Renal allograft injury is associated with urinary tract infection caused by Escherichia coli bearing adherence factors

Urinary tract infections are the most common infection in renal transplant patients and Escherichia coli (E. coli) is the most common clinical isolate. Although acute allograft injury (AAI) secondary to urinary tract infection (UTI) has been reported, the incidence of AAI associated with UTI, the virulence factors express by uropathic E. coli and whether virulence factors are associated with renal allograft outcome have not been described. We collected E. coli from our renal transplant patients with UTI, determined O:H serotypes, P and Dr fimbriae expression and the clinical presentation and allograft function during the UTI and post-UTI period. Pyelonephritis occurred in 40% of our patients, 82% of which had AAI (>20% increase in SCr). Sixty-two percent of E. coli isolates that expressed P fimbriae were associated with AAI, whereas only 29% that did not express P fimbriae had AAI (p = 0.03). The pattern of P fimbriae and O serotypes differed from reported isolates, as the P fimbriae PapG class II and the O25 serotype were the most common. Dr adhesin was expressed on 7 isolates, including 2 of 3 with urosepsis. We propose a unique pattern of uropathogenic serotypes and adherence factors contribute to acute allograft injury in renal transplant patients with UTI.

Fetal exposure to intact immunoglobulin E occurs via the gastrointestinal tract

BACKGROUND

Consideration of the evolutionary significance of IgE might provide insight into the immunological interactions occurring in utero and during early post-natal life that regulate later atopic disease.

OBJECTIVE

We postulated that the fetal gut is exposed to intact amniotic fluid IgE that might interact with local IgE receptors.

METHODS

IgE levels in matched maternal blood and amniotic fluid (n = 47) or breast milk (n = 15) collected from pregnant women in the UK (Southampton) and Brazil (Sao Paulo) were studied. Expression of IgE receptors, Fc epsilon RI and Fc epsilon RII (CD23), in fetal gastrointestinal tract (n = 19) and skin (n = 11) was examined immunohistochemically.

RESULTS

Human amniotic fluid at 16-18 weeks' gestation contained intact IgE at levels that increased as maternal circulating levels increased (Spearman's rho = 0.897; P < 0.001). Circulating IgE levels from women in Sao Paulo, Brazil, associated positively not only with term (> 37 weeks' gestation) amniotic fluid (rho = 0.993; P < 0.001) but also breast milk IgE levels (rho = 0.785; P = 0.001). Maternal levels of IgE did not change significantly over pregnancy and fetal circulating levels of IgE were very low (< 0.6 IU/mL). Low-affinity IgE receptors (CD23) were expressed in lymphoid follicles of the fetal gut from 16 weeks of gestation (6/8), but not from 11 to 16 weeks (0/11) or in the skin.

CONCLUSION

Amniotic fluid contains intact IgE that might bind to CD23+ cells within the lymphoid follicles of the fetal gastrointestinal tract. The evolutionary significance of these interactions might be to prepare the immune system for helminthic parasite exposure at birth via IgE-mediated antigen focusing, or "education" of the developing immune system about the prevailing extrauterine environment. However, at present in societies where helminthosis is not a significant health issue, this pathway may still be operational and associated with the development of atopic disease.

Late recurrence of lupus nephritis in a renal transplant recipient: response to mycophenolate mofetil

Clinically significant recurrence of lupus nephritis in the renal allograft is low, with an incidence of 1 to 3%, and usually occurs within the first 6 years after transplantation. We report an unusual case of a patient with end-stage renal disease caused by lupus nephritis who received a kidney transplant from a living relative; 13 years later, the patient had a severe recurrence of diffuse proliferative lupus nephritis. The patient relapsed after receiving intravenous cyclophosphamide therapy and had a partial response to oral mycophenolate mofetil. In this report we review the risk factors for the recurrence of the systemic lupus erythematosus in the kidney graft and the anti-lupus activity of mycophenolate mofetil.