Blood and endothelium in immune complex-mediated tissue injury

Immune complex disease in a chronic monkey study with a humanised, therapeutic antibody against CCL20 is associated with complement-containing drug aggregates

Despite the potential for the chemokine class as therapeutic targets in immune mediated disease, success has been limited. Many chemokines can bind to multiple receptors and many receptors have multiple ligands, with few exceptions. One of those exceptions is CCL20, which exclusively pairs to CCR6 and is associated with several immunologic conditions, thus providing a promising therapeutic target. Following successful evaluation in a single dose, first time in human clinical study, GSK3050002—a humanized IgG1 monoclonal antibody against human CCL20—was evaluated in a 26-week cynomolgus monkey toxicology study. A high incidence of unexpected vascular and organ inflammation was observed microscopically, leading to the decision to halt clinical development. Here we report a dose-responsive increase in the incidence and severity of inflammation in multiple organs from monkeys receiving 30 and 300 mg/kg/week by either subcutaneous or intravenous injection. Histomorphological changes resembled an immune complex-mediated pathology, which is often due to formation of anti-drug antibodies in monkeys receiving a human protein therapeutic and thus not predictive of clinical outcome. However, the presentation was atypical in that there was a clear dose response with a very high incidence of inflammation with a low incidence of ADA that did not correlate well individually. Additionally, the immunohistologic presentation was atypical in that the severity and distribution of tissue inflammation was greater than the numbers of associated immune complexes (i.e., granular deposits). An extensive ex vivo analysis of large molecular weight protein complexes in monkey serum from this study and in human serum samples demonstrated a time-dependent aggregation of GSK3050002, that was not predicted by in vitro assays. The aggregates also contained complement components. These findings support the hypothesis that immune complexes of drug aggregates, not necessarily including anti-drug antibodies, can fix complement, accumulate over time, and trigger immune complex disease. A situation which may have increased clinical relevance than typical anti-drug antibody-associated immune complex disease in monkeys administered human antibody proteins.

Vasculitis: mechanisms involved and clinical manifestations

Systemic vasculitis, an inflammatory necrotizing disease of the blood vessel walls, can occur secondary to autoimmune diseases, including connective tissue diseases. Various pathogenic mechanisms have been implicated in the induction of vasculitis, including cell-mediated inflammation, immune complex-mediated inflammation and autoantibody-mediated inflammation. This inflammatory activity is believed to contribute to accelerated atherosclerosis, and also leads to increased risk for cardiovascular events in patients with rheumatoid arthritis and systemic lupus erythematosus. Endothelial cell activation is a common pathogenic pathway in the systemic vasculitis associated with rheumatoid arthritis and systemic lupus erythematosus, with elevated levels of endothelin-1 potentially inducing vascular dysregulation.

Transient encephalopathy complicating poststreptococcal glomerulonephritis in an adult with diagnostic findings consistent with cerebral vasculitis

We report the case of a young woman who had transient encephalopathy with nausea, cognitive impairment, 2 generalized seizures accompanied by visual impairment, and stenotic alterations of cerebral vessels lasting for weeks until complete resolution. These findings were associated with an elevated antideoxyribonuclease B level and biopsy-proven poststreptococcal glomerulonephritis. At the time of the encephalopathy, the patient had no electrolyte level disturbances, an only mildly elevated urea level, and moderate arterial hypertension and was on methylprednisolone therapy. For a couple of days, cranial magnetic resonance imaging showed multiple disseminated asymmetric hyperintensities on T(2)-weighted and fluid-attenuated inversion recovery, suggesting vasogenic edema. However, Doppler ultrasound examinations showed stenoses of extracerebral and multiple intracerebral arteries that persisted for several weeks, lasting considerably longer than the cerebral edema. This finding does not fit the context of hypertensive or steroid-induced encephalopathy, but is consistent with diagnosis of an accompanying vasculitis. Treatment with methylprednisolone for several weeks was associated with resolution of arterial stenoses and neurological symptoms, complete reversibility of Doppler sonographic findings, and significant improvement in renal function.