Roy K. Cheung

Autoimmune islet destruction in spontaneous type 1 diabetes is not β-cell exclusive

Pancreatic islets of Langerhans are enveloped by peri-islet Schwann cells (pSC), which express glial fibrillary acidic protein (GFAP) and S100β. pSC-autoreactive T- and B-cell responses arise in 3- to 4-week-old diabetes-prone non-obese diabetic (NOD) mice, followed by progressive pSC destruction before detectable β-cell death. Humans with probable prediabetes generate similar autoreactivities, and autoantibodies in islet-cell autoantibody (lCA) –positive sera co-localize to pSC. Moreover, GFAP-specific NOD T-cell lines transferred pathogenic peri-insulitis to NOD/severe combined immunodeficient (NOD/SCID) mice, and immunotherapy with GFAP or S100β prevented diabetes. pSC survived in rat insulin promoter Iymphocytic choriomeningitis virus (rip–LCMV) glycoprotein/CD8+ T-cell receptorgp double-transgenic mice with virus-induced diabetes, suggesting that pSC death is not an obligate consequence of local inflammation and β-cell destruction. However, pSC were deleted in spontaneously diabetic NOD mice carrying the CD8+/8.3 T-cell receptor transgene, a T cell receptor commonly expressed in earliest islet infiltrates. Autoimmune targeting of pancreatic nervous system tissue elements seems to be an integral, early part of natural type 1 diabetes.

Transmembrane Ion Fluxes during Activation of Human T Lymphocytes: Role of Ca2+, Na+/H+ Exchange and Phospholipid Turnover

The importance of increases in [Ca2+]i, stimulation of Na+/H+ exchange, and turnover of membrane phospholipids as signals for mitogen-induced activation of human T cells has been reviewed. In the presence of optimal concentrations of lectin and appropriately presented antigen, T cells increase [Ca2+]i, secrete IL2, express IL2 receptors and later divide. An increase in [Ca2+]i is critical for IL2 secretion in contrast to the requirements for IL2 receptor expression and IL2-IL2 receptor interaction. Treatment of T cells with TPA appears to bypass the requirement for an increase in [Ca2+]i for IL2 secretion and cell proliferation, indicating that various mitogens can trigger T cells through both [Ca2+]i-dependent and [Ca2+]i-independent pathways. Influx of Ca2+ from the extracellular milieu appears essential for the induced increase in [Ca2+]i associated with IL2 secretion. These increases in [Ca2+]i, which are correlated with the degree of lymphoproliferation and IL2 secretion, are sensitive to changes in membrane potential. The changes in [Ca2+]i are not mediated by the opening of voltage-gated K+ channels but the nature of the potential-sensitive event remains to be determined. The membrane potential effects may be mediated through the gating of a putative Ca2+ channel or by affecting the inward electrochemical Ca2+ gradient. It is clear that lymphoid cells of both T and B lineage possess a functional Na+/H+ antiport, which plays a central role in the regulation of pHi. It is also generally agreed that the antiport can be stimulated by mitogens, co-mitogens and by agents that induce differentiation. The meaning of this stimulation is not, however, entirely understood. It may be an essential signal or link in the series of events triggered by the binding of ligands to their membrane receptors. Alternatively, it may represent an ancillary event, intended to increase H+ ejection in anticipation of an increased metabolic rate. Finally, a third possible reason for the stimulation of Na+/H+ exchange could be to increase the osmotic content of the cells, inducing cell swelling that may be an early requirement for cellular growth. Indeed, amiloride-sensitive cellular swelling has been detected electronically following treatment of T lymphocytes with TPA (Grinstein et al. 1985a). PHA is a potent activator of phosphatidylinositol hydrolysis. In other cell types, receptors are coupled to phospholipase C by a G protein(s). However, the transducing mechanism in human peripheral blood lymphocytes does not appear to be a pertussis toxin-sensitive G protein(s).(ABSTRACT TRUNCATED AT 400 WORDS)

Diagnosis of nasopharyngeal carcinoma by DNA amplification of tissue obtained by fine-needle aspiration.

BACKGROUND In nasopharyngeal carcinoma the primary lesion is often difficult to find. Metastatic lesions occur frequently but are difficult to distinguish from other head and neck tumors. The viral genome of the Epstein-Barr virus (EBV) can be identified in the cells of this carcinoma. METHODS We used the polymerase chain reaction (PCR) to test for the presence of EBV genomes in 15 samples of metastatic squamous-cell carcinoma of the neck obtained by fine-needle aspiration and in 26 samples obtained by biopsy of lymph nodes. For controls we used disease-free lymph nodes from 10 patients with various head and neck tumors, tonsillar tissue from 46 subjects, blood from 59 EBV-seropositive blood donors, and mononuclear cells from 8 patients with fatal lymphoproliferative lesions. RESULTS Of the 41 malignant lesions examined, only the nine nasopharyngeal carcinomas (one primary lesion and eight metastases) contained EBV genomes. None of the 20 nodes with other types of cancer, the 10 disease-free nodes, or any of the 105 normal control samples contained detectable EBV. In two patients with suspected metastases from occult primary tumors, the presence of EBV was predictive of nasopharyngeal carcinoma; in both cases overt nasopharyngeal carcinoma developed within one year. CONCLUSIONS In patients with suspected nasopharyngeal carcinoma, fine-needle aspiration can provide tissue for diagnosis by DNA amplification of EBV genomes. The presence of EBV in metastases from an occult primary tumor is predictive of the development of overt nasopharyngeal carcinoma.

Antigen-dependent increase in cytosolic free calcium in specific human T-lymphocyte clones

Calcium has been implicated as an intracellular messenger in the cellular response to various external stimuli. Exposure of lymphocytes to various mitogens and lectins results in rapid transmembrane calcium fluxes1–3 and increased cytoplasmic calcium concentrations ([Ca2+]i)4–7. It is not clear, however, whether the mechanisms by which these non-physiological stimuli activate cells are related to those involved in antigen-specific activation. We have now used antigen-specific T-cell clones8,9 to study changes in [Ca2+]i associated with specific activation and show here that these cells respond specifically in the presence of antigen and antigen-presenting cells (APC) with increased [Ca2+]i and that this increased [Ca2+]i shows the same genetic restrictions as are seen in the proliferation assay8,10,11. The kinetics of the [Ca2+]i response to antigen indicate that antigen undergoes a time-dependent processing step as a prerequisite for recognition by T cells, as has been shown for T-cell proliferative responses12–4, but that the [Ca2+]i response to processed antigen is extremely rapid. The close correlation between changes in [Ca2+]i and cell activation resulting in proliferation suggests that Ca2+ may act as an intracellular messenger in antigen-specific responses.

Type I Diabetes and Multiple Sclerosis Patients Target Islet Plus Central Nervous System Autoantigens; Nonimmunized Nonobese Diabetic Mice Can Develop Autoimmune Encephalitis

Type I diabetes and multiple sclerosis (MS) are distinct autoimmune diseases where T cells target either islet or CNS self-proteins. Unexpectedly, we found that autoreactive T cells in diabetic patients, relatives with high diabetes risk, nonobese diabetic (NOD) mice, and MS patients routinely target classical islet as well as CNS autoantigens. The pathogenic potential of CNS autoreactivity was testable in NOD mice. Pertussis holotoxin, without additional Ags or adjuvants, allowed development of an NOD mouse-specific, autoimmune encephalitis with variable primary-progressive, monophasic, and relapsing-remitting courses. T cells from diabetic donors transferred CNS disease to pertussis toxin-pretreated NOD.scid mice, with accumulation of CD3/IFN-γ transcripts in the brain. Diabetes and MS appear more closely related than previously perceived. NOD mouse-specific, autoimmune encephalitis provides a new MS model to identify factors that determine alternative disease outcomes in hosts with similar autoreactive T cell repertoires.

Immunological Aspects of Nutritional Diabetes Prevention in NOD Mice: A Pilot Study for the Cow's Milk–Based IDDM Prevention Trial

Human epidemiological studies delineated early exposure to intact dietary protein (e.g., most infant formulas) as an environmental risk factor for the development of IDDM. The Trial to Reduce IDDM in the Genetically at Risk (TRIGR), an international IDDM prevention trial, has been designed to determine if avoidance of intact dairy protein in high-risk infants ≤6 months of age can reduce the subsequent diabetes incidence. We here studied the casein hydrolysate-based trial diet (Nutramigen) in NOD mice. When given either continuously or for 10 weeks after weaning, the test diet was highly effective in preventing autoimmune diabetes (32-week incidence: 4.6 vs. 58.8%) and in preserving pancreatic insulin levels, with little effect on islet inflammation. Spleen cells from protected NOD mice failed to adoptively transfer diabetes into irradiated syngeneic recipients. When co-transferred with splenocytes from diabetic donors, cells from diet-protected mice inhibited adoptive diabetes transfer (incidence 50 vs. 94%, P < 0.001). T-cell reactivity to the islet cell autoantigens ICA69 (islet cell antigen 69) and GAD65 developed only in diabetic re recipients of spleen cell grafts, indicating that diabetes protection extends to more than one autoantigen. In protected mice, ICA69 T-cell reactivity was not detectable spontaneously nor after priming with this autoantigen; however, priming with the cross-reactive non-self-antigen bovine serum albumin recruited T-cells responsive to ICA69. Thus, diabetes prevention with the clinical trial diet is effective in NOD mice, where it affects some T-cell repertoires and allows development of regulatory cells that interfere with destructive autoimmunity.

Cholecalciferol Plus Calcium Suppresses Abnormal PBMC Reactivity in Patients with Multiple Sclerosis

CONTEXT The active metabolite of vitamin D, 1,25-dihydroxyvitamin D [1,25(OH)(2)D], is a potent modulator of immune cells in vitro. OBJECTIVE Our objective was to determine whether the sun-dependent nutrient, cholecalciferol, can alter disease-associated cellular immune abnormalities in patients with multiple sclerosis (MS). DESIGN This was an open-label, 12-month, randomized controlled trial. SETTING Patients with MS were recruited from the MS Clinic at St. Michaels Hospital, Toronto. PATIENTS Forty-nine patients were matched (for age, sex, disease duration, disease-modifying drug, and disability) and enrolled (treated n = 25; control n = 24). Four patients were lost to follow-up (n = 2 from each group). INTERVENTION Treated patients received increasing doses of cholecalciferol (4,000-40,000 IU/d) plus calcium (1200 mg/d), followed by equilibration to a moderate, physiological intake (10,000 IU/d). Control patients did not receive supplements. MAIN OUTCOME MEASURES At enrollment and at 12 months, peripheral blood mononuclear cell (PBMC) proliferative responses to disease-associated, MS-relevant, and control antigens were measured, along with selected serum biochemical markers. RESULTS At 12 months, mean serum 25-hydroxyvitamin D [25(OH)D] concentrations were 83 ± 35 nmol/liter and 179 ± 76 nmol/liter in control and treated participants, respectively (paired t, P < 0.001). Serum 1,25(OH)(2)D did not differ between baseline and 1 yr. In treated patients, 12-month PBMC proliferative responses to neuron antigens myelin basic protein and exon-2 were suppressed (P = 0.002). In controls, there were no significant changes in disease-associated PBMC responsiveness. There were no significant differences between groups in levels of selected biomarkers. INTERPRETATION MS-associated, abnormal T cell reactivities were suppressed in vivo by cholecalciferol at serum 25(OH)D concentrations higher than 100 nmol/liter.

Abnormal T‐cell reactivities in childhood inflammatory demyelinating disease and type 1 diabetes

Pediatric‐onset multiple sclerosis offers a unique window into early targets and mechanisms of immune dysregulation. It is unknown whether heightened T‐cell reactivities documented in adult patients, to both target‐organ and environmental antigens, emerge in parallel or develop as early or late events. Our objectives were to determine the presence, pattern, and specificity of abnormal T‐cell reactivities to such antigens in the earliest stages of the multiple sclerosis process.

A majority of inverted sinonasal papillomas carries Epstein-Barr virus genomes

Background. The relationship between sinonasal inverted papilloma (IP) and various strains of human papilloma virus (HPV) has been examined previously. Yet there is little consensus regarding the incidence or role of HPV in IP. The possible role of Epstein‐Barr virus (EBV), which, like HPV, is a DNA virus linked to human lymphoid and epithelial malignancies, was investigated.

Primary Sjögren's syndrome and deficiency of ICA69

BACKGROUND Sjögrens syndrome is a common (about 1% of the population) autoimmune disease of salivary and lacrimal glands. Its cause and pathogenesis are poorly understood, and treatments are mostly for symptoms of the disease. ICA69 is a self-antigen expressed in brain, pancreas, salivary, and lacrimal glands. NOD-strain mice are an animal model of spontaneous Sjögrens syndrome. We aimed to assess the role of ICA69 in autoimmunity against Sjögrens syndrome. METHODS We inactivated the genomic ICA69 locus, generated NOD congenic mice that were deficient in ICA69, and assessed development of Sjögrens syndrome. ICA69 autoimmunity was investigated in controls and in patients with primary Sjögrens syndrome or systemic lupus erythematosus, and in various NOD mice, some of which were given an ICA69-directed prototype peptide vaccine. FINDINGS Disruption of the ICA69 locus prevented lacrimal gland disease and greatly reduced salivary gland disease in NOD mice. In healthy NOD mice, ICA69-specific T cells accumulated in lymph nodes that drain salivary tissue. T-cell and B-cell autoreactivity against ICA69 was much the same in patients with primary Sjögrens syndrome, but not in those with systemic lupus erythematosus or in healthy controls. Immunotherapy with a high-affinity mimicry peptide targeting ICA69-specific T-cells reduced established Sjögrens syndrome in wild-type NOD mice in the long term. INTERPRETATION ICA69 is a new autoantigen in primary Sjögrens syndrome that has an important role in progression of disease and could be of diagnostic value. Immunotherapy of primary Sjögrens syndrome is promising, since autoimmunity in NOD mice with Sjögrens syndrome seems to be uniquely susceptible to such treatment even late in disease.