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N Talal

Publications and source records attributed to N Talal.

At least 37 records · Page 2Linked to original sources
PubMed1997

Fas and Fas ligand expression in the salivary glands of patients with primary Sjögren's syndrome.

OBJECTIVE: To assess the role of Fas-mediated apoptosis in the salivary glands of patients with primary Sjögren's syndrome (SS). METHODS: Expression of Fas, Fas ligand (FasL), and bcl-2 in salivary gland biopsy material was detected in situ by immunohistochemical staining and reverse transcriptase-polymerase chain reaction. DNA fragmentation in apoptotic cells was assessed by the enzymatic incorporation of labeled nucleotides (digoxigenin-dUTP). RESULTS: The acinar epithelial cells in SS were Fas+ and FasL+, and these cells died by apoptosis. The majority of infiltrating lymphocytes in SS were Fas+ and bcl-2+, while few lymphocytes expressed FasL. In situ detection of apoptosis showed minimal cell death of lymphocytes, particularly in dense periductal foci. Lymphocytic cell death was significantly lower (P < 0.0001) in these foci compared with that in the interstitium. CONCLUSION: Infiltrating lymphocytes in the focal lesions of the salivary glands of patients with SS are blocked in their ability to commit to apoptosis, even though they may express Fas. The presence of bcl-2 in these cells may explain their inability to undergo apoptosis. The acinar epithelial cells, in contrast, may undergo Fas-mediated apoptosis. These results suggest that the Fas death pathway may be an important mechanism leading to the glandular destruction found in SS.

Apoptosis↗
PubMed1996

Lymphocyte apoptosis and apoptosis-associated gene expression in Sjögren's syndrome.

OBJECTIVE: To study the mechanism and regulation of apoptosis in peripheral blood T and B lymphocytes from patients with Sjögren's syndrome (SS). METHODS: The mode of in vitro lymphocyte death in the peripheral blood of patients with SS was determined by fluorescence microscopic analysis, terminal deoxynucleotidyl transferase assay, and DNA fragmentation analysis. Apoptotic cell death of T and B cells was determined at 48 hours of culture by fluorescence-activated cell sorter analysis of propidium iodidestained cells. Messenger RNA (mRNA) expression of bcl-2, bcl-x, bax, and c-myc in T and B cells was determined by enzyme-linked immunosorbent assay-polymerase chain reaction (ELISA-PCR). Expression of bcl-xL and bcl-xS was determined by Southern blot analysis of PCR products. Gene expression was calculated as the ratio of each gene message to the message of the GAPDH gene. Bcl-2 protein levels in SS T cells were determined by ELISA. RESULTS: SS T cells showed increased in vitro apoptosis compared with normal T cells (mean +/- SD 12.3 +/- 4.5% versus 7.3 +/- 2.0%; P < 0.01). Freshly isolated SS T cells showed increased expression of bcl-2 mRNA compared with normal controls (mean +/- SD 1.50 +/- 0.65 versus 0.88 +/- 0.23; P < 0.05). There was no significant difference in levels of bax or c-myc mRNA in T cells and B cells between SS patients and normal controls. When SS T lymphocytes were cultured in vitro for 72 hours, Bcl-2 protein levels decreased with time. CONCLUSION: SS T cells showed accelerated apoptosis in vitro. Freshly isolated SS T cells had increased expression of bcl-2. An increase in death-promoter signals and decrease in death-suppressor signals in vitro may have been responsible, in part, for the apoptosis in SS T lymphocytes.

Adult↗
PubMed1996

Abnormality of Oct-1 DNA binding in T cells from Sjögren's syndrome patients.

Primary Sjögren's syndrome (SS) is an autoimmune rheumatic disease characterized by T cell hypoactivity. To understand the diminished T cell response to activation signals, we measured nucleoprotein DNA-binding activities regulating gene expression during T cell activation using the electrophoretic mobility shift assay. Peripheral blood lymphocytes from 9/19 SS patients were found to be defective in their ability to bind an october sequence (Oct-1). This Oct-1-binding phenotype remained stable in culture for up to 3 days prior to activation. This abnormality was not seen in resting T cells nor T cells from patients with systemic lupus erythematosus, rheumatoid arthritis (RA), or SS accompanied by RA. The SS Oct-1 DNA-binding abnormality correlated significantly with an inability of cells to exit the Gzero/G1 cell cycle phase when stimulated in vitro. Importantly, nucleoprotein extracts showing decreased DNA-binding activity had normal amounts of Oct-1 proteins as determined by immunoprecipitation, implying a functional defect in the Oct-1 protein. Moreover, defective DNA binding was corrected by treatment with acid phosphatase.

Adult↗
PubMed1996

Clinicopathological factors relating malignant lymphoma with Sjögren's syndrome.

This study was undertaken to summarize the current status of the clinicopathologic factors related to non-Hodgkin's lymphoma (NHL) development in patients with Sjögren's syndrome (SS). Through a MEDLINE search, pertinent articles on SS, monoclonality, and NHL were found and reviewed. Malignant lymphoma description was based on the International Lymphoma Study Group classification. Patients with SS are known to have an increased risk for developing B-cell NHL (B-NHL). However, such a complication occurs in less than 10% of patients, being reported mainly in those with primary SS. Extranodal low-grade B-NHL are observed most frequently. Persistent enlargement of parotid glands, adenopathy, monoclonal gammopathy, and cross-reactive idiotypes are all signs suggesting possible lymphoma evolution. Although monoclonality does not mean malignancy unequivocally, it is considered to be a precursor for NHL development in SS. Factors implicated into lymphomagenesis in SS include dysregulation in the mechanisms leading to apoptosis, hyperstimulation of B-1 cells, and an infectious agent. Polyclonal lymphoproliferation characterizing SS might in some instances transform into monoclonal, and then to malignancy. Further studies on the mechanism whereby NHL develops in SS are warranted.

Aged↗
PubMed1995

SLE-like autoantibodies and Sjögren's syndrome-like lymphoproliferation in TGF-beta knockout mice.

Mice bearing the TGF-beta 1 null mutation (-/-) develop lymphoid infiltrates in the heart, lungs, salivary glands, and other organs similar to those seen in the pseudolymphoma of Sjögren's Syndrome. We studied sera from -/- mice and found elevated Ab levels to dsDNA, ssDNA, and Sm ribonucleoprotein. No Abs to SSA/Ro or SSB/La and no IgM rheumatoid factor were found. Serum autoantibodies were predominately IgG and were specific as shown by ELISA inhibition studies. Antinuclear Ab patterns on Western blots varied from one mouse to the next, indicating a random process responsible for the diversity. Wild-type and heterozygote mice had no autoantibodies. Ig glomerular deposits were found in -/- mice, indicating that these autoantibodies may be pathogenic. Treatment of -/- mice with dexamethasone or TGF-beta 1 failed to suppress autoantibody production. These mice represent an overlap combining the autoimmune serology of SLE with the tissue infiltrates of SS. Our results support the concept that TGF-beta 1 is an important naturally occurring immunosuppressive cytokine whose absence can lead to a systemic autoimmune disease.

Animals↗
PubMed1995

Effects of calorie restriction on transforming growth factor beta 1 and proinflammatory cytokines in murine Sjogren's syndrome.

The present study was carried out to determine whether restricting dietary calories prevents salivary gland abnormalities and modulates expression of transforming growth factor beta and proinflammatory cytokines, IL-6, and TNF alpha in major salivary glands (SG) of autoimmune lupus-prone (NZB x NZW)F1 (B/W) female mice. These mice develop focal lymphocytic interstitial and periductal round cell infiltrates in salivary glands similar to those of humans with Sjogren's syndrome. Weanling B/W mice were fed a nutritionally adequate semipurified diet either ad libitum (AL) or a calorie-restricted (CR; 40% less calories than AL) diet. The mice were sacrificed at 3.5 months (young) and 8.5 months (old) of age. Histopathologic and histomorphometric analyses as well as growth factor and cytokine protein and mRNA expression were carried out in the SG. Histomorphometric analysis of SG from young mice showed no differences between AL and CR mice, but old AL (vs old CR) had a 7.3-fold higher focus score and a 34-fold increase in percentage area inflammation. mRNA analysis revealed significantly higher levels of TGF beta 1 in SG of old CR (6.8-fold) mice. In contrast, CR reduced mRNA expression of proinflammatory cytokines (IL-6, 2.9-fold for young and 4.8-fold for old; TNF alpha, old 3.9-fold). By immunoblotting, significantly higher levels of TGF beta 1 protein was detected in old CR mice (vs old AL; 13.2-fold). IL-6 and TNF alpha proteins were undetectable in both young and old CR groups, whereas an increase in IL-6 (4.7-fold) and TNF alpha (9.3-fold) was observed in old AL mice. These results indicate that amelioration of the histological severity of disease in SG of B/W mice is paralleled and possibly mediated by increased expression of immunosuppressive TGF beta 1 and decreased expression of proinflammatory cytokines.

Animals↗
PubMed1995

Induction of transcription factors in human T lymphocytes by aspirin-like drugs.

Aspirin-like drugs (ALD) induce calcium mobilization, an essential component of T cell activation, but do not induce the biosynthesis of IL-2. To understand the extent to which ALD may mimic mitogenic stimulation, we studied cytoplasmic and nuclear signaling steps in ALD-treated T cells. We found that ALD induce a transient activation of protein kinase (PKC) but have no effect (in comparison to anti-CD3 antibodies) on protein tyrosine phosphorylation nor on PCL gamma 1 tyrosine phosphorylation. ALD-induced calcium mobilization and PKC activation are independent of tyrosine protein kinase activity as shown by the lack of effect of herbimycin, a tyrosine-protein kinase-specific inhibitor. Although we detected no IL-2 mRNA in ALD-treated cells, the nuclei of these cells contain proteins capable of binding to three regulatory sequences in the IL-2 promoter region: NFAT, NF kappa B, and AP-1. These binding activities are expressed only in activated T cells. The expression of AP-1 depended on calcium mobilization and PKC activation. These data suggest that ALD cause transient but significant changes in T cell transmembrane signaling, although some events induced by stimulation with anti-CD3 antibodies are not induced by ALD. The signal is transmitted to the nucleus and induces DNA-binding activity by several transcription factors. However, the ALD stimulus is not capable of causing complete T cell activation.

Adult↗
PubMed1995

Analysis of transforming growth factor beta and other cytokines in autoimmune exocrinopathy (Sjögren's syndrome).

Cytokines play a major role in tissue destruction caused by autoimmune dysregulation. In Sjögren's syndrome (SS) patients, salivary glands are the target organs for autoimmune tissue damage. In the present study, reverse transcriptase-polymerase chain reaction (RT-PCR) was used to look for cytokine mRNA expressed in SS salivary glands. Focus score was used to determine the severity of the lesions. Cytokine production in supernatants of the salivary gland cell culture was measured by enzyme-linked immunosorbent assay (ELISA). Immunohistochemical staining was used to identify the local presence of transforming growth factor beta (TGF-beta). Interleukin (IL)-2, IL-6, and IL-10 mRNA were expressed in moderate to severe SS salivary gland lesions. TGF-beta mRNA was constitutively expressed in normal and SS salivary glands. In SS salivary gland cell cultures, IL-6 and IL-10 proteins were produced. TGF-beta production was reduced in high focus score SS glands. Normal and minimally involved SS salivary gland ductal epithelium and acinar cells were found to produce TGF-beta by immunostaining. In conclusion, an excess production of IL-2, IL-6, and IL-10 and a reduced production of the immunosuppressive cytokine, TGF-beta, may be responsible for the progression of the salivary gland lesion in SS. Specific immunotherapy can now be designed based on mechanisms to correct this cytokine imbalance and benefit patients with autoimmune diseases, such as SS.

Adult↗
PubMed1995

Primary Sjögren's syndrome in men.

OBJECTIVE: To describe the clinical expression of primary Sjögren's syndrome (SS) in men, focusing on extraglandular manifestations (EGM) and serological markers of disease. METHODS: In a cross sectional and comparative study, adult men with primary SS were identified from a cohort study on SS, and 26 age matched adult women with primary SS were selected as a control group. All patients met the European classification criteria for SS. They were compared for demographic, clinical and laboratory findings. RESULTS: Thirteen men with primary SS were identified. Mean age at onset was 39 (SEM 4) years and mean duration of disease was 7.8 (1) years. Sicca complex or parotitis was the presenting feature in eight patients (61.5%), and an EGM in five (38.5%). During the course of the disease, EGM were present in 12 patients (92%), polyarthralgias and lymphopenia being the most frequent (38.5% each). Rheumatoid factor was positive in 73% of patients, antinuclear antibodies in 85%, anti-(SS-A) in 62%, and anti-(SS-B) in 46%. No statistical differences in the frequency of EGM or in the presence of autoantibodies were observed between men and women. However, men patients were more likely to have EGM. CONCLUSION: Primary SS in men is an uncommon condition with clinical and serological characteristics similar to those observed in women. Sex hormones may be incriminated in the pathogenesis of SS. However, it remains poorly understood whether sex hormones play a major role in the severity of disease and have any importance with regard to treatment.

Adult↗
PubMed1995

Sjögren's syndrome in childhood.

OBJECTIVE: To describe the clinical characteristics of juvenile Sjögren's syndrome (JSS) and report 5 new primary cases. METHODS: Patients with SS whose disease began before age 16 were identified from a cohort study on SS. Previous patients with JSS published from 1952 to 1993 were found by literature review. Thirty-nine adult patients with primary SS were selected as a control group. RESULTS: Five patients with primary JSS were identified and described. Thirty-four published primary JSS were reviewed. Altogether, there were 30 girls (77%). The mean age at onset was 7.8 +/- 4 years. Parotitis was the most common first symptom. An extraglandular manifestation (EGM) was the presenting feature in 9.3% of cases. Rheumatoid factor (RF) was positive in 71% and antinuclear antibodies (ANA) in 67%. During the course of disease, at least one EGM was noted in 20 cases (51%). Leukopenia was the most frequent of these (7/20, 35%). HLA-DR3 was observed in 4 of 6 cases in which HLA typing was done. Compared with adult primary SS, parotitis at onset was more frequent in children (62.5 vs 13%). The frequency of ANA and articular manifestations were higher in adults (67 vs 92%, and 15.4 vs 38.5%, respectively). We reviewed 31 cases of secondary JSS, of which the most common associated autoimmune disease was juvenile rheumatoid arthritis (42%). JSS preceded by years the associated autoimmune disease in nearly 50% of cases. CONCLUSION: JSS may be a common disease. Parotitis and the presence of RF and ANA are the main features at onset. Characteristics similar to those seen in adults are observed in children. Long-term followup is needed to assess outcome associated factors.

Adolescent↗
PubMed1994

Longitudinal exposure of human T lymphocytes to weak oxidative stress suppresses transmembrane and nuclear signal transduction.

Products of polyamine oxidase activity, at micromolar levels and during a period of 2 to 3 days, down-regulate IL-2 mRNA levels and activity in human lymphocytes. We studied whether this suppression was associated with signal transduction abnormalities. We found that polyamine oxidase activity suppresses both anti-CD3-induced IL-2 production and protein tyrosine phosphorylation. Polyamine oxidase activity also caused a reduction in intracellular calcium mobilization after mitogenic stimulation. The most distal step of CD3-mediated signal transduction is dependent upon transcription factors that regulate a set of genes, including IL-2. We found that polyamine oxidase-treated cells exhibited very low DNA binding activity of two such factors: NFAT and NF-kappa B. On the other hand, AP-1 DNA binding activity was enhanced in polyamine oxidase-treated cells, suggesting a possible role for AP-1 in the human lymphocyte stress response. In accordance with the oxidation dependence of this suppressive mechanism, N-acetylcysteine (NAC; an antioxidant) significantly reversed the polyamine oxidase effects on lymphokine production and signal transduction. These results suggest that NAC contributes, under oxidizing conditions, to the preservation of immune function. In summary, our data suggest that chronic low-level oxidative stress, via suppression of mitogen-induced transmembrane signaling (protein-tyrosine phosphorylation and calcium mobilization), causes a decrease in the DNA binding activity of transcription factors that regulate the IL-2 gene. This results in decreased IL-2 production.

Acetylcysteine↗
PubMed1993

Induction of lupus-associated autoantibodies by immunization with native and recombinant Ig polypeptides expressing a cross-reactive idiotype 4B4.

A human mAb designated 4B4 with anti-Sm activity was derived from a patient with systemic lupus erythematosus. This antibody expressed a lupus-associated cross-reactive Id, partially related to the monoclonal murine anti-Sm (Y2) from MRL/lpr mice. Studies were performed to investigate the ability of 4B4 to induce lupus in nonautoimmune-prone mice. BALB/c mice immunized with 4B4 produced antibodies to dsDNA, ssDNA, Sm ribonucleoprotein, and mouse Fc fragment. There was no antibody activity against SSA/Ro, SSB/La, and hen egg lysozyme. Ag inhibition studies show that the autoantibodies were not polyreactive. Mice were also immunized with r4B4 polypeptides representing the H/L heterodimer, H chain and L chain. Autoantibodies were induced in mice immunized against the H/L and H polypeptides. No autoantibodies were induced in mice immunized with recombinant L chain. Furthermore, from 20 to 68% of antibody activity to Sm or dsDNA could be inhibited with anti-Id antiserum (either anti-4B4 or Y2). The autoantibody was initially IgM and then underwent an isotype switch to IgG. These results show that lupus-associated autoantibodies can be induced by immunization with 4B4 and that the 4B4 VH region is important in this induction process. The finding of murine IgG autoantibody expressing a cross-reactive Id similar to the immunizing 4B4 suggests a role for anti-idiotypic Th cells in this autoimmune response.

Animals↗
PubMed1993

Lessons from autoimmunity.

Autoimmunity is a common occurrence as shown by the human potential to make autoantibodies. New syndromes resembling clinical autoimmune diseases and arising from presumed immunotoxic exposure are presented. Future experimentation should attempt to harness this autoimmune potential to create more effective anticancer vaccines.

Animals↗