoidal endothelial cells with miR-20a-loaded nanoparticles reduces murine colon cancer metastasis to the liver

Phenotypic transformation of liver sinusoidal endothelial cells is one of the most important stages of liver metastasis progression. The miRNA effects on liver sinusoidal endothelial cells during liver metastasis have not yet been studied. Herein, whole genome analysis of miRNA expression in these cells during colorectal liver metastasis revealed repressed expression of microRNA-20a. Importantly, downregulation of miR-20a occurs in parallel with upregulation of its known protein targets. To restore normal miR-20a levels in liver sinusoidal endothelial cells, we developed chondroitin sulfate-sorbitan ester nanoparticles conjugated with miR-20a in a delivery system that specifically targets liver sinusoidal endothelial cells. The restoration of normal mir-20a levels in these cells induced downregulation of the expression of its protein targets, and this also resulted in a reduction of in vitro LSEC migration and a reduction of in vivo activation and tumor-infiltrating capacity and ability of the tumor decreased by ∼80% in a murine liver metastasis model.

Development and characterisation of chondroitin sulfate- and hyaluronic acid-incorporated sorbitan ester nanoparticles as gene delivery systems

Glycosaminoglycans (GAGs) are natural polymers that are broadly used in gene delivery systems to increase stability as well as decrease toxicity and nonspecific interactions, thereby increasing transfection efficiency. In this work, we propose sorbitan ester-based lipid nanoparticles (SENS) functionalised with the GAGs chondroitin sulfate (CS) and hyaluronic acid (HA) as gene delivery systems. For this purpose, we describe the design and evaluation of these nanosystems loaded with plasmid DNA, including an evaluation of their physicochemical characteristics, stability properties, ability to protect and efficiently transfect cells with Enhanced Green Fluorescent Protein plasmid (pEGFP) in vitro, and biocompatibility both in vitro and in vivo. We confirm that molecules with high biological value and targeting potential, such as HA and CS, can be successfully incorporated into our recently developed sorbitan ester-based nanoparticles (SENS) and that this incorporation leads to effective stabilisation of both nanosystems as well as protects plasmid DNA. We demonstrated that the aforementioned incorporation of HA and CS enables long-term stability of the nanosystems in both liquid and lyophilised states, which is a remarkable property that can aid in their transfer to industry. The ability of these functionalised nanosystems to transfect the A549 cell line without compromising cell viability was also shown, as well as their innocuous safety profile in vivo. Thus, we provide valuable evidence of the suitable properties and potential of these hybrid nanoparticles as gene delivery systems.

Inhibition of the metastatic progression of breast and colorectal cancer in vitro and in vivo in murine model by the oxidovanadium(IV) complex with luteolin

The anticancer and antimetastatic behavior of the flavonoid luteolin and its oxidovanadium(IV) complex [VO(lut)(H₂O)₂]Na·3H₂O (VOlut) has been investigated. Considering that the complex displayed strong anticancer activity on MDAMB231 human breast cancer cell line we herein determined through in vitro assays that the complex would probably reduce breast cancer cell metastasis in a higher extent than the natural antioxidant. In the CT26 colon cancer cell line a stronger anticancer effect has also been determined for the complex (IC₅₀ 0.9μM) and in addition it did not exert toxic effects on normal colon epithelial cells at concentrations up to 10μM. Working with a murine model of highly aggressive, orthotopic colon cancer model (CT26 cancer cell lines) it has been determined that the complex might prevent metastatic dissemination of the colon cancer cells to the liver. The flavonoid luteolin also exerted anticancer effects (at a low degree, IC₅₀ 5.9μM) on CT26 cell line and produced a 24% reduction of colon cancer liver metastasis.

The influence of dietary locust bean gum and live yeast on some digestive immunological parameters of piglets experimentally challenged with Escherichia coli

Gums and yeast cells are natural mannose-rich products that can be used as subtracts for adhesion of gram-negative bacteria. The aim of the study was to investigate the role of dietary locust bean gum (LBG; Salmosan, ITPSA, Spain) or live yeast (Saccharomyces cerevisiae Sc47; Actisaf, Lesaffre, France) as immunological enhancers of the intestinal function of piglets. Treatments included a noninfected group fed with a control diet and 4 other groups orally challenged with 1x10(8) cfu of Escherichia coli K88. The challenged groups were fed the control or the control diet supplemented with colistin, LBG, or yeast. Twenty-five Landrace × Duroc piglets weaned at 4 wk were used. The animals were group housed, challenged on day 14, and euthanized 2 d later. Blood, bile, ileum, and mesenteric lymph node (MLN) samples were obtained for analysis of C-reactive protein (CRP), secretory immunoglobulin A (sIgA), and Toll-like receptors 2 (TLR2) and 4 (TLR4). Challenge increased the level of CRP of piglets fed the control diet, but this did not happen in the piglets fed the supplemented diets (P < 0.001). Challenge upregulated TLR2 in MLN and TLR4 in ileum and MLN (P < 0.05). This was prevented by yeast supplementation for the TLR2 in MLN and TLR4 in ileum. Pigs fed colistin and LBG diets showed intermediate but nonsignificant responses. In conclusion, the results suggest that colistin, live yeast, and LBG reduce the levels of CRP in blood of piglets challenged with E. coli, and yeast reduces the expression of Toll-like receptors in the intestine.

Effect of feeding different cereal-based diets on the performance and gut health of weaned piglets with or without previous access to creep feed during lactation

A trial was conducted to evaluate the effect of different cereals on the performance, gut mucosa, and microbiota of weanling pigs with or without previous access to creep feed during lactation. A total of 108 newly weaned pigs (7.4 kg BW; 26 d of age; half with and half without creep feed) were used. Piglets were distributed by BW into 36 pens according to a 2 × 6 factorial arrangement of treatments with previous access to creep feed (with or without) and cereal source in the experimental diet [barley (Hordeum vulgare), rice (Oryza sativa)-wheat (Triticum aestivum) bran, corn (Zea mays), naked oats (Avena sativa), oats, or rice] as main factors. Pigs were offered the experimental diets for 21 d and performance was monitored. At day 21, 4 piglets from each treatment were killed and sampled for the histological evaluation of jejunal mucosa and the study of ileal and cecal microbiota by RFLP. The Manhattan distances between RFLP profiles were calculated and intragroup similarities (IGS) were estimated for each treatment. An interaction between cereal source and previous creep feeding was observed for ADFI (P < 0.05), indicating that whereas creep feeding increased ADFI for the rice-wheat bran diet it reduced it for naked oats. No differences in mucosal morphology were observed except for deeper crypts in pigs that did not have previous access to creep feed (P < 0.05). Cereal source had a significant effect on IGS of ileal and cecal microbiota (P < 0.01). In the ileum oats and corn had the highest IGS (i.e., lowest heterogeneity of the microbiota) followed by rice, naked oats, barley, and rice-wheat bran whereas in the cecum, IGS was highest for rice and oats followed by corn, barley, rice-wheat bran, and naked oats. An interaction between creep feeding and cereal was also observed for the IGS of the cecal microbiota at day 21 (P < 0.05). Access to creep feed reduced IGS in the piglets fed oats or barley but no differences were observed for the other cereal sources. It is concluded that the effect of creep feeding during lactation on the performance and the microbiota of piglets after weaning is dependent on the nature of the cereal in the postweaning diet.

Bacillus cereus var. toyoi promotes growth, affects the histological organization and microbiota of the intestinal mucosa in rainbow trout fingerlings

In this preliminary study, we evaluated the effects of a gram-positive soil bacteria Bacillus cereus var. toyoi on the growth performance, digestive enzyme activities, intestinal morphology, and microbiota in rainbow trout Oncorhynchus mykiss fingerlings. Trout were maintained in a recirculation system and fed 2 diets: 1) a commercial trout feed deprived of the probiotic and 2) the same diet but with the spores of the probiotic bacteria dissolved in fish oil during the manufacturing of the feed (final concentration = 2 × 10(4) cfu/g). Each diet was tested in three 400-L cylindroconical tanks (125 fish per tank; initial density = 1.3 kg/m(3); 13.2°C) for a period of 93 d. The probiotic-supplemented diet promoted growth, and the final mean BW and standard length in fish fed the probiotic were 3.4% and 2.1%, respectively, which was greater than the control group (P < 0.05). Fish fed the probiotic showed a more homogeneous distribution in the final BW, with a greater frequency of individuals around the modal of the normal distribution of the population. This result is of practical importance because homogenous production lots can improve rearing practices, reducing hierarchical dominance situations arising from individuals of larger sizes. In addition, the probiotic-supplemented diet increased the level of leukocyte infiltration in the lamina propria of the intestinal mucosa, the number of goblet cells (P < 0.010), and villi height (P < 0.001) but did not affect villi width. The administration of the probiotic changed the intestinal microbiota as indicated by 16S rDNA PCR-restriction fragment length polymorphism. In this sense, fish fed the probiotic formed a well-defined cluster composed of 1 super clade, whereas compared control fish had a greater degree of diversity in their gut microbiota. These changes in gut microbiota did not affect the specific activity of selected pancreatic and intestinal digestive enzymes. These results indicate that the inclusion of the probiotic bacteria in trout feeds could be beneficial for the host by enhancing its intestinal innate immune function and promoting growth.

Discoidin domain receptor 2 deficiency predisposes hepatic tissue to colon carcinoma metastasis

BACKGROUND

The transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts is a major mechanism for stroma development in hepatic metastasis, but their regulatory pathways remain unclear. Transdifferentiated HSCs from fibrotic liver express high levels of the fibrillar collagen receptor discoidin domain receptor 2 (DDR2), but it is unclear if DDR2 plays a direct profibrogenic role in the tumour microenvironment.

AIM

To assess the impact of DDR2 on the prometastatic role of HSC-derived myofibroblasts.

METHODS

Hepatic metastases were induced in DDR2(-/-) and DDR2(+/+) mice by intrasplenic injection of MCA38 colon carcinoma cells, and their growth and features were characterised. Stromagenic, angiogenic and cancer cell proliferation responses were quantified in metastases by immunohistochemistry. The adhesion-, migration- and proliferation-stimulating activities of supernatants from primary cultured DDR2(-/-) and DDR2(+/+) HSCs, incubated in MCA38 cell-conditioned medium, were evaluated in primary cultured liver sinusoidal endothelium cells (LSECs) and MCA38 cells. Gene expression signatures from freshly isolated DDR2(-/-) and DDR2(+/+) HSCs were compared and DDR2-regulated genes were studied by RT-PCR under basal conditions and after stimulation with MCA38 tumour-conditioned media.

RESULTS

Metastases were increased three fold in DDR2(-/-) livers, and contained a higher density of α-smooth muscle actin-expressing myofibroblasts, CD31-expressing microvessels and Ki67-expressing MCA38 cells than metastases in DDR2(+/+) livers. Media conditioned by MCA38-activated DDR2(-/-) HSCs significantly increased adhesion, migration and proliferation of LSECs and MCA38 cells, compared with DDR2(+/+) HSCs. DDR2 deficiency in HSCs led to decreased gene expression of interferon γ-inducing factor interleukin (IL)-18 and insulin-like growth factor-I; and increased gene expression of prometastatic factors IL-10, transforming growth factor (TGF)β and vascular endothelial growth factor (VEGF), bone morphogenetic protein-7 and syndecan-1. MC38 tumour-conditioned media further exacerbated expression changes in DDR2-dependent IL-10, TGFβ and VEGF genes.

CONCLUSION

DDR2 deficiency fosters the myofibroblast transdifferentiation of tumour-activated HSCs, generating a prometastatic microenvironment in the liver via HSC-derived factors. These findings underscore the role of stromal cells in conditioning the hepatic microenvironment for metastases through altered receptor-stroma interactions.

Epiprofin/Sp6 regulates Wnt-BMP signaling and the establishment of cellular junctions during the bell stage of tooth development

Epiprofin/Specificity Protein 6 (Epfn) is a Krüppel-like family (KLF) transcription factor that is critically involved in tooth morphogenesis and dental cell differentiation. However, its mechanism of action is still not fully understood. We have employed both loss-of-function and gain-of-function approaches to address the role of Epfn in the formation of cell junctions in dental cells and in the regulation of junction-associated signal transduction pathways. We have evaluated the expression of junction proteins in bell-stage incisor and molar tooth sections from Epfn(-/-) mice and in dental pulp MDPC-23 cells overexpressing Epfn. In Epfn(-/-) mice, a dramatic reduction occurs in the expression of tight junction and adherens junction proteins and of the adherens-junction-associated β-catenin protein, a major effector of canonical Wnt signaling. Loss of cell junctions and β-catenin in Epfn(-/-) mice is correlated with a clear decrease in bone morphogenetic protein 4 (BMP-4) expression, a decrease in nestin in the tooth mesenchyme, altered cell proliferation, and failure of ameloblast cell differentiation. Overexpression of Epfn in MDPC-23 cells results in an increased cellular accumulation of β-catenin protein, indicative of upregulation of canonical Wnt signaling. Together, these results suggest that Epfn enhances canonical Wnt/β-catenin signaling in the developing dental pulp mesenchyme, a condition that promotes the activity of other downstream signaling pathways, such as BMP, which are fundamental for cellular induction and ameloblast differentiation. These altered signaling events might underlie some of the most prominent dental defects observed in Epfn(-/-) mice, such as the absence of ameloblasts and enamel, and might throw light on developmental malformations of the tooth, including hyperdontia.

Wheat-barley-rye- or corn-fed growing pigs respond differently to dietary supplementation with a carbohydrase complex

Thirty-six pigs (22 kg of BW) were used to evaluate a carbohydrase preparation, with xylanase and β-glucanase as main activities, added to either wheat-barley-rye- (WBR) or corn-based diets on performance, intestinal environment, and nutrient digestibility. Pigs were offered 1 of 4 different dietary treatments for 27 d according to a factorial arrangement of treatments (a 2 × 2) with 2 cereal types (WBR or corn) and 2 levels of supplemental carbohydrase (0 or 0.01%). Pig growth and feed intake were individually measured every week until the end of the experiment when pigs were slaughtered to obtain samples of digesta and tissues. Cereal type affected performance only during wk 1, in which WBR improved ADG (590 vs. 440 g/d; P = 0.008) and G:F (0.61 vs. 0.43; P = 0.045) compared with corn. The WBR also increased the viscosity of the digestive contents in stomach (1.95 vs. 1.23 mPa·s; P = 0.001) and ileum (6.53 vs. 2.80 mPa·s; P = 0.001) and resulted in greater cecal starch digestibility (95.7 vs. 93.9%; P = 0.012). However, trends for a reduction in digestibility were observed for glucose in the nonstarch polysaccharide (NSP) fraction in the ileum (64.4 vs. 75.8%; P = 0.074) and galactose in the NSP fraction in the cecum (1.4 vs. 1.8%; P = 0.055). The use of the enzyme preparation increased ADFI during wk 2 (1,328 vs. 1,215 g/d; P = 0.028), and increased villus height (423 vs. 390 µm; P = 0.045) and tended to reduce relative pancreas weight (0.16 vs. 0.17% BW; P = 0.079) at d 27. The enzyme also improved cecal starch digestibility (95.5 vs. 94.1%; P = 0.043) and tended to improve ileal energy digestibility (61.3 vs. 53.7%; P = 0.090) and cecal glucose digestibility in the NSP fraction (76.0 vs. 54.5%; P = 0.055). However, it reduced the cecal digestibility of mannose in the NSP fraction (27.0 vs. 50.5%; P = 0.016). Interactions (P < 0.05) between cereal type and enzyme supplementation were observed for ADG and G:F during wk 2, BW and ADG during wk 3, and BW and ADFI over the whole trial; and also for villus-height-to-crypt-depth ratio and for cecal DM digestibility. In all instances, whereas the added enzyme had no effect in the case of the corn diet, improvements were observed with WBR. In conclusion, the multi-enzyme tested had different effects depending on the type of cereal present in the diet.

Downregulation of discoidin domain receptor 2 in A375 human melanoma cells reduces its experimental liver metastasis ability

Discoidin domain receptors (DDR1 and DDR2) are tyrosine kinase receptors for fibrillar collagen implicated in postnatal development, tissue repair, and primary and metastatic cancer progression. While DDR1 has been described in tumor cells, DDR2 has been localized in the tumor stroma, but its presence in the tumor cells remains unknown. The aim of this study was to elucidate the role of DDR2 signaling in tumor cells during hepatic metastasis progression. DDR2 expression and phosphorylation in cultured human A375 melanoma cells was documented by Western blot analysis. A375 cells were stably transfected with a small interfering RNA (siRNA) against DDR2 and two clones were selected: A375R2-70 and A375R2-40, with 70 and 40% of the DDR2 protein expression respectively, compared to mock-transfected cells (A375R2-100). Development of experimental liver metastasis by intrasplenic inoculation of A375R2-70 and A37R2-40 clones was reduced by 60 and 75%, respectively, measured as tumor volume, compared to livers injected with A375R2-100 cells. Accordingly, A375R2-70 and A37R2-40 clones showed reduced in vitro gelatinase activity and JNK phosphorylation, compared to mock transfected cells, with maximal inhibition in A375R2-40. Additionally, A375 melanoma, SK-HEP hepatoma and HT-29 colon carcinoma human cell lines transiently transfected with siRNA against DDR2 also showed reduced proliferation and migration rates compared to mock-transfected ones. In conclusion, DDR2 promotes A375 melanoma metastasis to the liver and the underlying mechanism implicates regulation of metalloproteinase release, cell growth and chemotactic invasion of the host tissue.

The response of gastrointestinal microbiota to avilamycin, butyrate, and plant extracts in early-weaned pigs

An experiment was designed to evaluate the effects of 3 different additives on the gastrointestinal microbiota of early-weaned pigs. Early-weaned (18 to 22 d; n = 32) pigs (6.0 +/- 0.10 kg of BW) from 8 litters were randomly distributed into 8 pens. Each pen was assigned 1 of 4 dietary treatments: a prestarter or control diet, the control diet with 0.04% avilamycin (AB), with 0.3% sodium butyrate, or with 0.03% plant extract mixture (XT; standardized mixture with 5% (wt/wt) carvacrol extracted from Origanum spp., 3% cinnamaldehyde extracted from Cinnamonum spp., and 2% capsicum oleoresin from Capsicum annum). At the end of the experimental period, 8 pigs per treatment were killed, and samples of their intestinal content were taken. The total bacterial load along the gastrointestinal tract (GIT; stomach, jejunum, cecum, and distal colon) and the lactobacilli and enterobacteria in the jejunum and cecum were measured by quantitative PCR. The total microbial counts along the GIT did not differ among the diets, but there was an increase in the lactobacilli:enterobacteria ratio in the cecum of the piglets on the XT diet (P = 0.003). Restriction fragment length polymorphism of the PCR-amplified V3, V4, and V5 regions of the 16S rDNA gene showed changes in the structure of the microbial community in the jejunum. Dendrograms grouped animals by diets; control with 0.3% sodium butyrate was the treatment that promoted the biggest changes in the microbial ecosystem, followed by AB and then XT. Biodiversity increased when using additives compared with the control diet (P = 0.002). Microbial metabolic activity along the hindgut was studied using the concentration of purine bases and carbohydrase activities. Different patterns for purine bases were observed between diets (diet x intestinal section, P = 0.01). The control diet reached a maximum purine base concentration at the end of the colon, whereas that of the AB diet was reached at the cecum. We could not detect any cellulase or xylanase activities in animals of this age. Appreciable amylase and amylopectinase activities were found, but they did not differ between diets. The results suggest that the effects of avilamycin, butyrate, or the plant extract would not be related to a reduction in the number of total bacteria inhabiting different sections of the GIT but rather to changes in the ecological structure and metabolic activity of the microbial community.

Neutral detergent-soluble fiber improves gut barrier function in twenty-five-day-old weaned rabbits1

The effect of neutral detergent-soluble fiber level on gut barrier function and intestinal microbiota was examined in weaned rabbits. A control diet (AH) containing 103 g of neutral detergent-soluble fiber/ kg of DM included alfalfa hay as main source of fiber. Another diet (B-AP) was formulated by replacing half of the alfalfa hay with a mixture of beet and apple pulp resulting in 131 g of soluble fiber/kg of DM. A third diet (OH) was obtained by substituting half of the alfalfa hay with a mix of oat hulls and a soybean protein concentrate and contained 79 g of soluble fiber/kg of DM. Rabbits weaned at 25 d and slaughtered at 35 d were used to determine ileal digestibility, jejunal morphology, sucrase activity, lamina propria lymphocytes, and intestinal microbiota. Suckling 35-d-old rabbits were used to assess mucosa morphology. Mortality (from weaning to 63 d of age) was also determined. Villous height of the jejunal mucosa increased with soluble fiber (P = 0.001). Rabbits fed with the greatest level of soluble fiber (BA-P diet) showed the highest villous height/ crypt depth ratio (8.14; P = 0.001), sucrase specific activity (8,671 mumol of glucose/g of protein; P = 0.019), and the greatest ileal starch digestibility (96.8%; P = 0.002). The opposite effects were observed in rabbits fed decreased levels of soluble fiber (AH and OH diets; 4.70, 5,848 mumol of glucose/g of protein, as average, respectively). The lowest ileal starch digestibility was detected for animals fed OH diet (93.2%). Suckling rabbits of the same age showed a lower villous height/crypt depth ratio (6.70) compared with the B-AP diet group, but this ratio was higher than the AH or OH diet groups. Lower levels of soluble fiber tended (P = 0.074) to increase the cellular immune response (CD8+ lymphocytes). Diet affected IL-2 production (CD25+, P = 0.029; CD5+CD25+, P = 0.057), with no clear relationship between soluble fiber and IL-2. The intestinal microbiota biodiversity was not affected by diets (P >/= 0.38). Rabbits fed the B-AP and AH diets had a reduced cecal frequency of detection compatible with Campylobacter spp. (20.3 vs. 37.8, P = 0.074), and Clostridium perfringens (4.3 vs. 17.6%, P = 0.047), compared with the OH diet group. Moreover, the mortality rates decreased from 14.4 (OH diet) to 5.1% (B-AP diet) with the increased presence of soluble fiber in the diet. In conclusion, increased levels of dietary soluble fiber improve mucosal integrity and functionality.

Effects of Lactococcus lactis on composition of intestinal microbiota: role of nisin

This study examined the ability of (i) pure nisin, (ii) nisin-producing Lactococcus lactis strain CHCC5826, and (iii) the non-nisin-producing L. lactis strain CHCH2862 to affect the composition of the intestinal microbiota of human flora-associated rats. The presence of both the nisin-producing and the non-nisin-producing L. lactis strains significantly increased the number of Bifidobacterium cells in fecal samples during the first 8 days but decreased the number of enterococci/streptococci in duodenum, ileum, cecum, and colon samples as detected by selective cultivation. No significant changes in the rat fecal microbiota were observed after dosage with nisin. Pearson cluster analysis of denaturing gradient gel electrophoresis profiles of the 16S rRNA genes present in the fecal microbial population revealed that the microbiota of animals dosed with either of the two L. lactis strains were different from that of control animals dosed with saline. However, profiles of the microbiota from animals dosed with nisin did not differ from the controls. The concentrations of nisin estimated by competitive enzyme-linked immunosorbent assay (ELISA) were approximately 10-fold higher in the small intestine and 200-fold higher in feces than the corresponding concentrations estimated by a biological assay. This indicates that nisin was degraded or inactivated in the gastrointestinal tract, since fragments of this bacteriocin are detected by ELISA while an intact molecule is needed to retain biological activity.

Effect of fishmeal replacement with spray-dried animal plasma and colistin on intestinal structure, intestinal microbiology, and performance of weanling pigs challenged with Escherichia coli K99

We evaluated spray-dried animal plasma (SDAP) as an alternative to antimicrobial medication with colistin sulfate in weanling pigs challenged with Escherichia coli K99. Forty-eight piglets weaned at 24 d of age were distributed into 12 pens, and each pen was assigned to one of four dietary treatments. All the piglets were given an oral dose of 5 x 10(7) cfu of E. coli K99 at weaning. The dietary treatments followed a factorial arrangement with two levels of SDAP (0 and 7%) and two levels of colistin (0 and 300 mg/kg of diet). The ADG and ADFI were measured on d 7 and 14 of trial. Three piglets from each treatment were killed on d 7 and 14 to remove the small intestine, and to obtain ileal and cecal digestive contents. The inclusion of SDAP improved ADG by 68 g (P < 0.05) and ADFI by 41 g (P < 0.10) in wk 1 of trial. During wk 2, SDAP improved ADG by 41 g (P < 0.10) and gain:feed ratio (G:F) by 25% (P < 0.01). On the other hand, whereas colistin had no effect on performance in wk 1, it improved ADG by 102 g (P < 0.01), ADFI by 62 g (P < 0.01), and G:F by 26% (P < 0.01) in wk 2. Over the 14 d of the trial, ADG was improved by 54 (P < 0.05) and 75 g (P < 0.05), and G:F was improved by 35 (P < 0.05) and 32% (P < 0.05) due to SDAP and colistin, respectively. There was interaction between colistin and SDAP for ADFI in wk 2 and between d 0 to 14 (P < 0.05), which indicates that their effects were not additive. The use of colistin was advantageous in the maintenance of the integrity of the intestinal mucosa of the pigs, as suggested by a small intestine that was 93 g heavier (P < 0.10) and with the tallest villi 106 microm longer (P < 0.10) than in pigs without colistin. The inclusion of SDAP in the diet favored the growth of lactobacilli in the ileum (P < 0.10) and the cecum (P < 0.05), whereas colistin reduced the number of enterococci in the cecum (P < 0.05) and of Escherichia coli both in the ileum and the cecum (P < 0.001). These results suggest that SDAP may be an alternative to medicated feed with antibiotics since it provided a level of protection against an experimental challenge with E. coli K99 similar to that obtained with colistin, an antibiotic of proven efficacy. The current situation in which the use of antimicrobials in animal feeding is being questioned should encourage further investigation into the use of SDAP as a means of preventing disease in pigs at weaning.

Expression of the Pasteurella multocida ompH gene is negatively regulated by the Fur protein

The fur gene of Pasteurella multocida has been cloned by complementation of an Escherichia coli fur mutant. The P. multocida fur gene, which encodes a predicted protein of 147 amino acids, displaying the highest identity (89%) with the same protein of Haemophilus influenzae, is negatively regulated by its own product. By construction of a P. multocida fur mutant, it has been demonstrated that the ompH gene, encoding a major structural protein of the outer membrane, presenting high antigenicity power, is negatively regulated by iron and glucose. Furthermore, wild-type and fur-defective cells of P. multocida show the same level of virulence.

Virulence of Pasteurella multocida recA mutants

In order to determine the role of the RecA protein in the virulence of Pasteurella multocida, a recA mutant was constructed and used in studies of virulence and competition in relation to wild-type strain. To achieve this, firstly, the recA gene was isolated and sequenced, showing an Escherichia coli-like SOS box and encoding a protein of 354 amino acids which has the closest identity with the Haemophilus influenzae RecA protein. Further, the recA mutant was constructed, by inactivating this gene by single recombination of a suicide plasmid containing an internal region of the P. multocida recA gene, and shown to be more sensitive to UV radiation than the parental strain. The P. multocida mutant was slightly attenuated in virulence, as indicated by the LD(50), the time of death of infected animals, and a failure to compete with the wild-type strain in mixed infections. Compared to the parent strain, the mutant had a similar growth rate but a longer lag phase. These data suggest that the diminished virulence of the recA mutant as well as its failure in competition were more a consequence of the long lag phase rather than a direct effect of the inactivation of the recA gene on genes involved in virulence.

Virulence and mutation rates of Salmonella typhimurium strains with increased mutagenic strength in a mouse model

Two strains of Salmonella typhimurium presenting increased mutation rates, either spontaneous or mediated by DNA damage, have been constructed. One of the strains carries a null mutS mutation, while the other harbors plasmid pRW30, which contains the Escherichia coli umuDC operon. The virulence of these strains has been determined by inoculating BALB/c or Swiss mice. The 50% lethal dose of both strains is identical to that obtained for the wild-type. Likewise, the two strains and the wild-type contribute equally to animal death in mixed infections. The frequency of Nal(R) mutants recovered from animals inoculated with either wild-type or MutS(-) cells was not affected by the presence of pRW30. These results indicate that the DNA damage which S. typhimurium cells can suffer during the infectious process by host cell metabolites does not cause induction of the SOS response at levels able to trigger the error-prone DNA repair pathway.

Importance of the galE gene on the virulence of Pasteurella multocida

The galE gene of Pasteurella multocida has been isolated by complementing galE-defective mutants of Salmonella typhimurium with a plasmid library of this organism. The complete nucleotide sequence of the P. multocida galE gene consists of 1017 nucleotides, encoding a predicted polypeptide of 339 amino acids. The deduced amino acid sequence displayed the highest identity (85%) to the GalE protein of Haemophilus influenzae. However, the gene organization surrounding the galE locus was different from that of H. influenzae. A galE-defective mutant of P. multocida was obtained by replacement of the active galE gene by a copy inactivated in vitro. The resulting galE mutant was highly attenuated as seen in a biological test carried out in a mouse model.