Skewed Th1/Th2 immune response to Sarcoptes scabiei

Scabies is a contagious skin disease of humans and many other species of mammals. Previous studies suggested that the balance between the Th1 and Th2 immune responses may influence the outcome of a scabies infestation in a sensitized host. Therefore, in this study, we examined the T-helper cell cytokine profiles of splenocytes and lymph node cells in BALB/c mice that were immunized with scabies extract (primary response), infested with scabies mites (primary response), or immunized and then infested (secondary response). Lymphocyte cytokine expression was analyzed by flow cytometry after staining for intracellular cytokines. Immunization with scabies extract induced production of interferon-gamma (IFNgamma) (Th1 response) by both spleen and lymph node cells. Mice that were infested with scabies increased production of interleukin-4 by lymph node cells and of IFNgamma by splenocytes. Mice that were first immunized and then infested with mites increased production of IFNgamma by both spleen and lymph node cells. However, this increased level of IFNgamma was only about half of that induced by immunization alone. These results suggest that live scabies mites produced something that inhibited IFNgamma production in the lymph nodes of scabies-immunized mice. Our data also indicate that lymphocytes in the spleen and lymph nodes can present different cytokine response profiles.     

Dendritic cell modulation by mast cells controls the Th1/Th2 balance in responding T cells

The cytokines secreted by pathogen-activated human dendritic cells (DC) are strongly regulated in vitro by histamine, a major component of mast cell granules, ultimately modulating the capacity of the DC to polarize naive T cells. Because DC and mast cells are located in close proximity in peripheral compartments, we hypothesized that mast cell products would influence the maturation of DC and hence the Th balance of an immune response in vivo. In this study, we show that specific mast cell degranulation stimuli, given s.c. in mice with Ag and adjuvant, produce effector T cells that proliferate to Ag but secrete dramatically reduced levels of IFN-gamma and increased amounts of IL-4 compared with control T cells primed in the absence of a mast cell stimulus. Immunization with Ag and adjuvant in the presence of a degranulation stimulus also resulted in the accumulation of DC in the draining lymph nodes that had reduced capacity to induce Ag-specific Th1 cells, in comparison with DC from mice lacking a degranulation stimulus. Therefore, by acting upon DC at sites of inflammation, mast cells play a critical role in determining the polarity of Ag-specific T cell responses in vivo.     

Peptide dose, affinity, and time of differentiation can contribute to the Th1/Th2 cytokine balance.

Opposing viewpoints exist regarding how Ag dose and affinity modulate Th1/Th2 differentiation, with data suggesting that both high and low level stimulation favors Th2 responses. With transgenic T cells bearing a single TCR, we present novel data, using peptides differing in affinity for the TCR, that show that the time period of differentiation can determine whether Th1 or Th2 responses predominate as the level of initial stimulation is altered. Over the short term, IFN-gamma-producing cells were induced by lower levels of stimulation than IL-4-producing cells, although optimal induction of both was seen with the same high level of stimulation. Over the long term, however, high doses of high affinity peptides led selectively to IFN-gamma-secreting cells, whereas IL-4- and IL-5-secreting cells predominated with lower levels of initial signaling, brought about by moderate doses of high affinity peptides. In contrast, too low a level of stimulation at the naive T cell stage, with low affinity peptides at any concentration, promoted only IL-2-secreting effectors or was not sufficient for long term T cell survival. These results demonstrate that the level of signaling achieved through the TCR is intimately associated with the induction of distinct cytokine-secreting T cells. We show that dose, affinity, time over which differentiation occurs, and initial production of IL-4 and IFN-gamma all can contribute to which T cell subset will predominate. Furthermore, these data reconcile the two opposing views on the effects of dose and affinity and provide a unifying model of Th1/Th2 differentiation based on strength of signaling and length of response.     

Defining Th1 and Th2 immune responses in a reciprocal cytokine environment in vivo

The ability of committed Th1 and Th2 cells to function in altered cytokine environments is a central issue in autoimmune and immune-mediated diseases. Therefore, it is of interest to study the ability of Th1 or Th2 cells to expand and produce cytokine reciprocal environments in vivo. Using STAT4- and STAT6-deficient mice, we studied the expansion and cytokine production of Ag-specific Th1 or Th2 cells after transfer into Th1, Th2, or wild-type recipients. Our data show that these Th1 or Th2 cells proliferated and clonally expanded normally, regardless of the in vivo cytokine environment. These data have implications for the treatment of immune-mediated diseases by immunomodulatory agents that alter the cytokine milieu in vivo.     

Absence of CC chemokine ligand 2 results in an altered Th1/Th2 cytokine balance and failure to expel Trichuris muris infection

Despite a growing understanding of the role of cytokines in immunity to intestinal helminth infections, the importance of chemokines has been neglected. As a chemokine with both chemoattractive properties and an ability to shape the quality of the adaptive immune response, CC chemokine ligand 2 (CCL2) was investigated as an attractive candidate for controlling resistance to these types of infection, which require highly polarized Th cell responses. We show here for the first time that CCL2 plays an important role in the development of resistance to infection by the gastrointestinal nematode Trichuris muris. Thus, in the absence of CCL2, worm expulsion does not occur, and the lymph node draining the site of infection becomes a Th1-promoting environment. Elevated levels of IL-12 are produced by polarizing APCs, and the composition of the APC environment itself is perturbed, with reduced numbers of macrophages.     

Th1/Th2 cytokine balance and nitric oxide in cerebrospinal fluid and serum from patients with multiple sclerosis

Tumor necrosis factor (TNF-alpha) and IL-10 are key regulators of the T helper (Th)1/Th2 balance, which is critically skewed in many pathological conditions including immune-mediated inflammatory diseases of central nervous system (CNS) such as multiple sclerosis (MS). Nitric oxide (NO) has been reported to have dual effects on CNS pathology, and to play an important role in MS. We performed a cross-sectional study in 17 randomly selected patients during MS flare-up, and compared levels of TNF-alpha, IL-10 and NO in serum and cerebrospinal fluid (CSF) with the serum values of these mediators in two different control groups, healthy subjects and HIV-infected untreated patients. Serum and CSF values of TNF-alpha, IL-10 and NO were higher in MS patients than in the serum of healthy controls. Two MS patients showed increased levels of NO in CSF, with inversion of the NO(SERUM)/NO(CSF) quotient, which is clearly indicative of an intrathecal production of NO. No correlation among the values of both cytokines and NO, and the laboratory parameters analysed in MS patients (IgG index, presence of IgG oligoclonal bands and albumin quotient) was found. The high levels of TNF-alpha and IL-10 (both in serum and CSF) accompanying an MS attack suggest a simultaneous expression of Th1 and Th2 cytokines as opposed to sequential expression of Th1 followed by Th2 as described in the models of experimental autoimmune encephalomyelitis (EAE). Globally, our results support the inherent heterogeneity of the disease.     

Cellular immune response and Th1/Th2 cytokines in human neurocysticercosis: lack of immune suppression.

Some reports have suggested that human neurocysticercosis (NCC) induces immunosuppression. To test this hypothesis, we performed a study on active cases of NCC who had not received cestocidal or immunosuppressive treatments. We examined blood counts and specific T cell markers (CD3, CD4, and CD8) by flow cytometry and found no differences between patients with NCC and healthy individuals. Both groups responded to concanavalin A (Con A), and patients with NCC responded more to a parasite crude antigen than uninfected individuals. Peripheral blood mononuclear cells were examined for interleukin (IL)-2, interferon-gamma, IL-10, and IL-4 mRNA. Regardless of infection status, more than 60% of individuals synthesized IL-2 mRNA and, less frequently, the other cytokines. These data suggest that immunosuppression does not occur in NCC patients.     

Silibinin attenuates antigen-specific IgE production through the modulation of Th1/Th2 balance in ovalbumin-sensitized BALB/c mice

The effect of silibinin on antigen-specific antibody production and T-cell cytokine expression was investigated. BALB/c mice were either left untreated or administered daily with vehicle (VH; saline) and/or silibinin (200 or 400 mg/kg) by gavage for 3 consecutive days prior to sensitization with ovalbumin (OVA). The antibody production in the serum and T-cell-derived cytokine expression by splenocytes were determined 7 days post OVA sensitization. Our results demonstrated that the production of OVA-specific serum IgE and total IgE was significantly attenuated by silibinin treatment, whereas OVA-specific IgG_2a was markedly enhanced. In parallel with the differential modulation of the production of IgG_2a and IgE, treatment of OVA-sensitized mice with silibinin markedly increased and decreased the production of IFN-γ and IL-4, respectively, by splenocytes cultured in the presence of OVA. Together, these results suggest that silibinin treatment polarizes the Th1/Th2 immune balance toward the Th1-dominant direction, which may be beneficial against IgE-mediated allergy.     

Th1/Th2 cytokine profile in childhood-onset systemic lupus erythematosus

ObjectiveTo determine the serum levels of Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines in childhood-onset SLE, first-degree relatives and healthy controls. To elucidate their association with disease activity, laboratory and treatment features.MethodsWe included 60 consecutive childhood-onset SLE patients [median age 18 years (range 10–37)], 64 first-degree relatives [median 40 (range 28–52)] and 57 healthy [median age 19 years (range 6–30 years)] controls. Controls were age and sex-matched to SLE patients. SLE patients were assessed for clinical and laboratory SLE manifestations, disease activity (SLEDAI), damage (SDI) and current drug exposures. Mood and anxiety disorders were determined through Becks Depression (BDI) and Anxiety Inventory (BAI). Th1 (IL-12, IFN-γ,TNF-α) and Th2 (IL-5, IL-6 and IL-10) cytokines levels were measured by ELISA and compared by non-parametric tests.ResultsSerum TNF-α (p = 0.004), IL-6 (p = 0.007) and IL-10 (p = 0.03) levels were increased in childhood-onset SLE patients when compared to first-degree relatives and healthy controls. TNF-α levels were significantly increased in patients with active disease (p = 0.014) and correlated directly with SLEDAI scores (r = 0.39; p = 0.002). IL-12 (p = 0.042) and TNF-α (p = 0.009) levels were significantly increased in patients with nephritis and TNF-α in patients with depression (p = 0.001). No association between cytokine levels and SDI scores or medication was observed.ConclusionTh1 cytokines may play a role in the pathogenesis of neuropsychiatric and renal manifestations in childhood-onset SLE. The correlation with SLEDAI suggests that TNF-α may be a useful biomarker for disease activity in childhood-onset SLE, however longitudinal studies are necessary to determine if increase of this cytokine may predict flares in childhood-onset SLE.     

DNA vaccines: influenza virus challenge of a Th2/Tc2 immune response results in a Th2/Tc1 response in the lung

For this study, we used DNA-based immunizations to elicit gamma interferon-producing (Tc1) or interleukin 4 (IL-4)-producing (Tc2) CD8 T cells to the influenza virus nucleoprotein. We examined the response of these cells to an intranasal viral challenge. Both the Tc2- and Tc1-biased responses were present in mice with predominantly IL-4-producing (Th2) CD4 T cells. After viral challenge, Tc1 cells underwent more efficient expansion than did Tc2 cells, and only Tc1 cells were detected at the site of infection. In contrast, the CD4 response remained IL-4 biased. However, only a limited number of CD4 cells appeared in the postchallenge lung, and these were strongly enriched for the Th1 phenotype. Thus, the type of memory T-cell response induced by DNA vaccination does not determine the type of response that will predominate at the site of an infection.     

A polarized Th1 type immune response to Cowdria ruminantium infection is detected in immune DBA/2 mice

Immune responses to Cowdria ruminantium, an intracellular organism that causes heartwater in domestic ruminants, were characterized in a DBA/2 mouse model. Immunity induced by infection and treatment was adoptively transferable by splenocytes and could be abrogated by in vivo depletion of T cells but not by inhibition of nitric oxide synthase using NG-monomethyl-L-arginine. IgG2a and IgG2b C. ruminantium-specific responses were detected in immune mice. Culture supernatants of splenocytes from immune DBA/2 mice, which were stimulated with crude C. ruminantium antigens or recombinant major antigenic proteins 1 or 2, contained significant levels of interferon (IFN)-gamma and interleukin (IL)-6, but insignificant levels of IL-1alpha, IL-2, IL-4, IL-5, IL-10, IL-12, tumor necrosis factor-alpha (TNF), and nitric oxide. A similar response was detected during primary infection, although IFN-gamma levels decreased significantly during clinical illness and then increased following natural or antibiotic-aided recovery. These data support the conclusion that protective immunity to C. ruminantium in DBA/2 mice is mediated by T cells and is associated with a polarized T helper 1 type of immune response. This murine model could be utilized to screen for protective C. ruminantium antigens that provoke Th1 type immune responses and for evaluation of these antigens in recombinant vaccines against heartwater.     

Interleukin-12 augments a Th1-type immune response manifested as lymphocyte proliferation and interferon gamma production in Leishmania infantum-infected dogs

The dog is the major reservoir for human visceral leishmaniasis caused by Leishmania infantum. Interleukin-12 is considered to have an essential role in the development of both innate and adaptive immunity to Leishmania spp. and other intracellular pathogens. This study focused on the influence of IL-12 in experimental and natural canine visceral leishmaniasis. Responses of peripheral blood mononuclear cells to IL-12, interleukin-10 and Leishmania soluble antigen were evaluated in L. infantum experimentally infected oligosymptomatic beagles, uninfected beagles, naturally infected polysymptomatic dogs, and their matched uninfected controls. Leishmania soluble antigen induced strong peripheral blood mononuclear cells proliferation both in experimentally infected dogs (median stimulation index [SI]=15.01), and in naturally infected dogs (SI=8.86), but not by cells from the control groups. IL-12 addition further enhanced cell proliferation in naturally (SI=14.95), but not in experimentally infected animals. Peripheral blood mononuclear cells from experimentally infected dogs were able to produce significant amounts of IFN-gamma (3.39 ng/ml) upon LSA stimulation, but no such production was detected in cells from naturally infected or control animals. Interestingly, addition of IL-12 reversed the inhibitory effect of LSA on IFN-gamma production by cells from polysymptomatic naturally infected dogs and the uninfected beagles (4.84 and 7.45 ng/ml, respectively), and further increased IFN-gamma production by peripheral blood mononuclear cells from experimentally infected oligosymptomatic dogs (29.28 ng/ml). IFN-gamma mRNA expression correlated well with IFN-gamma production. Addition of IL-10 to Leishmania soluble antigen stimulated peripheral blood mononuclear cells inhibited proliferation and IFN-gamma production in experimentally infected dogs. Thus, the ability of IL-12 to augment IFN-gamma production by peripheral blood mononuclear cells from dogs with experimental or natural symptomatic canine visceral leishmaniasis makes it a good candidate for cytokine therapy in dogs that are refractory to current therapy.     

Pre-existing adenovirus immunity modifies a complex mixed Th1 and Th2 cytokine response to an Ad5/HIV-1 vaccine candidate in humans

The results of the recent Step Study highlight a need to clarify the effects of pre-existing natural immunity to a vaccine vector on vaccine-induced T-cell responses. To investigate this interaction, we examined the relationship between pre-existing Ad5 immunity and T-cell cytokine response profiles in healthy, HIV-uninfected recipients of MRKAd5 HIV-1 gag vaccine (HVTN 050, ClinicalTrials.gov #{"type":"clinical-trial","attrs":{"text":"NCT00849732","term_id":"NCT00849732"}}NCT00849732). Participants were grouped by baseline Ad5 neutralizing antibody titer as either Ad5-seronegative (titer ≤18; n = 36) or Ad5-seropositive (titer >200; n = 34). Samples from vaccine recipients were analyzed for immune responses to either HIV-1 Gag peptide pools or Ad5 empty vector using an ex vivo assay that measures thirty cytokines in the absence of long-term culture. The overall profiles of cytokine responses to Gag and Ad5 had similar combinations of induced Th1- and Th2-type cytokines, including IFN-γ, IL-2, TNF-α, IP-10, IL-13, and IL-10, although the Ad5-specific responses were uniformly higher than the Gag-specific responses (p<0.0001 for 9 out of 11 significantly expressed analytes). At the peak response time point, PBMC from Ad5-seronegative vaccinees secreted significantly more IP-10 in response to Gag (p = 0.008), and significantly more IP-10 (p = 0.0009), IL-2 (p = 0.006) and IL-10 (p = 0.05) in response to Ad5 empty vector than PBMC from Ad5-seropositive vaccinees. Additionally, similar responses to the Ad5 vector prior to vaccination were observed in almost all subjects, regardless of Ad5 neutralizing antibody status, and the levels of secreted IFN-γ, IL-10, IL-1Ra and GM-CSF were blunted following vaccination. The cytokine response profile of Gag-specific T cells mirrored the Ad5-specific response present in all subjects before vaccination, and included a number of Th1- and Th2-associated cytokines not routinely assessed in current vaccine trials, such as IP-10, IL-10, IL-13, and GM-CSF. Together, these results suggest that vector-specific humoral responses may reduce vaccine-induced T-cell responses by previously undetected mechanisms.     

Co-expression of IL-18 binding protein and IL-4 regulates Th1/Th2 cytokine response in murine collagen-induced arthritis

We constructed a recombinant adenoviral vector containing a murine interleukin （IL）-18 binding protein （mlL-18BP） and murine IL-4 （mIL-4） fusion gene （AdmIL-18BP/mIL.4） and used a gene therapy approach to investigate the role of IL-18BP and IL-4 in modulating the T-helperl and T-helper2 （Th1/Th2） balance in mice with collagen-induced arthritis （CIA）. Mice with CIA were intra-articularly injected with 107 pfu/6 μl ofeitherAdmIL.18BP/mIL-4, or a controladenovirus, or with the control vehicle （phosphate-buffered saline）. After intra-articular gene therapy with AdmIL-18BP/mIL-4, the serum levels of tumor necrosis factor-α （TNF-α）, T-interferon （IFN-γ）, IL-4, IL-10, and IL-18 in mice with CIA were assessed by ELISA. IFN-T-expressing and IL-4-expressing CD4^＋ T cells from mice splenocytes were monitored by flow cytometry. Mice with CIA at weeks 1, 2, and 4 after intraarticular injection of AdmIL-18BP/mIL-4 showed significantly increased serum concentrations of IL-4 and IL-10 （P〈0.01 at all time points） but greatly decreased serum concentrations ofIFN-γ, TNF-α and IL-β （P〈0.01 at all time points ） compared to both the con trol adenovirus and phospha tebuffered saline control groups. The percentage of LFN-γ- producing CD4^＋ T cells was significantly decreased in response to local AdmIL-18BP/mIL-4 treatment. The percentage of IL-4-producing CD4^＋ T cells increased significantly at 1 week after local injection of AdmIL-18BP/ mIL-4 then returned to normal by week 4. These data indicated the significant modifying effects on the Th1/Th2 imbalance in murine CIA produced by local overexpression of IL-18BP and IL-4. Combination treatment with IL-18BP and IL-4 is a promising potential therapy for rheumatoid arthritis.