Decreased immunologic responsiveness following intensified vaginal immunization against urinary tract infection

Waging war against uropathogenic Escherichia coli: winning back the urinary tract

Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) is a substantial economic and societal burden-a formidable public health issue. Symptomatic UTI causes significant discomfort in infected patients, results in lost productivity, predisposes individuals to more serious infections, and usually necessitates antibiotic therapy. There is no licensed vaccine available for prevention of UTI in humans in the United States, likely due to the challenge of targeting a relatively heterogeneous group of pathogenic strains in a unique physiological niche. Despite significant advances in the understanding of UPEC biology, mechanistic details regarding the host response to UTI and full comprehension of genetic loci that influence susceptibility require additional work. Currently, there is an appreciation for the role of classic innate immune responses-from pattern receptor recognition to recruitment of phagocytic cells-that occur during UPEC-mediated UTI. There is, however, a clear disconnect regarding how factors involved in the innate immune response to UPEC stimulate acquired immunity that facilitates enhanced clearance upon reinfection. Unraveling the molecular details of this process is vital in the development of a successful vaccine for prevention of human UTI. Here, we survey the current understanding of host responses to UPEC-mediated UTI with an eye on molecular and cellular factors whose activity may be harnessed by a vaccine that stimulates lasting and sterilizing immunity.

The role of cranberry and probiotics in intestinal and urogenital tract health

Several forces are driving an expanded use of nutraceuticals, particularly functional foods and probiotics, as instruments of the restoration and maintenance of well-being. These include consumer desire to use natural rather than pharmaceutical products, the mounting scientific evidence that shows efficacy of certain nutraceutical products, and the increasing cost and continued failure of drugs to cure or prevent disease. There is now a strong scientific basis for use of cranberries to reduce the risk of E. coli adhesion to bladder cells and the onset of urinary tract infection. There is also a mechanistic basis and clinical support for use of Lactobacillus strains such as L. rhamnosus GR-1 and L. fermentum RC-14 to colonize the intestine and vagina and reduce the risk of intestinal and urogenital infections. For such alternative approaches to be successful, scientific rigor must be backed by public education and physician acceptance. Given the emergence of virulent and multidrug-resistant pathogens, time is not on our side.

Vaginal mucosa serves as an inductive site for tolerance

These data demonstrate that tolerance can be induced by vaginal Ag exposure. In these experiments, mice were given vaginal agarose gel suppositories containing either 5 mg OVA or saline for 6 h. Mice were given suppositories either during the estrous (estrogen dominant) or diestrous (progesterone dominant) stage of the estrous cycle. Mice were restrained during the inoculation period to prevent orovaginal transmission of the Ag. After 1 wk, mice were immunized s. c. with OVA in CFA. After 3 wk, mice were tested for delayed-type hypersensitivity responses by measuring footpad swelling and measuring in vitro proliferation of lymphocytes to Ag. Using ELISA, the magnitude of the serum Ab response was also measured. In some mice, FITC conjugated to OVA was used to track the dissemination of the protein into the systemic tissues. The magnitude of footpad swelling was significantly reduced in mice receiving OVA-containing suppositories during estrus compared with mice receiving saline suppositories. Concomitant decreases in the Ag-specific proliferative response were also observed in lymph node lymphocytes and splenocytes. Conversely, mice inoculated during diestrus did not show a decreased response to Ag by either footpad response or in vitro proliferation. Serum Ab titers in the estrus-inoculated mice did not decrease significantly. These data demonstrate that the reproductive tract can be an inductive site for mucosally induced tolerance. However, unlike other mucosal sites such as the lung and gastrointestinal tract, reproductive tract tolerance induction is hormonally regulated.

Phase I clinical trial of vaginal mucosal immunization for recurrent urinary tract infection

In a phase I clinical trial to test safety and patient acceptance 25 women with a history of recurrent urinary tract infections but no identifiable anatomic abnormality received a multivalent vaccine instilled into the vagina. The vaccine contained 6 heat-killed Escherichia coli strains and 4 nonE. coli uropathogens. Only minimal adverse reactions were observed in the 5-month period following immunization. Total vaginal and urinary IgG and IgA increased significantly (p < 0.01 by repeated measures analysis of variance). Serum antibodies to some of the nonE. coli strains but not to the E. coli strains increased after vaginal immunization. While efficacy is yet to be shown, this study indicates that this vaginally applied urinary tract infection vaccine is well tolerated, and capable of increasing vaginal and urinary antibody.

Immunization against urinary tract infection with a multi-valent vaginal vaccine

Systemic and local immune responses are thought to play an important role in susceptibility to urinary tract infection. In an attempt to boost local immunity, a vaccine was administered parenterally or vaginally to two mouse strains. Both routes of immunization increased the number of splenic antibody-forming cells against the bacterial strains in the vaccine. Following vaginal or parenteral immunization and subsequent induction of cystitis with live E. coli, immunized animals had fewer viable bladder E. coli than non-immunized animals.