Role of NK cells and TGF-beta in the regulation of T-cell-dependent antibody production in health and autoimmune disease

Rhinovirus Suppresses TGF-β-GARP Presentation by Peripheral NK Cells

Asthma is a chronic airway disease whose exacerbations are often triggered by rhinovirus infection. TGF-β1 induces rhinovirus replication in infected cells. Moreover, TGF-β1 is a pleiotropic mediator that is produced by many immune cells in the latent, inactive form bound to the latency-associated peptide (LAP) and to the transmembrane protein glycoprotein A repetitions predominant (GARP). In this study we wanted to investigate the effect of rhinovirus infection on the TGF-β secretion and the downstream signaling via TGF-βRI/RII in peripheral blood mononuclear cells from control and asthmatic patients after rhinovirus infection ex vivo. Here, we found a significant upregulation of TGF-βRII in untouched PBMCs of asthmatics as well as a suppression of TGF-β release in the rhinovirus-infected PBMC condition. Moreover, consistent with an effect of TGF-β on Tregs, PBMCs infected with RV induced Tregs, and TGF-βRII directly correlated with RV1b mRNA. Finally, we found via flow cytometry that NK cells expressed less GARP surface-bound TGF-β, while cytokine-producing NKbright cells were induced. In summary, we show that rhinovirus infection inhibits TGF-β release in PBMCs, which results in the activation of both Treg and NK cells.

Prolonged oral ingestion of microplastics induced inflammation in the liver tissues of C57BL/6J mice through polarization of macrophages and increased infiltration of natural killer cells

Microplastics (< 5 mm diameter) are one of most important environmental pollutants and contaminants worldwide. However, how microplastics affect liver immune microenvironment in not well understood. Microplastics (0.5 µm) were administered orally to C57BL/6J mice for 4 consecutive weeks at the rate of 0.5 mg/day. Non-parenchymal cells were isolated from of the mice through fractionation of fresh hepatic tissues. The immune landscape for four cell populations of B cells, T cells, NK cells and macrophages in the liver tissues was then evaluated using flow cytometry. The secretion level of inflammatory cytokines and associated signaling pathway were investigated using quantitative real-time polymerase chain reaction and western blot. Oral ingestion of microplastics increases liver weight, general liver index as well as expression of serum, liver function-related indicators. Microplastics also increased the infiltration of natural killer cells and macrophages to non-parenchymal liver cells, but reduced that of B cells to the same tissues. However, microplastics had no effect on the infiltration of T cell to non-parenchymal liver cells. Ingestion of MPs also up-regulated the expression of IFN-γ, TNF-α, IL-1β, IL-6 and IL-33 mRNA, but down-regulated that of IL-4, IL-5, IL-10, IL-18 and TGF-β1. Overall, the aforementioned processes were regulated via the NF-κB pathway in the hepatic non-parenchymal cells. Microplastics disrupts inflammatory process in liver tissues via the NF-κB signaling pathway. These findings provide a strong foundation on immune processes in hepatic tissues following prolonged ingestion of microplastics.

TGF-β1 +869T/C (rs1982073) gene polymorphism and susceptibility to rheumatoid arthritis: Updated systematic review and meta-analysis

Rheumatoid arthritis (RA) is a complex autoimmune disease that affects about 1% of the world's population. The conclusions about the relationship between TGF gene polymorphism and the risk of RA are still inconsistent. Therefore, we performed a meta-analysis to re-evaluate the relationship between TGF-β1 T869C gene polymorphism and the risk of rheumatoid arthritis.

METHOD

We performed a systematic electronic search in PubMed, Embase, Elsevier, Web of Science, Cochrane Library, Medline and China National Knowledge Infrastructure database (up to August 2020). In the subgroup analysis, we divide the research into three groups: Asian, European and Mediterranean, The combined OR and 95%CI of the five models (allele model, homozygous model, heterozygous model, dominant model, recessive model) were calculated, respectively.

RESULTS

15 case-control studies (14 articles) were involved in this meta-analysis, including 2103 cases and 2143 healthy controls. In the overall analysis, it showed that there may be an significant association between TGF-β1+869T/C polymorphism and RA sensitivity (allele model, T vs. C: OR=1.444, 95% CI=1.171-1.782, P=0.001; homozygous model, TT vs. CC: OR=1.910, 95% CI=1.322-2.761, P=0.001; heterozygous model, CT vs. CC: OR=1.558, 95% CI=1.179-2.059,P=0.002; dominant model, TT+CT vs. CC: OR= 1.742, 95% CI=1.303-2.329, P=0.001; recessive model, TT vs. CT+CC: OR=1.400, 95% CI= 1.058-1.852, P=0.018).However, the results of ethnic subgroup analysis indicated that rs1982073 was not associated with RA risk in Europeans(allele model, T vs. C: OR=0.993, 95% CI=0.849-1.162, P=0.931, I² <0.1%, P>0.1).

CONCLUSION

In summary, our meta-analysis showed that the rs1982073 T allele does not increase RA susceptibility in Europeans.

Dietary fish oil reduces the acute inflammatory response and enhances resolution of antigen-induced peritonitis

Dietary n-3 polyunsaturated fatty acids (PUFA) influence the inductive phase of inflammation but less is known about their effects on the resolution phase. This study examined the effects of dietary fish oil on induction and resolution of antigen-induced inflammation in mice. Mice were fed a control diet with or without 2.8% fish oil, immunized twice with methylated BSA (mBSA) and inflammation induced by intraperitoneal injection of mBSA. Prior to and at different time points after mBSA administration, peritoneal cells were analyzed and expression of surface molecules determined by flow cytometry. Concentration of chemokines, cytokines and soluble cytokine receptors was determined by ELISA. Mice fed the fish oil diet had fewer peritoneal neutrophils, shorter resolution interval and lower levels of pro-inflammatory cytokines and chemokines than mice fed the control diet. In mice fed the fish oil diet there was an early peak in peritoneal levels of the immunosuppressive molecules sIL-6R and TGF-β, that was not seen in mice fed the control diet. In the resolution phase, peritoneal macrophages from mice fed the fish oil diet expressed more of the atypical chemokine receptor D6 and peritoneal TGF-β levels were higher than that in mice fed the control diet. Furthermore, in the late-resolution phase there were more peritoneal eosinophils and macrophages in mice fed the fish oil diet than in mice fed the control diet. These results demonstrate a suppressive effect of n-3 PUFA on the inductive phase of inflammation and indicate an enhancing effect of n-3 PUFA on resolution of inflammation.

Long-term immunomodulatory effect of amniotic stem cells in an Alzheimer's disease model

Amyloid beta (Aβ) plays a major role in Alzheimer's disease (AD), and neuroinflammatory processes mediated by Aβ plaque-induced microglial cells and astrocytes contribute to AD pathogenesis. The present study examined human placenta amniotic membrane-derived mesenchymal stem cells (AMSCs), which have potent immunomodulatory and paracrine effects in a Tg2576 (APPswe) transgenic mouse model of AD. AMSCs secreted high levels of transforming growth factor-β under in vitro inflammatory environment conditions. Six weeks after the intravenous injection of AMSCs, APPswe mice showed evidence of improved spatial learning, which significantly correlated with the observation of fewer Aβ plaques in brain. The number of ED1-positive phagocytic microglial cells associated with Aβ plaques was higher in AMSC-injected mice than in phosphate-buffered saline-injected mice, and the level of Aβ-degrading enzymes (matrix metallopeptidase-9 and insulin-degrading enzyme) was also significantly higher. Furthermore, the level of proinflammatory cytokines, interleukin-1 and tumor necrosis factor-α, was lower and that of anti-inflammatory cytokines, interleukin-10 and transforming growth factor-β, was higher in AMSC-injected mice than phosphate-buffered saline-injected mice. These effects lasted until 12 weeks after AMSC injection. Taken together, these results collectively suggest that injection of AMSCs might show significant long-lasting improvement in AD pathology and memory function via immunomodulatory and paracrine mechanisms.

The Innate Immune System of the Perinatal Lung and Responses to Respiratory Syncytial Virus Infection

The response of the preterm and newborn lung to airborne pathogens, particles, and other insults is initially dependent on innate immune responses since adaptive responses may not fully mature and require weeks for sufficient responses to antigenic stimuli. Foreign material and microbial agents trigger soluble, cell surface, and cytoplasmic receptors that activate signaling cascades that invoke release of surfactant proteins, defensins, interferons, lactoferrin, oxidative products, and other innate immune substances that have antimicrobial activity, which can also influence adaptive responses. For viral infections such as respiratory syncytial virus (RSV), the pulmonary innate immune responses has an essential role in defense as there are no fully effective vaccines or therapies for RSV infections of humans and reinfections are common. Understanding the innate immune response by the preterm and newborn lung may lead to preventive strategies and more effective therapeutic regimens.

Naïve rat NK cells control the onset of T cell response

NK cell function in the rat is only defined in a rudimentary way due to missing tools for clear NK cell identification. The present study introduces the congenic LEW.BH-NKC rat strain which allows distinct detection of rat NK cells using commercial antibodies. LEW.BH-NKC rats were exposed in vivo to the porcine B cell line L23 by subcutaneous transfer of L23 cell suspension. We used Luciferase transgeneic L23 cells to follow the course of rejection by living imaging. L23 cells were rejected within five days after placement under the skin thus the rejection is mediated by innate immune responses in the first place. Indeed we found increased percentages of NK cells in the blood, spleen and in draining lymph nodes using flow cytometry methods. Surprisingly, we found as a consequence a decrease in proliferative T cell response in the draining lymph nodes. We identified NK cells as mediators of this regulation by in vitro performed mixed lymphocyte reactions. The remarkable feature was the naive state of NK cells exhibiting the regulative capacity. Furthermore, the regulation was not exclusively mediated by IL-10 as it has been reported before for influence of T cell response by activated NK cells but predominantly by TGF-β. Interestingly, after initiation of the adaptive immune response, NK cells failed to take influence on the proliferation of T cells. We conclude that naive NK cells build up a threshold of activation impulse that T cells have to overcome.

Natural killer cells and their role in rheumatoid arthritis: friend or foe?

Rheumatoid arthritis (RA) is a long-term disease that leads to inflammation of the joints and surrounding tissues. Natural killer (NK) cells are an important part of the innate immune system and are responsible for the first line of defense against pathogens during the initial immune challenge before the adaptive immune system eventually eliminates the infectious burden. NK cells have the capacity to damage normal cells or through interaction with other cells such as dendritic cells, macrophages, and T cells cause autoimmune diseases, such as RA. NK cells isolated from the joints of patients with RA suggest that they may play a role in this disease. However, the involvement of NK cells in RA pathology is not fully elucidated. Both protective and detrimental roles of NK cells in RA have recently been reported. A better understanding of NK cells' role in RA might help to develop new therapeutic strategies for treatment of the RA or other autoimmune diseases. We have decided in this paper to focus on the NK cell biology, and attempt to bring the interested readership of this Journal up to date on the NK cell, specifically its possible relation to RA.

Psoriasis and extra domain A fibronectin loops

We have previously postulated that as well as T-helper (Th) 1 and Th17 cells, the transforming growth factor (TGF)-beta/fibronectin (FN)/alpha5beta1 pathway is central to psoriasis pathogenesis. EDA+ FN refers to an alternatively spliced isoform of FN with an additional domain known as extra domain A. EDA+ FN has two important properties pertinent to psoriasis lesions: it stimulates keratinocyte hyperproliferation, and, through stimulation of Toll-like receptor (TLR) 4, stimulates production of proinflammatory cytokines. EDA+ FN production induced by TGF-beta stimulation can be maintained in psoriasis lesions via two main feedback loops. Firstly, EDA+ FN stimulates proliferation of keratinocytes, which, in an autocrine fashion, will release more EDA+ FN. Secondly, EDA+ FN stimulates TLR4 expressed by antigen-presenting cells resulting in the production of proinflammatory cytokines such as tumour necrosis factor-alpha, interleukin (IL)-1, IL-6 and IL-12. The resultant promotion of cutaneous inflammation results in the recruitment of Th1 cells, which also produce EDA+ FN. We propose that these 'FN loops' contribute to the maintenance and progression of psoriatic lesions. Finally, although the association between psoriasis and heart/thrombotic disease remains unclear one plausible link may be the promotion of atherosclerosis and thrombotic heart disease by EDA+ FN.

Natural killer cells modulate overt autoimmunity to homeostasis in nonobese diabetic mice after anti-CD3 F(ab')2 antibody treatment through secreting transforming growth factor-beta

Recently, the anti-CD3 antibody has been shown to be a promising candidate for the efficient treatment of overt autoimmunity. However, the mechanisms underlying this effect remain unclear. Our previous studies demonstrated that natural killer (NK)T cells and transforming growth factor (TGF)-beta were key elements in anti-CD3 F(ab')(2)-mediated re-establishment of glucose homeostasis and restoration of self tolerance to islets in type 1 diabetes. In this report, we further investigate the regulatory pathways involved, especially the cellular source of TGF-beta production. The treatment of new-onset nonobese diabetic mice with anti-CD3 F(ab')(2) resulted in a significant increase in the numbers of NK cells in spleen and pancreatic lymph nodes that secrete TGF-beta. Depletion of this cell population with a specific anti-AsGM1 antibody abrogated anti-CD3 F(ab')(2) therapeutic effects and splenic TGF-beta production. When fractionated from recovered mice after CD3 antibody therapy, these NK cells actively suppressed diabetogenic cell proliferation and prevented the cotransfer of diabetes into nonobese diabetic-severe combined immunodeficient mice in a TGF-beta-dependent manner. In addition, the regulatory NKT cells from remitting mice were capable of causing NK cells to exhibit a TGF-beta-producing phenotype by the secretion of the T helper 2 cytokines interleukins 4 and 10. Overall, these data indicate that NK cells are the main source of TGF-beta production after anti-CD3 F(ab')(2) treatment, which are controlled by a population of T helper 2-like NKT cells.

Expression of TGFbeta1 and its signaling components by peripheral lymphocytes in systemic lupus erythematosus

Transforming growth factor beta1 (TGFbeta1) is an important immunosuppressive cytokine. Defects in its production by lymphocytes and the failure of TGFbeta1 to regulate immunological functions have been described in SLE. Expression of TGFbeta1 and the related signaling pathway was studied in the peripheral lymphocytes of SLE patients. The total plasma TGFbeta1 level in active and inactive SLE patients compared to healthy controls was also measured. TGFbeta1 and all downstream signaling elements were expressed in normal cells. However, in more than 50% of SLE patients the isolated T cell population showed no TGFbeta1 mRNA expression and at least one member of the TGFbeta1 pathway was also missing (TGFbeta-RI, Smad2 and Smad3) in more than half of the patients. Total plasma TGFbeta1 level was increased in both active and inactive SLE groups compared to normal controls (p< 0.05). These data raise questions about the availability of TGFbeta1 signaling in lymphocytes in SLE patients, however, the elevated total plasma TGFbeta1 level suggests that the failure of TGFbeta1 effects is not the consequence of low level of this cytokine in SLE.

TGF-beta utilizes SMAD3 to inhibit CD16-mediated IFN-gamma production and antibody-dependent cellular cytotoxicity in human NK cells

TGF-beta can be a potent suppressor of lymphocyte effector cell functions and can mediate these effects via distinct molecular pathways. The role of TGF-beta in regulating CD16-mediated NK cell IFN-gamma production and antibody-dependent cellular cytotoxicity (ADCC) is unclear, as are the signaling pathways that may be utilized. Treatment of primary human NK cells with TGF-beta inhibited IFN-gamma production induced by CD16 activation with or without IL-12 or IL-2, and it did so without affecting the phosphorylation/activation of MAP kinases ERK and p38, as well as STAT4. TGF-beta treatment induced SMAD3 phosphorylation, and ectopic overexpression of SMAD3 resulted in a significant decrease in IFN-gamma gene expression following CD16 activation with or without IL-12 or IL-2. Likewise, NK cells obtained from smad3(-/-) mice produced more IFN-gamma in response to CD16 activation plus IL-12 when compared with NK cells obtained from wild-type mice. Coactivation of human NK cells via CD16 and IL-12 induced expression of T-BET, the positive regulator of IFN-gamma, and T-BET was suppressed by TGF-beta and by SMAD3 overexpression. An extended treatment of primary NK cells with TGF-beta was required to inhibit ADCC, and it did so by inhibiting granzyme A and granzyme B expression. This effect was accentuated in cells overexpressing SMAD3. Collectively, our results indicate that TGF-beta inhibits CD16-mediated human NK cell IFN-gamma production and ADCC, and these effects are mediated via SMAD3.

Pro- and antiinflammatory cytokine signaling: reciprocal antagonism regulates interferon-gamma production by human natural killer cells

Activated monocytes produce proinflammatory cytokines (monokines) such as interleukin (IL)-12, IL-15, and IL-18 for induction of interferon-gamma (IFN-gamma) by natural killer (NK) cells. NK cells provide the antiinflammatory cytokine transforming growth factor (TGF)-beta, an autocrine/negative regulator of IFN-gamma. The ability of one signaling pathway to prevail over the other is likely important in controlling IFN-gamma for the purposes of infection and autoimmunity, but the molecular mechanism(s) of how this counterregulation occurs is unknown. Here we show that in isolated human NK cells, proinflammatory monokines antagonize antiinflammatory TGF-beta signaling by downregulating the expression of the TGF-beta type II receptor, and its signaling intermediates SMAD2 and SMAD3. In contrast, TGF-beta utilizes SMAD2, SMAD3, and SMAD4 to suppress IFN-gamma and T-BET, a positive regulator of IFN-gamma. Indeed, activated NK cells from Smad3(-/-) mice produce more IFN-gamma in vivo than NK cells from wild-type mice. Collectively, our data suggest that pro- and antiinflammatory cytokine signaling reciprocally antagonize each other in an effort to prevail in the regulation of NK cell IFN-gamma production.

Immature NK cells suppress dendritic cell functions during the development of leukemia in a mouse model

To analyze the mechanisms by which cancer cells escape from hosts' immune surveillance, we investigated the changes in immune status during the progression of leukemia induced by injecting mice with WEHI-3B cells. In the bone marrow (BM) of leukemic mice, only DX5(+)CD3(-) cells were continuously increased, despite the progression of leukemia. In addition, DX5(+)CD3(-) cells were rapidly increased in peripheral blood (PB) 20 days after inoculation. We also found that myeloid dendritic cells (DCs) expressing low levels of I-A(d) and having low allo-T cell stimulatory activity were markedly increased in PB and spleen. The increase in DX5(+) cells in BM was thought to be induced by soluble factors from leukemic cells. DX5(+) cells from leukemic mice were CD3(-), B220(-), Gr-1(-), CD14(-), CD94(-), Ly-49C/F(-), asialo GM1(+), CD25(+), CD122(+), Thy-1(bright), and c-kit(dim) and showed low killing activity against YAC-1 cells, suggesting that those DX5(+) cells were immature NK cells. NK cells from leukemic PB down-regulated the expression of I-A(d) on DCs, an effect mediated by TGF-beta. Moreover, these NK cells significantly suppressed the allo-T cell stimulatory activity of DCs, an effect requiring cell-to-cell contact between NK cells and DCs and thought to involve CD25. Importantly, NK cells from leukemic PB inhibited generation of autotumor-specific CTL induced by DCs in primary MLR or by DC immunization. In conclusion, we identified circulating immature NK cells with immunosuppressive activities. These cells may be important for understanding the involvement of the host immune system during the development of leukemia.

NK cells in autoimmune disease

The role of NK cells in autoimmunity has not been extensively studied. Speaking for a disease-promoting role for NK cells in autoimmune diseases are recent results suggesting that IFN-gamma production by NK cells may help adaptive immune responses diverge in the direction of a Th1 response. NK cells may also be involved in direct killing of tissue cells, which could lead to acceleration of autoimmunity. However, NK cells have also been shown to protect from some autoimmune diseases. A possible reason for this discrepancy may lie in the capacity of NK cells also to produce Th2 cytokines, which could downregulate the Th1 responses that are common in autoimmune disorders. Thus there is at present no coherent view on the role of NK cells in autoimmunity, and more work is needed to clarify why NK cells in some cases aggravate disease and in some cases protect from disease.

NK cells: elusive players in autoimmunity

Natural killer (NK) cells were once regarded as relatively simple cells of the innate immune system. However, they are now revealing themselves as multifunctional regulatory cells that are present throughout the body. The role of NK cells in autoimmunity is attracting increased attention, although the picture is clouded by a conflicting literature that presents disease-promoting as well as disease-protective roles. In this review, we discuss how NK cells might use these dual roles, and suggest that future studies should focus on the impact of the anatomical localization of NK cells as well as the cytokine environment in which NK cells act in individual autoimmune diseases.

Estudo comparativo entre vitiligo, nevo halo e lúpus eritematoso vitiligóide por meio de métodos imunológicos, histológicos e imuno-histoquímicos

FUNDAMENTOS: O estudo compara o vitiligo, o nevo halo (NH) e lúpus eritematoso vitiligóide (LEV) do ponto de vista imunológico, histológico e histoquímico. OBJETIVOS: Avaliar diferenças imuno-histoquímicas entre essas doenças e investigar se a despigmentação do LEV deve-se à destruição pós-inflamatória ou à agressão imunológica aos melanócitos. MÉTODOS: Foram avaliados 20 pacientes com vitiligo, 17 com vitiligo e NH, cinco com NH isolado e 15 com LEV. Detecção de anticorpos: IF direta e indireta com células névicas e de melanoma. Citotoxicidade: atividade NK contra células de melanoma. Estudo anátomo-histoquímico: exame histológico com hematoxilina e eosina, Fontana-Masson, Dopa e Dopa mais prata (D+P) e exame histoquímico com proteína S-100. RESULTADOS: Doentes com vitiligo, NH e LEV apresentaram anticorpos antimelanócitos. Tanto no vitiligo e NH, como no LEV, demonstrou-se a presença de fatores de risco favorecedores da citotoxicidade celular. A coloração com D+P foi superior às colorações tradicionais e à proteína S-100 na detecção de melanócitos e melanina nas lesões de vitiligo, NH e LEV. CONCLUSÕES: Demonstrou-se a existência de anticorpos antimelanócitos no vitiligo e NH. É possível que a despigmentação no LEV se deva a fenômenos imunológicos semelhantes aos do vitiligo e NH. A detecção de melanócitos nas lesões de vitiligo sugere mais inibição funcional do que destruição dessas células.

Basic Concepts of Immune Response and Defense Development

The induction of immune responses requires critical interaction between innate parts of the immune system, which respond rapidly and in a relatively nonspecific manner, and other specific parts, which recognize particular epitopes on an antigen. A critical element in this interaction is the role played by dendritic cells (DCs), which represent "professional antigen-presenting cells." DCs endocytose and process antigen to peptide presented on the cell surface in association with major histocompatibility complex (MHC) molecules. This presentation results in interaction with and stimulation of helper T (Th) lymphocytes, which recognize peptide in association with either MHC class II or cytotoxic T (Tc) lymphocytes, which recognize peptide in association with MHC class I. Stimulation of Th lymphocytes produces the growth and differentiation factors (cytokines) essential for the B lymphocytes that have responded to a more intact form of the antigen and that differentiate into antibody-producing cells. The precise interaction between the cells depends on cognate ligand-receptor recognition between the B and Th lymphocytes. DCs also play a direct role with the stimulation of the B lymphocytes. It appears that DC can deliver antigen to the B lymphocytes in a more intact form than the processed form essential for stimulating T lymphocytes, and can release cytokines that assist the differentiation of the B lymphocytes into antibody-producing cells. This close relationship among the three cell types and the cytokines that are produced ensures the precise control and regulation necessary for immune response development.

Critical role for CD8 T cells in allograft acceptance induced by DST and CD40/CD154 costimulatory blockade

Donor-specific transfusion (DST) and CD40/CD154 costimulation blockade is a powerful immunosuppressive strategy which prolongs survival of many allografts. The efficacy of DST and anti-CD154 mAb for prolongation of hepatocellular allograft survival was only realized in C57BL/6 mice that have both CD4- and CD8-dependent pathways available (median survival time, MST, 82 days). Hepatocyte rejection in CD8 KO mice which is CD4-dependent was not suppressed by DST and anti-CD154 mAb treatment (MST, 7 days); unexpectedly DST abrogated the beneficial effects of anti-CD154 mAb for suppression of hepatocyte rejection (MST, 42 days) and on donor-reactive alloantibody production. Hepatocyte rejection in CD4 KO mice which is CD8-dependent was suppressed by treatment with DST and anti-CD154 mAb therapy (MST, 35 days) but did not differ significantly from immunotherapy with anti-CD154 mAb alone (MST, 32 days). Induction of hepatocellular allograft acceptance by DST and anti-CD154 mAb immunotherapy was dependent on host CD8(+) T cells, as demonstrated by CD8 depletion studies in C57BL/6 mice (MST, 14 days) and CD8 reconstitution of CD8 KO mice (MST, 56 days). These studies demonstrate that both CD4(+) and CD8(+) T-cell subsets contribute to induction of hepatocellular allograft acceptance by this immunotherapeutic strategy.

Genetic variations in humans associated with differences in the course of hepatitis C

The outcome of hepatitis C virus (HCV) infection varies among individuals, but the genetic factors involved remain unknown. We conducted a population-based association study in which 238 Japanese individuals positive for anti-HCV antibody were genotyped for 269 single nucleotide polymorphisms (SNPs) in 103 candidate genes that might influence the course of infection. Altogether, 50 SNPs in 32 genes were listed. Genetic polymorphisms in IL4, IL8RB, IL10RA, PRL, ADA, NFKB1, GRAP2, CABIN1, IFNAR2, IFI27, IFI41, TNFRSF1A, ALDOB, AP1B1, SULT2B1, EGF, EGFR, TGFB1, LTBP2, and CD4 were associated with persistent viremia (P < 0.05), whereas those in IL1B, IL1RL1, IL2RB, IL12RB1, IL18R1, STAT5A, GRAP2, CABIN1, IFNAR1, Mx1, BMP8, FGL1, LTBP2, CD34, and CD80 were associated with different serum alanine aminotransferase levels in HCV carriers (P < 0.05). The sorted genes allow us to draw novel hypotheses for future studies of HCV infection to ultimately identify bona fide genes and their variations.

Elevation of plasma transforming growth factor beta1 levels in stable nonatopic asthma

BACKGROUND

Increased transforming growth factor beta1 (TGF-beta1) levels have been reported in bronchoalveolar lavage fluid and bronchial biopsy specimens from asthmatic patients. However, systemic TGF-beta1 levels have not been reported in asthma.

OBJECTIVE

To evaluate the levels of plasma TGF-beta1 in asthmatic patients and matched, healthy controls to determine the associations with atopic status, disease severity, and duration.

METHODS

Asthmatic patients and healthy controls were recruited prospectively from a university hospital outpatient department between January 2001 and May 2002. Plasma TGF-beta1 and serum IgE levels were estimated using established methods. Patients were classified as atopic or nonatopic based on the presence or absence of serum specific IgE directed to common allergens.

RESULTS

Of the 56 patients recruited for the study, 32 were atopic and 24 nonatopic. The median value of plasma TGF-beta1 was significantly higher in nonatopic asthmatic patients (2.5 ng/mL) compared with controls (1.5 ng/mL, P = .002) and atopic asthmatic patients (1.4 ng/mL, P = .008). The median absolute neutrophil count in the nonatopic asthmatic patients (4.0 x 10(9)/L) was significantly higher compared with atopic asthmatic patients (3.0 x 10(9)/L) and healthy controls (3.5 x 10(9)/L) (P = .01 and P = .04). There was no significant correlation between the duration or severity of asthma and plasma TGF-beta1 levels. The distribution of moderate-persistent asthma cases was similar in atopic and nonatopic groups.

CONCLUSION

Compared with atopic asthmatic patients and healthy controls, patients with nonatopic asthma have elevated plasma TGF-beta1 levels and leukocytosis. These data suggest that nonatopic asthmatic patients exhibit an altered inflammatory response, perhaps to a respiratory infection.

The role of the combination of IL-2 and TGF-beta or IL-10 in the generation and function of CD4+ CD25+ and CD8+ regulatory T cell subsets

Recently, considerable attention has been focused on thymus‐derived CD4⁺ regulatory T cells that constitutively express CD25 and have a contact‐dependent, cytokine‐independent mechanism in vitro. However, peripheral CD4⁺ and CD8⁺ T cells can also be induced to become regulatory T cells. Here we review our studies using the combination of IL‐2 and transforming growth factor β (TGF‐β) to generate regulatory T cell subsets ex vivo, and the work of others using IL‐10 to induce suppressive activity. Under certain conditions, the autocrine effects of TGF‐β and IL‐10 induce peripheral T cells to produce immunosuppressive levels of each of these cytokines. This effect of TGF‐β is IL‐2 dependent. Under other conditions IL‐2 and TGF‐β can induce CD4⁺ cells to develop potent contact‐dependent, cytokine‐independent regulatory activity. At present, there is considerable confusion concerning the mechanism of action of CD4⁺ CD25⁺ cells because cytokine‐producing regulatory T cells generated in the periphery can express CD25 and other markers displayed by naturally occurring, thymus‐derived regulatory T cells. We, therefore, propose a nomenclature that identifies thymus‐derived and peripheral regulatory cells, and that also differentiates T regulatory cells from T helper cells. Because T regulatory cells broadly control T helper cell reactivity, the mechanisms that control regulatory cell function are also reviewed. Finally, the potential use of regulatory T cells generated ex vivo as an adoptive immunotherapy for certain autoimmune diseases, to prevent organ graft rejection, or to prevent pathologic host responses to infectious agents is discussed.

Lowering anti-dsDNA antibodies--what's new?

Antibodies to dsDNA are specific to SLE and are pathogenic, both due to their ability to deposit in tissues through a variety of mechanisms, and to their ability, when present in immune complexes, to activate inflammatory cells. The relationship of serum anti-dsDNA antibody levels to disease activity is a complex one and the factors that determine whether or not such antibodies will be pathogenic in an individual SLE patient are incompletely understood. Although anti-dsDNA antibodies can be made by naïve B cells and B cells belonging to the B1 and marginal zone subsets, pathogenic anti-dsDNA antibodies have the hallmarks of germinal center development and exposure to T cell help, including accumulation of somatic mutations and class switching to the IgG isotype. Epitope spreading may result in aquisition of cross-reactivities with multiple target organ antigens and aquisition of a memory phenotype will allow these B cells to acquire antigen presentation functions that amplify the autoreactive response. In the early stages of disease, or after remission induction protocols, autoreactive B cells may be susceptible to treatments that target T cell costimulation or that deplete or tolerize naïve and mature B cells. Therapeutic approaches targeting innate immune responses or regulatory T cells are starting to be tested in pre-clinical models. In later disease stages, memory and plasma cell accumulation may render patients more resistant to this type of therapeutic approach. Deposition of anti-dsDNA antibodies in target tissues can stimulate an inflammatory cascade that leads to tissue damage. A number of murine models have now been developed that show that interruption of this cascade can prevent or reverse such damage. This type of approach may be beneficial for individuals with established disease. As we learn more about the specific defects that cause SLE, it may become possible to individualize therapy based on patient specific biologic markers.

Molecular Biology and Immunology for Clinicians 22

Natural killer (NK) cells (called "third population cells" many years ago because they did not bear surface markers of the first two defined populations, B cells and T cells) are now known to occupy a pivotal position in the immune system, straddling the "divide" between the innate and adaptive responses. Natural killer cells are capable of production of many cytokines, both pro- and anti-inflammatory, and induction of target cell death by lysis and/or programmed cell death (apoptosis). Some of these cytokines are pivotal in the autoimmune and antipathogenic immune responses, implicating NK cells in the pathogenesis of many human diseases. Multiple detection systems allow tight control of the potent effector systems that mediate NK cells' effects. Recent studies have shown that NK cell function is under tight control, with complex inhibitory and activating signaling assuring that these cells can accurately detect intracellular infection and malignant degeneration without damaging healthy cells. Although NK cell receptors do not have antigenic specificity, they do detect certain patterns on the surface of target cells. Their ability to make many cytokines that alter antigen-specific immune responses mediated by other cells puts NK cells in a unique position to influence both innate and adaptive responses.

The natural killer cell -- friend or foe in autoimmune disease?

Autoimmune diseases are chronic conditions resulting from a loss of immunological tolerance to self-antigens. Recent observations have supported an ever-broader role for innate immune responses in directing and regulating adaptive immunity, including responses to self. This review summarizes recent findings supporting important functions of natural killer (NK) cells in regulating autoimmunity. A close survey of the current literature reveals multiple steps where NK cells can regulate inflammation and intervene in loss of self-tolerance. Importantly, the findings also caution against inferring a similar role for NK cells in all autoimmune phenomena or during separate stages of the same disease. Indeed, NK cells may have different influences during the priming and the effector phases of disease. Hence, an increased understanding of the involvement of NK cells in inflammation and infection should provide new insights into the pathogenesis of autoimmune disease.

Hypothesis: can glucose-insulin-potassium regimen in combination with polyunsaturated fatty acids suppress lupus and other inflammatory conditions?

In systemic lupus erythematosus, plasma concentrations of tumor necrosis factor alpha (TNF alpha) and other pro-inflammatory cytokines are elevated and those of transforming growth factor beta (TGF beta) are decreased. TNF alpha prevents lupus nephropathy whereas increased concentration of TGF beta causes glomerulosclerosis. Insulin inhibits TNF alpha and enhances TGF beta production, augments nitric oxide synthesis and blocks superoxide anion generation. Polyunsaturated fatty acids (PUFAs) also have actions similar to insulin. Hence, it is suggested that a combination of insulin (in the form of glucose-insulin-potassium) and PUFAs may be of benefit in lupus and other inflammatory conditions.

Th1 and Th2 cytokines in a patient with Evans' syndrome and profound lymphopenia

A case of Evans' syndrome with IgM deficiency and lymphopenia was studied before and after splenectomy. The lymphopenia was as a result of profound reduction of CD4 and CD8 cells. Study of cytokine secretion before splenectomy revealed a spontaneous Th1- and Th2-type cytokine production, and complete suppression of transforming growth factor (TGF)-beta. After splenectomy, the patient achieved clinical remission, the natural killer (NK) cell number increased and the pattern of cytokine production showed normalization of interleukin (IL)-2, IL-4, IL-10, TGF-beta and abolition of interferon (IFN)-gamma production. We conclude that splenectomy had a beneficial effect owing to an increase in NK cells and an associated increase in TGF-beta production.