Recognizing the new disorder "idiopathic hypocryoglobulinaemia" in patients with previously unidentified clinical conditions

A considerable number of patients with high clinical suspicion for cryoglobulinaemic vasculitis either show negative results for the detection of cryoglobulins or show only trace amounts which cannot be characterized for composition. We aimed at establishing whether the failure to detect or the detection of trace amounts of cryoglobulin with conventional methods either identifies a peculiar subset of low level cryoglobulinaemia (from now on hypocryoglobulinaemia) or represents a separate entity. Using a modified precipitation technique in hypo-ionic medium, we prospectively identified between 2008 and 2021 237 patients (median age 60.8 years [22-97], 137 females) having < 0.5% cryocrit and clinical suspicion of autoimmune disorder. Of these 237 patients, only 54 (22.7%) had a history of HCV infection. One hundred and sixty-nine out of 237 patients (71%) had an established underlying disease, while 68 patients (28.6%) (median age 62.9 years [29-93], 35 females) did not show either laboratory markers or clinical symptoms consonant with an underlying aetiology. These 68 cases with only trace amounts of cryoglobulins were defined as having a putatively idiopathic hypocryoglobulinaemia. Nineteen of these 68 patients (27.9%) had a history of HCV infection. Twenty-four patients out of 68 (35.3%) were positive for rheumatoid factor (RF), while 25 (36.7%) patients had signs of complement consumption (i.e., C4 < 15 mg/dl and/or C3 < 80 mg/dl ), and 36 (52.9%) had increased inflammatory indexes. Seven patients only had arthralgia and constitutional symptoms while 61 out of 68 (89.7%) presented with at least one of the three cardinal signs of cryoglobulinaemic vasculitis including skin lesions, peripheral nerve involvement, and glomerulonephritis. Seventy-five percent of the subjects had type III hypocryoglobulins. In patients with hypocryoglobulinaemia the histologic features of glomerulonephritis (also examined by electron microscopy) resembled those of mixed cryoglobulinaemia-associated glomerulonephritis. In conclusion, hypocryoglobulins are often polyclonal and are mainly unrelated to HCV infection. Patients who present high clinical suspicion for vasculitis, especially glomerulonephritis and yet test negative for cryoglobulinaemia detected by standard techniques, could require deeper investigation even in the absence of HCV infection, RF activity or signs of complement consumption.

Cryoglobulinemic glomerulonephritis: clinical presentation and histological features, diagnostic pitfalls and controversies in the management. State of the art and the experience on a large monocentric cohort treated with B cell depletion therapy

Cryoglobulinemia is defined by the presence of immunoglobulins having the following characteristics: forming a gel when temperature is <37 °C, precipitate in a reversible manner in the serum, and redissolve after rewarming. The presence of both polyclonal IgG and monoclonal IgM (type II), or of polyclonal IgG and polyclonal IgM (type III) identifies the mixed cryoglobulinemia (MC). The identification of the Hepatitis C virus (HCV) infection in most of the cases previously defined as "essential" represented a cornerstone in the understanding the pathogenesis of this condition. The picture of MC comprehends heterogeneous clinical presentations: from arthralgias, mild palpable purpura, fatigue to severe vasculitis features with skin necrotic pattern, peripheral neuropathy and, less commonly, lungs, central nervous system, gastrointestinal tract, and heart involvement. The kidney represents the most common organ presentation, and the presence of glomerulonephritis is a key element when considering prognosis. We discuss the clinical presentation and histological features, diagnostic pitfalls, and controversies in the management of patients with cryoglobulinemic glomerulonephritis, with a special focus on reporting our experience in treating patients with B cell depletion therapy.

Inhibitory anti ADAMTS13 antibodies with a new rapid fully automated CLiA assay

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder characterized by severe ADAMTS13 deficiency. The acquired form is associated with autoantibodies directed against ADAMTS13. Both noninhibitory and inhibitory autoantibodies can be detected by ELISA assay, while only inhibitory autoantibodies are detected by Bethesda assay. Due to its short TAT and good performance, chemiluminescence (CliA) ADAMTS13 activity (HemosIL Acustar) has proven to be a good choice in the diagnosis of TTP in emergency settings. Aim of this study was to analyse the performance of the CliA ADAMTS13 activity assay in detecting inhibitory ADAMTS13 antibodies using the Bethesda assay.

METHODS

A method comparison study was performed on 69 stored samples: 11 acute TTPs, 38 TTP follow-ups, 5 TTP relapses, 1 congenital TTP, 10 HUS, 4 suspected TTPs. We retrieved the results of tests previously run in ELISA for both activity and autoantibodies. At the same time, we reran new tests including ELISA and CliA activity, ELISA autoantibodies, and ELISA and CliA Bethesda assays on thawed frozen samples.

RESULTS

Very good correlation was observed between ELISA and CliA activity assay results (r = 0.96) and between archived ELISA and CliA activity results (r = 0.93). Agreement between the anti-ADAMTS13 assays ranged from good (k = 0.63) to very good (k = 0.92).

CONCLUSIONS

CliA and ELISA Bethesda assays showed very good agreement with samples run at the same time using ELISA ADAMTS13-autoantibody assay. Albeit more expensive, the CliA Bethesda assay identified inhibitory anti-ADAMTS13 within almost the same TAT as ELISA, but with better automation and limited operator involvement.

The challenge of treating hepatitis C virus-associated cryoglobulinemic vasculitis in the era of anti-CD20 monoclonal antibodies and direct antiviral agents

Mixed cryoglobulinemia syndrome (MC) is a systemic vasculitis involving kidneys, joints, skin, and peripheral nerves. While many autoimmune, lymphoproliferative, and neoplastic disorders have been associated with this disorder, hepatitis C virus (HCV) is known to be the etiologic agent in the majority of patients. Therefore, clinical research has focused on anti-viral drugs and, more recently, on the new, highly potent Direct-acting Antiviral Agents (DAAs). These drugs assure sustained virologic response (SVR) rates >90%. Nevertheless, data on their efficacy in patients with HCV-associated cryoglobulinemic vasculitis are disappointing, possibly due to the inability of the drugs to suppress the immune-mediated process once it has been triggered.Despite the potential risk of exacerbation of the infection, immunosuppression has traditionally been regarded as the first-line intervention in cryoglobulinemic vasculitis, especially if renal involvement is severe. Biologic agents have raised hopes for more manageable therapeutic approaches, and Rituximab (RTX), an anti CD20 monoclonal antibody, is the most widely used biologic drug. It has proved to be safer than conventional immunosuppressants, thus substantially changing the natural history of HCV-associated cryoglobulinemic vasculitis by providing long-term remission, especially with intensive regimens.The present review focuses on the new therapeutic opportunities offered by the combination of biological drugs, mainly Rituximab, with DAAs.

IgG4-related kidney disease: the effects of a Rituximab-based immunosuppressive therapy

IgG4-related disease (IgG4-RD) is a recently recognized disorder, characterized by elevated serum IgG4 concentrations, dense tissue infiltration of IgG4-positive plasma cells and storiform fibrosis. Treatment is usually based on steroids, however, relapses and long-term adverse effects are frequent. We prospectively studied 5 consecutive patients with histologically-proven IgG4-RD and renal involvement, treated with an extended Rituximab protocol combined with steroids. Two doses of intravenous cyclophosphamide were added in 4 patients. Five patients with IgG-RD were investigated: three had tubulointerstitial nephritis (TIN), while two had retroperitoneal fibrosis (RPF). In the patients with TIN, renal biospy was repeated after 1 year. In the patients with TIN, estimated glomerular filtration rate (eGFR) at 12 months increased from 9 to 24 ml/min per 1.73 m²; IgG/IgG4 decreased from 3,236/665 to 706/51 mg/dl; C3/C4 increased from 49/6 to 99/27 mg/dl; CD20⁺ B-cells decreased from 8.7% to 0.5%; Regulatory T-cells decreased from 7.2% to 2.5%. These functional and immunologic changes persisted at 24 months and in two patients at 36 months. A repeat renal biopsy in the patients with TIN showed a dramatic decrease in interstitial plasma cell infiltrate with normalization of IgG4/IgG positive plasma cells. The patients with RPF showed a huge regression of retroperitoneal tissue. In this sample of patients with aggressive IgG4-RD and renal involvement, treatment aimed at depleting B cells and decreasing antibody and cytokine production was associated with a substantial, persistent increase in eGFR, and a definite improvement in immunologic, radiologic and histological parameters.

Outpatient percutaneous native renal biopsy: safety profile in a large monocentric cohort

OBJECTIVES

We aim to evaluate the safety of performing percutaneous native kidney biopsy (PKB) as an outpatient procedure (implying an observation period of 6 hours) compared with the traditional inpatient policy.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

Group I, in whom PKB was performed in the outpatient department (2012-2016) and followed by 6 hours' observation period and then by regular outpatient visits and group II, in whom PKB was performed and followed by at least 1 day hospital admission. Group II included retrospectively retrieved patients who underwent PKB in our Institution between January 2000 and November 2012 as an inpatient procedure. All biopsies were performed by a single nephrologist following a structured protocol.

RESULTS

462 biopsies were reviewed, 210 (45.5%) of patients were women and the mean age was 54.7±17.9 years. One hundred and twenty-nine (27.9%) of these biopsies were performed in outpatients. A total of 36 (7.8%) of patients developed a complication, and of those, 9 (1.9%) suffered for a major complication (arteriovenous fistula (six cases, 1.2%), ischaemic stroke (2; 0.4%), thromboembolic pulmonary embolism (1; 0.2%)) and 27 (5.8%) for minor(macroscopic haematuria (12 cases, 2.6%), haematomas on sonography not requiring intervention (15 cases, 3.2%)). When comparing the complication rate between groups I and II, no statical difference was observed. When analysing together both groups, after multivariate analysis, serum creatinine >3 mg/dL (OR 2.03, 95% CI 1.18 to 6.81) and known severe hypertension (OR 2.01, 95% CI 1.2 to 4.7) were found to be independent risk factors for minor and major complications, respectively. Conversely, we found no association of risk with the number of biopsy passes, gender, age, diagnosis, presence of haematuria before the kidney biopsy nor the degree of proteinuria.

CONCLUSIONS

Outpatient biopsy could be a valuable, safe and perhaps cost-effective method of obtaining diagnostic renal tissue in the majority of patients.

Thrombin generation assay: interactions between chronic inflammation and haemostasis in patients with autoimmune diseases

OBJECTIVES

Growing evidences show a direct link between inflammation and activation of haemostasis. That could increase thrombotic and cardiovascular risk in patients with active autoimmune diseases such as rheumatoid arthritis (RA) and systemic sclerosis (SSc). The aim of this study was to evaluate a possible hypercoagulable condition in RA and SSc patients, using the thrombin generation assay (TGA).

METHODS

TGA was assessed in 44 RA [33 with active disease (actRA) and 11 inactive (non-actRA)], 25 SSc patients and 41 healthy controls using a fluorimetric technique and the TGA RB Low reagent. The Lag time (tLag), the time to thrombin peak (tPeak), the maximal concentration of formed thrombin (Peak), the velocity of thrombin generation (velocity) and the total amount of thrombin generated (AUC) were determined.

RESULTS

As compared to the control group, tLag was found to be significantly reduced both in patients with actRA (p=0.0001) and non-actRA (p=0.01); tPeak was found to be reduced in actRA patients (p=0.0002). Similarly, as compared to healthy subjects, Peak and AUC were found to be increased in actRA patients (p=0.01; p=0.002), as well as D-dimer (p=0.01). Analysing SSc vs RA, a higher Peak and AUC were detected in RA patients.

CONCLUSIONS

The TGA profile identified in actRA patients (decreased tLag and tPeak combined with higher thrombin peak and greater AUC) reflects a hypercoagulable state that could make patients more susceptible to develop a cardiovascular disease.

[Hepatitis virus-related nephropathies]

The extrahepatic manifestations of hepatitis B virus infection include reactive arthritis, vasculitis (panarteritis nodosa) and primary glomerulonephritis (membranous nephropathy, membranoproliferative glomerulonephritis and, less frequently, IgA nephropathy, focal and segmental glomerulosclerosis, minimal change disease, and extracapillary glomerulonephritis). No specific histomorphological patterns have been reported in association with HDV infection. Cryoglobulinemic glomerulonephritis is the only pattern of glomerular involvement unequivocally related to HCV infection. The treatment of HBV-related glomerulopathies is essentially antiviral. Corticosteroids have been proven to be ineffective (except in panarteritis nodosa), while immunosuppressants can lead to exacerbation of HBV infection. The treatment of HCV-related nephritis, especially cryoglobulinemic glomerulonephritis, encompasses various options including both conventional and novel immunomodulatory agents, possibly combined with antiviral therapy.