Health Expenditures After Bariatric Surgery: A Retrospective Cohort Study.

OBJECTIVE: Bariatric surgery leads to substantial improvements in weight and weight-related conditions, but prior literature on post-surgical health expenditures is equivocal. In a retrospective cohort study, we compared expenditures between surgical and matched non-surgical patients. SUMMARY BACKGROUND DATA AND METHODS: In a retrospective study, total, outpatient, inpatient and medication expenditures 3 years before and 5.5 years after surgery were compared between 22,698 bariatric surgery (n=7,127 RYGB, 15,571 sleeve gastrectomy) patients from 2012-2019 and 66,769 matched non-surgical patients, using generalized estimating equations. We also compared expenditures between patients receiving the two leading surgical procedures in weighted analyses. RESULTS: Surgical and non-surgical cohorts were well matched, 80-81% female, with mean body mass index (BMI) of 44, and mean age of 47 (RYGB) and 44 (SG) years. Estimated total expenditures were similar between surgical and non-surgical groups 3 years before surgery ($27 difference, 95% confidence interval (CI): -42, 102)), increased 6 months prior to surgery for surgical patients, and decreased below pre-period levels for both groups after 3-5.5 years to become similar (difference at 5.5 y=-$61, 95% CI: -166, 52). Long-term outpatient expenditures were similar between groups. Surgical patients' lower long-term medication expenditures ($314 lower at 5.5 y, 95% CI: -419, -208) were offset by a higher risk of hospitalization. Total expenditures were similar between RYGB and SG patients 3.5 to 5.5 years after surgery. CONCLUSIONS: Bariatric surgery translated into lower medication expenditures than matched controls, but not lower overall long-term expenditures. Expenditure trends appear similar for the two leading bariatric operations.

Incorporating Acute Conditions into Risk-Adjustment for Provider Profiling: The Case of the US News and World Report Best Hospitals Rankings Methodology.

Several years ago, the US News and World Report changed their risk-adjustment methodology, now relying almost exclusively on chronic conditions for risk adjustment. The impacts of adding selected acute conditions like pneumonia, sepsis, and electrolyte disorders ("augmented") to their current risk models ("base") for 4 specialties-cardiology, neurology, oncology, and pulmonology-on estimates of hospital performance are reported here. In the augmented models, many acute conditions were associated with substantial risks of mortality. Compared to the base models, the discrimination and calibration of the augmented models for all specialties were improved. While estimated hospital performance was highly correlated between the 2 models, the inclusion of acute conditions in risk-adjustment models meaningfully improved the predictive ability of those models and had noticeable effects on hospital performance estimates. Measures or conditions that address disease severity should always be included when risk-adjusting hospitalization outcomes, especially if the goal is provider profiling.

Linking Medicare-Medicaid Claims for Patient-Centered Outcomes Research Among Dual-Eligible Beneficiaries.

BACKGROUND: Evaluation of Medicare-Medicaid integration models' effects on patient-centered outcomes and costs requires multiple data sources and validated processes for linkage and reconciliation. OBJECTIVE: To describe the opportunities and limitations of linking state-specific Medicaid and Centers for Medicare & Medicaid Services administrative claims data to measure patient-centered outcomes for North Carolina dual-eligible beneficiaries. RESEARCH DESIGN: We developed systematic processes to (1) validate the beneficiary ID linkage using sex and date of birth in a beneficiary ID crosswalk, (2) verify dates of dual enrollment, and (3) reconcile Medicare-Medicaid claims data to support the development and use of patient-centered outcomes in linked data. PARTICIPANTS: North Carolina Medicaid beneficiaries with full Medicaid benefits and concurrent Medicare enrollment (FBDE) between 2014 and 2017. MEASURES: We identified need-based subgroups based on service use and eligibility program requirements. We calculated utilization and costs for Medicaid and Medicare, matched Medicaid claims to Medicare service categories where possible, and reported outcomes by the payer. Some services were covered only by Medicaid or Medicare, including Medicaid-only covered home and community-based services (HCBS). RESULTS: Of 498,030 potential dual enrollees, we verified the linkage and FBDE eligibility of 425,664 (85.5%) beneficiaries, including 281,174 adults enrolled in Medicaid and Medicare fee-for-service. The most common need-based subgroups were intensive behavioral health service users (26.2%) and HCBS users (10.8%) for adults under age 65, and HCBS users (20.6%) and nursing home residents (12.4%) for adults age 65 and over. Medicaid funded 42% and 49% of spending for adults under 65 and adults 65 and older, respectively. Adults under 65 had greater behavioral health service utilization but less skilled nursing facility, HCBS, and home health utilization compared with adults 65 and older. CONCLUSIONS: Linkage of Medicare-Medicaid data improves understanding of patient-centered outcomes among FBDE by combining Medicare-funded acute and ambulatory services with Medicaid-funded HCBS. Using linked Medicare-Medicaid data illustrates the diverse patient experience within FBDE beneficiaries, which is key to informing patient-centered outcomes, developing and evaluating integrated Medicare and Medicaid programs, and promoting health equity.

Dementia and Parkinson's disease diagnoses in electronic health records vs. Medicare claims data: a study of 101,980 linked patients.

BACKGROUND: Medicare claims and electronic health record data are both commonly used for research and clinical practice improvement; however, it is not known how concordant diagnoses of neurodegenerative diseases (NDD, comprising dementia and Parkinson's disease) are in these data types. Therefore, our objective was to determine the sensitivity and specificity of neurodegenerative disease (NDD) diagnoses contained in structured electronic health record (EHR) data compared to Medicare claims data. METHODS: This was a retrospective cohort study of 101,980 unique patients seen at a large North Carolina health system between 2013-2017, which were linked to 100% North and South Carolina Medicare claims data, to evaluate the accuracy of diagnoses of neurodegenerative diseases in EHRs compared to Medicare claims data. Patients age > 50 who were enrolled in fee-for-service Medicare were included in the study. Patients were classified as having or not having NDD based on the presence of validated ICD-CM-9 or ICD-CM-10 codes associated with NDD or claims for prescription drugs used to treat NDD. EHR diagnoses were compared to Medicare claims diagnoses. RESULTS: The specificity of any EHR diagnosis of NDD was 99.0%; sensitivity was 61.3%. Positive predictive value and negative predictive value were 90.8% and 94.1% respectively. Specificity of an EHR diagnosis of dementia was 99.0%, and sensitivity was 56.1%. Specificity of an EHR diagnosis of PD was 99.7%, while sensitivity was 76.1%. CONCLUSIONS: More research is needed to investigate under-documentation of NDD in electronic health records relative to Medicare claims data, which has major implications for clinical practice (particularly patient safety) and research using real-world data.

Non-overdose acute care hospitalizations for opioid use disorder among commercially-insured adults: a retrospective cohort study.

BACKGROUND: Acute care inpatient admissions outside of psychiatric facilities have been increasingly identified as a critical touchpoint for opioid use disorder (OUD) treatment. We sought to describe non-opioid overdose hospitalizations with documented OUD and examine receipt of post-discharge outpatient buprenorphine. METHODS: We examined acute care hospitalizations with an OUD diagnosis in any position within US commercially-insured adults age 18-64 years (IBM MarketScan claims, 2013-2017), excluding opioid overdose diagnoses. We included individuals with ≥ 6 months of continuous enrollment prior to the index hospitalization and ≥ 10 days following discharge. We described demographic and hospitalization characteristics, including outpatient buprenorphine receipt within 10 days of discharge. RESULTS: Most (87%) hospitalizations with documented OUD did not include opioid overdose. Of 56,717 hospitalizations (49,959 individuals), 56.8% had a primary diagnosis other than OUD, 37.0% had documentation of an alcohol-related diagnosis code, and 5.8% end in a self-directed discharge. Where opioid use disorder was not the primary diagnosis, 36.5% were due to other substance use disorders, and 23.1% were due to psychiatric disorders. Of all non-overdose hospitalizations who had prescription medication insurance coverage and who were discharged to an outpatient setting (n = 49, 237), 8.8% filled an outpatient buprenorphine prescription within 10 days of discharge. CONCLUSIONS: Non-overdose OUD hospitalizations often occur with substance use disorders and psychiatric disorders, and very few are followed by timely outpatient buprenorphine. Addressing the OUD treatment gap during hospitalization may include implementing medication for OUD for inpatients with a broad range of diagnoses.

Neighborhood socioeconomic deprivation, healthcare access, and 30-day mortality and readmission after sepsis or critical illness: findings from a nationwide study.

BACKGROUND: To determine if neighborhood socioeconomic deprivation independently predicts 30-day mortality and readmission for patients with sepsis or critical illness after adjusting for individual poverty, demographics, comorbidity burden, access to healthcare, and characteristics of treating healthcare facilities. METHODS: We performed a nationwide study of United States Medicare beneficiaries from 2017 to 2019. We identified hospitalized patients with severe sepsis and patients requiring prolonged mechanical ventilation, tracheostomy, or extracorporeal membrane oxygenation (ECMO) through Diagnosis Related Groups (DRGs). We estimated the association between neighborhood socioeconomic deprivation, measured by the Area Deprivation Index (ADI), and 30-day mortality and unplanned readmission using logistic regression models with restricted cubic splines. We sequentially adjusted for demographics, individual poverty, and medical comorbidities, access to healthcare services; and characteristics of treating healthcare facilities. RESULTS: A total of 1,526,405 admissions were included in the mortality analysis and 1,354,548 were included in the readmission analysis. After full adjustment, 30-day mortality for patients was higher for those from most-deprived neighborhoods (ADI 100) compared to least deprived neighborhoods (ADI 1) for patients with severe sepsis (OR 1.35 95% [CI 1.29-1.42]) or with prolonged mechanical ventilation with or without sepsis (OR 1.42 [95% CI 1.31, 1.54]). This association was linear and dose dependent. However, neighborhood socioeconomic deprivation was not associated with 30-day unplanned readmission for patients with severe sepsis and was inversely associated with readmission for patients requiring prolonged mechanical ventilation with or without sepsis. CONCLUSIONS: A strong association between neighborhood socioeconomic deprivation and 30-day mortality for critically ill patients is not explained by differences in individual poverty, demographics, measured baseline medical risk, access to healthcare resources, or characteristics of treating hospitals.

Neighborhood Socioeconomic Disadvantage, Healthcare Access, and Outcomes of Hospitalizations for Common Pulmonary Conditions: A National Study of Medicare Beneficiaries.

Rationale: Understanding how systemic forces and environmental exposures impact patient outcomes is critical to advancing health equity and improving population health for patients with pulmonary disease. This relationship has not yet been assessed at the population level nationally. Objectives: To determine whether neighborhood socioeconomic deprivation is independently associated with 30-day mortality and readmission for hospitalized patients with pulmonary conditions, after controlling for demographics, access to healthcare resources, and characteristics of admitting healthcare facilities. Methods: This was a retrospective, population-level cohort study of 100% of United States nationwide Medicare inpatient and outpatient claims from 2016-2019. Patients were admitted for one of four pulmonary conditions (pulmonary infections, chronic lower respiratory disease, pulmonary embolism, and pleural and interstitial lung diseases), defined by diagnosis-related group. The primary exposure was neighborhood socioeconomic deprivation, measured by the area deprivation index. The main outcomes were 30-day mortality and 30-day unplanned readmission, defined by Centers for Medicare and Medicaid Services methodologies. Generalized estimating equations were used to estimate logistic regression models for the primary outcomes, addressing clustering by hospital. A sequential adjustment strategy was first adjusted for age, legal sex, Medicare-Medicaid dual eligibility, and comorbidity burden, then adjusted for metrics of access to healthcare resources, and finally adjusted for characteristics of the admitting healthcare facility. Results: After full adjustment, patients from low socioeconomic status neighborhoods had greater 30-day mortality after admission for pulmonary embolism (odds ratio [OR], 1.26; 95% confidence interval [CI], 1.13-1.40), respiratory infections (OR, 1.20; 95% CI, 1.16-1.25), chronic lower respiratory disease (OR, 1.31; 95% CI, 1.22-1.41), and interstitial lung disease (OR, 1.15; 95% CI, 1.04-1.27) when compared to patients from the highest SES neighborhoods. Low neighborhood socioeconomic status was also associated with 30-day readmission for all groups except the interstitial lung disease group. Conclusions: Neighborhood socioeconomic deprivation may be a key factor driving poor health outcomes for patients with pulmonary diseases.

Health Care Use and Spending Among Need-Based Subgroups of Medicare Beneficiaries With Full Medicaid Benefits.

Importance: Beneficiaries dual eligible for Medicare and Medicaid account for a disproportionate share of expenditures due to their complex care needs. Lack of coordination between payment programs creates misaligned incentives, resulting in higher costs, fragmented care, and poor health outcomes. Objective: To inform the design of integrated programs by describing the health care use and spending for need-based subgroups in North Carolina's full benefit, dual-eligible population. Design, Setting, and Participants: This cross-sectional study using Medicare and North Carolina Medicaid 100% claims data (2014-2017) linked at the individual level included Medicare beneficiaries with full North Carolina Medicaid benefits. Data were analyzed between 2021 and 2022. Exposure: Need-based subgroups: community well, home- and community-based services (HCBS) users, nursing home (NH) residents, and intensive behavioral health (BH) users. Measures: Medicare and Medicaid utilization and spending per person-year (PPY). Results: The cohort (n = 333 240) comprised subgroups of community well (64.1%, n = 213 667), HCBS users (15.0%, n = 50 095), BH users (15.2%, n = 50 509), and NH residents (7.5%, n = 24 927). Overall, 61.1% reported female sex. The most common racial identities included Asian (1.8%), Black (36.1%), and White (58.7%). Combined spending for Medicare and Medicaid was $26 874 PPY, and the funding of care was split evenly between Medicare and Medicaid. Among need-based subgroups, combined spending was lowest among community well at $19 734 PPY with the lowest portion (38.5%) of spending contributed by Medicaid ($7605). Among NH residents, overall spending ($68 359) was highest, and the highest portion of spending contributed by Medicaid (70.1%). Key components of spending among HCBS users' combined total of $40 069 PPY were clinician services on carrier claims ($14 523) and outpatient facility services ($9012). Conclusions and relevance: Federal and state policy makers and administrators are developing strategies to integrate Medicare- and Medicaid-funded health care services to provide better care to the people enrolled in both programs. Substantial use of both Medicare- and Medicaid-funded services was found across all need-based subgroups, and the services contributing a high proportion of the total spending differed across subgroups. The diversity of health care use suggests a tailored approach to integration strategies with comprehensive set benefits that comprises Medicare and Medicaid services, including long-term services and supports, BH, palliative care, and social services.

Factors Associated With Receipt of Molecular Testing and its Impact on Time to Initial Systemic Therapy in Metastatic Non-Small Cell Lung Cancer.

BACKGROUND: Despite recommendations for molecular testing irrespective of patient characteristics, differences exist in receipt of molecular testing for oncogenic drivers amongst metastatic non-small cell lung cancer (mNSCLC) patients. Exploration into these differences and their effects on treatment is needed to identify opportunities for improvement. PATIENTS AND METHODS: We conducted a retrospective cohort study of adult patients diagnosed with mNSCLC between 2011 and 2018 using PCORnet's Rapid Cycle Research Project dataset (n = 3600). Log-binomial, Cox proportional hazards (PH), and time-varying Cox regression models were used to ascertain whether molecular testing was received, and time from diagnosis to molecular testing and/or initial systemic treatment in the context of patient age, sex, race/ethnicity, and multiple comorbidities status. RESULTS: The majority of patients in this cohort were ≤ 65 years of age (median [25th, 75th]: 64 [57, 71]), male (54.3%), non-Hispanic white individuals (81.6%), with > 2 comorbidities in addition to mNSCLC (54.1%). About half the cohort received molecular testing (49.9%). Patients who received molecular testing had a 59% higher probability of initial systemic treatment than patients who were yet to receive testing. Multiple comorbidity status was positively associated with receipt of molecular testing (RR, 1.27; 95% CI 1.08, 1.49). CONCLUSION: Receipt of molecular testing in academic centers was associated with earlier initiation of systemic treatment. This finding underscores the need to increase molecular testing rates amongst mNSCLC patients during a clinically relevant period. Further studies to validate these findings in community centers are warranted.

Association Between Neighborhood Socioeconomic Status and 30-Day Mortality and Readmission for Patients With Common Neurologic Conditions.

BACKGROUND AND OBJECTIVES: Patients of low individual socioeconomic status (SES) are at a greater risk of unfavorable health outcomes. However, the association between neighborhood socioeconomic deprivation and health outcomes for patients with neurologic disorders has not been studied at the population level. Our objective was to determine the association between neighborhood socioeconomic deprivation and 30-day mortality and readmission after hospitalization for various neurologic conditions. METHODS: This was a retrospective study of nationwide Medicare claims from 2017 to 2019. We included patients older than 65 years hospitalized for the following broad categories based on diagnosis-related groups (DRGs): multiple sclerosis and cerebellar ataxia (DRG 058-060); stroke (061-072); degenerative nervous system disorders (056-057); epilepsy (100-101); traumatic coma (082-087), and nontraumatic coma (080-081). The exposure of interest was neighborhood SES, measured by the area deprivation index (ADI), which uses socioeconomic indicators, such as educational attainment, unemployment, infrastructure access, and income, to estimate area-level socioeconomic deprivation at the level of census block groups. Patients were grouped into high, middle, and low neighborhood-level SES based on ADI percentiles. Adjustment covariates included age, comorbidity burden, race/ethnicity, individual SES, and sex. RESULTS: After exclusions, 905,784 patients were included in the mortality analysis and 915,993 were included in the readmission analysis. After adjustment for age, sex, race/ethnicity, comorbidity burden, and individual SES, patients from low SES neighborhoods had higher 30-day mortality rates compared with patients from high SES neighborhoods for all disease categories except for multiple sclerosis: magnitudes of the effect ranged from an adjusted odds ratio of 2.46 (95% CI 1.60-3.78) for the nontraumatic coma group to 1.23 (95% CI 1.19-1.28) for the stroke group. After adjustment, no significant differences in readmission rates were observed for any of the groups. DISCUSSION: Neighborhood SES is strongly associated with 30-day mortality for many common neurologic conditions even after accounting for baseline comorbidity burden and individual SES. Strategies to improve health equity should explicitly consider the effect of neighborhood environments on health outcomes.

Racial/ethnic disparities in dementia incidence, outcomes, and health-care utilization.

INTRODUCTION: Racial/ethnic disparities exist in many aspects of health care, but data on racial/ethnic disparities for neurodegenerative diseases (NDDs), such as dementia and Parkinson's disease (PD), are limited. METHODS: We used North and South Carolina Medicare claims from 2013 to 2017 to evaluate disparities in incidence of NDDs and in health-care utilization and outcomes for patients with NDDs. RESULTS: Disparities in incidence of NDD between Black and White beneficiaries narrowed by 0.37 per 100 person-years from 2014 to 2017. After thorough covariate adjustment, Black beneficiaries had a 4% higher risk of all-cause hospitalization, spent 8% more days in skilled nursing facilities and 14% fewer days in hospice facilities, were 38% less likely to receive physical/occupational therapy services, were 8% less likely to receive dementia medications, and were 19% less likely to receive PD medications than White beneficiaries. DISCUSSION: Effective system-level approaches to promote health equity in NDD diagnosis, treatment, and outcomes are clearly needed. HIGHLIGHTS: Racial disparities in neurodegenerative disease incidence narrowed between 2014 and 2017. Black patients were less likely than White patients to receive hospice services. Black patients were less likely than White patients to receive physical therapy. Black patients were less likely than White patients to receive Alzheimer's disease or Parkinson's disease medications. There is a shortage of neurologists in counties with high dementia incidence.

Caregiving in U.S. Gulf States During Natural Disasters and COVID-19.

Objectives: To ascertain common experiences and needs of a diverse group of caregivers challenged by hurricanes/floods and COVID-19. Methods: In-depth interviews with unpaid caregivers in U.S. Southeast/Gulf Coast states who had experienced caregiving during a natural disaster and during COVID-19. Results: Caregivers report challenges including daily living disruption, altered social supports, complicated health management, additional disaster planning, and emotional/financial impacts. Caregivers suggested helpful resources, policy options, and preparatory tools at individual, local, and health system levels to mediate discontinuity. Conclusions: Our data describe combined caregiver experiences of hurricanes/floods and the pandemic. Caregivers experience unique burdens related to care recipient diagnosis, location, and veteran status. Access to community supports varies as they manage the tasks required for care recipients' health and safety. Our findings indicate the need for public health reinforcement of caregiving though caregiver pre-planning and targeted support. Bolstering understanding of communities' caregiving capacity though first responder trainings and caregiver registries may enhance health and safety.

Individual and program Characteristics May Drive Variability in Outcomes After Caregivers Participate in a Tailored Support Intervention.

Critically needed programs designed to support family caregivers have shown inconsistent reductions in stress and burden. To explore drivers of improvement in caregiver outcomes after participation in a support intervention we analyzed data from a one-on-one, tailored problem-solving intervention targeting caregiver wellbeing (2015-2019, n = 503). We explored data patterns across 21 individual, household, and program-level variables using elastic net regression to identify drivers of improvements, and their relative importance. Baseline subjective burden, baseline depressive symptom scores, baseline caregiver problem solving, African American race, and site and coach fixed effects were the most consistent drivers of changes across the explored caregiver outcomes. Caregiver and program characteristics may be promising avenues to target to decrease distress and burden during intervention design. Interventions focusing on highly distressed caregivers may lead to greater improvements. More research is needed to identify how site or interventionists characteristics drive positive intervention effects.

Silica Exposure Differentially Modulates Autoimmunity in Lupus Strains and Autoantibody Transgenic Mice.

Inhalational exposure to crystalline silica is linked to several debilitating systemic autoimmune diseases characterized by a prominent humoral immune component, but the mechanisms by which silica induces autoantibodies is poorly understood. To better understand how silica lung exposure breaks B cell tolerance and unleashes autoreactive B cells, we exposed both wildtype mice of healthy C57BL/6 and lupus-prone BXSB, MRL, and NZB strains and mice carrying an autoantibody transgene on each of these backgrounds to instilled silica or vehicle and monitored lung injury, autoimmunity, and B cell fate. Silica exposure induced lung damage and pulmonary lymphoid aggregates in all strains, including in genetically diverse backgrounds and in autoantibody transgenic models. In wildtype mice strain differences were observed in specificity of autoantibodies and site of enhanced autoantibody production, consistent with genetic modulation of the autoimmune response to silica. The unique autoantibody transgene reporter system permitted the in vivo fate of autoreactive B cells and tolerance mechanisms to be tracked directly, and demonstrated the presence of transgenic B cells and antibody in pulmonary lymphoid aggregates and bronchoalveolar lavage fluid, respectively, as well as in spleen and serum. Nonetheless, B cell enumeration and transgenic antibody quantitation indicated that B cell deletion and anergy were intact in the different genetic backgrounds. Thus, silica exposure sufficient to induce substantial lung immunopathology did not overtly disrupt central B cell tolerance, even when superimposed on autoimmune genetic susceptibility. This suggests that silica exposure subverts tolerance at alternative checkpoints, such as regulatory cells or follicle entry, or requires additional interactions or co-exposures to induce loss of tolerance. This possibility is supported by results of differentiation assays that demonstrated transgenic autoantibodies in supernatants of Toll-like receptor (TLR)7/TLR9-stimulated splenocytes harvested from silica-exposed, but not vehicle-exposed, C57BL/6 mice. This suggests that lung injury induced by silica exposure has systemic effects that subtly alter autoreactive B cell regulation, possibly modulating B cell anergy, and that can be unmasked by superimposed exposure to TLR ligands or other immunostimulants.

Altered toll-like receptor responsiveness underlies a dominant heritable defect in B cell tolerance in autoimmune New Zealand Black mice.

Systemic lupus erythematosus is a debilitating autoimmune disease in which autoantibodies and autoreactive T cells destroy kidneys and other organs. Disease is clinically and genetically heterogeneous, suggesting that underlying mechanisms vary between patients. We previously used an autoantibody transgenic mouse reporter system to examine the effect of different autoimmune backgrounds on B-cell tolerance, failure of which is a fundamental defect in lupus. We identified a defect consistent with reversible anergy induced by endotoxin stimulation of B cells from Ig transgenic New Zealand Black (NZB) mice. Herein we report that the tolerance defect is revealed by TLR7 and TLR9 as well as TLR4 ligands, with additive effect, and is partially reversed by Mek inhibition. Gene expression analysis reveals significant differences in transcription of multiple TLR pathway genes and ptpn22 in stimulated NZB compared to B6 B cells. Additionally, the defect is detected in Ig transgenic NZB F1 hybrid strains (NZBxNZW)F1 and (B6xNZB)F1. These results implicate an inherited defect wherein NZB anergic B cells maintain coordinated TLR/BCR signaling that permits autoantibody production. Agents targeting these pathways may have therapeutic benefit in the subset of lupus patients that manifest similar defects in B-cell regulation.

A murine Ig light chain transgene reveals IGKV3 gene contributions to anti-collagen types IV and II specificities.

A subset of autoimmune diseases result from autoantibodies targeting epitopes on matrix collagen. The most extensively studied are anti-glomerular basement membrane glomerulonephritis (or its systemic counterpart Goodpasture's disease) that destroys kidneys and lungs, and rheumatoid arthritis that leads to disabling arthritis. Autoantibodies in these disorders bind evolutionarily conserved conformational epitopes on the noncollagenous domain 1 (NC1) of the alpha3 chain of type IV [alpha3(IV)NC1] collagen in glomerular and alveolar basement membranes, and on native or citrullinated type II collagen (CII) in joint cartilage, respectively. The genetic origins of pathogenic anti-collagen B cells in these diseases is unknown, but observations from murine models raise the possibility that they overlap despite distinct in vivo immunopathologies. Monoclonal autoantibodies isolated from mice immunized with alpha3(IV)NC1 collagen or CII show a biased use of Ig light chains (LC) encoded by genes of the IGKV3 subgroup (previously Vk21 family), paired with diverse Ig heavy chains. To further explore this relationship and determine if a single murine IGKV3 LC independently predisposes to both anti-collagen responses, we generated a novel transgenic (Tg) C57BL/6 mouse that expresses a productively rearranged IGKV3-encoded LC, termed mLCV3-Tg, in conjunction with endogenously rearranged Ig heavy chains. Tg mice are also genetically deficient in endogenous kappa chains to permit tracking of the mLCV3 transgene. We show that mLCV3-Tg mice are susceptible to humoral autoimmunity against both collagen chains. Anti-alpha3(IV)NC1 collagen, but not anti-CII, mLCV3-encoded Ig are detected in serum of unmanipulated Tg mice, while Toll-like receptor ligands induce secretion of mLCV3-Tg autoantibodies of both collagen specificities from splenocytes ex vivo. This indicates developmental survival of mLCV3-Tg B cells reactive with each antigen, and is consistent with production of the two anti-collagen autoIg from distinct B cell populations. Reduced B cell numbers, low serum Ig kappa levels, low cell surface Ig kappa density, and abundant endogenous lambda chain expression suggest that subsets of IGKV3-encoded B cells are regulated in vivo by mechanisms that include deletion, anergy, and LC editing. These results support the notion that murine IGKV3 LCs contribute structural fitness to antigen binding sites that support diverse anti-collagen autoimmune responses, that these responses are regulated in vivo, and that these cells can nonetheless readily escape immune regulation.

Uncommon structural motifs dominate the antigen binding site in human autoantibodies reactive with basement membrane collagen.

Autoantibodies mediate organ destruction in multiple autoimmune diseases, yet their origins in patients remain poorly understood. To probe the genetic origins and structure of disease-associated autoantibodies, we engrafted immunodeficient mice with human CD34+ hematopoietic stem cells and immunized with the non-collagenous-1 (NC1) domain of the alpha3 chain of type IV collagen. This antigen is expressed in lungs and kidneys and is targeted by autoantibodies in anti-glomerular basement membrane (GBM) nephritis and Goodpasture syndrome (GPS), prototypic human organ-specific autoimmune diseases. Using Epstein Barr virus transformation and cell fusion, six human anti-alpha3(IV)NC1 collagen monoclonal autoantibodies (mAb) were recovered, including subsets reactive with human kidney and with epitopes recognized by patients' IgG. Sequence analysis reveals a long to exceptionally long heavy chain complementarity determining region3 (HCDR3), the major site of antigen binding, in all six mAb. Mean HCDR3 length is 25.5 amino acids (range 20-36), generated from inherently long DH and JH genes and extended regions of non-templated N-nucleotides. Long HCDR3 are suited to forming noncontiguous antigen contacts and to binding recessed, immunologically silent epitopes hidden from conventional antibodies, as seen with self-antigen crossreactive broadly neutralizing anti-HIV Ig (bnAb). The anti-alpha3(IV)NC1 collagen mAb also show preferential use of unmutated variable region genes that are enriched among human chronic lymphocytic leukemia antibodies that share features with natural polyreactive Ig. Our findings suggest unexpected relationships between pathogenic anti-collagen Ig, bnAb, and autoreactive Ig associated with malignancy, all of which arise from B cells expressing unconventional structural elements that may require transient escape from tolerance for successful expansion.

Recovery of a human natural antibody against the noncollagenous-1 domain of type IV collagen using humanized models.

BACKGROUND: Anti-glomerular basement membrane nephritis and Goodpasture syndrome result from autoantibody (Ab)-mediated destruction of kidney and lung. Ab target the noncollagenous 1 (NC1) domain of alpha3(IV) collagen, but little is known about Ab origins or structure. This ignorance is due in part to the inability to recover monoclonal Ab by transformation of patients' blood cells. The aim of this study was to assess the suitability of two humanized models for this purpose. METHODS: NOD-scid-gamma immunodeficient mice were engrafted either with human CD34+ hematopoietic stem cells (HSC) (Hu-HSC mice) and immunized with alpha3(IV)NC1 collagen containing the Goodpasture epitopes or with nephritis patients' peripheral blood leukocytes (PBL) (Hu-PBL mice). After in vivo immune cell development and/or expansion, recovered human B cells were Epstein Barr virus (EBV)-transformed, screened for antigen (Ag) binding, electrofused with a mouse-human heterohybridoma, subcloned, and human Ab RNA sequenced by PCR after reverse transcription to cDNA. Flow cytometry was used to assess human B cell markers and differentiation in Hu-PBL mice. RESULTS: Sequence analysis of a human Ab derived from an immunized Hu-HSC mouse and reactive with alpha3(IV)NC1 collagen reveals that it is encoded by unmutated heavy and light chain genes. The heavy chain complementarity determining region 3, a major determinant of Ag binding, contains uncommon motifs, including an N-region somatically-introduced highly hydrophobic tetrapeptide and dual cysteines encoded by a uniquely human IGHD2-2 Ab gene segment that lacks a murine counterpart. Comparison of human and mouse autoantibodies suggests that structurally similar murine Ab may arise by convergent selection. In contrast to the Hu-HSC model, transformed human B cells are rarely recovered from Hu-PBL mice, in which human B cells terminally differentiate and lose expression of EBV receptor CD21, thus precluding their transformation and recovery. CONCLUSIONS: Hu-HSC mice reveal that potentially pathogenic B cells bearing unmutated Ig receptors reactive with the NC1 domain on alpha3(IV) collagen can be generated in, and not purged from, the human preimmune repertoire. Uniquely human gene elements are recruited to generate the antigen binding site in at least a subset of these autoantibodies, indicating that humanized models may provide insights inaccessible using conventional mouse models.

Lack of galectin-1 or galectin-3 alters B cell deletion and anergy in an autoantibody transgene model.

Members of the galectin family of proteins have been shown to regulate the development and the function of immune cells. We previously identified the increased expression of galectin-1 and galectin-3 mRNA and protein in anergic B cells relative to their naïve counterparts. To investigate the role of these galectins in maintaining B cell tolerance, we crossed mice deficient in galectin-1 or galectin-3 with mice bearing a lupus autoantigen-binding transgenic (Tg) B cell receptor, using a model with a well-characterized B cell tolerance phenotype of deletion, receptor editing and anergy. Here, we present data showing that the global knockout of galectin-1 or galectin-3 yields subtle alterations in B cell fate in autoantibody Tg mice. The absence of galectin-3 leads to a significant increase in the number of Tg spleen B cells, with the recovery of anti-laminin antibodies from a subset of mice. The B cell number increases further in antibody Tg mice with the dual deficiency of both galectin-1 and galectin-3. Isolated galectin-1 deficiency significantly enhances the proliferation of Tg B cells in response to lipopolysaccharide stimulation. These findings add to the growing body of evidence indicating a role for the various galectin family members, and for galectins 1 and 3 in particular, in the regulation of autoimmunity.