Repeat modules and N-linked glycans define structure and antigenicity of a critical enterotoxigenic E. coli adhesin.

Enterotoxigenic Escherichia coli (ETEC) cause hundreds of millions of cases of infectious diarrhea annually, predominantly in children from low-middle income regions. Notably, in children, as well as human volunteers challenged with ETEC, diarrheal severity is significantly increased severity in blood group A (bgA) individuals. EtpA, is a secreted glycoprotein adhesin that functions as a blood group A lectin to promote critical interactions between ETEC and blood group A glycans on intestinal epithelia for effective bacterial adhesion and toxin delivery. EtpA is highly immunogenic resulting in robust antibody responses following natural infection and experimental challenge of human volunteers with ETEC. To understand how EtpA directs ETEC-blood group A interactions and stimulates adaptive immunity, we mutated EtpA, mapped its glycosylation by mass-spectrometry (MS), isolated polyclonal (pAbs) and monoclonal antibodies (mAbs) from vaccinated mice and ETEC-infected human volunteers, and determined structures of antibody-EtpA complexes by cryo-electron microscopy. Both bgA and mAbs that inhibited EtpA-bgA interactions and ETEC adhesion, bound to the C-terminal repeat domain highlighting this region as crucial for ETEC pathogen-host interaction. MS analysis uncovered extensive and heterogeneous N-linked glycosylation of EtpA and cryo-EM structures revealed that mAbs directly engage these unique glycan containing epitopes. Finally, electron microscopy-based polyclonal epitope mapping revealed antibodies targeting numerous distinct epitopes on N and C-terminal domains, suggesting that EtpA vaccination generates responses against neutralizing and decoy regions of the molecule. Collectively, we anticipate that these data will inform our general understanding of pathogen-host glycan interactions and adaptive immunity relevant to rational vaccine subunit design.

Iliac vein recanalisation and stenting accelerate healing of venous leg ulcers associated with severe venous outflow obstruction.

Obstruction involving the iliac veins and/or inferior vena cava is highly comorbid in patients with chronic venous leg ulcers and is a barrier to healing. Intervention with venous stenting is recommended to promote wound healing; however, there is limited data to quantify the effects of venous outflow restoration on wound healing. We retrospectively identified patients with venous ulcers and comorbid venous outflow obstruction. Data regarding demographics, wound size, degree of obstruction, interventions, wound healing and recurrence were collected. Intervention was performed when possible and patients were grouped based on whether or not the venous outflow was reopened successfully and maintained for at least 1 year. Outcomes, including time to wound healing, wound recurrence, stent patency and ulcer-free time, were measured. Patients who maintained a patent venous outflow tract experienced higher rates of wound healing (79.3%) compared to those with persistent outflow obstruction (22.6%) at 12 months (p < 0.001). Ulcer-free time for the first year was also greater with patent venous outflow (7.6 ± 4.4 months versus 1.8 ± 3.0 months, p < 0.0025). Patients with severe obstruction of the venous outflow tract experience poor healing of VLUs despite appropriate wound care. Healing time is improved and ulcer-free time increased after venous intervention with stenting to eliminate obstruction.

Analysis of wound healing time and wound-free period in patients with chronic limb-threatening ischemia treated with and without revascularization.

BACKGROUND: The traditionally reported outcomes for patients with ischemic wounds have centered on amputation-free survival. However, that discounts the importance of other patient-centered outcomes such as the wound healing time (WHT) and wound-free period (WFP). We evaluated the long-term wound outcomes of patients treated for chronic limb-threatening ischemia at our institution. METHODS: From 2014 to 2017, we identified all patients with chronic limb-threatening ischemia and ischemic wounds using symptomatic and hemodynamic criteria. The primary data included the wound size, wound location, WIfI (wound, ischemia, foot infection) grade, WHT, WFP, minor and major amputation, and death. Wounds were not considered healed if the patient had required a major amputation or had died before wound healing. The WHT was calculated as the interval in days between the diagnosis and determination of a healed wound. The WFP was calculated as the interval in days between a healed wound and wound recurrence, major amputation, death, or the end of the study period. A comparison of the wound healing parameters stratified by revascularization status was performed using the Student t test. A generalized linear model adjusted for age, sex, initial wound size, and WIfI grade was used to evaluate the risk of wound healing with and without revascularization. RESULTS: A total of 256 patients had presented with 372 wounds. Of the 256 patients, 48% had undergone revascularization. During the study period, 97 minor amputations and 100 major amputations had been required, and 132 patients had died. The average wound size was 13.9 ± 52.0 cm2; however, for the 155 wounds that had healed, the average size was only 4.0 ± 9.6 cm2 (P = .002). No differences were found in the wound size when stratified by revascularization status (P = .727). Adjusted for the initial wound size, the risk of wound healing was not different when stratified by revascularization (risk ratio, 1.22; 95% confidence interval, 0.80-1.87; P = .354). For those whose wounds had healed, the average WHT and WFP were 173 ± 169 days and 775 ± 317 days, respectively. The WHT was not faster for the revascularized group (155 days vs 188 days; P = .221). When stratified by revascularization status, the rate of wound recurrence was 4.6 vs 8.9 wounds per 100 person-years for the revascularized and nonrevascularized groups, respectively (P = .125). CONCLUSIONS: In our study, we found that, except for patients who presented with severe ischemia, revascularization was not associated with improved rates of wound healing. Among the wounds that healed, regardless of the initial ischemia grade, revascularization was not associated with a faster WHT or longer WFPs.