Still's disease associated with adenovirus infection and defect in adenovirus directed natural killing

An Update on the Pathogenic Role of Macrophages in Adult-Onset Still's Disease and Its Implication in Clinical Manifestations and Novel Therapeutics

Increasing evidence indicates a pivotal role of macrophages in innate immunity, which contributes to the pathogenesis of adult-onset Still's disease (AOSD). Despite the available reviews that summarized the pathogenic role of proinflammatory cytokines in AOSD, a systematic approach focusing on the crucial role of macrophages in this disease is still lacking. This review summarizes the updated functions of macrophages in AOSD and their implication in clinical manifestations and therapeutics. We searched the MEDLINE database using the PubMed interface and reviewed the English-language literature as of 31 March 2021, from 1971 to 2021. We focus on the existing evidence on the pathogenic role of macrophages in AOSD and its implication in clinical characteristics and novel therapeutics. AOSD is an autoinflammatory disease mainly driven by the innate immune response. Among the innate immune responses, macrophage activation is a hallmark of AOSD pathogenesis. The pattern recognition receptors (PRRs) on macrophages recognize pathogen-associated molecular patterns and damage-associated molecular patterns and subsequently cause overproduction of proinflammatory cytokines and recruit adaptive immunity. Some biomarkers, such as ferritin and gasdermin D, reflecting macrophage activation were elevated and correlated with AOSD activity. Given that macrophage activation with the overproduction of proinflammatory cytokines plays a pathogenic role in AOSD, these inflammatory mediators would be the therapeutic targets. Accordingly, the inhibitors to interleukin- (IL-) 1, IL-6, and IL-18 have been shown to be effective in AOSD treatment. Gaining insights into the pathogenic role of macrophages in AOSD can aid in identifying disease biomarkers and therapeutic agents for this disease.

Roles of Interactions Between Toll-Like Receptors and Their Endogenous Ligands in the Pathogenesis of Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease

Systemic juvenile idiopathic arthritis (JIA) and adult-onset Still’s disease (AOSD) are systemic inflammatory disorders that manifest as high-spiking fever, joint pain, evanescent skin rash, and organomegaly. Their pathogenesis is unclear, but inflammation is triggered by activation of the innate immune system with aberrant production of proinflammatory cytokines. Along with extrinsic factors, intrinsic pathways can trigger an unexpected immune response. Damage-associated molecular patterns (DAMPs) induce the activation of innate immune cells, leading to sterile inflammation in systemic JIA and AOSD. These endogenous proteins interact with Toll-like receptors (TLRs), which are pattern recognition receptors, and mediate immune signaling following stimulation by pathogen-associated molecular patterns and DAMPs. Several DAMPs, such as S100 proteins, play a role in the development or severity of systemic JIA and AOSD, in which their interactions with TLRs are altered. Also, the expression levels of genes encoding DAMPs contribute to the susceptibility to systemic JIA and AOSD. Herein, we review reports that TLR and DAMP signaling initiates and/or maintains the inflammatory response in systemic JIA and AOSD, and their correlations with the clinical characteristics of those diseases. In addition, we assess their utility as biomarkers or therapeutics for systemic JIA and AOSD.

Serological findings in patients with acute syndromes fulfilling the proposed criteria of adult onset Still's disease

In order to analyse possible triggering or contributing infections and HLA-B27 frequency in patients with acute febrile joint syndrome fulfilling the proposed criteria of adult Still's disease (AOSD), we studied prospectively the serological findings of 25 patients. They were aged 15-62 years and diagnosed between 1978-1992. We then compared results with a control group consisting of 119 healthy persons. Positive viral or bacterial serology was found in 12 patients (48%) in the AOSD group compared with 13 cases (11%) in the control group (p < 0.001). Fourfold or higher viral antibody rise was found in two patients and bacterial antibody rise in three patients. High stable viral antibody titre was observed in one patient and high stable bacterial antibody titre in six patients. HLA-B27 was not overrepresented in the study group (12%) compared with a healthy Finnish population (14%). We conclude that many different bacterial and viral infections may trigger or contribute to AOSD.

Participation of immune complexes in adenovirus infection

To determine the participation of immune complexes during adenovirus infection, we evaluated serum and necropsy specimens of patients with confirmed adenovirus infection of the lower respiratory tract. In lung and kidney from seven dead patients, immunofluorescence revealed the presence of hexon, immunoglobulins and complement. These patients had clinical manifestations of kidney dysfunction. In dead patients (3/3 in whom serum was available) neither anti-adenovirus antibodies nor adenovirus-specific immune complexes could be found in the final stage of the infection. However, two of these patients had anti-adenovirus antibodies and immune complexes in samples obtained early in the infection. Most patients (16/19) who survived the infection had circulating anti-adenovirus antibodies. Half also had immune complexes specific for adenovirus in some moment of the illness. This suggests that immune complexes arise during respiratory infection by adenovirus, probably contributing to its clinical picture.