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Neurological consequences of immune dysfunction: lessons from HIV infection and multiple sclerosis.

In a recent workshop held on Sanibel Island, Florida (18-21 January 1992), the two most common neuroimmunologic diseases of young adults, multiple sclerosis (MS) and HIV encephalopathy, were jointly discussed. The logic of assembling investigators from these two fields was based not on an assumed etiologic connection between MS and retroviral infection of the central nervous system (CNS), but rather in the hope of uncovering potential common pathogenic mechanisms, particularly as might relate to trafficking of mononuclear cells into the central nervous system, the distribution and function of macrophages and microglia, the structure and function of the blood-brain barrier, and the role of cytokines released by activated cells. Multiple sclerosis is a disease without a known etiologic agent or pathogenesis. While the causative agent for HIV leukoencephalopathy is known, the pathogenesis of the disease remains entirely enigmatic (a topic covered by R. Johnson). This meeting brought together two different groups of investigators to compare and contrast the diseases and to share perspectives, paradigms, and data with the aim of cross-fertilizing the disciplines and generating healthy hybrids.

Acquired Immunodeficiency Syndrome

Relationship between antibody to LAV/HTLV-III and the natural course of subclinical cellular immune dysfunction in homosexual men.

To assess the epidemiology and natural history of persistent generalized lymphadenopathy (PGL) and subclinical immunodeficiency in relation to serologic evidence of lymphadenopathy-associated virus/human T-lymphotropic virus type III (LAV/HTLV-III) infection, 109 homosexual men with PGL, 47 homosexual men without lymphadenopathy who attended a sexually transmitted disease (STD) clinic, 25 homosexual male university students, and 26 heterosexual men who attended the STD clinic were studied. In 1982-1983 antibody to LAV/HTLV-III was present in 97%, 35%, 21%, and 4% of the four groups, respectively (P less than .001). Subclinical immunodeficiency was more closely associated with LAV/HTLV-III seropositivity than with lymphadenopathy. Cohorts of 78 homosexual subjects with PGL, 35 homosexual subjects from STD clinic, and 15 homosexual university students were followed for median periods of 13.5, 20, and 14.5 months, respectively. The seroconversion rate was 23% per year among seronegative subjects, and 4% of seropositive subjects developed overt acquired immunodeficiency syndrome (AIDS). Among seronegative subjects, there was significant improvement in T4:T8 ratios (P = .001), whereas most seropositive subjects continued to have subnormal total counts of T4 lymphocytes and low T4:T8 ratios. Some cases of subclinical cellular immunodeficiency apparently are unrelated to LAV/HTLV-III infection, and the presence of antibody to this virus is associated with an unfavorable immunologic prognosis.

AIDS-Related Complex

[Cellular immune dysfunction in the NOD mouse: suppression of concanavalin A-induced responses in spleen cells by activated macrophages].

It is generally accepted that T lymphocyte-mediated autoimmunity contributes to the pathogenesis of Type 1 diabetes in humans and animals. Using spleen cells from nonobese diabetic (NOD) mice, a model of human Type 1 diabetes, we have analyzed the subset of T lymphocytes by flow cytometry and investigated concanavalin A (Con A)-induced interleukin 2 (IL-2) production and cell proliferation. NOD mice showed a higher percentage of Thy1.2+, L3T4+, and Lyt2+ T lymphocytes than did control ICR mice through the whole age examined. Spleen cells from a large majority of NOD mice were found to generate very low IL-2 production and cell proliferation in response to Con A. However, a few mice preserved their responsiveness to Con A. The following reasons may indicate that macrophage-mediated suppression participates in the deficient function of NOD spleen cells. (a) Macrophage depletion from NOD spleen cells retrieved Con A-induced IL-2 production. (b) Thioglycollate-induced peritoneal exudate cells containing many activated macrophages could completely suppress cell proliferation. (c) Prostaglandin synthetase inhibitor indomethacin reversed the suppression of IL-2 production by macrophages. (d) Conversely, exogenous prostaglandins could show the partial suppression of IL-2 production. These results suggest that activated macrophages suppress the response of NOD spleen cells to Con A mostly through prostaglandins. This impairment may contribute to the pathogenesis of Type 1 diabetes in NOD mice.

Animals

Animal model for immune dysfunction associated with adenosine deaminase deficiency.

An in vivo murine model for immunodeficiency of both B and T cells is produced by continuous intraperitoneal infusion of 2'-deoxycoformycin (DCF), a specific tightly binding inhibitor of adenosine deaminase (ADase; adenosine aminohydrolase, EC 3.5.4.4). After DCF infusion, ADase of thymus, spleen, and lymph nodes was inhibited to varying degrees ranging from 57% to 100%. Immunodeficiency under these conditions was indicated by: (i) a striking decrease in lymphocyte response to the T-cell mitogens concanavalin A and phytohemagglutinin; (ii) an impairment of delayed hypersensitivity measured by the footpad reaction; (iii) a decrease in antibody production measured in both in vivo and in vitro plaque-forming cell assay; (iv) a significant prolongation of mouse skin allograft survival after transplantation into the C57BL/6J (H-2b) strain of skin from BALB/c (H-2d) mice; and (v) a marked lymphopenia. Histological examination indicated lymphoid degeneration in the thymus, lymph nodes, and spleen with no alterations in other tissues including bone marrow, kidney, lung, gastrointestinal tract, and liver except for the occurrence of hepatitis. A decrease in the number of Thy-1-positive cells in both spleen and lymph nodes further supported the fact of cytotoxicity of DCF to T cells. Anorexia and weight loss were observed within 5 days of continuous DCF infusion at 0.4 mg/kg body weight per day. These data indicate that this method provides an experimental model for future studies on the biochemical mechanisms responsible for the genetically determined severe combined immunodeficiency disease in man.

Adenosine

Immune dysfunction--a potential target for treatment in endometriosis.

The treatment approach towards endometriosis has been traditionally either surgical or hormonal in nature. Since endometriosis is, to a large extent, a microscopic disease, a surgical approach cannot be expected to eradicate the disease. Treatment is, therefore, generally attempted by hormonal manipulation, an approach based on the known oestrogen sensitivity of endometriosis. Hormonal manipulation can only temporarily affect endometriosis, and quite clearly does not address the underlying aetiology and/or pathophysiology of the disease. Since neither is, at present, well understood, one can only speculate as to the treatment approach that would, in fact, affect the pathophysiology of the condition. Endometriosis has, in recent years, been characterized by a large number of immunological abnormalities in the host. It is, therefore, very tempting to speculate that an immunological defect represents the basic abnormality which later leads to the occurrence of the disease. This assumption is supported by the observation that those immunological defects are already present in the mildest forms of the disease. In fact, if one believes that many cases of unexplained infertility represent undiagnosed microscopic endometriosis, then evidence suggests that this precursor stage of the disease is basically characterized by an identical immunological profile to that of endometriosis. An immunological aetiology and/or pathophysiology of endometriosis should lead to an immunological treatment approach toward the disease. Specifically, a number of non-specific immunomodulators, presently utilized in a variety of medical conditions with immunological aetiologies, would seem to represent promising new therapeutic strategies to conquer endometriosis at its roots. A new treatment approach to endometriosis appears urgently needed since, at least with regard to the effects of endometriosis on fertility and pregnancy loss, present approaches have proven ineffective.

Autoantibodies

Immune dysfunction in diabetes-prone BB rats. Interleukin 2 production and other mitogen-induced responses are suppressed by activated macrophages.

Spleen cells of diabetes-prone BB Wistar rats were found to generate excessively low proliferative responses, and interleukin 2 (IL-2) levels in response to T-dependent mitogens. This abnormality was not due solely to abnormal T cell numbers since: (a) addition of BB spleen cells of BB splenic macrophages to normal major histocompatibility complex (MHC)-matched Wistar Furth (WF) spleen cells resulted in severe suppression of concanavalin A (Con A)-, phytohemagglutinin (PHA)-, and pokeweed mitogen (PWM)-mediated proliferation, and IL-2 production; (b) macrophage depletion from BB spleen cells, but not B cell or T cell depletion, removed completely the suppressive effects of BB cells on WF cells; (c) macrophage depletion greatly enhanced the response of BB lymphocytes to T-dependent mitogens. Although suppressor macrophages could also be found in the spleen of WF control rats they were present in much smaller numbers than in the spleen of BB rats. The suppressive effect of BB macrophages was partially reduced by addition of the prostaglandin synthetase inhibitor indomethacin to cultures. Furthermore, indomethacin (but not catalase or PMA) considerably augmented IL-2 secretion of Con A-stimulated BB spleen cells, but had little effect on WF spleen cells. In contrast, prostaglandins E1 and E2 (PGE1 and PGE2) suppressed IL-2 production. While IL-2 secretion was severely depressed in BB rats unstimulated and lipopolysaccharide (LPS)-stimulated IL-1 secretion by splenic macrophages was normal. BB macrophages did not inactivate IL-2. Low IL-2 production and macrophage-mediated suppression were features of all BB rats tested.

Animals

Natural killer cytotoxicity in the diagnosis of immune dysfunction: criteria for a reproducible assay.

Current evidence indicates that natural killer (NK) cells, which are large granular lymphocytes that mediate non-major histocompatibility complex (MHC)-restricted cytotoxicity and antibody-dependent cytotoxicity and that are involved in multiple regulatory, developmental, and immunologic processes, are important in health. Immunodeficiency states presenting with low NK activity are often associated with malignancies, chronic viral infections, or autoimmune diseases. Monitoring of NK function appears to be indicated as an aid to diagnosis, prognosis, and follow-up after therapy. Reliable performance of NK assays in a clinical laboratory requires that uniform criteria be established and followed for the acceptability of results. Statistical analysis of daily variability can be of great assistance in identifying and tracking sources of error, but routine statistical adjustments are not generally advisable. The quality control program described here provides a degree of assurance that this cytotoxicity assay can be dependable whether performed at one time point or serially. The successful implementation of this program requires laboratory resources, biostatistical support, and interpretative skills, all of which are available in a modern clinical laboratory.

Cytotoxicity Tests, Immunologic

Variations in macrophage antigen phenotype: a correlation between Ia antigen reduction and immune dysfunction during tumor growth.

Variable Ia antigen expression by macrophages (M phi) was examined during tumor growth by measuring: Ia antigen masking and immunofluorescence by anti-Ia antibody, accessory cell function in concanavalin A (Con A) and mixed lymphocyte reaction (MLR)-induced T cell proliferation, and M phi stimulatory function in the MLR. Tumor-induced progressive loss of Ia antigen expression was shown by immunofluorescence and corroborated by anti-Ia blockade of MLR stimulatory activity of normal but not tumor-bearing hosts (TBH) splenic M phi. The TBH splenic M phi supported Con A-induced proliferation of syngeneic T cells (Ia antigen-independent) but did not support syngeneic T cell proliferation in the MLR (Ia antigen-dependent). Irrespective of tissue source, normal and TBH M phi differed in their MLR stimulatory capabilities. In general, splenic M phi preparations were better stimulators of allogeneic T cell blastogenesis in the MLR than thioglycollate-elicited peritoneal M phi. Kinetic studies with TBH M phi showed a significant progressive loss in MLR stimulatory activity, which was especially pronounced with peritoneal M phi. Expression of Ia antigens by normal but not TBH M phi were diminished by 24-h in vivo plating of the peritoneal M phi. Indomethacin treatment showed Prostaglandin E2 was not a direct in vitro factor in Ia antigen-mediated reduction of splenic M phi MLR stimulatory activity. Taken together, these data delineate a loss of M phi Ia antigen expression, resulting in a decrease in Ia antigen-mediated functional activities during tumor growth.

Animals

Integrated Multi-omics Profiling of 2,4-dinitrochlorobenzene (DNCB)-induced Atopic Dermatitis in Mice Reveals a Coordinated Network of Barrier Dysfunction, Immune Activation, and Metabolic Reprogramming.

Atopic dermatitis (AD) is caused by a combination of epidermal barrier defect and immune imbalance. However, the molecular networks between these structural abnormalities and metabolic variations are unclear. This study aim of this research was to examine the concurrent molecular alterations in skin barrier damage and metabolic disorders in an AD-like mouse model by a multi-omics strategy. A 2,4-dinitrochlorobenzene (DNCB)-induced AD-like mouse model was established and the skin tissues were examined through the combination of transcriptomic, quantitative proteomic, and metabolomic analyses. Cross-omics correlation and network analyses were performed to identify consistently abnormal molecular pathways and crucial regulatory molecules. DNCB treatment caused severe epidermal hyperplasia, and prominent infiltration of CD3⁺ T cells, F4/80⁺ macrophages, and mast cells. Transcriptomic and proteomic analysis indicated significant disruption in keratinocyte differentiation, extracellular matrix organization, and cornified envelope formation pathways. Combined analysis detected 171 molecules which were simultaneously altered at both mRNA and protein levels, and network analysis identified FLG2 and KRT6B as central barrier-related molecules. Pathway enrichment analysis consistently showed the participation of AMPK and PPAR signaling pathways. Metabolomic analysis also revealed coordinated changes in lipid and amino acid metabolism which were closely associated with cornified envelope-associated genes and collagen-modifying enzymes. These findings indicate a close relationship between barrier, immune and metabolic regulation in DNCB-induced dermatitis and provide a multi-omics resource for future mechanistic studies of atopic skin inflammation.

Animals

Immune dysfunction in rabbits associated with chronic administration of enemas and rectal insemination.

NZ rabbits were treated with various combinations of enemas and intrarectal insemination (1 or 3 ml of semen a week) to investigate the effects of intestinal uptake and immunogenicity of seminal components and of an unrelated antigen, bovine serum albumin (BSA), given simultaneously. For 5 months the treatment was limited to enemas and/or semen, and total immunoglobulins and antisperm and antilymphocyte antibodies were determined. Then, without interruption of the treatments, the animals received two courses of three consecutive daily intrarectal administrations of BSA, and the humoral response was determined 7 days after each course of administration. Only 1 of 18 intrarectally inseminated animals responded with production of antisperm antibodies; none had antilymphocyte antibodies. Total immunoglobulins, however, were significantly increased in animals receiving enemas alone (p less than 0.02) or followed by insemination (p less than 0.05). The humoral response to BSA was significantly (p less than 0.01) enhanced by prior administration of enemas but was moderately reduced by simultaneous administration of semen, in a dose-related fashion.

Animals