Management of Aspirin-Exacerbated Respiratory Disease: What Does the Future Hold?

Aspirin-exacerbated respiratory disease (AERD) is a subtype of chronic rhinosinusitis with polyps (CRSwNP) and asthma with higher recurrence of nasal polyps after surgery and severe asthma. Patients with CRSwNP and asthma should be screened for AERD by detailed history of aspirin/nonsteroidal anti-inflammatory drug reactions and review of medications that may mask aspirin reaction or directly by aspirin challenge. Treatment of AERD may require more intensive therapy, including endoscopic sinus surgery, daily aspirin therapy, leukotriene modifiers, or biologics.

Perioperative management of mastocytosis

PURPOSE

Patients with mastocytosis have an increased risk of anaphylaxis during surgical procedures with general anesthesia. Therefore, we reviewed the anesthesia course of a large cohort of patients with mastocytosis.

METHODS

We retrospectively reviewed adult and pediatric patients with mastocytosis who underwent surgical procedures with general anesthesia at Mayo Clinic from January 1, 2000, through June 30, 2021. We also included any procedures with general anesthesia that occurred during the 3-year period preceding mastocytosis diagnosis and designated the patients who underwent these procedures as having an unknown diagnosis at the time of their surgical procedure. We analyzed whether patients received chronic antimediator treatment for mastocytosis and/or prophylactic medications before the procedures. We also determined whether medications indicative of mastocytosis-related adverse events were intraoperatively administered.

RESULTS

We identified 113 patients who underwent 219 procedures during the study period; 25 procedures were performed before mastocytosis diagnosis. Of 194 procedures in patients with known mastocytosis, patients received chronic antimediator therapy and/or perioperative prophylactic medications for 178 (91.8%) procedures. Among these procedures, 10 were potentially complicated by mast cell activation, which was inferred from administration of inhaled albuterol (n = 3) or intravenous diphenhydramine (n = 8). In addition, there was only one case of intraoperative anaphylaxis which occurred in a patient who underwent anesthesia before mastocytosis diagnosis and therefore did not receive prophylaxis.

CONCLUSION

Intraoperative anaphylaxis can be the first presenting sign of mastocytosis. Patients with mastocytosis who received chronic antimediator therapy and/or preoperative prophylactic medications had an uneventful surgical course.

Risk for Postmarket Black Box Warnings in FDA-Approved Monoclonal Antibodies

Objective

To estimate the potential risk for a future postmarket black box warning (BBW) of US Food and Drug Administration (FDA)-approved monoclonal antibodies (mAbs) because of the importance for medical clinicians to understand mAb risks and benefits, including unknown future risks, especially for recently approved mAbs.

Methods

The complete dates of the study were March 16, 2020, through May 12, 2021. We searched the FDALabel database online and reviewed the scientific literature to determine current and previous FDA-approved mAbs as of March 2020. The BBWs and initial FDA-issued safety warnings were identified. The BBWs were categorized as premarket or postmarket. For mAbs with specific postmarket BBWs, previous FDA labels were evaluated to identify the presence or absence of an initial corresponding specific FDA warning.

Results

In March 2020, a total of 83 mAbs had FDA approval; 33 had BBWs (27 premarket and 13 postmarket BBWs). Of these 33 mAbs, 55 individual specific BBWs existed (36 premarket and 19 postmarket specific warnings). On average, the specific BBWs occurred in the postmarket period at a rate of 3.4% (19/562) per year. Most (73.7%; 14/19) specific postmarket BBWs were preceded by an FDA warning in a median time of 3.61 (interquartile range, 1.36-5.78) years. Specific postmarket BBWs not preceded by a specific FDA product label warning occurred at an average rate of 0.9% (5/562) per year.

Conclusion

Specific postmarket BBWs occurred in FDA-approved mAbs at a rate of 3.4% per year. Specific postmarket BBWs not preceded by a specific FDA product label warning had a rate of 0.9% per year.

Outcomes among patients with COVID-19 and asthma: A systematic review and meta-analysis

Background: It remains unclear if asthma is a risk factor associated with worse outcomes among patients with coronavirus disease 2019 (COVID-19). Methods: We performed a comprehensive database search for studies published from January 1, 2019, to October 2, 2020. We included studies that evaluated outcomes among patients with COVID-19 and underlying asthma. Outcomes of interest included the need for hospitalization, length of hospitalization, intensive care unit (ICU) admission, and death. The meta-analysis was conducted by using random-effects methodology. Results: A total of 389 studies were identified through data base searches. After abstract and full-text screening, 16 observational studies with 92,275 patients were included in the analysis. Of the 16 studies, 15 were retrospective and 1 was a prospective cohort study. The average age was 39.6 years, with 48% female patients. Six of the studies included pediatric patients, and one of these studies only evaluated pediatric patients. One study only evaluated pregnant patients. Among patients with COVID-19, the presence of asthma was not associated with any significant increase in risk of hospitalization (odds ratio [OR] 1.46 [95% confidence interval {CI}, 0.29-7.28]), length of hospitalization (1.59 days [-0.55 to 3.74]), ICU admission (OR 1.65 [95% CI, 0.56-4.17]), or death (OR 0.73 [95% CI, 0.38-1.40]). The overall risk of bias of the included studies was high. Conclusion: Among the patients with COVID-19, asthma did not seem to significantly increase the risk of hospitalization, length of hospitalization, ICU admission, or death.

Temozolomide desensitization followed by metronomic dosing in patients with hypersensitivity

PURPOSE

Temozolomide is the most effective chemotherapy for malignant glioma. Hypersensitivity requiring interruption of therapy may significantly impact patient survival. We have successfully employed temozolomide desensitization followed by metronomic dosing of temozolomide. Our purpose was to report patient characteristics and outcomes in patients with glioma (Grade 2-4) and temozolomide hypersensitivity managed by desensitization and metronomic dosing.

METHODS

We performed an observational study of 15 patients at Mayo Clinic (Rochester) with a diagnosis of glioma who underwent temozolomide desensitization with subsequent metronomic dosing from May 2012 to January 2017. We calculated overall and progression-free survival using the Kaplan-Meier method, and log-rank analyses to assess for differences in survival by WHO Grade or treatment initiation.

RESULTS

Median age at time of desensitization was 49.3 years (26.8-64.7 years). Median follow-up after desensitization was 35.5 months. One patient (6.7%) was unable to resume temozolomide due to recurrent allergy. The median time from first desensitization to discontinuation of metronomic temozolomide was 4.2 months (0-15.2 months). Median OS and PFS for the whole sample were 181.7 months and 44.9 months. For Grade 4, OS was 100% at 1 year, 40% at 3 years, 20% at 5 years; and PFS was 60% at 1 year, 40% at 3 years, and 20% at 5 years.

CONCLUSION

Our results suggest that rapid-desensitization followed by metronomic temozolomide should be considered in patients with glioma who experience hypersensitivity. This strategy provides comparable outcomes to therapy with standard protocols, with the majority of patients able to tolerate temozolomide after desensitization with favorable disease control.

A diagnostic codes-based algorithm improves accuracy for identification of childhood asthma in archival data sets

OBJECTIVE

While a single but truncated ICD code (493) had been widely used for identifying asthma in asthma care and research, it significantly under-identifies asthma. We aimed to develop and validate a diagnostic codes-based algorithm for identifying asthmatics using Predetermined Asthma Criteria (PAC) as the reference.

METHODS

This is a retrospective cross-sectional study which utilized two different coding systems, the Hospital Adaptation of the International Classification of Diseases, Eighth Revision (H-ICDA) and the International Classification of Diseases, Ninth Revision (ICD-9). The algorithm was developed using two population-based asthma study cohorts, and validated in a validation cohort, a random sample of the 1976-2007 Olmsted County Birth Cohort. Performance of the diagnostic codes-based algorithm for ascertaining asthma status against manual chart review for PAC (gold standard) was assessed by determining both criterion and construct validity.

RESULTS

Among eligible 267 subjects of the validation cohort, 50% were male, 70% white, and the median age at last follow-up was 17 (interquartile range, 8.7-24.4) years. Asthma prevalence by PAC through manual chart review was 34%. Sensitivity and specificity of the codes-based algorithm for identifying asthma were 82% and 98% respectively. Associations of asthma-related risk factors with asthma status ascertained by the code-based algorithm were similar to those by the manual review.

CONCLUSIONS

The diagnostic codes-based algorithm for identifying asthmatics improves accuracy of identification of asthma and can be a useful tool for large scale studies in a setting without automated chart review capabilities.

Revision endoscopic sinus surgery rates by chronic rhinosinusitis subtype

BACKGROUND

Revision surgery rates following endoscopic sinus surgery (ESS) range between 7% and 50% and are influenced by many factors. This study investigates ESS outcomes for chronic rhinosinusitis (CRS) subtypes.

METHODS

Retrospective review of adult CRS patients undergoing ESS with a single surgeon (2010-2015) was conducted. Outcomes were analyzed by CRS subtypes.

RESULTS

ESS was performed in 424 CRS patients (CRS with nasal polyps [CRSwNP], n = 170; CRS without polyps [CRSsNP], n = 254). Most patients (309; 72.9%) could not be specifically subtyped; 115 (27.1%) were subtyped as follows: aspirin-exacerbated respiratory disease (AERD), n = 47 (11.1%); allergic fungal sinusitis (AFS), n = 39 (9.2%); immunodeficiency, n = 21 (5.0%); granulomatosis with polyangiitis (GPA), n = 5 (1.2%); and eosinophilic granulomatosis with polyangiitis (EGPA), n = 3 (0.7%). All subgroups experienced clinically meaningful reduction in postoperative 22-item Sino-Nasal Outcome Test (SNOT-22) scores. At median follow-up of 28 months (interquartile range [IQR], 10-47 months), 19 patients (4%) underwent revision ESS (CRSwNP, n = 6; CRSsNP, n = 13). Revision ESS rates were 3.5% and 5.1% for CRSwNP and CRSsNP, respectively. Revision ESS rate for subtypes were: AERD 2%; AFS 2%; immunodeficiency 14%; GPA 40%; EGPA 0%; and "all other CRS" 4% at median follow-up duration of 36, 28, 41, 37, 44, and 26 months, respectively.

CONCLUSION

All CRS subtypes demonstrated clinically meaningful improvement in postoperative SNOT-22 scores following ESS. Our overall revision ESS rate was 4% (3.5% in CRSwNP). AFS, AERD, and EGPA groups demonstrated low revision rates, while immunodeficiency and GPA patients required more revision surgery. A contemporary understanding of CRSwNP subtypes facilitated surgical and medical strategies in improving outcomes for AERD, AFS, and EGPA patients. CRSsNP subtypes with immunodeficiency and GPA merit further investigation to optimize outcomes.

SNOT-22-based clusters in chronic rhinosinusitis without nasal polyposis exhibit distinct endotypic and prognostic differences

BACKGROUND

Endotypic and prognosticating features of chronic rhinosinusitis without nasal polyposis (CRSsNP) are poorly understood. Our objectives were to use an unbiased symptom-based approach to: (1) study symptoms, clinical and endotypic features; and (2) identify features predicating outcomes from endoscopic sinus surgery (ESS).

METHODS

Clinical, computed tomography (CT), histopathology, and 22-item Sino-Nasal Outcome Test (SNOT-22) data was collected on 146 adult CRSsNP patients who underwent ESS. Unsupervised network modeling of presurgical SNOT-22 scores was performed to classify symptom-based clusters. Subject characteristics and post-ESS SNOT-22 scores were compared between clusters.

RESULTS

Baseline characteristics of the subject population were as follows: females, 56.2%; revision ESS status in 35%; asthma prevalence, 32.6%; median Lund-Mackay CT score, 8; and median SNOT-22 total score, 43. Network mapping and unsupervised clustering of preoperative SNOT-22 scores revealed 4 clusters: (A) severely burdened with high scores in all 4 subdomains; (B) moderately burdened with high scores in the rhinologic subdomain; (C) moderately burdened with high scores in psychological-sleep subdomains; and (D) mildly burdened. The number of previous ESS and asthma prevalence differed significantly between clusters; CT scores were similar. Asthma burden and tissue eosinophilia were greatest in cluster A (p = 0.03). All groups showed significant improvement at 3 months post-ESS (p < 0.0001). At 6 months, patients in cluster C tended to worsen.

CONCLUSION

SNOT-22-based network modeling of CRSsNP patients yielded 4 clusters with distinct features. Asthma prevalence and tissue eosinophilia were highest in the cluster with highest SNOT-22 scores. All patients showed significant improvement from ESS at 3 months; those with high sleep-psychosocial symptoms tended to show worsening at 6 months.

Gender-specific analysis of outcomes from endoscopic sinus surgery for chronic rhinosinusitis

BACKGROUND

Women electing endoscopic sinus surgery (ESS) for chronic rhinosinusitis (CRS) report higher symptom burden but have lower computed tomography (CT) scores. Gender-specific analysis of outcomes from ESS therefore merits further study. The objective of this work was to study gender-specific differences in outcomes from ESS for CRS by analyzing preoperative and postoperative 22-item Sino-Nasal Outcome Test (SNOT-22) scores.

METHODS

Data from adult CRS patients electing ESS (2011-2013) were retrospectively collected. SNOT-22 total, rhinologic/nonrhinologic subdomain, and individual item scores were analyzed for gender-specific differences.

RESULTS

Two hundred and forty-eight patients met study criteria (mean age 55.4 years; 49.6% female). Preoperatively, mean Lund-Mackay CT score was 11.1; average total SNOT-22 score was 41.9. Compared to men, women had lower CT score (10.2 vs 12.0; p = 0.004) but higher total SNOT-22 score (44.7 vs 39.1; p = 0.02). Both genders showed significant improvement in total SNOT-22 scores at 3, 6, 12, and 24 months following ESS (p < 0.001), with largely similar slopes of improvement. The greatest improvement occurred at 3 months (SNOT-22 decreased by 25.4 points), with stable improvement after 12 months (SNOT-22 decreased by 21.3 points). Higher total SNOT-22 scores in females were noted preoperatively and until 6 months post-ESS; these were driven by rhinologic and nonrhinologic-otolaryngic subdomain items. No gender differences in anxiety/depression prevalence or psychological subdomain scores were noted preoperatively or postoperatively.

CONCLUSION

Both male and female CRS patients showed significant and durable symptom relief following ESS. Women reported higher symptom burden prior to surgery, and in the early postoperative period. However, after 1-year post-ESS, both genders showed similar symptom scores. The trend and magnitude of improvement were similar in both genders.

Immunological profiling in chronic rhinosinusitis with nasal polyps reveals distinct VEGF and GM-CSF signatures during symptomatic exacerbations

BACKGROUND

The mechanisms and immune pathways associated with chronic rhinosinusitis (CRS) are not fully understood. Immunological changes during acute exacerbation of CRS may provide valuable clues to the pathogenesis and perpetuation of the disease.

OBJECTIVE

To characterize local and systemic immune responses associated with acute worsening of sinonasal symptoms during exacerbation in CRS with nasal polyps (CRSwNP) compared to controls.

METHODS

This was a non-interventional prospective study of individuals with CRSwNP and normal controls. Subjects underwent a baseline visit with collection of nasal secretions, nasal washes, and serum specimens. Within 3 days of acute worsening of sinonasal symptoms, subjects underwent a study visit, followed by a post-visit 2 weeks later. The sinonasal outcome test-22 (SNOT-22) scores and immunological parameters in the specimens were analysed using a novel, unsupervised learning method and by conventional univariate analysis.

RESULTS

Both CRSwNP patients and control subjects showed a significant increase in SNOT-22 scores during acute exacerbation. Increased nasal levels of IL-6, IL-5, and eosinophil major basic protein were observed in CRSwNP patients. A network analysis of serum specimens revealed changes in a set of immunological parameters, which are distinctly associated with CRSwNP but not with controls. In particular, systemic increases in VEGF and GM-CSF levels were notable and were validated by a conventional analysis.

CONCLUSIONS

CRSwNP patients demonstrate distinct immunological changes locally and systemically during acute exacerbation. Growth factors VEGF and GM-CSF may be involved in the immunopathogenesis of subjects with CRS and nasal polyps experiencing exacerbation.

Refractory intraoperative hypotension with elevated serum tryptase

Severe intraoperative hypotension has been reported in patients on angiotensin-converting enzyme inhibitors and angiotensin II receptor subtype 1 antagonists. We describe a patient on lisinopril who developed refractory intraoperative hypotension associated with increased serum tryptase level suggesting mast cell activation (allergic reaction). However, allergology workup ruled out an allergic etiology as well as mastocytosis, and hypotension recalcitrant to treatment was attributed to uninterrupted lisinopril therapy. Elevated serum tryptase was attributed to our patient's chronic renal insufficiency.

Antigen-specific effector CD4 T lymphocytes school lamina propria dendritic cells to transfer innate tolerance

Dendritic cells (DCs) have been shown to play a major role in oral tolerance, and this function has been associated with their ability to produce anti-inflammatory cytokines and to induce suppressive regulatory T cells. In this study, we demonstrate that upon oral administration of Ag, lamina propia (LP) DCs engage specific T cells and acquire a novel mechanism by which they transfer tolerance against diverse T cell specificities. Indeed, when Ig-myelin oligodendrocyte glycoprotein (MOG) carrying the MOG(35-55) epitope was orally administered into either T cell-sufficient or -deficient mice, only the T cell-sufficient hosts yielded CD8α(+) and CD8α(-) LP DCs that were able to transfer tolerance to a variety of MHC class II-restricted effector T cells. Surprisingly, these LP DCs upregulated programmed cell death ligand 1 during the initial interaction with MOG-specific T cells and used this inhibitory molecule to suppress activation of T cells regardless of Ag specificity. Furthermore, oral Ig-MOG was able to overcome experimental autoimmune encephalomyelitis induced with CNS homogenate, indicating that the DCs are able to modulate disease involving diverse T cell specificities. This previously unrecognized attribute potentiates DCs against autoimmunity.

T cell dynamics during induction of tolerance and suppression of experimental allergic encephalomyelitis

The cell dynamics associated with induction of peripheral T cell tolerance remain largely undefined. In this study, an in vivo model was adapted to two-photon microscopy imaging, and T cell behavior was analyzed on tolerogen-induced modulation. FcγR-deficient (FcγR(-/-)) mice were unable to resist or alleviate experimental allergic encephalomyelitis when treated with Ig-myelin oligodendrocyte glycoprotein (MOG) tolerogen, an Ig carrying the MOG35-55 peptide. However, when FcγR(+/+) dendritic cells (DCs) are adoptively transferred into FcγR(-/-) mice, uptake and presentation of Ig-MOG occurs and the animals were able to overcome experimental allergic encephalomyelitis. We then fluorescently labeled FcγR(+/+) DCs and 2D2 MOG-specific TCR-transgenic T cells, transferred them into FcγR(-/-) mice, administered Ig-MOG, and analyzed both T cell-DC contact events and T cell motility. The results indicate that tolerance takes place in lymphoid organs, and surprisingly, the T cells do not become anergic but instead have a Th2 phenotype. The tolerant Th2 cells displayed reduced motility after tolerogen exposure similar to Th1 cells after immunization. However, the Th2 cells had higher migration speeds and took longer to exhibit changes in motility. Therefore, both Th1 immunity and Th2 tolerance alter T cell migration on Ag recognition, but the kinetics of this effect differ among the subsets.

Fetal exposure to high-avidity TCR ligand enhances expansion of peripheral T regulatory cells

Lately, it has become clear that regulatory T cells (Tregs) play a major role in the maintenance of peripheral tolerance and control of autoimmunity. Despite these critical functions, the process underlying the development of Tregs remains largely undefined. Herein, altered peptide ligand (APL) variants derived from the proteolipid protein-1 (PLP1) epitope were expressed on immunoglobulins (Igs) and the resulting Ig-APLs were used to deliver the APLs from mother to fetus through the maternal placenta to influence thymic T cell selection. This delivery system was then adapted to the SJL/J mouse, a strain that expresses only the DM20 form of PLP, which lacks the dominant PLP1 epitope in the thymus during fetal and neonatal development. This model, which restores thymic T cell selection for PLP1, was then used to determine whether affinity plays a role in the development of Tregs. The findings show that fetal exposure to low-affinity peptide ligand was unable to drive development of Tregs while variants with higher affinity to the TCR resulted in significant seeding of the periphery with mature, naive Tregs. Thus, contrary to pathogenic T cells, Tregs require avid TCR-ligand interaction to undergo thymic development and maturation.

Early effector T cells producing significant IFN-gamma develop into memory

Currently, transition of T cells from effector to memory is believed to occur as a consequence of exposure to residual suboptimal Ag found in lymphoid tissues at the waning end of the effector phase and microbial clearance. This led to the interpretation that memory arises from slightly activated late effectors producing reduced amounts of IFN-gamma. In this study, we show that CD4 T cells from the early stage of the effector phase in which both the Ag and activation are optimal also transit to memory. Moreover, early effector T cells that have undergone four divisions expressed significant IL-7R, produced IFN-gamma, and yielded rapid and robust memory responses. Cells that divided three times that had marginal IL-7R expression and no IFN-gamma raised base level homeostatic memory, whereas those that have undergone only two divisions and produced IFN-gamma yielded conditioned memory despite low IL-7R expression. Thus, highly activated early effectors generated under short exposure to optimal Ag in vivo develop into memory, and such transition is dependent on a significant production of the cell's signature cytokine, IFN-gamma.

In trans T cell tolerance diminishes autoantibody responses and exacerbates experimental allergic encephalomyelitis

A number of Ag-specific approaches have been developed that ameliorate experimental allergic encephalomyelitis (EAE), an animal model for the human autoimmune disease multiple sclerosis. Translation to humans, however, remains a consideration, justifying the search for more insight into the mechanism underlying restoration of self-tolerance. Ig-proteolipid protein (PLP) 1 and Ig-myelin oligodendrocyte glycoprotein (MOG) are Ig chimeras carrying the encephalitogenic PLP 139-151 and MOG 35-55 amino acid sequence, respectively. Ig-PLP1 ameliorates EAE in SJL/J (H-2(s)) mice while Ig-MOG modulates the disease in C57BL/6 (H-2(b)) animals. In this study, we asked whether the chimeras would suppress EAE in F(1) mice expressing both parental MHC alleles and representing a polymorphism with more relevance to human circumstances. The results show that Ig-MOG modulates both PLP1 and MOG peptide-induced EAE in the F(1) mice, whereas Ig-PLP1 counters PLP1 EAE but exacerbates MOG-induced disease. This in trans aggravation of MOG EAE by Ig-PLP1 operates through induction of PLP1-specific T cells producing IL-5 that sustained inhibition of MOG-specific Abs leading to exacerbation of EAE. Thus, in trans T cell tolerance, which should be operative in polymorphic systems, can aggravate rather than ameliorate autoimmunity. This phenomenon possibly takes place through interference with protective humoral immunity.

Innocuous IFNgamma induced by adjuvant-free antigen restores normoglycemia in NOD mice through inhibition of IL-17 production

The role of Th17 cells in type I diabetes (TID) remains largely unknown. Glutamic acid decarboxylase (GAD) sequence 206–220 (designated GAD2) represents a late-stage epitope, but GAD2-specific T cell receptor transgenic T cells producing interferon γ (IFNγ) protect against passive TID. Because IFNγ is known to inhibit Th17 cells, effective presentation of GAD2 peptide under noninflammatory conditions may protect against TID at advanced disease stages. To test this premise, GAD2 was genetically incorporated into an immunoglobulin (Ig) molecule to magnify tolerance, and the resulting Ig-GAD2 was tested against TID at different stages of the disease. The findings indicated that Ig-GAD2 could not prevent TID at the preinsulitis phase, but delayed TID at the insulitis stage. More importantly, Ig-GAD2 sustained both clearance of pancreatic cell infiltration and β-cell division and restored normoglycemia when given to hyperglycemic mice at the prediabetic stage. This was dependent on the induction of splenic IFNγ that inhibited interleukin (IL)-17 production. In fact, neutralization of IFNγ led to a significant increase in the frequency of Th17 cells, and the treatment became nonprotective. Thus, IFNγ induced by an adjuvant free antigen, contrary to its usual inflammatory function, restores normoglycemia, most likely by localized bystander suppression of pathogenic IL-17–producing cells.

Distinct subsets of dendritic cells drive tolerance in two models of CD4 T cell mediated autoimmunity (129.14)

Dendritic cells (DCs) are professional antigen presenting cells that are capable of presenting both self and foreign antigens to T cells thereby inducing either tolerance or immunity respectively. What is still not clear is whether T cell tolerance requires a specific subset or any population of DCs can drive tolerance. To address this question different subsets of DCs were tested for suppression of autoimmunity in two major animal models- type I diabetes (T1D) and experimental allergic encephalomyelitis (EAE).

There are 3 major subsets of DCs in spleen- CD8α+, CD8α−CD4+ and CD8α−CD4−. In this study we investigated the ability of these subsets to induce tolerance in TID and EAE. Indeed the CD8α−CD4− DC subset mediated protection against diabetes in non-obese diabetic (NOD) mice. In fact, mice had reduced destructive infiltration within the islets and the antigen-specific lymphocytes showed reduced proliferation and an increase in IFNγ and IL-10 response. Surprisingly, in EAE it is the CD8α−CD4+ DC subset that supported protection against the disease. The lymphocytes from treated mice displayed more of a Th1 biased response. Both the protective subsets were mature and expressed significant levels of class II MHC and costimulatory molecules. However, the subsets trafficked differently to spleen and draining lymph nodes. Thus, distinct DC subsets drive tolerance in the two models of autoimmunity despite the fact that both diseases are mediated by CD4+ T cells.

Research supported by grants DK65748 and NS37406 from NIH.

Visualizing mechanisms of peripheral tolerance against autoreactive T cells (129.35)

Where and how T cell tolerance happens remains largely undefined. Here, we used an established in vivo model and investigated the site and the mechanisms that govern APC-mediated inactivation of autoreactive T cells.

Fcγ receptor-deficient (FcγR−/−) mice were induced for experimental allergic encephalomyelitis (EAE), with a myelin oligodendrocyte glycoprotein (MOG) 35-55 peptide and when the disease became apparent the mice were given FcγR+/+ APCs and treated with Ig-MOG, a tolerogenic Ig expressing MOG peptide. Under this regimen the mice were able to reverse their EAE only when given FcγR+/+ APCs that can present Ig-MOG and carry out T cell tolerance. This system was then used to visualize encounter of the APCs with the pathogenic T cells. The results indicate that tolerance occurs in a time dependent fashion when both the T cells and APCs have accumulated in sufficient number at the encounter site but unlike immunity, can take place in the non-draining lymph nodes. Two-Photon microscopy analysis revealed that tolerized T cells exhibit organ-specific changes in motility, pattern of migration and trafficking which could be related to functional matters as tolerance manifest the form of Th2 deviation in the lymph node and anergy in the spleen.

Research supported by grant NS37406 from NIH.

MHC polymorphism translates T cell tolerance into B cell autoimmunity. (131.29)

Experimental allergic encephalomyelitis (EAE) is a mouse model for human multiple sclerosis (MS). While effective treatments of EAE have been developed, adapting these for use in human MS has proven difficult and therefore investigations into this model continue. Here, we examine the effects of MHC polymorphism on the control of tolerance. Our previous studies have shown that treatment of EAE with immunoglobulins (Ig) containing proteolipid protein (PLP) or myelin oligodendrocyte glycoprotein (MOG) epitopes reverses ongoing disease in both SJL/J and C57Bl/6 mice. We used F1(SJL/J x Bl/6) mice to test Ig-PLP and Ig-MOG for reversal of compatible as well as “in trans” EAE wherein disease induced by MOG epitope is treated with Ig-PLP and EAE induced by PLP epitope is treated with Ig-MOG. The findings indicated that EAE induced in F1 mice by PLP is successfully treated with Ig-PLP or Ig-MOG. However, an asymmetrical effect was observed for the treatment of MOG EAE whereby Ig-MOG reverses MOG EAE while Ig-PLP exacerbated MOG induced EAE. The mechanism underlying disease exacerbation correlated with a cytokine-induced Ig class switch among anti-MOG antibodies during treatment with Ig-PLP.

Research supported by grant NS37406 from NIH.

Treg Development and Suppression of Experimental Allergic Encephalomyelitis (129.28)

Many autoimmune disorders have been linked to a lack in T regulatory cells. As such, an understanding of how these cells develop and mature is critical. While thymic T cell selection has been described, this process remains largely undefined for Tregs. Since only the DM20 form of proteolipid protein (PLP) is expressed in the thymus during fetal and neonatal life, thymic selection against PLP139-151 which is missing in DM20 is not operative during those periods. PLP139-151 (designated PLP1) as well as PLP1 derived altered peptide with degenerate affinity to PLP1-specific T cells were expressed on immunoglobulin (Ig) and the resulting chimeras were used to cross the maternal placenta, deliver the peptides from mother to fetus, and restore peptide selection during the fetal and neonatal period. This model was then used to determine whether Tregs are subject to thymic selection and to gauge the affinity required for such selection. The findings indicate that selection of functional Tregs requires high affinity. Indeed, Ig chimeras harboring high avidity peptides facilitated development of Tregs that conferred protection against experimental allergic encephalomyelitis (EAE) while chimeras incorporating low affinity peptide did not drive selection of Tregs and the animals remained susceptible to EAE.