The prevalence and clinical significance of anti-neutrophil cytoplasmic antibodies [ANCAs] in patients with lupus nephritis [LN] is not fully elucidated. Our aim was to determine whether LN patients with ANCA positivity had different clinicopathological features and outcomes compared to ANCA-negative patients. Methods. Among our LN patients we retrospectively selected those who underwent ANCA testing the day of the kidney biopsy and before the start of induction treatment. Clinical/histopathological features at kidney biopsy and renal outcome of ANCA-positive patients were compared with those of ANCA-negative subjects. Results. We included 116 Caucasian LN patients in the study; 16 patients [13.8%] were ANCA-positive. At kidney biopsy, ANCA-positive patients presented more frequently with an acute nephritic syndrome than ANCA-negative ones; the difference however does not reach statistical significance [44 vs. 25%, p = 0.13]. At histological evaluation, proliferative classes [100% vs 73%; p = 0.02], class IV [68.8% vs 33%; p < 0.01] and necrotizing tuft lesions [27 vs 7%, p = 0.04] were more frequent, and the activity index was higher [10 vs 7; p = 0.03] in ANCA-positive than in ANCA-negative patients. Despite worse histological features, after a 10-year observation period, there were no significant differences in the number of patients with chronic kidney function impairment (defined as eGFR < 60 mL/min per 1.73 m²) between the ANCA-positive and negative groups [24.2 vs 26.6%, p = 0.9]. This could be the result of the more aggressive therapy, with rituximab plus cyclophosphamide, that ANCA-positive patients received more frequently than ANCA-negative ones [25 vs. 1.3%, p < 0.01]. Conclusions. ANCA-positive LN patients frequently have histological markers of severe activity (proliferative classes and high activity index) that require timely diagnosis and aggressive therapy to limit the development of irreversible chronic kidney damage. Graphical Abstract

The podocyte injury, and consequent proteinuria, that characterize the pathology of idiopathic membranous nephropathy (IMN) is mediated by an autoimmune reaction against podocyte antigens. In particular, the activation of pathways leading to abundant renal deposits of complement is likely to involve the binding of mannose-binding lectin (MBL) to aberrant glycans on immunoglobulins. To obtain a landscape of circulatory IgG Fc glycosylation characterizing this disease, we conducted a systematic N-glycan profiling study of IgG1, 2, and 4 by mass spectrometry. The cohort included 57 IMN patients, a pathological control group with nephrotic syndrome (PN) (n = 20), and 88 healthy control subjects. The effect of sex and age was assessed in all groups and controlled by rigorous matching. Several IgG Fc glycan traits were found to be associated with IMN. Interestingly, among them, only IgG4-related results were specific for IMN and not for PN. Hypo-galactosylation of IgG4, already shown for IMN, was observed to occur in the absence of core fucose, in line with a probable increase of pro-inflammatory IgG. In addition, elevated levels of fucosylated IgG4, along with low levels of hybrid-type glycans, were detected. Some of these IgG4 alterations are likely to be more pronounced in high PLA2R (phospholipase A2 receptor) patients. IgG Fc glycosylation patterns associated with IMN warrant further studies of their role in disease mechanisms and may eventually enrich the diagnostic spectrum regarding patient stratification.

Idiopathic membranous nephropathy (IMN) is a pathologically defined disorder of the glomerulus, primarily responsible for nephrotic syndromes (NS) in nondiabetic adults. The underlying molecular mechanisms are still not completely clarified. To explore possible molecular and functional signatures, an optimised mass spectrometry (MS) method based on next-generation data-independent acquisition combined with ion-mobility was applied to serum of patients affected by IMN (n = 15) or by other glomerulopathies (PN) (n = 15). The statistical comparison highlighted a panel of 57 de-regulated proteins with a significant increase in lipoprotein-related proteins (APOC1, APOB, APOA1, APOL1 and LCAT) and a substantial quantitative alteration of key serpins (including A4, D1, A7, A6, F2, F1 and 1) possibly associated with IMN or NS and podocyte stress. A critical dysregulation in metabolisms of lipids (e.g., VLDL assembly and clearance) likely to be related to known hyperlipidemia in IMN, along with involvement of non-classical complement pathways and a putative enrolment of ficolin-2 in sustaining the activation of the lectin-mediated complement system have been pinpointed. Moreover, mannose receptor CD206 (MRC1-down in IMN) and biotinidase (BTD-up in IMN) are able alone to accurately distinguish IMN vs. PN. To conclude, our work provides key proteomic insights into the IMN complexity, opening the way to an efficient stratification of MN patients.

Anderson–Fabry disease is a hereditary, progressive, multisystemic lysosomal storage disorder caused by a functional deficiency of the enzyme α-galactosidase A (α-GalA). This defect is due to mutations in the GLA gene, located in the long arm of the X chromosome (Xq21-22). Functional deficiency of the α-GalA enzyme leads to reduced degradation and accumulation of its substrates, predominantly globotriaosylceramide (Gb3), which accumulate in the lysosomes of numerous cell types, giving rise to the symptomatology. Clinical diagnosis can still be difficult today due to the peculiarities of the disease, which presents with clinical manifestations that overlap with those of other pathologies and a wide possibility of differential diagnoses, which lead to missed diagnoses, misdiagnosis, or a diagnostic delay. Patients with clinical suspicion of Fabry disease undergo a diagnostic workup that includes an evaluation of α-GALA enzyme activity, genetic analysis of the GLA gene, and the measurement of blood Lyso-Gb3, a soluble derivative of Gb3. In this paper, we describe four novel mutations identified in the GLA gene which are associated with absent or reduced α-GalA activity, pathological accumulation of the specific substrate, and characteristic clinical manifestations of Fabry disease. We identified two mutations (c.583insGAATA and p.Y207X) that result in the formation of a premature translation stop codon, resulting in a truncated protein and thus a completely non-functional enzyme. The other two identified gene alterations (p.G261C and c.786G>T, which determine p.W262C) are missense mutations that cause reduced α-GALA activity, the accumulation of blood Lyso-Gb3, and symptoms consistent with Fabry disease, and therefore may be associated with this disorder. The identification of these new mutations in patients with symptoms attributable to Fabry disease increases the molecular knowledge of the GLA gene and provides important support to the clinician, for a more accurate and timely diagnosis of the pathology.