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Objective There is an unmet need for therapies that target the underlying pathophysiology of osteoarthritis (OA). However, defining appropriate measures for clinical trials of such therapies is challenging. Our objective is to propose concept clinical endpoints that directly capture clinical benefit in this setting and evaluate the feasibility of their use. Methods This analysis used the multi-center, longitudinal, observational Osteoarthritis Initiative (OAI) database. OAI participants primarily had knee OA, with follow-up of up to nine years and assessments of joints, surgical interventions, performance outcomes, and patient-reported outcomes (PROs). We examined this dataset to identify existing outcome measures of direct clinical benefit. We evaluated the feasibility of conducting trials using these candidate endpoints by estimating incidence rates and resulting required sample sizes and study durations in time-to-event analyses. Results We identified candidate endpoints based on total knee replacement (TKR) and composite endpoints defined by TKR and conservative thresholds of PROs of pain and function. Using time to TKR as an endpoint, a study with an average follow-up time of three years requires approximately 3,000 to 18,000 subjects depending on effect size. Alternatively, a composite endpoint such as 'time to TKR or severe pain or severely impaired functioning', the required sample sizes ranged from approximately 2,000 to 11,000 for a three-year study. Conclusion The proposed concept endpoints can reliably and feasibly evaluate effectiveness of therapies for this unmet need. In particular, the composite endpoint approach can substantially reduce sample sizes (up to approximately 40%) compared to the use of TKR alone.

OBJECTIVE: To summarize proceedings of a workshop convened to discuss the current state of science in the disease of osteoarthritis (OA), identify the knowledge gaps, and examine the developmental and regulatory challenges in bringing these products to market. DESIGN: Summary of the one-day workshop held virtually on June 22nd, 2021. RESULTS: Speakers selected by the Planning Committee presented data on the current approach to assessment of OA therapies, biomarkers in OA drug development, and the assessment of disease progression and long-term benefit. CONCLUSIONS: Demonstrated by numerous failed clinical trials, OA is a challenging disease for which to develop therapeutics. The challenge is magnified by the slow time of onset of disease and the need for clinical trials of long duration and/or large sample size to demonstrate the effect of an intervention. The OA science community, including academia, pharmaceutical companies, regulatory agencies, and patient communities, must continue to develop and test better clinical endpoints that meaningfully reflect disease modification related to long-term patient benefit.

Polyarticular juvenile idiopathic arthritis (pJIA) is a pediatric chronic inflammatory arthritis, much like rheumatoid arthritis (RA) in adults. Drug development for pJIA can potentially be expedited by using extrapolation of efficacy from adult RA; however, the lack of understanding of the response and exposure relationship between pJIA and RA to therapeutic interventions has been a major roadblock. To address this, the objective of our analysis was to conduct a systematic response and exposure comparison between pJIA and RA trials for biologic products. Data from registration RA and pJIA clinical trials (parallel or withdrawal design) for infliximab, tocilizumab, golimumab, and adalimumab were utilized. First, exposure was compared between the pJIA trials and RA pivotal trials. Subsequently, the pJIA vs. RA response similarity was assessed by comparing similar individual subcomponents of the American College of Rheumatology (ACR) scores between the two populations. The exposure comparison demonstrated that at the pJIA trial dose, exposure in pediatric patients was similar to or higher than adults for all biologics evaluated except infliximab, where lower exposure was observed in pJIA patients ≤ 35 kg. Response comparison for individual subcomponents indicated that in a majority of the cases, pJIA response was similar or higher as compared with response from RA trials. Overall, this analysis suggests response similarity between pJIA and RA across the biologic products when exposures are matched between the two populations. These analyses provide support for the use of pharmacokinetic exposure-matching for extrapolation of efficacy from adult RA to pediatric pJIA for the products with established mechanism(s) of action.

The COVID‐19 pandemic caused by infection with SARS‐CoV‐2 has led to more than 600,000 deaths worldwide. Patients with severe disease often experience acute respiratory distress characterized by upregulation of multiple cytokines. Immunomodulatory biological therapies are being evaluated in clinical trials for the management of the systemic inflammatory response and pulmonary complications in patients with advanced stages of COVID‐19. In this review, we summarize the clinical pharmacology considerations in the development of immunomodulatory therapeutic proteins for mitigating the heightened inflammatory response identified in COVID‐19. This article is protected by copyright. All rights reserved

This literature review aims to provide a comprehensive current summary of the pathogenesis, clinical features, disease course, host immune responses, and current investigational antiviral and immunomodulatory pharmacotherapies, in order to facilitate the development of future therapies and measures for prevention and control. This article is protected by copyright. All rights reserved

We evaluated late effects of AdhAQP1 administration in five subjects in a clinical trial for radiation-induced salivary hypofunction (http://www.clinicaltrials.gov/ct/show/NCT00372320?order=). All were identified as initially responding to human aquaporin-1 (hAQP1) gene transfer (Baum et al, 2012). They were followed for 3-4 years after AdhAQP1 delivery to one parotid gland. At intervals we examined salivary flow, xerostomic symptoms, saliva composition, vector presence and efficacy in the targeted gland, clinical laboratory data, and adverse events. All displayed marked increases (71-500% above baseline) in parotid flow 3-4.7 years after treatment, with improved symptoms for ~ 2-3 years. There were some changes in [Na+] and [Cl−] consistent with elevated salivary flow, but no uniform changes in secretion of key parotid proteins. There were no clinically significant adverse events, nor consistent negative changes in laboratory parameters. One subject underwent a core needle biopsy of the targeted parotid gland 3.1 years post treatment and displayed evidence of hAQP1 protein in acinar, but not duct, cell membranes. All subjects responding to hAQP1 gene transfer initially had benefits for much longer times. First generation adenoviral vectors typically yield transit effects, but these data show beneficial effects can continue years after parotid gland delivery.

Determination of appropriate pharmacokinetic end point to bridge different dosing regimens is often a challenge when developing a new route of administration. Trough concentrations (Ctrough) are often considered the most relevant PK end point to predict efficacy (ACR20/DAS28) in the treatment of rheumatoid arthritis for biologics. However, no systematic research has been conducted to evaluate this approach. We developed a novel strategy to predict the most relevant PK variables that may be used to support a change in the route of administration for biological products. Our analysis indicated that matching only Ctrough when switching from intravenous dosing to subcutaneous dosing with decreasing dosing interval may result in a lower treatment response. If only average concentration (Cave) is considered as the relevant variable, our analysis showed that treatment response may be worsened when switching from subcutaneous dosing to intravenous dosing with increasing dosing interval. The study results demonstrated that matching a single pharmacokinetic end point (Ctrough or Cave) may not be sufficient to ensure efficacy when switching between intravenous dosing and subcutaneous dosing. A practical novel pharmacokinetic bridging approach is provided to support a change in the route of administration for biological products.

Objectives The autonomic nervous system (ANS) modulates exocrine gland function. Available data show poor correlation between the degree of exocrine gland function and destruction in primary Sjogren’s syndrome (pSS) suggesting other mechanisms, such as autonomic dysfunction may be important in these patients. We performed a comprehensive analysis of sympathoneural and sympathetic cholinergic function in well-characterized patients with pSS.

The goal of a development programme for a biosimilar product is to prove its biosimilarity to the reference product, rather than independently establish its safety and efficacy. In this Perspectives article, the authors describe the US FDA's rigorous approach to the assessment of biosimilarity for proposed biosimilar therapeutic proteins, including those intended to treat rheumatologic conditions. Biologic products have revolutionized the management of many rheumatic diseases, but access to these products might be limited by their relatively high costs. The US Biologics Price Competition and Innovation Act of 2009, which is contained within the Patient Protection and Affordable Care Act, established an abbreviated pathway for licensure by the FDA of biologic products that are demonstrated to be biosimilar to or interchangeable with FDA-licensed biologic products, termed reference products. This law allows for the approval of biosimilar biologic products, which are expected to increase access to treatment for patients, and ensuring the implementation of this Act is a high priority for the FDA. In this Perspectives article we describe the considerations for approval of proposed biosimilar products, including those to treat rheumatological conditions, by describing the FDA's rigorous approach to assessment of biosimilarity.

Objectives The purpose of this study was to examine the humoral and cellular immune reactivity to adenoviral vector (AdhAQP1) administration in the human parotid gland over the first 42 days of a clinical gene therapy trial. Methods Of eleven treated subjects, five were considered as positive responders (Baum et al, 2012). Herein, we measured serum neutralizing antibody titers, circulating cytotoxic lymphocytes, and lymphocyte proliferation in peripheral blood mononuclear cells. Additionally, after adenoviral vector stimulation of lymphocyte proliferation, we quantified secreted cytokine levels. Results Responders showed little to modest immune reactivity during the first 42 days following gene transfer. Additionally, baseline serum neutralizing antibody titers to serotype 5-adenovirus generally were not predictive of a subject's response to parotid gland administration of AdhAQP1. Cytokine profiling from activated peripheral blood mononuclear cells could not distinguish responders and non-responders. Conclusions The data are the first to describe immune responses after adenoviral vector administration in a human parotid gland. Importantly, we found that modest (2–3 fold) changes in systemic cell-mediated immune reactivity did not preclude positive subject responses to gene transfer. However, changes beyond that level likely impeded the efficacy of gene transfer.

No conventional therapy exists for salivary hypofunction in surviving head and neck cancer patients with Radiation Therapy Oncology Group late grade 2–3 toxicity. We conducted a phase I clinical trial to test the safety and biologic efficacy of serotype 5, adenoviral-mediated aquaporin-1 cDNA transfer to a single previously irradiated parotid gland in 11 subjects using an open label, single-dose, dose-escalation design (AdhAQP1 vector; four dose tiers from 4.8 × 10 7 to 5.8 × 10 9 vector particles per gland). Treated subjects were followed at scheduled intervals. Multiple safety parameters were measured and biologic efficacy was evaluated with measurements of parotid salivary flow rate. Symptoms were assessed with a visual analog scale. All subjects tolerated vector delivery and study procedures well over the 42-d study period reported. No deaths, serious adverse events, or dose-limiting toxicities occurred. Generally, few adverse events occurred, and all were considered mild or moderate. No consistent changes were found in any clinical chemistry and hematology parameters measured. Objective responses were seen in six subjects, all at doses 9 vector particles per gland. Five of these six subjects also experienced subjective improvement in xerostomia. AdhAQP1 vector delivery to a single parotid gland was safe and transfer of the hAQP1 cDNA increased parotid flow and relieved symptoms in a subset of subjects.

Wiskott-Aldrich syndrome (WAS) is a rare X-linked disorder caused by mutations in the WAS gene. Glomerulonephritis is a frequent complication, however, histopathological data from affected patients is scarce because the thrombocytopenia that affects most patients is a contraindication to renal biopsies. We found that WASp-deficient mice develop proliferative glomerulonephritis reminiscent of human IgA nephropathy (IgAN). We examined whether increased aberrant IgA production is associated with the development of glomerulonephritis in WASp-deficient mice. Serum IgA and IgA production by splenic B cells was increased in WASp-deficient mice compared to wild-type (WT) mice. A lectin-binding study revealed a reduced ratio of sialylated and galactosylated IgA in the sera from old WASp-deficient mice. Circulating IgA-containing immune complexes showed significantly higher titers in WASp-deficient mice compared to WT mice. These results indicate that the increased IgA production and aberrant glycosylation of IgA may be critically involved in the pathogenesis of glomerulonephritis in WAS.

Autoimmunity is a surprisingly common complication of primary immunodeficiencies, yet the molecular mechanisms underlying this clinical observation are not well understood. One widely known example is provided by Wiskott-Aldrich syndrome (WAS), an X-linked primary immunodeficiency disorder caused by mutations in the gene encoding the WAS protein (WASp) with a high incidence of autoimmunity in affected patients. WASp deficiency affects T-cell antigen receptor (TCR) signaling and T-cell cytokine production, but its role in TCR-induced apoptosis, one of the mechanisms of peripheral immunologic tolerance, has not been investigated. We find that WASp-deficient mice produce autoantibodies and develop proliferative glomerulonephritis with immune complex deposition as they age. We also find that CD4+ T lymphocytes from WASp-deficient mice undergo reduced apoptosis after restimulation through the TCR. While Fas-induced cell death is normal, WASp deficiency affects TCR-induced secretion of Fas ligand (FasL) and other components of secretory granules by CD4+ T cells. These results describe a novel role of WASp in regulating TCR-induced apoptosis and FasL secretion and suggest that WASp-deficient mice provide a good model for the study of autoimmune manifestations of WAS and the development of more specific therapies for these complications.

Background Radiation-induced salivary hypofunction is a common side-effect of treatment for head and neck cancers. Patients suffer significant morbidity and there is no suitable conventional therapy. We are conducting a Phase I clinical trial, using a first-generation serotype 5 adenoviral (Ad5) vector encoding human aquaporin-1 (AdhAQP1) to treat such patients. One week after the administration of AdhAQP1 to an enrolled, generally healthy patient, E1-containing adenovirus was detected in parotid saliva. Methods The real-time quantitative polymerase chain reactuion (PCR) was used to measure the Ad5 E1 gene and AdhAQP1 in saliva and serum. PCR and sequencing were used to characterize viral/vector DNA extracted from saliva. The presence of infectious adenovirus was assessed by the inoculation of A549 cells with aliquots of saliva. Serum Ad5 neutralizing antibodies were measured by the inhibition of 293-cell transduction with an Ad5 vector encoding luciferase. Multiple clinical evaluations were performed. Results On day 7 after AdhAQP1 delivery, low levels of the Ad5 E1 gene were detected in parotid saliva (82 copies/µl). In addition, significant levels of AdhAQP1 were also detected (1.5 × 103 copies/µl). The patient was asymptomatic and subsequent analysis of parotid saliva samples prior to day 7 and after day 7 until day 42 was negative for both virus and vector. No virus or vector was detected in serum at any time. Detailed PCR analyses of DNA extracted from the day 7 parotid saliva sample suggested the absence of a recombination event, and no infectious virus was found. Conclusions The patient most likely had a latent Ad5 infection in the targeted parotid gland that was activated after gene transfer and was without clinical consequence. Published in 2009 by John Wiley & Sons, Ltd.

Although it may seem paradoxical, primary immunodeficiency disorders are frequently complicated by autoimmune and inflammatory conditions. These conditions pose significant diagnostic and therapeutic challenges for clinicians caring for these patients. There have been a number of new insights into how immunodeficiencies can predispose to autoimmunity, and rheumatologists should understand the basis for and manifestations of autoimmunity in primary immunodeficiency disorders to more effectively care for these patients.A number of mechanisms have recently been found to link primary immunodeficiencies and autoimmunity, including increased homeostatic proliferation in primary immunodeficiencies associated with lymphopenia and defects in regulatory T cells in the Wiskott-Aldrich syndrome. Primary immunodeficiencies that affect the innate immune system can also lead to inappropriate inflammation through impairing negative regulatory mechanisms in innate immune cells.The realization that primary immunodeficiencies can also impair negative regulation of immune responses has provided a new framework for the understanding of autoimmunity associated with these conditions. These insights may lead to new, more targeted therapies for autoimmune complications in primary immunodeficiency patients.

Single nucleotide polymorphisms in the STAT4 gene have recently been shown to be associated with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Primary Sjögren's syndrome (pSS) is a related autoimmune disease thought to have a pathogenesis similar to these diseases. To test the hypothesis that the variant haplotype of STAT4 seen in RA and SLE is also associated with pSS, we genotyped rs7574865, the most strongly disease-associated SNP in the variant STAT4 haplotype, in 124 Caucasian pSS subjects and compared them to 1143 Caucasian controls. The disease-associated T allele was more common in chromosomes of the pSS patients (29.6%) than in controls (22.3%), leading to a P-value for association of 0.01. These results implicate polymorphisms in the STAT4 gene in the pathogenesis of pSS.

Background A 23-year-old white woman with a 3-year history of systemic lupus erythematosus and a 15-month history of lupus nephritis and retinal vasculitis was successfully treated with antibiotics for Pseudomonas aeruginosa pneumonia while on moderate doses of corticosteroids. Even though her pneumonia had improved, she developed acute changes in her mental status that rapidly progressed to encephalopathy with coma. Investigations Physical examination, fundoscopic examination, laboratory tests for metabolic abnormalities, cerebrospinal fluid analysis, microbiology and serologic testing, electroencephalogram, tests for IgM and IgG anticardiolipin antibodies, neuroimaging including CT of the brain and T1-weighted MRI before and after gadolinium contrast, and flow-attenuated inversion recovery MRI. Diagnosis Vasculitis of the central nervous system associated with systemic lupus erythematosus. Management Intravenous methylprednisolone 1,000 mg/day for 3 days, one dose of intravenous pulse cyclophosphamide 750 mg/m2, intravenous immunoglobulin 400 mg/kg/day for 4 days, plasmapheresis on alternate days for five cycles, and prednisone 40 mg/day. She continued monthly doses of intravenous pulse cyclophosphamide and intravenous pulse methylprednisolone for 6 months, followed by maintenance infusions every 3 months over 2 years. Prednisone was tapered over 18 months. Cyclophosphamide was discontinued after 2 years because of poor bone-marrow tolerance, and was replaced with mycophenolate mofetil 3,000 mg/ day and ciclosporin 50 mg twice daily.

The autonomic nervous system (ANS) modulates exocrine gland function. Available data show poor correlation between the degree of function and destruction of the exocrine glands in primary Sjögren's syndrome (SS), suggesting that other mechanisms, such as autonomic dysfunction, may be important in these patients. The aim of this study was to perform a comprehensive analysis of sympathoneural and sympathetic cholinergic function in well-characterized patients with primary SS.Twenty-one patients with primary SS (mean ± SEM age 44.2 ± 2.8 years) and 13 healthy control subjects (mean ± SEM age 50.8 ± 1.9 years) were assessed during orthostasis and intravenous injection of edrophonium (10 mg). The postganglionic sympathetic cholinergic system was evaluated by assessing sweat production by means of the Quantitative Sudomotor Axon Reflex Test (QSART). Tests of gastric emptying were used to assess the gastrointestinal ANS in primary SS patients.The velocity index and the acceleration index were significantly higher (P 0.05) in patients with primary SS as compared to controls, both before and during the orthostatic and edrophonium tests. Findings of other hemodynamic and neurochemical parameters did not differ between primary SS patients and controls during the orthostasis and edrophonium test; however, the edrophonium-induced saliva increment was lower in primary SS patients (P = 0.002). Abnormally low sweat production was found in 4 primary SS patients but in none of the controls, as determined by the QSART. Gastric empting was delayed in 53% of primary SS patients.We observed subtle differences in several ANS domains, including the gastrointestinal and sympathocholinergic systems, suggesting the presence of a complex ANS dysfunction in primary SS. The impact was greatest on the exocrine glands, with subtle differences in the cardiac parasympathetic function that were independent of glandular inflammation and atrophy, suggesting an alternative mechanism of disease pathogenesis in primary SS.

Salivary glands are an attractive target for gene transfer. Salivary epithelial cells are considered to be highly differentiated and have low rates of cell division (~6 months), affording the opportunity to obtain relatively long-term transgene expression in the absence of genomic integration. Here, we report a novel modified hybrid adenoretroviral vector, which provides stable transgene expression in salivary epithelial cells in vivo for up to 6 months in the absence of genomic integration. This modified hybrid vector, Ad(ΔE1/3)LTR(2)EF1α-hEPO, encodes human erythropoietin (hEPO) and differs from a previously developed hybrid vector, AdLTR(2)EF1α-hEPO, by having more extensive E3 gene deletion. Following direct salivary gland gene transfer by retroductal cannulation, rats transduced with Ad(ΔE1/3)LTR(2)EF1α-hEPO had sustained, elevated serum hEPO levels and hematocrits for 6 months (length of experiment), as compared with ~2 months for animals administered the AdLTR(2)EF1α-hEPO vector. Immunohistochemistry demonstrated that this novel vector could transduce both acinar and ductal cells. Interestingly, the Ad(ΔE1/3)LTR(2)EF1α-hEPO vector evoked much weaker local (salivary gland) immune responses than seen after AdLTR(2)EF1α-hEPO vector delivery, which likely permits its significantly lengthened transgene expression in this tissue.

Understanding the pathogenesis of Sjogren’s syndrome (SS) has proved to be challenging. Both immune-mediated and non-immune-mediated mechanisms have been implicated, which adds to the complexity of the problem. However, recent developments in science and technology have given researchers new opportunities for exploring this fascinating disease. In this chapter we provide a synopsis of the progress in our understanding of the role of the autonomic nervous system in SS pathogenesis, the role of microRNAs as novel tools in advancing research in this field, and gene therapy as potential therapeutic avenue.

Sjogren's syndrome (SjS) patients often have a variety of extraglandular manifestations including neurological and gastrointestinal involvement. In this study we evaluated the diagnostic performance of luciferase immunoprecipitation system (LIPS) that employs mammalian cell-produced recombinant antigens for analyzing SjS autoantibody responses. LIPS testing of mammalian cell-produced La, Ro60 and Ro52 recombinant antigens with defined commercial antibodies demonstrated highly specific immunoprecitation of each antigen without cross-reactivity. Next, sera from 57 SjS and 25 volunteers were evaluated by LIPS against a panel of human autoantigens. LIPS detected robust anti-La antibody levels in 43/57 SjS patients (75% sensitivity) and markedly outperformed an ELISA (46% sensitivity). Profiling of other SjS-associated autoantigens revealed the presence of anti-Ro60, anti-Ro52 in 63% and 61%, of SjS patients, respectively. Interestingly, a C-terminal fragment of Ro52 (Ro52-Delta2), a protein fragment not previously found to be antigenic by ELISA, also showed positive immunoreactivity in 42/57 SjS patients (65% sensitivity). Additional profiling of other autoantigens revealed that certain SjS patients also showed positive immunoreactivity with thyroid peroxidase (14%), AQP-4 (12%) and the H(+)/K(+) gastric ATPase (16%) suggesting potential autoantibody attack of thyroid, neuronal and gastric parietal cells, respectively. These heterogeneous autoantibody responses detected by LIPS in SjS will likely be useful for diagnosis and for evaluating extraglandular manifestations.

To summarize recent developments in our understanding of the pathogenesis of Sjögren's syndrome with a focus on the relationship between inflammation and exocrine dysfunction.Animal models demonstrated the complex interactions between immunologic and nonimmunologic mechanisms in Sjögren's syndrome. Activation of the innate immune system can lead to exocrine dysfunction before or without significant inflammation, whereas in other models, salivary gland function is preserved despite intense inflammatory infiltrates. Primary or inflammation-related abnormalities in water channels contribute to the exocrinopathy. Activation of the innate immunity in patients is demonstrated by the upregulation of type-1 interferon-regulated genes (interferon signature) in peripheral blood and salivary glands and abnormal expression of B cell-activating factor and its receptors. Nonimmune mechanisms that may contribute to exocrine dysfunction include local and systemic androgen deficiency and autonomic nervous system dysfunction. Autoantibodies against the muscarinic acetylcholine receptors would provide a link between autoimmunity and exocrine dysfunction, but the data on the presence, frequency and physiologic affect of these antibodies remain controversial.Recent discoveries from studies in patients with Sjögren's syndrome and animal models suggest a complex interplay between genetic factors, environmental and stochastic events that involve innate and adaptive immunity, hormonal mechanisms and the autonomic nervous system. Some of these findings suggest that exocrine gland dysfunction may precede autoimmunity or represent a process independent from inflammation in the pathogenesis of Sjögren's syndrome.

Irradiation damage to salivary glands is a common iatrogenic consequence of treatment for head and neck cancers. The subsequent lack of saliva production leads to many functional and quality-of-life problems for affected patients and there is no effective conventional therapy. To address this problem, we developed an in vivo gene therapy strategy involving viral vector-mediated transfer of the aquaporin-1 cDNA to irradiation-damaged glands and successfully tested it in two pre-clinical models (irradiated rats and miniature pigs), as well as demonstrated its safety in a large toxicology and biodistribution study. Thereafter, a clinical research protocol was developed that has received approval from all required authorities in the United States. Patients are currently being enrolled in this study.

Hematopoietic stem cells (HSCs) have the capacity for self-renewal and the potential to differentiate into all types of hematopoietic and immune system cells. These features have been successfully used to treat a multitude of hematologic malignancies and nonmalignant diseases such as aplastic anemia, hemoglobinopathies, inborn errors of metabolism and congenital immunodeficiency states. The application of HSC transplantation has been expanded over the past decade to include immune-mediated diseases such as multiple sclerosis, treatment-refractory rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis. Transplantation of HSCs for the treatment of autoimmune diseases aims to fundamentally correct the dysregulated immune system, which could result in sustained clinical remission or potential cure. The use of this approach is currently restricted to clinical research, as there is no standard conditioning regimen to attain these aims in autoimmune diseases. HSC transplantation is associated with inherent morbidity and mortality, both treatment-related and disease-related, and selecting the correct group of patients with the best risk:benefit ratio is a challenging task.

Apoptosis is a physiological process of self-destruction for cells that are damaged or programmed to die. Apoptosis occurs through a series of regulated events that allow cellular debris to be contained and efficiently phagocytosed without initiating a proinflammatory immune response. Recent data have linked physiological apoptosis and the uptake of apoptotic cells by macrophages and some subsets of dendritic cells to the maintenance of peripheral immune tolerance. However, when cells die through necrosis, spilling their intracellular contents, or are infected with various pathogens, activation of antigen-presenting cells and induction of an immune response can occur. Receptors for extrinsic pathogen-associated structures, such as membrane bound Toll-like receptors (TLRs) or intracellular Nod-like receptors (NLRs) can also respond to cross-reactive host molecules from dying cells and may focus autoimmune responses onto these antigens. Several autoimmune disorders have been linked to defects in the apoptotic process. Defective apoptosis of immune cells leads to autoimmunity, as in autoimmune lymphoproliferative syndrome (ALPS) associated with mutations in the death receptor Fas. Defective clearance of apoptotic cell debris can also lead to autoantibody production. We will discuss how cell death and apoptotic cell clearance may affect the finely tuned balance between peripheral immune tolerance and autoimmunity.

We report on the likely mechanism of an exacerbation of neurological symptoms developed during immune reconstitution after autologous non-myeloablative hematopoietic stem cell transplantation in a 33-year-old man with systemic lupus erythematosus- associated recurrent transverse myelitis. Cerebrospinal fluid examination revealed prominent neutrophilic pleocytosis and no evidence of infection or of reactivation of lupus. Following a course of corticosteroid treatment the exacerbation resolved completely and the patient's neurological function continued to improve, resulting in net gain above pre-treatment for over 1 year follow-up without maintenance immunosuppression. Granulocytic invasion of the central nervous system represents a novel and possibly preventable cause of neurological complications during haematologic reconstitution.

The cytochrome P450 CYP1B1 enzyme metabolically activates polycyclic aromatic hydrocarbons and is a major P450 isoenzyme in human monocytes and macrophages. We have shown previously that mice deficient in CYP1B1 were resistant to induced tumors after 7,12-dimethylbenz[a]anthracene exposure. The pathology of aging CYP1B1 null mice on a B6; 129 background was studied in groups of 29 males and 30 females. By 12 months, 50% of the female mice had developed a unusual progressive glomerulonephritis while males had similar renal lesions later in life. This disease followed a sequence of proliferative, membranoproliferative and sclerotic glomerulonephritis. Anti-DNA antibodies were found in the blood of the mice along with immune deposits containing immunoglobulins in subepithelial locations of the glomerular basement membrane. The lesions were unlike those found in aging wild-type B6;129 mice or mice of other strains. We found that macrophages from CYP1B1-null mice were impaired in the phagocytosis of apoptotic, necrotic, and opsonized cells. This suggests a generalized defect in the phagocytic activity of CYP1B1-null mouse macrophages. Male mice also developed a high incidence (62—64%) of histiocytic sarcomas. Our study provides evidence that deficiency of CYP1B1 can play a role in the development of glomerular disease, normal processing of catabolic DNA and tumors of the mononuclear phagocyte system. The function of CYP1B1 in histiocytes and macrophages may involve both self-tolerance and tumor suppression.