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In amyotrophic lateral sclerosis, a disease driven by abnormal transactive response DNA-binding protein of 43 kDa aggregation, CSF may contain pathological species of transactive response DNA-binding protein of 43 kDa contributing to the propagation of pathology and neuronal toxicity. These species, released in part by degenerating neurons, would act as a template for the aggregation of physiological protein contributing to the spread of pathology in the brain and spinal cord. In this study, a robust seed amplification assay was established to assess the presence of seeding-competent transactive response DNA-binding protein of 43 kDa species in CSF of apparently sporadic amyotrophic lateral sclerosis patients. These samples resulted in a significant acceleration of substrate aggregation differentiating the kinetics from healthy controls. In parallel, a second assay was developed to determine the level of target engagement that would be necessary to neutralize such species in human CSF by a therapeutic monoclonal antibody targeting transactive response DNA-binding protein of 43 kDa. For this, evaluation of the pharmacokinetic/pharmacodynamic effect for the monoclonal antibody, ACI-5891.9, in vivo and in vitro confirmed that a CSF concentration of ≍1100 ng/mL would be sufficient for sustained target saturation. Using this concentration in the seed amplification assay, ACI-5891.9 was able to neutralize the transactive response DNA-binding protein of 43 kDa pathogenic seeds derived from amyotrophic lateral sclerosis patient CSF. This translational work adds to the evidence of transmission of transactive response DNA-binding protein of 43 kDa pathology via CSF that could contribute to the non-contiguous pattern of clinical manifestations observed in amyotrophic lateral sclerosis and demonstrates the ability of a therapeutic monoclonal antibody to neutralize the toxic, extracellular seeding-competent transactive response DNA-binding protein of 43 kDa species in the CSF of apparently sporadic amyotrophic lateral sclerosis patients., Competing Interests: T.A. and T.S. are co-inventors on a patent application, publication number WO2020/234473. R.O., T.A. and T.S. are co-inventors on a patent application, publication number WO2022/034228. M.A., L.F., R.O., M.R., M.L.R.-B., E.C., A.F. , A.F.U, K.P., R.L.-C., O.A., A.P., M.K.-V., T.S. and T.A. are employees of AC Immune and entitled to options and/or shares. N.T., A.-L.E., M.C. and L.M. were employees of AC Immune at the time of this study. The other authors declare no competing interests., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Guarantors of Brain.)

The treatment of Alzheimer's disease (AD) remains challenging and requires a better in depth understanding of AD progression. Particularly, the link between amyloid protein precursor (APP) processing and Tau pathology development remains poorly understood. Growing evidences suggest that APP processing and amyloid-β (Aβ) release are upstream of Tau pathology but the lack of animal models mimicking the slow progression of human AD raised questions around this mechanism. Here, we described that an AD-like βAPP processing in adults wild-type rats, yielding to human APP, βCTF and Aβ levels similar to those observed in AD patients, is sufficient to trigger gradual Tauopathy. The Tau hyperphosphorylation begins several months before the formation of both amyloid plaques and tangle-like aggregates in aged rats and without associated inflammation. Based on a longitudinal characterization over 30 months, we showed that extrasynaptic and emotional impairments appear before long-term potentiation deficits and memory decline and so before Aβ and Tau aggregations. These compelling data allowed us to (1) experimentally confirm the causal relationship between βAPP processing and Tau pathology in vivo and without Tau transgene overexpression, (2) support the amyloidogenic cascade and (3) propose a 4-step hypothesis of prodromal AD progression.

Azathioprine is commonly used in Crohn's disease. It has been administered to many pregnant women over many years without significant side effects. However, pancytopenia and severe combined immune deficiency-like disease have been reported in infants whose mothers received azathioprine throughout pregnancy. Moreover, myelotoxicity has been described in patients being treated with azathioprine and having a low or absent thiopurine S-methyl transferase [TPMT] activity.Here, we describe the case of a newborn girl found to be highly lymphopenic [< 300 CD3+ T cells] after a positive newborn screening for severe combined immuno deficiency. The clinical examination was normal. The mother was treated with azathioprine throughout her pregnancy, without any reduction of the dose. It was shown that the mother was heterozygous for the 3A [TPMT] activity mutation and that the baby was homozygous for the same mutation; 6-thioguanine nucleotides were high (744 pmol/8.108 red blood cells [RBC]) in the mother and detectable in the infant [177 pmol/8.108 RBC].Although rare, this case illustrates the potential grave consequences of unsuspected TPMT homozygosity in a newborn of a mother receiving thiopurines during pregnancy. Because of the severity of the risk for the newborn, consideration should be given to performing maternal genetic testing and newborn routine blood count in cases of thiopurine treatment during pregnancy., (Copyright © 2017 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Interleukin-2 (IL-2)-deficient mice have cytoarchitectural hippocampal modifications and impaired learning and memory ability reminiscent of Alzheimer's disease. IL-2 stimulates regulatory T cells whose role is to control inflammation. As neuroinflammation contributes to neurodegeneration, we investigated IL-2 in Alzheimer's disease. Therefore, we investigated IL-2 levels in hippocampal biopsies of patients with Alzheimer's disease relative to age-matched control individuals. We then treated APP/PS1ΔE9 mice having established Alzheimer's disease with IL-2 for 5 months using single administration of an AAV-IL-2 vector. We first found decreased IL-2 levels in hippocampal biopsies of patients with Alzheimer's disease. In mice, IL-2-induced systemic and brain regulatory T cells expansion and activation. In the hippocampus, IL-2 induced astrocytic activation and recruitment of astrocytes around amyloid plaques, decreased amyloid-β42/40 ratio and amyloid plaque load, improved synaptic plasticity and significantly rescued spine density. Of note, this tissue remodelling was associated with recovery of memory deficits, as assessed in the Morris water maze task. Altogether, our data strongly suggest that IL-2 can alleviate Alzheimer's disease hallmarks in APP/PS1ΔE9 mice with established pathology. Therefore, this should prompt the investigation of low-dose IL-2 in Alzheimer's disease and other neuroinflammatory/neurodegenerative disorders., (© The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objective: To describe the clinical manifestations of the anti-synthetase syndrome (ASS) specifically associated with anti-alanyl-tRNA (anti-PL12) synthetase antibodies., Methods: In a retrospective study, 17 patients (eight males, nine females, mean age = 60.3 years) with ASS symptoms confirmed by two consecutive tests (cyto-dot and/or immunoblot, or both), with positive results for anti-PL12 antibodies, were included., Results: All patients presented with interstitial lung disease (ILD), which was associated with mild myositis in 41% of the cases. RP and general impairment were common, whereas rheumatic and dermatological symptoms were uncommon. Four patients suffered from SS, and four others had an atypical oesophageal involvement. The long-term course was assessable for 10 patients (follow-up of 41.1 months). Five patients required immunosuppressive drugs. Two patients are waiting for a lung transplant because of disproportionate and refractory pulmonary hypertension., Conclusion: The severity of anti-PL12 ASS varied because of the constant pulmonary involvement. ILD was the predominant prognosis factor, which was notable in cases associated with pulmonary hypertension.

Objectives: Two types of anti-Ro/SSA antibodies have been described, anti-SSA-52 kDa (aSSA52) and anti-SSA-60 kDa (aSSA60), each specific to different antigens. However, conflicting data exist concerning the involvement of the aSSA52 in autoimmune diseases (ADs). We therefore determined the clinical significance of these antibodies in patients displaying aSSA52, but not aSSA60., Methods: The 2005-08 retrospective monocentric study: all patients positive for aSSA60 and/or aSSA52 antibodies were investigated., Results: Among 297 patients, 82 were aSSA52 positive and aSSA60 negative. There were 21 males and 61 females. Forty-eight (58.5%) patients met our criteria for an AD. Two groups were distinguished according to the association (Group 1) or not (Group 2) of the aSSA52 with other autoantibodies. In Group 1, 33 out of 34 patients suffered from an AD. The two most common being SLE and SSc. The prevalence of AD was lower in Group 2 (15 out of 48, 31.3%, P = 0.001). aSSA52 levels were similar in patients with or without AD., Conclusions: The existence of aSSA52 in association with other antibodies did not predict the presence of AD. There was no evidence to suggest that aSSA52 antibodies were associated with a specific clinical form of SLE or SSc. In the absence of other autoantibodies, aSSA52 was less associated with the presence of an AD. A positive aSSA52 test is of low diagnostic value for AD. Nevertheless, a longitudinal prospective follow-up study would determine whether or not persistence of these autoantibodies was of use in diagnosing AD.

We tested whether rat and human MPO have similar antigenic determinants using 36 human MPO-ANCA positive sera, one mouse anti-rat MPO and four mouse anti-human MPO monoclonal reagents. Purified rat and human MPO were used in ELISA, with or without crossinhibition by preincubation with human MPO or irrelevant antigen in the liquid phase. Only one human MPO ANCA positive serum exhibited significant binding in rat MPO ELISA. This binding was poorly inhibited by preincubation with human MPO in the liquid phase, but was conserved after adsorption of non specific anti-rat activity in a chromatography column. Three mouse anti-human MPO IgG monoclonal antibodies did not recognize rat MPO. Only one mouse anti-human MPO IgA monoclonal antibody bound to rat MPO. This binding was poorly inhibited by preincubation with human MPO (35% at 2 micro g/ml). Conversely, the mouse anti-rat MPO monoclonal did not bind human MPO. We have concluded that: (1) Most human MPO-ANCA recognize antigenic determinants on human MPO which are absent on rat MPO. Therefore, human auto-antibodies bind to epitopes which recently appeared after species evolution; (2) Inversely, the mouse anti-rat MPO monoclonal do not bind human MPO. Therefore, rat MPO epitopes have been altered during species evolution; (3) Mice injected with human MPO preferentially develop antibodies against xeno-epitopes which are not present in rodents. Therefore, human MPO may not be the best antigen to raise ANCA in animal models and (4) A comparison of the amino acid sequences of rat and human MPO may help elucidate the major antigenic epitopes.

Objectives: To define the specificity and positive predictive value of anti-beta(2)-glycoprotein 1 (anti-beta(2)GP1) antibodies for the diagnosis of antiphospholipid syndrome (APS)., Methods: We determined the presence of anticardiolipin (aCL) antibodies and anti-beta(2)-glycoprotein 1 (anti-beta(2)GP1) immunoglobulin (Ig) G and IgM in 191 consecutive sera from 191 patients and reviewed clinical data separately. aCL IgG and IgM were detected separately using commercial ELISA kits. Anti-beta(2)GP1 antibodies were detected with an in-house ELISA using beta(2)GP1., Results: Seven patients were diagnosed as having APS and 184 as having other diseases. Thirty-six patients were aCL-positive and 12 were anti-beta(2)GP1-positive, seven of these 12 were APS patients. The specificity for anti-beta(2)GP1 in our population was 97%, with a positive predictive value (PPV) of 58%. Among the aCL-positive patients, specificity was 90% and PPV 70-87%., Conclusions: This study shows that anti-beta(2)GP1 antibodies have a higher specificity and PPV than aCL for APS. The PPV of anti-beta(2)GP1 was greater in aCL-positive than in all patients. We conclude that screening for anti-beta(2)GP1 antibodies in aCL-positive patients increases the specificity and the PPV of aCL testing. In addition, we show that there is no need to screen for anti-beta(2)GP1 antibodies in the absence of aCL antibodies and in the absence of strong clinical suspicion of APS.

Background: ANCA are autoantibodies directed against polymorphonuclear cell antigens, mainly proteinase 3 (PR3) and myeloperoxidase (MPO), which are implicated in the pathogenesis of small-vessel necrotizing vasculitis. Alpha1-antitrypsin is the main inhibitor of neutral serine proteinase [i.e. human leukocyte elastase (HLE) and PR3] present in PMN alpha-granules (alphaGr). An association first reported by us between PR3 ANCA and the deficient PiZZ phenotype in ANCA-positive systemic vasculitis, now widely confirmed by others, led us to study the incidence and specificity of ANCA among PiZZ subjects., Methods: We tested a population of 191 PiZZ (273 sera) for ANCA activity versus 272 PiMM matched control subjects using alphaGr or antigen-specific ELISA [PR3, HLE, MPO, lactoferin (LF) and bactericidal/ permeability increasing protein (BPI)]., Results: The incidence of antibodies directed against alphaGr and HLE but not PR3, MPO, LF or BPI was increased in the PiZZ as compared to the PiMM group (Fisher probability respectively P < 0.0001 and P < 0.05)., Conclusions: ANCA not directed against classical antigens (MPO and PR3) may be found in PiZZ patients. However, these patients do not develop systemic vasculitis features. Therefore, alpha1-antitrypsin deficiency is not sufficient to induce ANCA positive vasculitides, and may only act as a second hit amplifying factor.

Objective: To evaluate the prevalence of antineutrophil cytoplasmic antibodies (ANCA) and rheumatic manifestations associated with chronic haematological malignancies., Methods: Two groups of patients were prospectively studied (group I: 60 patients with myelodysplastic syndromes and group II: 140 patients with lymphoid malignancies) for clinical 'immune' manifestations and ANCA., Results: In the myelodysplastic group, six patients had ANCA-negative systemic medium-size vasculitis, one had systemic vasculitis with cytoplasmic ANCA, one relapsing polychondritis, one giant cell arteritis, one polymyalgia rheumatica, one polyarthritis and two fasciitis. In group II, two patients had ANCA-negative systemic vasculitis, two had leucocytoclastic vasculitis associated with tuberculosis, two had polyarthritis, one polymyalgia rheumatica and one giant cell arteritis. Six sera were ANCA-positive with perinuclear pattern in four cases, atypical pattern in one and cytoplasmic pattern in one. Two sera had anti-myeloperoxidase (MPO) specificity, and others had no known specificity; none had anti-proteinase 3 (PR3) specificity. Global prevalence of ANCA in our cohort was 3%, similar to the French general population., Conclusion: Polyarteritis nodosa-type systemic vasculitis and polymyalgia rheumatica were the most frequent findings (18%) in myelodysplastic syndromes and particularly in chronic myelomonocytic leukaemia. ANCA were not helpful for the diagnosis of vasculitis. Vasculitis associated with infection, in particular tuberculosis, must be ruled out.

Myeloperoxidase (MPO) is one of the main antigen targets of anti-neutrophil cytoplasmic antibodies (ANCA) in systemic vasculitides. It has been suggested that anti-MPO antibodies may recognize a single epitope on recombinant MPO. If confirmed on native MPO, this might allow specific therapeutic intervention with anti-idiotypic MoAbs to prevent antibody antigen interaction which is thought to cause activation of neutrophils and vasculitis. We searched for restriction in the epitope recognition profile in 50 patients with anti-MPO autoantibodies, using both native and recombinant MPO. Mouse monoclonals were purified and tested in competition assays. At least four epitopes were identified on native MPO using these monoclonals and only two were conserved on recombinant MPO. We found that human MPO autoantibody response was not restricted to a single epitope on native MPO, as all sera tested did not show the same profile in competitive studies with monoclonals. Furthermore, 30% of human anti-native MPO sera failed to recognize rMPO.

Although antiperinuclear factor (APF) has the same specificity for rheumatoid arthritis (RA) as rheumatoid factor (RF), there is no evidence that this specificity is maintained in patients with positive RF-agglutination tests. Thus, we evaluated the specificity and usefulness of APF for RA diagnosis, regardless of RF titre. APF was tested (1:100 threshold) on 214 sera sent for RF evaluation over a 9-month period. These sera were previously determined to have latex or Rose-Waaler (RW) titres > or = 12 or 4 IU, respectively, but not necessarily above the threshold values of 100 and 32 IU. The APF test was performed blindly, and physicians were not advised of the results. In the patient population (119 RA and 95 non-RA) APF still demonstrated good specificity (0.82) for RA. As expected, APF proved useful for RA diagnosis in 28/33 (85%) RA cases with an RF level below 1:100 for latex and 1:32 for RW, thus reducing the number of 'seronegative' RA from 33/119 to 5/119. However, it also improved the serological positive predictive value for RA, even in cases when RW results were > or = 32 IU. Indeed, the positive predictive value for RA when both tests were positive was 0.94 (68/72), whereas concordant results (either positive or negative) for both APF and RW tests allowed correct classification (RA or non-RA) in 94% of cases.