CD38 as a novel therapeutic treatment target for Systemic Lupus Erythematosus

Der Systemische Lupus erythematodes (SLE) ist eine systemische Autoimmunerkrankung mit bisher nur zum Teil geklärter Ätiopathogenese. Ein wichtiger Aspekt der Krankheitsentstehung ist die Entwicklung von antinukleären Autoantikörpern, die von kurz- und langlebigen Plasmazellen sezerniert werden. Langlebige Plasmazellen tragen zur Chronizität der Erkrankung bei und stellen eine therapeutische Herausforderung dar, da sie durch konventionelle immunsuppressive oder B-Zell-gerichtete Therapien nur unzureichend unterdrückt werden können. CD38 ist ein Oberflächenprotein, das auf unterschiedlichen Gruppen von Immunzellen entweder konstitutiv oder nach Stimulation exprimiert wird und insbesondere von Plasmazellen stark exprimiert wird. In dieser Arbeit wurde zunächst die Expression von CD38 auf verschiedenen Immunzellen im Blut von 35 SLE Patienten und 20 gesunden Kontrollen (HC) analysiert. Dabei konnte eine signifikant erhöhte CD38 Expression auf verschiedenen Immunzellsubsets von SLE-Patienten nachgewiesen werden, insbesondere bei plasmazytoiden dendritischen Zellen (pDC), Gedächtnis- B- und T-Zellen und auch zirkulierenden Plasmazellen. Zusätzlich wurde der therapeutische Effekt des gegen CD38 gerichteten monoklonalen Antikörpers Daratumumab bei zwei SLE-Patientinnen mit refraktärem, lebensbedrohlichen SLE untersucht. Dabei erhielten die Patientinnen 4 wöchentliche Infusionen mit Daratumumab und wurden für ein Jahr klinisch und immunologisch nachbeobachtet. Die Daratumumab Behandlung resultierte bei beiden Patientinnen in einer klinisch relevanten Verbesserung der Krankheitsaktivität bei insgesamt guter Verträglichkeit. Insbesondere konnte ein günstiger Effekt auf Lupus-Nephritis und autoimmun-hämolytische Anämie beobachtet werden. Die therapeutischen Effekte waren assoziiert mit einem Abfall von Autoantikörpern und Impftitern, was auf eine relevante Depletion von langlebigen Plasmazellen hindeutet. Zusätzlich war eine Reduktion der Typ-I Interferon-Aktivität und eine modulierte Genexpression von Gedächtnis T-Zellen nachweisbar. Die Depletion von autoreaktiven Plasmazellen ist nicht nur beim SLE ein wichtiges Therapiekonzept – so berichten wir zusätzlich über die Behandlung eines Patienten mit einer therapierefraktären Anti-CASPR2-Antikörper vermittelten Enzephalitis mit Daratumumab. Auch bei diesem Patienten kam es unter der Therapie zu klinischer Besserung der neurologischen Symptomatik und Reduktion der Autoantikörper. Allerdings entwickelte dieser Patient in der Rehabilitation eine Sepsis und verstarb wenig später an der Infektion. Insgesamt weisen diese Daten auf ein hohes Potenzial einer gegen CD38 gerichteten Therapie bei SLE, was möglicherweise auch auf andere Autoantikörper-vermittelte Erkrankungen übertragbar ist. Allerdings muss die Effektivität und Sicherheit von Daratumumab in diesen Erkrankungen in klinischen, kontrollierten Studien untersucht werden.Systemic Lupus erythematosus (SLE) is a rheumatologic autoimmune disease, the pathogenesis and aetiology of which are only partially understood. One important aspect of the mechanisms of disease is the generation and maintenance of short- and long-lived, autoreactive plasma cells, which produce autoantibodies. Long-lived plasma cells with their continuous secretion of autoantibodies contribute to the chronicity of the disease and are not sufficiently targeted by conventional immunosuppressants or B cell targeted therapies. CD38 is a surface protein that is expressed either constitutionally or upon stimulation on a host of different immune cell subsets and that is particularly highly expressed on plasma cells. In this work, we examined the expression of CD38 on different immune cell subsets in the peripheral blood of 35 SLE patients and 20 healthy controls. We were able to show that the expression of CD38 is increased on various subsets of peripheral blood leukocytes of SLE patients, such as plasmacytoid dendritic cells, memory B and T cells, as well as plasma blasts was increased. Additionally, we investigated the therapeutic effects of the anti-CD38 monoclonal antibody Daratumumab in two SLE patients with refractory, life-threatening disease with the anti-CD38 monoclonal antibody Daratumumab. The patients received four weekly infusions of Daratumumab and were followed up clinically and immunologically for one year. The treatment of two SLE patients with Daratumumab was, apart from the expected hypogammaglobulinemia, safe and induced a clinical and immunological improvement of the disease that was sustained after one year of follow-up. Especially, amelioration of lupus nephritis and autoimmune haemolytic anaemia were observed. The therapeutic effects were associated with a decline in the titres of both autoantibodies and vaccine-induced protective antibodies declined, indicating a depletion of (long-lived) antibody-secreting cells. Additionally type 1 interferon activity and single-cell transcription analysis of memory T cells showed a downregulation of T cell transcripts associated with chronic T cell activation. The depletion of autoreactive plasma cells could also be an important framework work the treatment of other autoimmune diseases – here, we additionally report the treatment of a patient with refractory anti-CASPR2 antibody mediated encephalitis with daratumumab. Similar to the SLE patients, the treatment resulted in clinical improvement of the neurological manifestations as well as a reduction in autoantibody titres. However, this patient developed septicemia after discharge into a neurological rehabilitation centre and subsequently died. Our results indicate that a CD38-target therapy is a modality that has large potential for the treatment of SLE and likely also many other autoantibody-mediated diseases. The safety and efficacy of Daratumumab for these diseases, however, will need to be investigated in clinical-controlled Trials

Low-Density Granulocytes Are a Novel Immunopathological Feature in Both Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

Objective: To investigate whether low-density granulocytes (LDGs) are an immunophenotypic feature of patients with multiple sclerosis (MS) or neuromyelitis optica spectrum disorder (NMOSD). Methods: Blood samples were collected from 20 patients with NMOSD and 17 patients with MS, as well as from 15 patients with Systemic Lupus Erythematosus (SLE) and 23 Healthy Donors (HD). We isolated peripheral blood mononuclear cells (PBMCs) with density gradient separation and stained the cells with antibodies against CD14, CD15, CD16, and CD45, and analyzed the cells by flow cytometry or imaging flow cytometry. We defined LDGs as CD14-CD15(high) and calculated their share in total PBMC leukocytes (CD45+) as well as the share of CD16(hi) LDGs. Clinical data on disease course, medication, and antibody status were obtained. Results: LDGs were significantly more common in MS and NMOSD than in HDs, comparable to SLE samples (median values HD 0.2%, MS 0.9%, NMOSD 2.1%, SLE 4.3%). 0/23 of the HDs, but 17/20 NMOSD and 11/17 MS samples as well as 13/15 SLE samples had at least 0.7 % LDGs. NMOSD patients without continuous immunosuppressive treatment had significantly more LDGs compared to their treated counterparts. LDG nuclear morphology ranged from segmented to rounded, suggesting a heterogeneity within the group. Conclusion: LDGs are a feature of the immunophenotype in some patients with MS and NMOSD

SIGLEC1 (CD169): a marker of active neuroinflammation in the brain but not in the blood of multiple sclerosis patients

We aimed to evaluate SIGLEC1 (CD169) as a biomarker in multiple sclerosis (MS) and Neuromyelitis optica spectrum disorder (NMOSD) and to evaluate the presence of SIGLEC1(+) myeloid cells in demyelinating diseases. We performed flow cytometry-based measurements of SIGLEC1 expression on monocytes in 86 MS patients, 41 NMOSD patients and 31 healthy controls. Additionally, we histologically evaluated the presence of SIGLEC1(+) myeloid cells in acute and chronic MS brain lesions as well as other neurological diseases. We found elevated SIGLEC1 expression in 16/86 (18.6%) MS patients and 4/41 (9.8%) NMOSD patients. Almost all MS patients with high SIGLEC1 levels received exogenous interferon beta as an immunomodulatory treatment and only a small fraction of MS patients without interferon treatment had increased SIGLEC1 expression. In our cohort, SIGLEC1 expression on monocytes was-apart from those patients receiving interferon treatment-not significantly increased in patients with MS and NMOSD, nor were levels associated with more severe disease. SIGLEC1(+) myeloid cells were abundantly present in active MS lesions as well as in a range of acute infectious and malignant diseases of the central nervous system, but not chronic MS lesions. The presence of SIGLEC1(+) myeloid cells in brain lesions could be used to investigate the activity in an inflammatory CNS lesion

7 Tesla MRI of Balo's concentric sclerosis versus multiple sclerosis lesions

Background: Baló’s concentric sclerosis (BCS) is a rare condition characterized by concentrically layered white matter lesions. While its pathogenesis is unknown, hypoxia-induced tissue injury and chemotactic stimuli have been proposed as potential causes of BCS lesion formation. BCS has been suggested to be a variant of multiple sclerosis (MS). Here, we aimed to elucidate similarities and differences between BCS and MS by describing lesion morphology and localization in high-resolution 7 Tesla (7 T) magnetic resonance imaging (MRI) scans. Methods: Ten patients with Baló-type lesions underwent 7 T MRI, and 10 relapsing remitting MS patients served as controls. The 7 T MR imaging protocol included 3D T1-weighted (T1w) magnetization-prepared rapid gradient echo, 2D high spatial resolution T2*-weighted (T2*w) fast low-angle shot and susceptibility-weighted imaging. Results: Intralesional veins were visible in the center of all but one Baló-type lesion. Four Baló-type lesions displayed inhomogeneous intralesional T2*w signal intensities, which are suggestive of microhemorrhages or small ectatic venules. Eight of 10 BCS patients presented with 97 additional lesions, 36 of which (37%) had a central vein. Lesions involving the cortical gray matter and the U-fibers were not detected in BCS patients. Conclusion: Our findings support the hypothesis that BCS and MS share common pathogenetic mechanisms but patients present with different lesion phenotypes

Analyzing nicotinamide adenine dinucleotide phosphate oxidase activation in aging and vascular amyloid pathology

In aging individuals, both protective as well as regulatory immune functions are declining, resulting in an increased susceptibility to infections as well as to autoimmunity. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2-deficiency in immune cell subsets has been shown to be associated with aging. Using intravital marker-free NAD(P)H-fluorescence lifetime imaging, we have previously identified microglia/myeloid cells and astrocytes as main cellular sources of NADPH oxidase (NOX) activity in the CNS during neuroinflammation, due to an overactivation of NOX. The overactivated NOX enzymes catalyze the massive production of the highly reactive O−2, which initiates in a chain reaction the overproduction of diverse reactive oxygen species (ROS). Age-dependent oxidative distress levels in the brain and their cellular sources are not known. Furthermore, it is unclear whether in age- dependent diseases oxidative distress is initiated by overproduction of ROS or by a decrease in antioxidant capacity, subsequently leading to neurodegeneration in the CNS. Here, we compare the activation level of NOX enzymes in the cerebral cortex of young and aged mice as well as in a model of vascular amyloid pathology. Despite the fact that a striking change in the morphology of microglia can be detected between young and aged individuals, we find comparable low-level NOX activation both in young and old mice. In contrast, aged mice with the human APPE693Q mutation, a model for cerebral amyloid angiopathy (CAA), displayed increased focal NOX overactivation in the brain cortex, especially in tissue areas around the vessels. Despite activated morphology in microglia, NOX overactivation was detected only in a small fraction of these cells, in contrast to other pathologies with overt inflammation as experimental autoimmune encephalomyelitis (EAE) or glioblastoma. Similar to these pathologies, the astrocytes majorly contribute to the NOX overactivation in the brain cortex during CAA. Together, these findings emphasize the role of other cellular sources of activated NOX than phagocytes not only during EAE but also in models of amyloid pathology. Moreover, they may strengthen the hypothesis that microglia/monocytes show a diminished potential for clearance of amyloid beta protein

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer‐reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state‐of‐the‐art handbook for basic and clinical researchers.DFG, 389687267, Kompartimentalisierung, Aufrechterhaltung und Reaktivierung humaner Gedächtnis-T-Lymphozyten aus Knochenmark und peripherem BlutDFG, 80750187, SFB 841: Leberentzündungen: Infektion, Immunregulation und KonsequenzenEC/H2020/800924/EU/International Cancer Research Fellowships - 2/iCARE-2DFG, 252623821, Die Rolle von follikulären T-Helferzellen in T-Helferzell-Differenzierung, Funktion und PlastizitätDFG, 390873048, EXC 2151: ImmunoSensation2 - the immune sensory syste

Increased levels of immature and activated low density granulocytes and altered degradation of neutrophil extracellular traps in granulomatosis with polyangiitis

Granulomatosis with Polyangiitis (GPA) is a small vessel vasculitis typically associated with release of neutrophil extracellular traps (NETs) by activated neutrophils. In this study, we further aimed to investigate the contributions of neutrophils and NETs to the complex disease pathogenesis. We characterized the phenotype of neutrophils and their capacity to induce NETs. In addition, the level of circulating NETs, determined by neutrophil elastase/DNA complexes, and the capacity of patient sera to degrade NETs were investigated from blood samples of 12 GPA patients, 21 patients with systemic lupus erythematosus (SLE) and 21 healthy donors (HD). We found that GPA patients had significantly increased levels of low-density granulocytes (LDGs) compared to HD, which displayed an activated and more immature phenotype. While the propensity of normal-density granulocytes to release NETs and the levels of circulating NETs were not significantly different from HD, patient sera from GPA patients degraded NETs less effectively, which weakly correlated with markers of disease activity. In conclusion, increased levels of immature and activated LDGs and altered degradation of circulating NETs may contribute to pathogenesis of GPA, potentially by providing a source of autoantigens that trigger or further enhance autoimmune responses

Daratumumab for autoimmune diseases: a systematic review

Objective Refractory autoimmune diseases remain a significant challenge in clinical practice and new therapeutic options are needed. This systematic review evaluates the existing reported data on the CD38-targeting antibody daratumumab as a new therapeutic approach in autoantibody-mediated autoimmune diseases.Methods A protocolised systematic literature review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. Two databases (Medline and Embase) were searched for suitable studies. Usage of daratumumab in non-oncological or non-transplantation associated diseases with autoimmune pathophysiology was analysed including patient characteristics, therapeutic regimen, adverse events and patient outcome.Results 38 publications reporting the clinical course of 83 patients met the inclusion criteria. Daratumumab usage was reported in therapy-refractory cases (median of 5 different previous therapies) in 24 different autoimmune diseases. The median number of applications of daratumumab was 4, mainly via intravenous applications (87%). Concomitant treatment included glucocorticoids in 64% of patients, intravenous immunoglobulins (33%) and rituximab (17%). Remission or improvement of disease was reported in 81% of patients. Autoantibody depletion or reduction was stated in 52% of patients. Death occurred in three patients (3%). Adverse events were reported in 45% of patients including application-associated reaction (20%), infection (19%) and hypogammaglobulinaemia (33%).Conclusion Targeting CD38 via daratumumab is a new promising therapeutic option in therapy refractory autoimmune diseases. Efficacy as well as optimal therapeutic regimen and management or prevention of adverse events require further investigation. Therefore, systematic clinical trials of this therapeutic approach are needed

Dysregulated CD38 Expression on Peripheral Blood Immune Cell Subsets in SLE

Given its uniformly high expression on plasma cells, CD38 has been considered as a therapeutic target in patients with systemic lupus erythematosus (SLE). Herein, we investigate the distribution of CD38 expression by peripheral blood leukocyte lineages to evaluate the potential therapeutic effect of CD38-targeting antibodies on these immune cell subsets and to delineate the use of CD38 as a biomarker in SLE. We analyzed the expression of CD38 on peripheral blood leukocyte subsets by flow and mass cytometry in two different cohorts, comprising a total of 56 SLE patients. The CD38 expression levels were subsequently correlated across immune cell lineages and subsets, and with clinical and serologic disease parameters of SLE. Compared to healthy controls (HC), CD38 expression levels in SLE were significantly increased on circulating plasmacytoid dendritic cells, CD14(++)CD16(+) monocytes, CD56(+) CD16(dim) natural killer cells, marginal zone-like IgD(+)CD27(+) B cells, and on CD4(+) and CD8(+) memory T cells. Correlation analyses revealed coordinated CD38 expression between individual innate and memory T cell subsets in SLE but not HC. However, CD38 expression levels were heterogeneous across patients, and no correlation was found between CD38 expression on immune cell subsets and the disease activity index SLEDAI-2K or established serologic and immunological markers of disease activity. In conclusion, we identified widespread changes in CD38 expression on SLE immune cells that highly correlated over different leukocyte subsets within individual patients, but was heterogenous within the population of SLE patients, regardless of disease severity or clinical manifestations. As anti-CD38 treatment is being investigated in SLE, our results may have important implications for the personalized targeting of pathogenic leukocytes by anti-CD38 monoclonal antibodies