Postoperative Ustekinumab Drug Levels and Disease Activity in Patients with Crohn's Disease.

AIMS: This study investigated how post-operative ustekinumab levels relate to surgery type, endoscopic, biochemical, and clinical outcomes in patients with Crohn's Disease. METHODS: A retrospective study of patients with Crohn's Disease with a disease-related operation between 2016 and 2022 assessed outcomes based on ustekinumab levels. Patients were included if they had an ustekinumab trough level within two years post-operatively. Patients were separated into groups based on whether their ustekinumab trough levels were adequate, defined as ≥ 4 µg/mL, or suboptimal < 4 µg/mL. A subset of patients with ustekinumab levels taken within two years both before and after surgery was compared to non-surgical treatment-escalated controls outside the initial patient set. Harvey-Bradshaw index was used to evaluate clinical disease activity. Rutgeert's and Simple Endoscopic Score for Crohn's Disease was used to evaluate endoscopic disease activity. C-reactive protein and fecal calprotectin values were collected to evaluate the molecular inflammatory disease state. CBC data were used to evaluate anemia. RESULTS: Forty-four patients were identified, which had ustekinumab levels after Crohn's Disease-related surgery. Twelve of these patients had pre-operative levels and were compared to 26 non-surgical treatment-escalated controls. No relationship between ustekinumab levels and endoscopic or clinical disease activity post-operatively was found. This also held true when looking at different surgery types. Adequate levels of ustekinumab post-operatively yielded lower risk of anemia. Surgery itself did not have an impact on ustekinumab levels. CONCLUSIONS: This study provided new insights into how post-operative ustekinumab levels impact several factors in patients having undergone Crohn's disease-related surgery.

The Role of Vitamin D in Patients with Inflammatory Bowel Disease Treated with Vedolizumab.

BACKGROUND: Many clinical factors can contribute to the efficacy of medical therapy in Inflammatory Bowel Disease (IBD). We assessed their effects on the efficacy of vedolizumab therapy in a cohort of patients with IBD. METHODS: We conducted a retrospective study on patients between 18 and 80 years of age with ulcerative colitis (UC) or Crohn's disease (CD) who were seen in the IBD program at Houston Methodist in Houston, TX and treated with vedolizumab for at least 6 months from 2018 to 2022. We investigated factors prior to the initiation of therapy that best predicted treatment response, with an emphasis on vitamin D levels and examined several variables including patients' demographics and clinical information on disease location and severity and nutritional status before and after the initiation of vedolizumab. Post-treatment data were gathered after a minimum of 6 months of vedolizumab therapy. The clinical parameters used for the study were the Harvey-Bradshaw Index for CD and the Activity Index for UC. RESULTS: There were 88 patients included in our study of whom 44 had CD and 44 had UC.; median age was 39.5 (31.0, 53.25) years; 34% patients were male; and 80.7% were Caucasian. All patients received an induction dosing of 300 mg vedolizumab at 0, 2, and 6 weeks then maintenance dosing as standard of care every 8 weeks. Among UC patients with vitamin D ≥ 30 ng/mL at the initiation of vedolizumab therapy, UC Endoscopic Index of Severity (UCEIS) scores after 6 months of therapy were significantly lower than in those who had low pre-treatment vitamin D levels (1.5 vs. 3.87, p = 0.037). After treatment, vitamin D levels improved more significantly in the higher pre-treatment vitamin D group, with a median level of 56 ng/mL, than in the lower pre-treatment vitamin D group, with a median level of only 31 ng/mL (p = 0.007). In patients with CD with vitamin D ≥ 30 ng/mL at the initiation of vedolizumab therapy, we found higher iron saturation (12 vs. 25%, p = 0.008) and higher vitamin B12 levels (433.5 vs. 885 pg/mL, p = 0.003) than in those with vitamin D < 30 ng/mL. After treatment, CD patients with high pre-treatment vitamin D levels had significantly higher vedolizumab levels (27.35 vs. 14.35 µg/mL, p = 0.045) than those with low pre-treatment vitamin D. Post-treatment scores and inflammatory markers in CD patients (HBI, CRP, ESR, and SES-CD) were lower in those who had lower baseline vitamin D. CONCLUSIONS: Our results show higher pre-treatment vitamin D levels predicted significant endoscopic improvement in patients with ulcerative colitis (UC). Improving vitamin D levels lowered C-reactive protein levels significantly in CD patients. Higher vitamin D levels were seen after treatment in both UC and CD patients. Vitamin D can play a role in clinical and endoscopic outcomes and should be assessed routinely and optimized in patients with IBD.

Residual stress and osmotic swelling of the periodontal ligament.

Osmotic swelling and residual stress are increasingly recognized as important factors in soft tissue biomechanics. Little attention has been given to residual stress in periodontal ligament (PDL) biomechanics despite its rapid growth and remodeling potential. Those tissues that bear compressive loads, e.g., articular cartilage, intervertebral disk, have received much attention related to their capacities for osmotic swelling. To understand residual stress and osmotic swelling in the PDL, it must be asked (1) to what extent, if any, does the PDL exhibit residual stress and osmotic swelling, and (2) if so, whether residual stress and osmotic swelling are mechanically significant to the PDL's stress/strain behavior under external loading. Here, we incrementally built a series of computer models that were fit to uniaxial loading, osmotic swelling and residual stretch data. The models were validated with in vitro shear tests and in vivo tooth-tipping data. Residual stress and osmotic swelling models were used to analyze tension and compression stress (principal stress) effects in PDL specimens under external loads. Shear-to-failure experiments under osmotic conditions were performed and modeled to determine differences in mechanics and failure of swollen periodontal ligament. Significantly higher failure shear stresses in swollen PDL suggested that osmotic swelling reduced tension and thus had a strengthening effect. The in vivo model's first and third principal stresses were both higher with residual stress and osmotic swelling, but smooth stress gradients prevailed throughout the three-dimensional PDL anatomy. The addition of PDL stresses from residual stress and osmotic swelling represents a unique concept in dental biomechanics.