Dwight H. Kono

Restricted use of T cell receptor V genes in murine autoimmune encephalomyelitis raises possibilities for antibody therapy

Experimental allergic encephalomyelitis (EAE) is a paralytic autoimmune disease induced in susceptible animals by active immunization with myelin basic protein (MBP) or by passive transfer of MBP-specific T helper (TH) lymphocytes. We have analyzed the T cell receptor genes of 33 clonally distinct TH cells specific for a nonapeptide of MBP inducing EAE in B10.PL (H-2u) mice. All 33 TH cells used two alpha variable gene segments (V alpha 2.3, 61%; V alpha 4.2, 39%), the same alpha joining gene segment (J alpha 39), and two V beta and J beta gene segments (V beta 8.2-J beta 2.6, 79%; V beta 13-J beta 2.2, 21%). The anti-V beta 8 monoclonal antibody F23.1 was found to block completely recognition of the nonapeptide by V beta 8 TH cells in vitro and to reduce significantly the susceptibility of B10.PL mice to peptide-induced EAE.

Type-I Interferon Receptor Deficiency Reduces Lupus-like Disease in NZB Mice

Indirect evidence suggests that type-I interferons (IFN-α/β) play a significant role in the pathogenesis of lupus. To directly examine the contribution of these pleiotropic molecules, we created congenic NZB mice lacking the α-chain of IFN-α/βR, the common receptor for the multiple IFN-α/β species. Compared with littermate controls, homozygous IFN-α/βR-deleted NZB mice had significantly reduced anti-erythrocyte autoantibodies, erythroblastosis, hemolytic anemia, anti-DNA autoantibodies, kidney disease, and mortality. These reductions were intermediate in the heterozygous-deleted mice. The disease-ameliorating effects were accompanied by reductions in splenomegaly and in several immune cell subsets, including B-1 cells, the major producers of anti-erythrocyte autoantibodies. Decreases of B and T cell proliferation in vitro and in vivo, and of dendritic cell maturation and T cell stimulatory activity in vitro were also detected. Absence of signaling through the IFN-α/βR, however, did not affect increased basal levels of the IFN-responsive p202 phosphoprotein, encoded by a polymorphic variant of the Ifi202 gene associated with the Nba2 predisposing locus in NZB mice. The data indicate that type-I IFNs are important mediators in the pathogenesis of murine lupus, and that reducing their activity in the human counterpart may be beneficial.

TLR-dependent and TLR-independent pathways of type I interferon induction in systemic autoimmunity

We formulate a two-phase paradigm of autoimmunity associated with systemic lupus erythematosus, the archetypal autoimmune disease. The initial Toll-like receptor (TLR)-independent phase is mediated by dendritic cell uptake of apoptotic cell debris and associated nucleic acids, whereas the subsequent TLR-dependent phase serves an amplification function and is mediated by uptake of TLR ligands derived from self-antigens (principally nucleic acids) complexed with autoantibodies. Both phases depend on elaboration of type I interferons (IFNs), and therapeutic interruption of induction or activity of these cytokines in predisposed individuals might have a substantial mitigating effect in lupus and other autoimmune diseases.

Encephalitogenic T cells in the B10.PL model of experimental allergic encephalomyelitis (EAE) are of the Th-1 lymphokine subtype

T helper cells reactive to myelin basic protein are clearly implicated in the pathogenesis of murine EAE. We have developed a T cell line, BML-1 that (1) is reactive to the encephalitogenic amino terminal nonapeptide (1-9NAC) of MBP, (2) is I-Au restricted, and (3) induces relapsing EAE in B10.PL (H-2u) mice. Measurement of the lymphokine profile of BML-1 revealed secretion of IL-2, interferon-gamma and lymphotoxin but not IL-4. This profile is consistent with the Th1/DTH subtype. Coculture of BML-1 with MBP-primed B cells shows that BML-1 does not provide significant helper function in vitro. In addition, BML-1 secretion of interferon-gamma was found to inhibit LPS-induced anti-MBP antibody responses. This suggested that anti-MBP antibodies may not be necessary for induction of EAE. Sera from mice, in which severe disease was induced with the 1-9NAC peptide and Bordetella pertussis, showed no development of serum antibodies to MBP. These data show that MBP-reactive Th cells of the Th-1/DTH subtype can induce EAE and do not provide Th function for anti-MBP responses and that serum anti-MBP antibodies are not found in peptide 1-9NAC-induced disease. T cell lines specific for encephalitogenic epitopes and characterized for lymphokine secretion will provide a useful tool for understanding the role of T cells in the induction of EAE.

ICOS-dependent extrafollicular helper T cells elicit IgG production via IL-21 in systemic autoimmunity

The role of specialized follicular helper T (TFH) cells in the germinal center has become well recognized, but it is less clear how effector T cells govern the extrafollicular response, the dominant pathway of high-affinity, isotype-switched autoantibody production in the MRL/MpJ-Faslpr (MRLlpr) mouse model of lupus. MRLlpr mice lacking the Icos gene have impaired extrafollicular differentiation of immunoglobulin (Ig) G+ plasma cells accompanied by defects in CXC chemokine receptor (CXCR) 4 expression, interleukin (IL) 21 secretion, and B cell helper function in CD4 T cells. These phenotypes reflect the selective loss of a population of T cells marked by down-regulation of P-selectin glycoprotein ligand 1 (PSGL-1; also known as CD162). PSGL-1lo T cells from MRLlpr mice express CXCR4, localize to extrafollicular sites, and uniquely mediate IgG production through IL-21 and CD40L. In other autoimmune strains, PSGL-1lo T cells are also abundant but may exhibit either a follicular or extrafollicular phenotype. Our findings define an anatomically distinct extrafollicular population of cells that regulates plasma cell differentiation in chronic autoimmunity, indicating that specialized humoral effector T cells akin to TFH cells can occur outside the follicle.

Syndromes of Toluene Sniffing in Adults

Clinical and laboratory findings in 25 adults, ages ranging from 18 to 40 years, who were hospitalized for problems related to paint sniffing are presented. All but one were chronically unemployed. Three different patterns of symptoms led to hospitalization: muscle weakness (n = 9), gastrointestinal complaints including abdominal pain and hematemesis (n = 6) and neuropsychiatric disorders including altered mental status, cerebellar abnormalities, and peripheral neuropathy (n = 10). Hypokalemia (n = 13), hypophosphatemia (n = 10), hyperchloremia (n = 22), and hypobicarbonatemia (n = 23) were common. The average serum potassium and phosphorus concentrations of 1.7 mmol/L and 1.5 mg/dL were significantly lower in the muscle weakness group than in the other two groups. Rhabdomyolysis occurred in 10 patients. Hyperchloremic acidosis was found in 19 of 22 patients evaluated. The muscle weakness and gastrointestinal syndromes resolved within 1 to 3 days with abstinence from sniffing and repletion of fluid and electrolyte stores. Inhalation of paint or glue vapors should be considered in the differential diagnosis of the symptoms and laboratory findings described above.

Interferons as pathogenic effectors in autoimmunity

Summary:  Interferons (IFNs) type‐1 (IFN α/β) and type‐II (IFN‐γ) are the most pleiotropic molecules in the intricate cytokine network. This dominance arises from three crucial factors: (i) initiation of IFN‐α/β and IFN‐γ production at the inception of most innate immune responses, which primes for the ensuing adaptive immune responses, primarily through the sine qua non upregulation of major histocompatibility complex and costimulatory molecules; (ii) magnification of their production and signaling by cross‐talk between themselves, and synergistic or antagonistic effects on other cytokines; and (iii) direct or indirect initiation of transcription of hundreds of immunologically relevant genes. Considering that aberrant immune responses against self‐molecules seem to depend on the same constituents and pathways as those against exogenous antigens, it follows that IFNs are also major effectors in the pathogenesis of autoimmunity. Here, we review the diverse biological effects of IFNs on the immune system, discuss findings pertaining to the nature of exogenous and endogenous stimuli that might induce IFN production through the engagement of Toll‐like receptors, and summarize the detrimental and, in some instances, beneficial effects of IFNs in systemic and organ‐specific autoimmune diseases.

Treatment of murine lupus with cDNA encoding IFN-γR/Fc

IFN-γ, a pleiotropic cytokine, is a key effector molecule in the pathogenesis of several autoimmune diseases, including lupus. Importantly, deletion of IFN-γ or IFN-γR in several lupus-predisposed mouse strains resulted in significant disease reduction, suggesting the potential for therapeutic intervention. We evaluated whether intramuscular injections of plasmids with cDNA encoding IFN-γR/Fc can retard lupus development and progression in MRL-Faslpr mice. Therapy significantly reduced serum levels of IFN-γ, as well as disease manifestations (autoantibodies, lymphoid hyperplasia, glomerulonephritis, mortality), when treatment was initiated at the predisease stage, particularly when IFN-γR/Fc expression was enhanced by electroporation at the injection site. Remarkably, disease was arrested and even ameliorated when this treatment was initiated at an advanced stage. This therapy represents a rare example of disease reversal and makes application of this nonviral gene therapy in humans with lupus (and perhaps other autoimmune/inflammatory conditions) highly promising.

The role of IFN-gamma in systemic lupus erythematosus: a challenge to the Th1/Th2 paradigm in autoimmunity

The classification of T helper cells into type 1 (Th1) and type 2 (Th2) led to the hypothesis that Th1 cells and their cytokines (interleukin [IL]-2, interferon [IFN]-γ) are involved in cell-mediated autoimmune diseases, and that Th2 cells and their cytokines (IL-4, IL-5, IL-10, IL-13) are involved in autoantibody(humoral)-mediated autoimmune diseases. However, this paradigm has been refuted by recent studies in several induced and spontaneous mouse models of systemic lupus erythematosus, which showed that IFN-γ is a major effector molecule in this disease. These and additional findings, reviewed here, suggest that these two cross-talking classes of cytokines can exert autoimmune disease-promoting or disease-inhibiting effects without predictability or strict adherence to the Th1-versus-Th2 dualism.

Quantitative polymerase chain reaction analysis reveals marked overexpression of interleukin-1β, interleukin-10 and interferon-γ mRNA in the lymph nodes of lupus-prone mice

The nature of the stimuli driving autoantibody production in systemic lupus erythematosus (SLE) is unclear, but cytokines are believed to play an important role. Since cytokines primarily appear to act locally at the tissue level, we analysed mRNA expression of several cytokines (IL-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IFNγ, TNFα, TNFβ and TGFβ1) in the lymph nodes of lupus-prone mice, in models of early onset disease. We constructed a multispecific competitor fragment that allowed quantification of these cytokine transcripts by competitive PCR assay. The results reveal considerable overexpression of IL-1β, IL-10 and IFNγ transcripts in SLE-prone MRL-lprlpr (MRLl) and BXSB male (BXSBm) mice, but with some strain differences. IFNγ was most markedly augmented in MRLl mice (in some cases over 100-fold greater than control mice), IL-1β was most severely overexpressed in BXSBm mice while IL-10 was equally increased in both strains. In addition, TGFβ1 expression was moderately elevated in the lymph nodes of BXSBm (but not MRLl) mice. We found no abnormality in the expression of the other cytokines. Cytokine transcript levels were only slightly altered at 4 weeks of age, but were elevated from 10 to 22 weeks of age. The latter phase corresponds to a period where lupus-like disease escalates, resulting in frequent mortality. Interestingly, our results do not reveal a clear Th1 or Th2 cytokine expression pattern in these lupus-prone mice. IL-1β, IFNγ and IL-10 are pleiotropic cytokines with pro-inflammatory and B-cell stimulatory effects. These results point to certain cytokines as potential targets for immunotherapy in lupus.