Sepsis is characterized by a systemic inflammatory response followed by immunosuppression of the host. Metabolic defects and mitochondrial failure are common in immunocompromised patients with sepsis. The NLRP3 inflammasome is important for establishing an inflammatory response after activation by the purinergic P2X7 receptor. Here, we study a cohort of individuals with intra-abdominal origin sepsis and show that patient monocytes have impaired NLRP3 activation by the P2X7 receptor. Furthermore, most sepsis-related deaths are among patients whose NLRP3 activation is profoundly altered. In monocytes from sepsis patients, the P2X7 receptor is associated with mitochondrial dysfunction. Furthermore, activation of the P2X7 receptor results in mitochondrial damage, which in turn inhibits NLRP3 activation by HIF-1α. We show that mortality increases in a mouse model of sepsis when the P2X7 receptor is activated in vivo. These data reveal a molecular mechanism initiated by the P2X7 receptor that contributes to NLRP3 impairment during infection.

Immune cells are equipped with a number of receptors that recognize sterile injury and pathogens. We find that host immune cells release ATP as an inflammatory signal in response to allogeneic transplantation. ATP then acts via a feedback mechanism on the P2X7 channel to activate the NLRP3 inflammasome and subsequently process and release interleukin (IL)-18. This process is a necessary stage in the deleterious Th1 response against allotransplantation via interferon-γ production. Lack of IL-18 resulted in a decrease in graft-infiltrating CD8 cells but an increase in regulatory T cells. In human liver transplant patients undergoing progressive immunosuppressive drug withdrawal, we found that patients experiencing acute rejection had higher levels of the P2X7 receptor in circulating inflammatory monocytes compared to tolerant patients. These data suggest that the pharmacological inhibition of the P2X7 receptor or the NLRP3 inflammasome will aid in inducing transplant tolerance without complete immunoparalysis.

Human liver allografts do sometimes survive in a recipient after withdrawal of immunosuppression (IS), commonly referred to as "operational tolerance." Preliminary clinical data have suggested an increase in the frequency of regulatory T cells (Treg) CD4+CD25 high and FoxP3 expression in operationally tolerant liver transplant recipients (Gr-T). In the context of human liver transplantation, the dynamics of Treg have not been studied. We designed a prospective study to ascertain the profile of the Treg population and FoxP3 expression during IS withdrawal. To identify such parameters, we analyzed peripheral blood mononuclear cell populations and FoxP3 mRNA expression in 12 liver allograft recipients under cyclosporine A-based IS, who showed stable function of the allograft for more than 2 years. An increase was observed in the frequency of CD4+CD25 high cells when the IS was withdrawn in Gr-T patients (n=5). These patients exhibited a 3.5-fold increase for relative mRNA FoxP3 expression before the complete IS withdrawal and this continued when IS therapy was stopped. In patients who suffered rejection (n=7) there was no increase in the CD4+CD25 high cells or FoxP3 expression. With the present study, the first evidence is provided that the increase of CD4+CD25 high T cells and FoxP3 transcripts is associated with operational tolerance in liver transplanted patients during IS withdrawal.

Southeastern Spain is a cosmopolitan area where there is a growing British and Irish population. The objective is to analyze the attitude toward organ donation among British and Irish citizens living in southeastern Spain. A sample was taken stratified according to a respondent's country of origin (n = 1700) between November 2005 and April 2006. Attitude was evaluated using a validated questionnaire, which was self-administered and completed anonymously. A sample of 2000 Spanish citizens was used as a control group. The survey completion rate was 95% (n = 1611). Attitude toward donation is favorable in 72% (n = 1155) of respondents with 8% (n = 122) against and 20% (n = 334) undecided. Attitude is more favorable than in the control group (72% vs. 63%; p < 0.0001). The following factors influence this attitude: (1) attitude toward the donation of a family member's organs (OR = 4.891); (2) having discussed the matter of organ donation within the family (OR = 2.513); (3) a willingness to accept an autopsy if it were necessary (OR = 1.706); (4) having no concern about the mutilation of the deceased donor (OR = 3.294); (5) having a partner who is in favor of donation (OR = 2.786) and (6) a respondent's belief that he or she might need a transplant in the future (OR = 2.243). The attitude of this population is more positive than in the native Spanish population and is determined by many psychosocial factors.

The Latin American (LA) population has similarities with the Spanish population which makes its integration into Spanish society easier. Objective: to analyze the attitude toward organ donation among Latin American citizens residing in Spain, to determine the psychosocial variables which affect this attitude, and to examine the correlation between donation rates of LA citizens in Spain and in their countries of origin. A random sample of LA residents in Spain was taken and stratified according to the respondent's nationality (n = 1.314), in the year 2010. Attitude was assessed using a validated questionnaire (PCID-DTO Dr Rios). The survey was self-administered and completed anonymously. Statistical analysis: Student's t-test, the χ² test, and logistic regression analysis. There was a 94% completion rate (n = 1.237). Attitude toward donation was favorable in 60% of cases (n = 745), 12% (n = 145) were against, and 28% (n = 347) were undecided. The following variables were associated with attitude toward donation: sex (P = 0.038), level of formal education (P < 0.001), country of origin (P = 0.002), attitude toward the donation of a family member's organs (P < 0.001), having discussed donation with the family (P < 0.001), carrying out prosocial activities (P = 0.025), attitude toward cremation of the body (P < 0.001), attitude toward burial of the body (P < 0.001), attitude toward having an autopsy carried out (P < 0.001), previous experience of the organ donation and transplantation process (P < 0.001), fear of mutilation after donation (P < 0.001), knowledge that the Church has a positive attitude toward organ donation and transplantation (P < 0.001), knowledge of one's partner's attitude toward organ donation (P < 0.001), and a belief that one might need a transplant in the future (P < 0.001). The donation rates in this population group in Spain are higher than those recorded in their countries of origin (55.76 vs. <10 pmp; P < 0.001). The attitude toward organ donation among LA citizens residing in Spain is slightly worse than that reported in the native Spanish population and is determined by many psychosocial factors. The donation rates of LA citizens in Spain are higher than those in their countries of origin.

Medical students represent a new generation of medical thought, and if they have a favourable attitude towards organ donation this will greatly encourage its promotion. To analyse the attitude of medical students in Spanish universities towards the donation of their own organs and to determine the factors affecting this attitude. Type of study: A sociological, interdisciplinary, multicentre, and observational study in Spain. Students studying a degree in medicine enrolled in Spain (n = 34,000). A sample of 9598 students (confidence of 99% and precision of ±1%), stratified by geographical area and academic year. Instrument of measurement: A validated questionnaire of attitude towards organ donation and transplantation (PCID-DTO RIOS) was self-administered and completed anonymously. The questionnaire completion rate was 95.7% (n = 9.275). 80% were in favour of donation, 2% against and 18% were undecided. The following main variables were related to a favourable attitude: being of the female sex (Odds Ratio = 1.739); being in the sixth year of the degree (OR = 2.506); knowing a donor (OR = 1.346); having spoken about the subject with one's family (OR = 2.132) and friends (OR = 1.333); having a family circle that is in favour, more specifically, having a father (OR = 1.841), mother (OR = 2.538) or partner in favour (OR = 2.192); being a blood donor (OR = 2.824); acceptance of the mutilation of the body if it were necessary (OR = 2.958); and being an atheist or an agnostic (OR = 1.766). Spanish medical students generally have a favourable attitude towards organ donation, although 20% are not in favour.