Programmed death 1 (PD-1) and its ligands, PD-L1 and PD-L2, deliver inhibitory signals that regulate the balance between T cell activation, tolerance, and immunopathology. Immune responses to foreign and self-antigens require specific and balanced responses to clear pathogens and tumors and yet maintain tolerance. Induction and maintenance of T cell tolerance requires PD-1, and its ligand PD-L1 on nonhematopoietic cells can limit effector T cell responses and protect tissues from immune-mediated tissue damage. The PD-1:PD-L pathway also has been usurped by microorganisms and tumors to attenuate antimicrobial or tumor immunity and facilitate chronic infection and tumor survival. The identification of B7-1 as an additional binding partner for PD-L1, together with the discovery of an inhibitory bidirectional interaction between PD-L1 and B7-1, reveals new ways the B7:CD28 family regulates T cell activation and tolerance. In this review, we discuss current understanding of the immunoregulatory functions of PD-1 and its ligands and their therapeutic potential.

PD-1 and its ligands in tolerance and immunity

Consensus statement on the pathology of IgG4-related disease

IgG4-related disease.

IgG4-related disease (IgG4-RD) is a novel clinical disease entity characterized by elevated serum IgG4 concentration and tumefaction or tissue infiltration by IgG4+ plasma cells Although IgG4-RD is not rare and is clinically important, its clinical diagnostic criteria have not been established Comprehensive diagnostic criteria for IgG4-RD, including the involvement of various organs, are intended for the practical use of general physicians and nonspecialists Two IgG4-RD study groups, the Umehara and Okazaki teams, were organized by the Ministry of Health, Labor and Welfare Japan As IgG4-RD comprises a wide variety of diseases, these groups consist of physicians and researchers in various disciplines, including rheumatology, hematology, gastroenterology, nephrology, pulmonology, ophthalmology, odontology, pathology, statistics, and basic and molecular immunology throughout Japan, with 66 and 56 members of the Umehara and Okazaki teams, respectively Collaborations of the two study groups involved detailed analyses of clinical symptoms, laboratory results, and biopsy specimens of patients with IgG4-RD, resulting in the establishment of comprehensive diagnostic criteria for IgG4-RD Although many patients with IgG4-RD have lesions in several organs, either synchronously or metachronously, and the pathological features of each organ differ, consensus has been reached on two diagnostic criteria for IgG4RD: (1) serum IgG4 concentration >135 mg/dl, and (2) >40% of IgG+ plasma cells being IgG4+ and >10 cells/high powered field of biopsy sample Although the comprehensive diagnostic criteria are not sufficiently sensitive for the diagnosis of type 1 IgG4-related autoimmune pancreatitis (IgG4-related AIP), they are adequately sensitive for IgG4-related Mikulicz’s disease (MD) and kidney disease (KD) In addition, the comprehensive diagnostic criteria, combined with organ-specific diagnostic criteria, have increased the sensitivity of diagnosis to 100% for IgG4-related MD, KD, and AIP Our comprehensive diagnostic criteria for IgG4-RD are practically useful for general physicians and nonspecialists

Comprehensive diagnostic criteria for IgG4-related disease (IgG4-RD), 2011

The B7 family consists of activating and inhibitory co-stimulatory molecules that positively and negatively regulate immune responses. Recent studies have shown that human and rodent cancer cells, and stromal cells and immune cells in the cancer microenvironment upregulate expression of inhibitory B7 molecules and that these contribute to tumour immune evasion. In this Review, we focus on the roles of these B7 molecules in the dynamic interactions between tumours and the host immune system, including their expression, regulation and function in the tumour microenvironment. We also discuss novel therapeutic strategies that target these inhibitory B7 molecules and their signalling pathways to treat human cancer.

Inhibitory B7-family molecules in the tumour microenvironment

The rapidly emerging disorder now known as IgG(4)-related disease (IgG(4)-RD) includes a variety of clinical entities once regarded as being entirely separate diseases. Manifestations of IgG(4)-RD have now been reported in essentially all organ systems. Regardless of which organ is involved, tissue biopsies reveal striking histopathological similarities. The hallmark pathology findings are diffuse lymphoplasmacytic infiltrates, abundant IgG(4)-positive plasma cells, modest tissue eosinophilia, and extensive fibrosis. Tumorous swelling and obliterative phlebitis are other frequently observed features. Polyclonal elevations of serum IgG(4) are found in approximately 70% of patients. Many questions pertaining to the etiology, pathophysiology, epidemiology, clinical features, therapy, disease monitoring, and long-term outcomes remain to be addressed. This paper focuses on the clinical and pathological features of IgG(4)-RD.

The Clinical and Pathological Features of IgG(4)-Related Disease.

Diagnostic guidelines for IgG4-related disease with a focus on histopathological criteria

BACKGROUND: There are few reports of COVID-19 in pediatric patients with rheumatic diseases. This study describes the clinical presentation and outcomes of COVID-19 in this population. METHODS: We analyzed a single-center case series of pediatric patients with rheumatic diseases and laboratory-confirmed COVID-19. Demographic, baseline and COVID-19 associated clinical features were compared between ambulatory and hospitalized patients using univariate analysis. RESULTS: Fifty-five cases were identified: 45 (81.8%) in the ambulatory group and 10 (18.2%) hospitalized. African American race (OR 7.78; 95% CI [1.46-55.38]; p = 0.006) and cardiovascular disease (OR 19.40; 95% CI 2.45-254.14; p = 0.001) predominated in hospitalized patients. Active rheumatic disease (OR 11.83; 95% CI 1.43-558.37; p = 0.01), medium/high-dose corticosteroid use (OR 14.12; 95% CI [2.31-106.04]; p = 0.001), mycophenolate use (OR 8.84; 95% CI [1.64-63.88]; p = 0.004), rituximab use (OR 19.40; 95% CI [2.45-254.14]; p = 0.001) and severe immunosuppression (OR 34.80; 95% CI [3.94-1704.26]; p = < 0.001) were associated with increased odds of hospitalization. Fever (OR 7.78; 95% CI [1.46-55.38]; p = 0.006), dyspnea (OR 26.28; 95% CI [2.17-1459.25]; p = 0.003), chest pain (OR 13.20; 95% CI [1.53-175.79]; p = 0.007), and rash (OR 26.28; 95% CI [2.17-1459.25]; p = 0.003) were more commonly observed in hospitalized patients. Rheumatic disease flares were almost exclusive to hospitalized patients (OR 55.95; 95% CI [5.16-3023.74]; p < 0.001).. One patient did not survive. CONCLUSIONS: Medium/high-dose corticosteroid, mycophenolate and rituximab use, and severe immunosuppression were risk factors for hospitalization. Fever, dyspnea, chest pain, and rash were high-risk symptoms for hospitalization. Rheumatic disease activity and flare could contribute to the need for hospitalization.

/pdf/outcomes-of-covid-19-in-a-cohort-of-pediatric-patients-with-4qc2ofj87g.pdf

Outcomes of COVID-19 in a cohort of pediatric patients with rheumatic diseases.

IgG4‐Related Disease

To determine clinical course and outcomes in rheumatic disease patients with coronavirus disease 2019 (COVID-19) and compare results to uninfected patients. We conducted a case cohort study of autoimmune disease patients with COVID-19 (confirmed by severe acute respiratory syndrome coronavirus 2 PCR) from February 1, 2020, to July 31, 2020, and compared them in a 1:3 ratio with uninfected patients who were matched based on race, age, sex, and comorbidity index. Patient demographics, clinical course, and outcomes were compared among these patient groups. A total of 70 rheumatic disease patients with COVID-19 (mean age, 56.6 years; 64% African American) were identified. The 34 (49%) patients who were hospitalized used oral glucocorticoids more frequently than those treated as outpatients (p < 0.01). All 10 patients using anti-TNFα medications were treated as outpatients (p < 0.01). Those hospitalized with COVID-19 more often required ICU admission (17 (50%) vs 27 (26%), p = 0.01) and intubation (10 (29%) vs 6 (6%), p < 0.01) than uninfected patients and had higher mortality rates (6 (18%) vs 3 (3%), p < 0.01). Of the six COVID-19 patients who died, only one was of African ancestry (p = 0.03). Rheumatic disease patients infected with COVID-19 were more likely to require ICU admission, ventilation, and died more frequently versus uninfected patients with autoimmune disease. Patients on anti-TNFα medications were hospitalized less frequently, while those on chronic glucocorticoids were hospitalized more frequently. These findings have important implications for medication choice in rheumatic disease patients during the ongoing spread of COVID-19.

/pdf/clinical-course-and-outcomes-of-covid-19-in-rheumatic-1t84gklmxc.pdf

Arezou Khosroshahi

Papers

The Clinical and Pathological Features of IgG(4)-Related Disease.

Diagnostic guidelines for IgG4-related disease with a focus on histopathological criteria

Outcomes of COVID-19 in a cohort of pediatric patients with rheumatic diseases.

IgG4‐Related Disease

Clinical course and outcomes of COVID-19 in rheumatic disease patients: a case cohort study with a diverse population.