Citations

e24086 Background: Nasal vestibulitis has been infrequently described as a side effect of cancer-directed therapy; however, a preliminary study reported that 71% of patients undergoing taxane chemotherapy experienced nasal vestibulitis symptoms. This natural history trial describes the incidence, characteristics, and severity of nasal vestibulitis symptoms among patients undergoing paclitaxel, docetaxel, and non-taxane chemotherapy. Methods: Eligible participants who reported baseline (prior to starting chemotherapy) nasal symptoms ≤ 2 on a 10-point scale were enrolled in this trial upon initiation of a new treatment regimen, involving paclitaxel or docetaxel, or non-taxane chemotherapy. Participants completed nasal symptom logs each time they received a dose of therapy until either the regimen was stopped or four months had passed. The proportion of patients reporting new nasal symptoms was estimated within each cohort with the 95% exact confidence interval (CI). A cumulative incidence model was utilized to quantify the incidence of treatment-emergent nasal symptoms within each cohort, while controlling for age, sex, smoking history, and history of asthma or allergies. Results: Thirty-five participants received paclitaxel, 21 received docetaxel, and 25 received other types of chemotherapy. 86.4% of participants were female, mean age was 60.2 ± 11.2 years; 93.8% of participants completed 2 or more surveys. A higher percentage of participants in the paclitaxel cohort experienced new nasal vestibulitis symptoms than participants in the other two cohorts. The percentage (95% CI) of participants with nasal symptoms, for patients receiving paclitaxel, docetaxel, and non-taxane chemotherapy were 74.3% (56.7%, 87.5%), 47.6% (25.7%, 70.2%), and 44.0% (24.4%, 65.1%), respectively. Epistaxis was reported by 60% of participants in the paclitaxel cohort. Paclitaxel-receiving participants also reported nasal dryness (48.6%), scabbing (40.0%), and pain (20.0%). Nearly half of participants reported moderate symptoms (4-7 out of a 10-point scale), with 8.6% reporting symptoms as severe (8-10 on a 10-point scale). Conclusions: Nasal vestibulitis is a common side effect of chemotherapy, especially paclitaxel chemotherapy.

Abstract The immune system contains a series of checks and balances that maintain tolerance and prevent autoimmunity. Sialic acid-binding Ig-type lectins (Siglecs) are cell surface receptors found on immune cells and inhibit inflammation by recruiting protein tyrosine phosphatases to ITIMs. Islet-resident macrophages express Siglec-E, and Siglec-E expression decreases on islet-resident macrophages as insulitis progresses in the NOD mouse. The sialyltransferase ST8Sia6 generates α-2,8-disialic acids that are ligands for Siglec-E in vivo. We hypothesized that engaging Siglec-E through ST8Sia6-generated ligands may inhibit the development of immune-mediated diabetes. Constitutive overexpression of ST8Sia6 in pancreatic β cells mitigated hyperglycemia in the multiple low-dose streptozotocin model of diabetes, demonstrating that engagement of this immune receptor facilitates tolerance in the setting of inflammation and autoimmune disease.

Abstract NKAP and HDAC3 are critical for T cell maturation. NKAP and HDAC3 physically associate, and a point mutation in NKAP, NKAP(Y352A), abrogates this interaction. To evaluate the significance of NKAP and HDAC3 association in T cell maturation, transgenic mice were engineered for cre-mediated endogenous NKAP gene deletion coupled to induction of NKAP(Y352A) or a wild type (WT) control transgene, NKAP(WT), in double positive thymocytes or regulatory T cells (Tregs). T cell maturation was normal in mice with endogenous NKAP deletion coupled to NKAP(WT) induction. However, severe defects occurred in T cell and Treg maturation and in iNKT cell development when NKAP(Y352A) was induced, recapitulating NKAP deficiency. Conventional T cells expressing NKAP(Y352A) failed to enter the long-term T cell pool, did not produce cytokines, and remained complement susceptible, whereas Tregs expressing NKAP(Y352A) were eliminated as recent thymic emigrants leading to lethal autoimmunity. Overall, these results demonstrate the significance of NKAP–HDAC3 association in T cells.

Abstract Recent thymic emigrants that fail postpositive selection maturation are targeted by complement proteins. T cells likely acquire complement resistance during maturation in the thymus, a complement-privileged organ. To test this, thymocytes and fresh serum were separately obtained and incubated together in vitro to assess complement deposition. Complement binding decreased with development and maturation. Complement binding decreased from the double-positive thymocyte to the single-positive stage, and within single-positive thymocytes, complement binding gradually decreased with increasing intrathymic maturation. Binding of the central complement protein C3 to wild-type immature thymocytes required the lectin but not the classical pathway. Specifically, MBL2 but not MBL1 was required, demonstrating a unique function for MBL2. Previous studies demonstrated that the loss of NKAP, a transcriptional regulator of T cell maturation, caused peripheral T cell lymphopenia and enhanced complement susceptibility. To determine whether complement causes NKAP-deficient T cell disappearance, both the lectin and classical pathways were genetically ablated. This blocked C3 deposition on NKAP-deficient T cells but failed to restore normal cellularity, indicating that complement contributes to clearance but is not the primary cause of peripheral T cell lymphopenia. Rather, the accumulation of lipid peroxides in NKAP-deficient T cells was observed. Lipid peroxidation is a salient feature of ferroptosis, an iron-dependent nonapoptotic cell death. Thus, wild-type thymocytes naturally acquire the ability to protect themselves from complement targeting by MBL2 with maturation. However, NKAP-deficient immature peripheral T cells remain scarce in complement-deficient mice likely due to ferroptosis.

Abstract Intricate life-versus-death decisions are programmed during T cell development, and the regulatory mechanisms that coordinate their activation and repression are still under investigation. In this study, HDAC3-deficient double-positive (DP) thymocytes exhibit a severe decrease in numbers. The thymic cortex is rich in ATP, which is released by macrophages that clear apoptotic DP thymocytes that fail to undergo positive selection. We demonstrate that HDAC3 is required to repress expression of the purinergic receptor P2X7 to prevent DP cell death. HDAC3-deficient DP thymocytes upregulate the P2X7 receptor, increasing sensitivity to ATP-induced cell death. P2rx7/HDAC3-double knockout mice show a partial rescue in DP cell number. HDAC3 directly binds to the P2rx7 enhancer, which is hyperacetylated in the absence of HDAC3. In addition, RORγt binds to the P2rx7 enhancer and promotes P2X7 receptor expression in the absence of HDAC3. Therefore, HDAC3 is a critical regulator of DP thymocyte survival and is required to suppress P2X7 receptor expression.