A complex web of dynamic relationships between innate and adaptive immunity is now evident for many autoinflammatory and autoimmune disorders, the first deriving from abnormal activation of innate immune system without any conventional danger triggers and the latter from self-/non-self-discrimination loss of tolerance, and systemic inflammation. Due to clinical and pathophysiologic similarities giving a crucial role to the multifunctional cytokine interleukin-1, the concept of autoinflammation has been expanded to include nonhereditary collagen-like diseases, idiopathic inflammatory diseases, and metabolic diseases. As more patients are reported to have clinical features of autoinflammation and autoimmunity, the boundary between these two pathologic ends is becoming blurred. An overview of monogenic autoinflammatory disorders, PFAPA syndrome, rheumatoid arthritis, type 2 diabetes mellitus, uveitis, pericarditis, Behçet's disease, gout, Sjögren's syndrome, interstitial lung diseases, and Still's disease is presented to highlight the fundamental points that interleukin-1 displays in the cryptic interplay between innate and adaptive immune systems.

Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenopathy (PFAPA) syndrome is a mysterious disorder characterized by periodically recurrent fevers, oropharyngeal inflammation, and adenitis, which mainly affects children, though in very recent times, it has been also recognized in adulthood. We enrolled 115 unrelated pediatric and adult patients with history of periodic fevers who fulfilled the current diagnostic criteria for PFAPA syndrome in three Italian referral centers and highlighted differences between children and adults. Eighty-five children and 30 adults were evaluated: the frequency of flares was significantly higher in pediatric cases, while febrile attack duration was significantly longer in adults. Clockwork periodicity of fever and recurrent pharyngitis were more frequently observed in childhood, but no differences were identified for aphthosis and cervical adenopathy. Conversely, joint symptoms, myalgia, headache, fatigue, ocular signs, and rashes were more common in adults. The simultaneous occurrence of two or three cardinal PFAPA signs did not show any statistical difference between the groups, while the occurrence of only one cardinal manifestation was more frequent in adults. Corticosteroids were effective in 98.82 % of children and 88.2 % of adults. Tonsillectomy was rarely performed, resulting effective in only two patients. Our data illustrate the clinical overlap between pediatric and adult cases of PFAPA syndrome. Adults are characterized by a wider repertoire of inflammatory signs, suggesting that onset in adulthood might leave the disease misdiagnosed. Clinicians, not only pediatricians, should take into account this clinical entity in every patient of whatever age suffering from recurrent fevers of unknown origin.

Kawasaki syndrome (KS) is the most relevant cause of heart disease in children living in developed countries. Intravenous immunoglobulin (IVIG) has a preventive function in the formation of coronary artery abnormalities and a poor strictly-curative action in established coronary damage. More than two decades ago, the Harada score was set to assess which children with KS should be subject to administration of IVIG, evaluating retrospectively a large cohort of patients with regard to age, sex and laboratory data. Nowadays, high dose IVIG is administered to all children with a confirmed diagnosis of KS, but a tool for predicting non-responsiveness to the initial infusion of IVIG has not been found. The prediction of IVIG resistance is a crucial issue, as recognising these high-risk patients should consent the administration of an intensified initial treatment in combination with IVIG in order to prevent coronary injuries. Few reports have focused on factors, referring to both clinical parameters and laboratory data at the onset of KS, in order to predict which patients might be IVIG non-responsive. We have analysed three different risk scores which were formulated to predict IVIG resistance in Japanese children with typical KS, but their application in non-Japanese patients or in those with incomplete and atypical patterns of the disease has been studied in a fragmentary way. Overall, our analysis showed that early and definite ascertainment of likely IVIG non-responders who require additional therapies reducing the development of coronary artery involvement in children with KS is still a challenge.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS), formerly known as familial Hibernian fever, is the most common autosomal dominant autoinflammatory disease, resulting from mutations in the TNFRSF1A gene, encoding the 55-kD tumor necrosis factor receptor. The pathophysiologic mechanism of TRAPS remains ambiguous and only partially explained. The onset age of the syndrome is variable and the clinical scenery is characterized by recurrent episodes of high-grade fever that typically lasts 1-3 weeks, associated with migrating myalgia, pseudocellulitis, diffuse abdominal pain, appendicitis-like findings, ocular inflammatory signs, and risk of long-term amyloidosis. Fever episodes are responsive to high-dose corticosteroids, but different classes of drugs have been reported to be ineffective. The use of etanercept is unable to control systemic inflammation, while interleukin-1 blockade has been shown as effective in the control of disease activity in many patients reported so far.

SARS-CoV-2 infection in children can trigger cardiovascular manifestations potentially requiring an intensive treatment and defining a new entity named Multisystem Inflammatory Syndrome in Children (MIS-C), whose features partially overlap with Kawasaki Disease (KD). A cross-sectional study including all diagnoses of MIS-C and KD from April 2020 to May 2021 in our metropolitan area was conducted evaluating clinical, laboratory (including immunological response, cytokines, and markers of myocardial damage), and cardiac (coronary and non-coronary) features at onset of the diseases. Evolution of ventricular dysfunction, valve regurgitations, and coronary lesions was documented. The severity of the disease was also considered based on the need for inotropic support and ICU admission. Twenty-four MIS-C were diagnosed (14 boys, median age 82 months): 13/24 cases (54.17%) presented left ventricular dysfunction, 12/24 (50%) required inotropic support, and 10/24 (41.67%) developed coronary anomalies (CALs). All patients received steroids and IVIG at a median time of 5 days (IQR1:4, IQR3:6.5) from onset of fever and heart function normalized 6 days (IQR1: 5, IQR3: 7) after therapy, while CALs persisted in one. One patient (12.5%) required infliximab because of refractory disease and still presented CALs 18 days after therapy. During the same study period, 15 KD were diagnosed: none had ventricular dysfunction, while 7/15 (46.67%) developed CALs. Three out of 15 patients (20%) still presented CALs 46 days from onset. Compared to KD, MIS-C pts have significantly higher IL8 and similar lymphocytes subpopulations. Despite a more severe presentation and initial cardiac findings compared to KD, the myocardial injury in MIS-C has a rapid response to immunomodulatory treatment (median time 6 days), in terms of ventricular function, valve regurgitations, and troponin. Incidence of CALs is similar at onset, but it tends to regress in most of the cases of MIS-C differently than in KD where CALs persist in up to 40% in the subacute stage after treatment.