Periodic Fever syndromes

Hyperactivation of the NLRP3 inflammasome protects mice against influenza A virus infection via IL-1β mediated neutrophil recruitment

Host innate immune system is critical for combating invading microbes including Influenza A virus (IAV). As an important arm of the innate immunity, the NLRP3 inflammasome has been found essential for protecting host against IAV challenge, while the mechanism remained elusive. Here we found that mice carrying a gain-of-function mutation in the Nlrp3 gene (Nlrp3^R258W) are strongly resistant to IAV infection. Upon H1N1 IAV infection, the Nlrp3^R258W mice exhibited decreased weight loss, increased survival rate and attenuated lung damage compared with WT littermate controls. Mechanistically, the resistance of Nlrp3^R258W mice to IAV infection was dependent on IL-1β-mediated neutrophil recruitment. Upon IAV infection, mice carrying the Nlrp3^R258W mutation produced more IL-1β than WT mice in the lung, which enhanced neutrophil recruitment locally. The recruited neutrophils facilitated IAV clearance, so that the viral load in Nlrp3^R258W mice was lower than that in control mice. Conversely, neutrophil depletion in Nlrp3^R258W mice compromised IAV clearance. Taken together, our results demonstrate a previously undescribed mechanism by which hyperactivation of the NLRP3 Inflammasome protects mice from IAV infection through IL-1β mediated neutrophil recruitment, thus suggest that positively fine tuning the physiological function of NLRP3 inflammasome can be beneficial for a mammalian host against IAV challenge.

Remodelling of the gut microbiota by hyperactive NLRP3 induces regulatory T cells to maintain homeostasis

Inflammasomes are involved in gut homeostasis and inflammatory pathologies, but the role of NLRP3 inflammasome in these processes is not well understood. Cryopyrin-associated periodic syndrome (CAPS) patients with NLRP3 mutations have autoinflammation in skin, joints, and eyes, but not in the intestine. Here we show that the intestines of CAPS model mice carrying an Nlrp3^R258W mutation maintain homeostasis in the gut. Additionally, such mice are strongly resistant to experimental colitis and colorectal cancer; this is mainly through a remodelled gut microbiota with enhanced anti-inflammatory capacity due to increased induction of regulatory T cells (T_regs). Mechanistically, NLRP3^R258W functions exclusively in the lamina propria mononuclear phagocytes to directly enhance IL-1β but not IL-18 secretion. Increased IL-1β boosts local antimicrobial peptides to facilitate microbiota remodelling. Our data show that NLRP3^R258W-induced remodelling of the gut microbiota, induces local T_regs to maintain homeostasis and compensate for otherwise-detrimental intestinal inflammation.

Inflammasomes are involved in gut homeostasis and inflammatory pathologies. The authors show that a hyperactive NLRP3 inflammasome maintains gut homeostasis through remodelling of the gut microbiota and induction of regulatory T cells.

Coexistence of hereditary angioedema in a case of familial Mediterranean fever with partial response to colchicine

Hereditary angioedema (HAE) is a very rare and potentially life-threatening genetic disease characterised by episodes of edema in various parts of the body, including the extremities, face, and airway. The disease is usually associated with attacks of abdominal pain. On the other hand, familial Mediterranean fever (FMF) is an inherited condition characterised by recurrent episodes of painful inflammation in the abdomen, chest, or joints. In this report, we present a child with FMF and undiagnosed HAE, which made him a partial responder to colchicine treatment. Consequently, HAE must be considered in differential diagnosis of cases in which a partial response is obtained from FMF treatment, particularly in countries where FMF is frequently encountered, because early diagnosis of HAE can facilitate prevention of life-threatening complications, such as upper airway obstruction. To our knowledge, our patient is the first patient reported in the literature with the diagnosis of HAE and FMF together.

Regulation of adaptive immunity; the role of interleukin-10

Since the discovery of interleukin-10 (IL-10) in the 1980s, a large body of work has led to its recognition as a pleiotropic immunomodulatory cytokine that affects both the innate and adaptive immune systems. IL-10 is produced by a wide range of cell types, but for the purposes of this review we shall focus on IL-10 secreted by CD4(+) T cells. Here we describe the importance of IL-10 as a mediator of suppression used by both FoxP3(+) and FoxP3(-) T regulatory cells. Moreover, we discuss the molecular events leading to the induction of IL-10 secretion in T helper cell subsets, where it acts as a pivotal negative feedback mechanism. Finally we discuss how a greater understanding of this principle has allowed for the design of more efficient, antigen-specific immunotherapy strategies to exploit this natural phenomenon clinically.

Febrile conditions in rheumatology

Fever is not the most frequent symptom in rheumatology; however, its occurrence always draws attention to a severe underlying pathologic process. The rheumatologic assessment of febrile patients usually takes place for three reasons: the patient's fever is associated with known rheumatic disease or musculoskeletal symptoms, or rheumatologic cause is suggested as the underlying cause of fever of unknown origin. The primary task of the rheumatologist is to rule out infections and autoimmune processes. In addition to the musculoskeletal and accompanying symptoms, the information about the course of fever and the observation of the continuity or periodicity of fever provide help to establish the diagnosis. A summarising discourse about this issue is rarely published in this speciality; therefore, we found it important to provide an overview of rheumatological diseases accompanied by fever.

An atypical familial Mediterranean fever patient who developed ulcers in the terminal ileum and recurrent abscess-like lesions in multiple organs

We herein describe the case of a 25-year-old woman who suffered from atypical familial Mediterranean fever for more than a decade. She presented with a periodic fever, abdominal pain and persistent ulcers in the terminal ileum. Colchicine was effective, and familial Mediterranean fever was diagnosed. A genetic study showed a heterozygous E148Q mutation in the MEFV gene. Multiple, recurrent, abscess-like lesions developed asynchronously in the spleen, liver, and a lung. Infliximab was administered when colchicine treatment became ineffective. However, infliximab treatment soon became ineffective, probably because antibodies were generated against it. Therefore, etanercept treatment was started, and the patient showed an immediate response.

Treatment-refractory autoimmune sensorineural hearing loss: response to infliximab

We conducted a retrospective study to assess the effects of infliximab, a chimeric monoclonal antibody, on hearing in patients with autoimmune sensorineural hearing loss who had previously not responded to steroid therapy and/or treatment with other immunosuppressive drugs such as methotrexate and cyclophosphamide. We reviewed the records of 8 such patients. Our objective measures of outcome were pure-tone averages at 500, 1,000, 2,000, and 3,000 Hz and speech discrimination scores. At the completion of treatment, no patient exhibited a positive response to infliximab therapy by objective measurements, and only 1 patient (12.5%) reported subjective improvement.