Salmonella enterica Serovar Typhimurium Exploits Inflammation to Compete with the Intestinal Microbiota

Most mucosal surfaces of the mammalian body are colonized by microbial communities (“microbiota”). A high density of commensal microbiota inhabits the intestine and shields from infection (“colonization resistance”). The virulence strategies allowing enteropathogenic bacteria to successfully compete with the microbiota and overcome colonization resistance are poorly understood. Here, we investigated manipulation of the intestinal microbiota by the enteropathogenic bacterium Salmonella enterica subspecies 1 serovar Typhimurium (S. Tm) in a mouse colitis model: we found that inflammatory host responses induced by S. Tm changed microbiota composition and suppressed its growth. In contrast to wild-type S. Tm, an avirulent invGsseD mutant failing to trigger colitis was outcompeted by the microbiota. This competitive defect was reverted if inflammation was provided concomitantly by mixed infection with wild-type S. Tm or in mice (IL10−/−, VILLIN-HACL4-CD8) with inflammatory bowel disease. Thus, inflammation is necessary and sufficient for overcoming colonization resistance. This reveals a new concept in infectious disease: in contrast to current thinking, inflammation is not always detrimental for the pathogen. Triggering the host's immune defence can shift the balance between the protective microbiota and the pathogen in favour of the pathogen

Blastocyst transfer after aseptic vitrification of zygotes: an approach to overcome an impaired uterine environment

In some IVF cycles, no fresh embryo transfer in the stimulated cycle is advisable. The cryopreservation of zygotes and the transfer of blastocysts in a cryo-embryo transfer is an option to circumvent an inadequate uterine environment due to risk of ovarian hyperstimulation syndrome, inappropriate endometrium build up, endometrial polyps or uterine myomas. For this strategy, highly secure and safe cryopreservation protocols are advisable. This study describes a protocol for aseptic vitrification of zygotes that results in high survival rates and minimizes the potential risk of contamination in liquid nitrogen during cooling and long-term storage. In mouse zygotes, there was no difference in efficiency as compared with a conventional open vitrification system. In IVF patients, aseptically vitrified zygotes showed no difference in blastocyst formation rate as compared with sibling zygotes kept in fresh culture. A clinical study comprising 173 cryo-cycles with a transfer of blastocysts originating from vitrified zygotes showed an ongoing pregnancy rate of 40.9%. The live birth rate per patient was 36.8%. A combination of good clinical results and increased safety conditions due to aseptic vitrification encourages the use of cryo-embryo transfer for patients with a suboptimal uterine environment in a fresh cycle

Chapter 13: Adaptation of a Universal Procedure for Cryopreservation of Different Developmental Stages: Is it Conceivable?

A RENEWED INTEREST IN CRYOPRESERVATION: WHY? It is now well recognized that the proportion of births following transfer of cryopreserved gametes or embryos will increase dramatically. Several reasons may explain this rising interest for embryo transfer (ET) after cryopreservation. The improvement of in vitro culture technique enables gaining better quality embryos associated with the policy of single embryo transfer (SET) results in the increasing proportion of supernumerary embryos cryopreserved at different stages of development. Moreover, with the increased efficiency of the cryopreservation technique such as vitrification, there is now a tendency to shift from fresh ET to cryopreserved ET in artificial or natural cycles. This attitude is relevant especially when the progesterone level before oocyte pick-up is above a physiological limiting value, a not optimal thickness of the endometrium or when embryos are originated from an in vitro maturation cycle. Cryopreserved ET is also an opportunity, when fresh ET cycles are cancelled because of hyperstimulation. With the introduction of vitrification, there is also an emergent change in the general attitude towards oocyte cryopreservation offering available solution, for example, in the field of preservation of fertility, ovarian hyperstimulation syndrome, poor responder, absence of sperm at the time of oocyte pick-up, cryo-banking for egg donation program or for social reason and finally to overcome ethical concerns and legal restrictions