Treatment of refractory rheumatoid arthritis with a chimeric anti-CD4 monoclonal antibody. Long-term followup of CD4+ T cell counts

Lymphopenia and Mechanisms of T-Cell Regeneration

Chronic lymphopenia, in particular, T-lymphocyte deficiency, increases the risk of death from cancer, cardiovascular and respiratory diseases and serves as a risk factor for a severe course and poor outcome of infectious diseases such as COVID-19. The regeneration of T-lymphocytes is a complex multilevel process, many questions of which still remain unanswered. The present review considers two main pathways of increasing the T-cell number in lymphopenia: production in the thymus and homeostatic proliferation in the periphery. Literature data on the signals that regulate each pathway are summarized. Their contribution to the quantitative and qualitative restoration of the immune cell pool is analyzed. The features of CD4⁺ and CD8⁺ T-lymphocytes’ regeneration are considered.

OX40-Fc Fusion Protein Alleviates PD-1-Fc-Aggravated Rheumatoid Arthritis by Inhibiting Inflammatory Response

BACKGROUND

Researches have confirmed that the abnormal signals of OX40 and PD-1 lead to the changes of T cell biological behavior, thus participating the immunopathological process of RA. However, the pathogenesis of RA immunopathological process has not been clarified yet.

METHODS

30 DBA/1 mice were randomly divided into 5 groups (6 mice per group): control group, collagen-induced arthritis (CIA) group, PD-1-Fc/CIA group, OX40-Fc/CIA group, and PD-1-Fc + OX40-Fc/CIA group. The pathological changes in mice joints were observed by H&E staining. The proportion of CD4+ T, CD8+ T, CD28+, and CD19+ cells in peripheral blood mononuclear cells (PBMCs) was detected by flow cytometry. Serum inflammatory factors (CRP, IL-2, IL-4, IL-1β, INF-γ) and bone metabolism-related genes (CTX-I, TRACP-5b, BALP) were detected by ELISA assay. Western blotting was applied to measure the NF-κB signaling pathway-related protein (p-IKKβ, p-IκBα, p50) expression in synovial tissue of mice joint.

RESULTS

Compared with the control group, CIA mice showed significant increases in arthritis score and pathological score. In the CIA group, a marked decrease was identified in the proportion of CD8+ T, CD19+, and CD68+ cells. Additionally, the CIA group was associated with upregulation of secretion of inflammatory factors in serum and expression of bone metabolism-related genes and NF-κB pathway-related proteins. Compared with the CIA group, the same indexes above showed a further aggravation in the PD-1-Fc group while all indexes improved in the OX40-Fc group. Besides, OX40-Fc fusion protein slowed down significantly the further deterioration of CIA mouse pathological process caused by PD-1-Fc fusion protein.

CONCLUSION

OX40-Fc fusion protein alleviates PD-1-Fc-aggravated RA by inhibiting inflammatory response. This research provides biological markers with clinical significance for diagnosis and prognosis of RA, as well as offers theoretical and experimental foundation to the new targets for immune intervention.

Preclinical Targeting of Human Acute Myeloid Leukemia Using CD4-specific Chimeric Antigen Receptor (CAR) T Cells and NK Cells

Acute myeloid leukemia (AML) is an aggressive malignancy lacking targeted therapy due to shared molecular and transcriptional circuits as well as phenotypic markers with normal hematopoietic stem cells (HSCs). Identifying leukemia specific markers expressed on AML or AML subtypes for therapeutic targeting is of exquisite clinical value. Here we show that CD4, a T lymphocytes membrane glycoprotein that interacts with major histocompatibility complex class II antigens and is also expressed in certain AML subsets but not on HSCs is a proper target for genetically engineered chimeric antigen receptor T cells (CAR-T cells). Treatment with CD4 redirected CAR-T cell (CD4CAR) specifically eliminated CD4-expressing AML cell lines in vitro and exhibited a potent anti-leukemic effect in a systemic AML murine model in vivo. We also utilized natural killers as another vehicle for CAR engineered cells and this strategy similarly and robustly eliminated CD4- expressing AML cells in vitro and had a potent in vivo anti-leukemic effect and was noted to have shorter in vivo persistence. Our data offer a proof of concept for immunotherapeutic targeting of CD4 as a strategy to treat CD4 expressing refractory AML as a bridge to stem cell transplant (SCT) in a first in human clinical trial.

Preclinical targeting of human T-cell malignancies using CD4-specific chimeric antigen receptor (CAR)-engineered T cells

Peripheral T-cell lymphomas (PTCLs) are aggressive lymphomas with no effective upfront standard treatment and ineffective options in relapsed disease, resulting in poorer clinical outcomes as compared with B-cell lymphomas. The adoptive transfer of T cells engineered to express chimeric antigen receptors (CARs) is a promising new approach for treatment of hematological malignancies. However, preclinical reports of targeting T-cell lymphoma with CARs are almost non-existent. Here we have designed a CAR, CD4CAR, which redirects the antigen specificity of CD8+ cytotoxic T cells to CD4-expressing cells. CD4CAR T cells derived from human peripheral blood mononuclear cells and cord blood effectively redirected T-cell specificity against CD4+ cells in vitro. CD4CAR T cells efficiently eliminated a CD4+ leukemic cell line and primary CD4+ PTCL patient samples in co-culture assays. Notably, CD4CAR T cells maintained a central memory stem cell-like phenotype (CD8+CD45RO+CD62L+) under standard culture conditions. Furthermore, in aggressive orthotropic T-cell lymphoma models, CD4CAR T cells efficiently suppressed the growth of lymphoma cells while also significantly prolonging mouse survival. Combined, these studies demonstrate that CD4CAR-expressing CD8+ T cells are efficacious in ablating malignant CD4+ populations, with potential use as a bridge to transplant or stand-alone therapy for the treatment of PTCLs.

Foxp3+ T cells inhibit antitumor immune memory modulated by mTOR inhibition

Inhibition of mTOR signaling enhances antitumor memory lymphocytes. However, pharmacologic mTOR inhibition also enhances regulatory T-cell (Treg) activity. To counter this effect, Treg control was added to mTOR inhibition in preclinical models. Tregs were controlled with CD4-depleting antibodies because CD4 depletion has high translational potential and already has a well-established safety profile in patients. The antitumor activity of the combination therapy was CD8 dependent and controlled growth of syngeneic tumors even when an adoptive immunotherapy was not used. Lymphocytes resulting from the combination therapy could be transferred into naïve mice to inhibit aggressive growth of lung metastases. The combination therapy enhanced CD8 memory formation as determined by memory markers and functional studies of immune recall. Removal of FoxP3-expressing T lymphocytes was the mechanism underlying immunologic memory formation following CD4 depletion. This was confirmed using transgenic DEREG (depletion of regulatory T cells) mice to specifically remove Foxp3(+) T cells. It was further confirmed with reciprocal studies where stimulation of immunologic memory because of CD4 depletion was completely neutralized by adoptively transferring tumor-specific Foxp3(+) T cells. Also contributing to tumor control, Tregs that eventually recovered following CD4 depletion were less immunosuppressive. These results provide a rationale for further study of mTOR inhibition and CD4 depletion in patients.

Molecular characterization of woodchuck CD4 (wCD4) and production of a depletion monoclonal antibody against wCD4

CD4 T cells play an important role in the immune response against hepatitis B virus (HBV) infection. Woodchucks represent an excellent animal model to study HBV infection. In this study, we characterized the cDNA sequence of woodchuck CD4 (wCD4). The deduced wCD4 protein has four extracellular immunoglobulin-like domains comparable to the other mammalian CD4 molecules. The important extracellular cysteine residues and the intracellular tyrosine protein kinase-binding site of wCD4 are also conserved. The deduced wCD4 protein shows 53-63% identity with the counterparts of other mammalians. Phylogenetic analysis indicates that wCD4 is closely related with the counterparts of primates. Two polyclonal antibodies (pAbs) and four monoclonal Abs (mAbs) against wCD4 were produced. Two pAbs and one mAbs (G2) were found to effectively suppress ConA induced proliferation in vitro. Anti-wCD4 mAb G2 depleted 60% of CD4 cells from healthy woodchucks, while the remaining CD4 cells responded well to ConA stimulation. This work provides a basis for studying CD4 T cell mediated immune responses against HBV infection in the woodchuck model.

Role of human CD4 D1D2 domain in HIV-1 infection

Broadly neutralizing antibodies and appropriate immunogens are critical for preexposure prophylaxis and therapeutic HIV vaccines. In this study, we aimed to explore effective antibodies against the genetically diverse HIV-1 strains by investigating the roles of human CD4 D1D2 domain and nonvariable immugens. The human CD4 D1D2 domain and the chimeric protein of mouse D1 domain/human D2 domain were expressed in Sf9 insect cells and purified by gel-filtration chromatography. The human CD4 D1D2 domain potently inhibited the infection of 77.8% HIV-1 pseudoviruses, including the clades AE, B' and BC, with less than 20 μg/mL of IC(50). pcDNA3.1-mhD1D2m and pcDNA3.1-mhD2m plasmids were used for the production of mouse anti-human CD4 polyclonal antibodies. The neutralizing activities of the polyclonal antibodies were determined by using pseudotyped HIV-1 viruses. The antibodies induced by plasmids containing human CD4 D1D2 domain were able to potently inhibit all pseudotyped HIV-1 strains. The antibodies from mhD1D2m-immunized mice also showed strong binding capacity to CD4 expressed on the surface of TZM-bl cells. The potent and broad inhibitory activity of antibodies against the human CD4 D1D2 domain may be used to develop effective passive immunization agent to control the spread of HIV infection.

MTRX1011A, a humanized anti-CD4 monoclonal antibody, in the treatment of patients with rheumatoid arthritis: a phase I randomized, double-blind, placebo-controlled study incorporating pharmacodynamic biomarker assessments

Introduction

The purpose of this study was to evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of the humanized anti-CD4 monoclonal antibody MTRX1011A in a randomized, double-blind placebo-controlled Phase 1 study in patients with rheumatoid arthritis (RA).

Methods

In the single ascending dose (SAD) portion of the study, patients received single doses of a placebo or MTRX1011A at 0.3, 1.0, 3.5 and 7.0 mg/kg intravenously (IV) or 1.0 and 3.5 mg/kg subcutaneously (SC), followed by five weeks of evaluation. In the multi-dose (MD) portion of the study, placebo or MTRX1011A was administered weekly for eight doses at 1.5 or 3.5 mg/kg SC, or 5 mg/kg IV, followed by eight weeks of evaluation.

Results

MTRX1011A was well tolerated in the SAD phase up to 7 mg/kg IV and in the MD phase up to 1.5 mg/kg SC. At weekly doses of 3.5 mg/kg SC and 5 mg/kg IV, a moderate pruritic papular rash was observed in some MTRX1011A-treated patients, which was considered a dose-limiting toxicity for this clinical indication. No serious adverse events occurred in any cohort. Reduction in disease activity was modest. PD assessments demonstrated that MTRX1011A induced a dose-dependent down-modulation of CD4 expression on peripheral blood CD4 T cells, CD4 receptor occupancy, increases in serum sCD4-MTRX1011A complexes and up-regulation of CD69 on T cells, but was non-depleting.

Conclusions

The maximum tolerated dose of MTRX1011A was 1.5 mg/kg SC administered weekly. At this dose MTRX1011A did not achieve maximum PD activity expected to be required for reduction in disease activity.

Protective versus pathogenic anti-CD4 immunity: insights from the study of natural resistance to HIV infection

HIV-1 exposure causes several dramatic unbalances in the immune system homeostasis. Here, we will focus on the paradox whereby CD4 specific autoimmune responses, which are expected to contribute to the catastrophic loss of most part of the T helper lymphocyte subset in infected patients, may display the characteristics of an unconventional protective immunity in individuals naturally resistant to HIV-1 infection. Reference to differences in fine epitope mapping of these two oppositely polarized outcomes will be presented, with particular reference to partially or totally CD4-gp120 complex-specific antibodies. The fine tuning of the anti-self immune response to the HIV-1 receptor may determine whether viral exposure will result in infection or, alternatively, protective immunity.

Along this line, an efficacious anti-HIV strategy can rely on the active (i.e., through immunization) or passive targeting of cryptic epitopes of the CD4-gp120 complex, including those harboured within the CD4 molecule. Such epitopes are expected to be safe from genetic drift and thus allow for broad spectrum of efficacy. Moreover, since these epitopes are not routinely exposed in uninfected individuals, they are expected to become targets of neutralizing antibodies or other specifically designed molecules only after viral exposure, with a predictable low impact in terms of potentially harmful anti-CD4 self-reactivity.

The experimentum naturae of naturally resistant individuals indicates a strategy to design innovative strategies to neutralize HIV-1 by acting on the sharp edge between harmful and protective self-reactivity.

Clinical efficacy of zanolimumab (HuMax-CD4): two phase 2 studies in refractory cutaneous T-cell lymphoma

The efficacy and safety of zanolimumab in patients with refractory cutaneous T-cell lymphoma (CTCL) have been assessed in two phase 2, multicenter, prospective, open-label, uncontrolled clinical studies. Patients with treatment refractory CD4+ CTCL (mycosis fungoides [MF], n = 38; Sézary syndrome [SS], n = 9) received 17 weekly infusions of zanolimumab (early-stage patients, 280 and 560 mg; advanced-stage patients, 280 and 980 mg). The primary end point was objective response (OR) as assessed by composite assessment of index lesion disease activity score. Secondary end points included physician's global assessment (PGA), time to response, response duration, and time to progression. ORs were recorded for patients in both CTCL types (MF, 13 ORs; SS, 2 ORs). In the high-dose groups (560 and 980 mg dose groups), a response rate of 56% was obtained with a median response of 81 weeks. Adverse events reported most frequently included low-grade infections and eczematous dermatitis. Zanolimumab showed marked clinical efficacy in the treatment of patients with refractory MF, with early onset of response, high response rate, and durable responses. The treatment was well tolerated with no dose-related toxicity other than the targeted depletion of peripheral T cells. A pivotal study has been initiated based on these findings.

Biologic therapies in rheumatology: lessons learned, future directions

During the past decade biologic therapies such as monoclonal antibodies and fusion proteins have revolutionized the management of rheumatic disease. By targeting key cytokines and immune cells biologics have provided more specific therapeutic interventions with less immunosuppression. Clinical use, however, has revealed that their theoretical simplicity hides a more complex reality. Efficacy, toxicity and even pharmacodynamic effects can deviate from those predicted, as poignantly illustrated by the catastrophic effects witnessed during the first-into-human administration of TGN1412. This review summarizes lessons gleaned from practical experience and discusses how these can inform future discovery and development of new biologic therapies for rheumatology.

Anti-proliferative effects induced by anti-CD4 human/murine chimeric antibody and murine anti-CD4 monoclonal antibody

The effects of chimeric anti-CD4 human/murine chimeric antibody and murine anti-CD4 monoclonal antibody (McAb) on the proliferation induced by anti-CD3 McAb, phytohemagglutinin (PHA), IL-2, and allogeneic cells were studied. The results showed that chimeric anti-CD4 antibody and murine anti-CD4 McAb could inhibit the proliferation induced by the above inducers and the inhibitory effects were related to the dosage of the antibodies.

T cell dynamics in HIV-1 infection

In the absence of antiretroviral treatment, HIV-1 establishes a chronic, progressive infection of the human immune system that invariably, over the course of years, leads to its destruction and fatal immunodeficiency. Paradoxically, while viral replication is extensive throughout the course of infection, deterioration of conventional measures of immunity is slow, including the characteristic loss of CD4(+) T cells that is thought to play a key role in the development of immunodeficiency. This conundrum suggests that CD4(+) T cell-directed viral cytopathicity alone cannot explain the course of disease. Indeed, recent advances now indicate that HIV-1 pathogenesis is likely to result from a complex interplay between the virus and the immune system, particularly the mechanisms responsible for T cell homeostasis and regeneration. We review these data and present a model of HIV-1 pathogenesis in which the protracted loss of CD4(+) T cells results from early viral destruction of selected memory T cell populations, followed by a combination of profound increases in overall memory T cell turnover, damage to the thymus and other lymphoid tissues, and physiological limitations in peripheral CD4(+) T cell renewal.

TNF receptor gene therapy results in suppression of IgG2a anticollagen antibody in collagen induced arthritis

BACKGROUND

Therapeutic strategies to block tumour necrosis factor alpha (TNFalpha) activity in experimental autoimmune arthritis models and rheumatoid arthritis (RA) have proved highly successful, and provide sustained beneficial effects.

OBJECTIVE

To examine whether TNFalpha inhibition has immunological activity beyond the reduction of inflammation in collagen induced arthritis (CIA), an established experimental model of RA.

METHODS

Arthritic DBA/1 mice received single periarticular injections of retroviral constructs encoding human TNF receptor (TNF-R) into the affected arthritic paw, at the onset of arthritis. Severity of arthritis, antibodies to collagen type II (CII), and extent of pathological joint damage of arthritic paws were compared between TNF-R and media treated (control) animals 3, 7, 14, 21, and 49 days after disease onset.

RESULTS

Severity of CIA was significantly decreased in TNF-R treated animals compared with controls, 14-34 days after disease onset. Joint destruction was reduced in TNF-R injected joints and in the uninjected contralateral and ipsilateral paws of TNF-R treated animals. Seven days after disease onset, TNF-R treated mice had lower levels of inflammatory Th1 driven IgG2a antibodies to CII (p<0.05) than controls. This altered the anticollagen IgG2a:IgG1 ratio towards Th2 driven IgG1.

CONCLUSIONS

Local TNF-R gene therapy in CIA appears to have systemic effects on the anti-CII antibodies. The overall influence of TNF-R gene therapy is that it inhibits the progression of CIA mainly by suppressing the inflammatory Th1 response rather than by stimulating a Th2 response. Therefore, periarticular TNF-R gene therapy may have excellent therapeutic potential in RA.

Immune modulator studies in primates: the utility of flow cytometry and immunohistochemistry in the identification and characterization of immunotoxicity

Exposure to natural environmental products, biopharmaceuticals, or investigational adjuvants has the potential to negatively impact the immune system, resulting in either up- or downregulation of immune function (immunomodulation). Many current protocols for primate toxicologic testing call for the evaluation of changes in immune cell number (peripheral blood or tissue), alterations in the weights of immune system organs (lymph nodes, spleen, thymus), and/or increases in the overall incidence of infections or neoplasms; these data are relied upon to suggest altered immune function. However, these are informative only when clear differences in frequency and/or severity of effects can be distinguished across control and dosed groups. In the absence of such distinct morphologic or clinical pathologic changes, the identification of potential immunomodulatory effects can present a much greater challenge. Additional evaluations may be needed to detect altered immune system integrity; these are based on in vivo assessments in primates of cellular or humoral responsiveness. Immunomodulatory effects can be characterized by in vitro or in vivo immune function tests: these tests require prestudy planning to integrate assessments into ongoing toxicology programs. These methods also involve specialized training and equipment, particularly if the intent is to evaluate parameters in a GLP laboratory setting. In primate toxicology, the added costs required to perform a complete functional analysis of the immune system can be substantial, but may be warranted depending on the clinical development plans. Two analytical methods that are easily incorporated into the standard toxicology profile in primates are flow cytometry and immunohistochemistry. Flow cytometry (FC) is used to assess changes in the relative distribution of immune cell marker expression, and where marker expression is known to fluctuate with the state of cell activation, can also provide information on functional attributes of immune cells. Immunohistochemistry (IHC) provides a means to evaluate similar characteristics of immune cells within tissue sections. Used together, FC and IHC can aid in the identification of changes in immune system that may not be apparent by traditional testing procedures (such as H&E staining), thus aiding in the characterization of immune system alterations. This presentation focused on the utility of flow cytometry and immunohistochemistry in a standard primate toxicology evaluation, with representative examples showing the benefits of these technologies in the diagnosis of potential immunomodulatory effects.

Advances in the management of psoriasis: monoclonal antibody therapies

Psoriasis is a common skin disorder characterized by erythematous, scaling plaques. Until recently, therapies for this disease have been aimed at reducing keratinocyte proliferation. We have learned that psoriasis is not primarily a disorder of keratinocyte hyperproliferation, but is an inflammatory disease. This knowledge, especially our current understanding of the role of activated T cells in psoriasis, has led to new therapeutic options and new areas of research. Immunosuppressive agents such as cyclosporine have proven very useful in the treatment of psoriasis, but their use is limited by toxicity. Monoclonal antibodies directed against key components of the inflammatory process have been studied in an attempt to produce safer, more selective immunosuppressive agents. This review summarizes much of the available literature describing the use of monoclonal antibodies in the treatment of psoriasis.

Reconstitution of naive T cells during antiretroviral treatment of HIV-infected adults is dependent on age

OBJECTIVE

To determine the influence of age on the regeneration rate of naive and memory T cells in the blood of 45 adults on highly active antiretroviral therapy (HAART).

METHODS

The age of the patients ranged from 25 to 57 years. Naive cells were defined as CD45RA+CD27+. Cells negative for CD45RA and/or CD27 were considered memory type cells.

RESULTS

The recovery rates of naive CD4 and CD8 T cells were similar, were negatively correlated with age and were decreasing 5% and 3.6% per year, respectively. In a multivariate regression analysis, only age was significantly correlated with the naive T cell recovery rates. The recovery rate of memory T cells showed no relation to age. The average regeneration rate of naive CD4 T cells during HAART, i.e., 0.34 x 10(6) cells/l per day, is not lower than regeneration rates in HIV-negative adults following cytotoxic chemotherapy or CD4 monoclonal antibody therapy.

CONCLUSION

These observations suggest that the thymus contributes considerably to the regeneration of naive T cells in adults on HAART, and that the impact of HIV infection on naive T cell production is small, or rapidly reversible.

The use of monoclonal antibodies to restore self-tolerance in established autoimmunity

The author hopes to convince the reader that the data presented argue for a stage during the development of IDDM when beta-cell destruction can be counteracted and tolerance to beta cells restored, provided the immune aggression is arrested. This argument constitutes a solid rationale for immunointervention in established IDDM, especially by using potent agents such as CD3. The future for the application of monoclonal antibodies not only in autoimmunity but also in transplantation is exiting. With the development of humanized monoclonal antibodies, therapeutic uses for them are likely to expand. Enormous progress has been made in the last 15 years, and it is likely that before a similar time period has elapsed, monoclonal antibodies will have become standard tools that will dispense the need for long-term immunosuppression and its inherent dangers in various clinical arenas.

Costimulatory blockade in patients with rheumatoid arthritis: a pilot, dose-finding, double-blind, placebo-controlled clinical trial evaluating CTLA-4Ig and LEA29Y eighty-five days after the first infusion

OBJECTIVE

T cells are involved in the pathogenesis of rheumatoid arthritis (RA). In animal models of autoimmune diseases, blockade of costimulatory molecules on antigen-presenting cells has been demonstrated to be effective in preventing or treating this disease by preventing T cell activation. To date, the effect of costimulatory blockade in patients with RA is unknown. The goal of this multicenter, multinational study was to determine the safety and preliminary efficacy of costimulatory blockade using CTLA-4Ig and LEA29Y in RA patients who have been treated unsuccessfully with at least 1 disease-modifying agent.

METHODS

CTLA-4Ig, LEA29Y (0.5, 2, or 10 mg/kg), or placebo was administered intravenously to 214 patients with RA. Patients received 4 infusions of study medication, on days 1, 15, 29, and 57, and were evaluated on day 85. The primary end point was the proportion of patients meeting the American College of Rheumatology 20% improvement criteria (ACR20). All patients were monitored for treatment safety and tolerability.

RESULTS

CTLA-4Ig and LEA29Y infusions were well tolerated at all dose levels. Peri-infusional adverse events were carefully monitored, and showed similar incidence across all dose groups with the exception of headaches, which were slightly more frequent in the 2 treatment groups. The incidence of discontinuations due to worsening of RA was 19%, 12%, and 9% at 0.5, 2, and 10 mg/kg, respectively, in the CTLA-4Ig-treated patients and 3%, 3%, and 6% at 0.5, 2, and 10 mg/kg, respectively, in the LEA29Y-treated patients (versus 31% in the placebo group). ACR20 responses on day 85 had increased in a dose-dependent manner (23%, 44%, and 53% of CTLA-4Ig-treated patients and 34%, 45%, and 61% of LEA29Y-treated patients at 0.5, 2.0, and 10 mg/kg, respectively, versus 31% of placebo-treated patients).

CONCLUSION

Both of the costimulatory blocking molecules studied were generally safe and well tolerated. As compared with placebo, both CTLA-4Ig and LEA29Y demonstrated efficacy in the treatment of RA.

Differential clinical efficacy of anti-CD4 monoclonal antibodies in rat adjuvant arthritis is paralleled by differential influence on NF-kappaB binding activity and TNF-alpha secretion of T cells

The aim of this study was to analyze the differential effects of three anti-CD4 monoclonal antibodies (mAbs) (with distinct epitope specifities) in the treatment of rat adjuvant arthritis (AA) and on T-cell function and signal transduction. Rat AA was preventively treated by intraperitoneal injection of the anti-CD4 mAbs W3/25, OX35, and RIB5/2 (on days -1, 0, 3, and 6, i.e. 1 day before AA induction, on the day of induction [day 0], and thereafter). The effects on T-cell reactivity in vivo (delayed-type hypersensitivity), ex vivo (ConA-induced proliferation), and in vitro (mixed lymphocyte culture) were assessed. The in vitro effects of anti-CD4 preincubation on T-cell receptor (TCR)/CD3-induced cytokine production and signal transduction were also analyzed. While preventive treatment with OX35 and W3/25 significantly ameliorated AA from the onset, treatment with RIB5/2 even accelerated the onset of AA by approximately 2 days (day 10), and ameliorated the arthritis only in the late phase (day 27). Differential clinical effects at the onset of AA were paralleled by a differential influence of the mAbs on T-cell functions, i.e. in comparison with OX35 and W3/25, the 'accelerating' mAb RIB5/2 failed to increase the delayed-type hypersentivity (DTH) to Mycobacterium tuberculosis, increased the in vitro tumor necrosis factor (TNF)-alpha secretion, and more strongly induced NF-kappaB binding activity after anti-CD4 preincubation and subsequent TCR/CD3-stimulation. Depending on their epitope specificity, different anti-CD4 mAbs differentially influence individual proinflammatory functions of T cells. This fine regulation may explain the differential efficacy in the treatment of AA and may contribute to the understanding of such treatments in other immunopathologies.

Morbidity and mortality in rheumatoid arthritis patients with prolonged and profound therapy-induced lymphopenia

OBJECTIVE

Therapies that deplete lymphocytes often improve symptoms in patients with otherwise refractory autoimmune disease but may result in long-term lymphopenia, the consequences of which are uncertain. To assess the impact of prolonged lymphopenia on morbidity and mortality, we studied patients who had previously received lymphocytotoxic monoclonal antibody (mAb) therapy for rheumatoid arthritis (RA).

METHODS

Fifty-three patients who received the lymphocytotoxic mAb CAMPATH-1H between 1991 and 1994 in the United Kingdom were assessed for mortality and infectious and malignant morbidity, by interview and case-note review. In addition, patients were monitored via the National Health Service Central Registry, to verify notification of death. Peripheral blood lymphocyte subsets were analyzed by flow cytometry. A retrospective, matched-cohort study of mortality was also performed with 102 control subjects selected from the European League Against Rheumatism database, which comprises patients with rheumatic disorders who have received immunosuppressive drugs.

RESULTS

There was profound and persistent peripheral blood lymphopenia in the mAb-treated patients, affecting predominantly the CD4+ subset. Median CD4+, CD8+, and CD19+ peripheral blood lymphocyte counts at 73-84 months after therapy were 185 cells/microl, 95 cells/microl, and 115 cells/microl, respectively. At a median followup of 71 months (range 14-90), 13 patients had died (24.5%), compared with 18% of the matched controls, providing a mortality rate ratio of 1.45 (95% confidence interval 0.65-3.13). During 283 patient-years of followup, there were 36 infections classified as major (12.7 per 100 patient-years). The causes of death and the spectrum of infections documented were similar to those expected in a hospital-based RA cohort. Patients who received more than 1 course of therapy had more severe lymphopenia than did patients who received a single course, but this did not have an impact on mortality or morbidity.

CONCLUSION

Despite the occurrence of profound and long-lasting lymphopenia following treatment with antilymphocyte mAb therapy for RA, this therapy is not associated with a large excess of mortality nor with an unusual spectrum of infections, at least during a medium-term period of followup. These data are also relevant to patients receiving lymphocytotoxic mAb therapy for other indications, and to patients receiving other lymphodepleting therapies such as autologous stem cell transplantation.

Preclinical efficacy and safety of mepolizumab (SB-240563), a humanized monoclonal antibody to IL-5, in cynomolgus monkeys

BACKGROUND

Allergic respiratory diseases are characterized by large numbers of eosinophils and their reactive products in airways and blood; these are believed to be involved in progressive airway damage and remodeling. IL-5 is the principal cytokine for eosinophil maturation, differentiation, and survival. Mepolizumab (SB-240563), a humanized monoclonal antibody (mAb) specific for human IL-5, is currently in clinical trials for treatment of asthma.

OBJECTIVE

The purpose of this study was to characterize the pharmacologic activity and long-term safety profile of an anti--human IL-5 mAb to support clinical trials in asthmatic patients.

METHODS

Naive and Ascaris suum -sensitive cynomolgus monkeys received various dose levels of mepolizumab and were monitored for acute and chronic pharmacologic and toxic responses.

RESULTS

To support preclinical safety assessment, cynomolgus monkey IL-5 was cloned, expressed, and characterized. Although monkey IL-5 differs from human IL-5 by 2 amino acids (Ala27Gly and Asn40His), mepolizumab has comparable inhibitory activity against both monkey IL-5 and human IL-5. In A suum--sensitive monkeys, single doses of mepolizumab significantly reduced blood eosinophilia, eosinophil migration into lung airways, and levels of RANTES and IL-6 in lungs for 6 weeks. However, mepolizumab did not affect acute bronchoconstrictive responses to inhaled A suum. In an IL-2--induced eosinophilia model (up to 50% blood eosinophilia), 0.5 mg/kg mepolizumab blocked eosinophilia by >80%. Single-dose and chronic (6 monthly doses) intravenous and subcutaneous toxicity studies in naive monkeys found no target organ toxicity or immunotoxicity up to 300 mg/kg. Monkeys did not generate anti-human IgG antibodies. Monthly mepolizumab doses greater than 5 mg/kg caused an 80% to 100% decrease in blood and bronchoalveolar lavage eosinophils lasting 2 months after dosing, and there was no effect on eosinophil precursors in bone marrow after 6 months of treatment. Eosinophil decreases correlated with mepolizumab plasma concentrations (half-life = 13 days).

CONCLUSION

These studies demonstrate that chronic antagonism of IL-5 by mepolizumab in monkeys is safe and has the potential, through long-term reductions in circulating and tissue-resident eosinophils, to be beneficial therapy for chronic inflammatory respiratory diseases.

From bench to bedside: discovering rules for antibody design, and improving serotherapy with monoclonal antibodies

Anti-T-cell monoclonal antibodies (mAbs) form a unique class of therapeutic agent. Their precise specificity offers tremendous potential for the treatment of autoimmune and inflammatory diseases but also prevents meaningful preclinical animal studies. In particular, adverse reactions to therapy may be unanticipated, and the first administration of a novel T-cell mAb to a patient thus marks the beginning of a unique experiment. By comparing clinical parameters and laboratory measurements, small-scale pilot studies can provide detailed information about mAb biology that both predicts and suggests solutions to the complications of therapy. In this essay I illustrate this concept with reference to three specific areas: lymphocyte depletion, mAb immunogenicity and cytokine-release syndromes. In each case, systematic clinical and laboratory science has improved our understanding of the problem and suggested solutions; most of these solutions have been or are being adopted. Thus, small, open studies are an essential step in the development of novel mAbs, provide an ideal platform for the study of mAb biology, and serve as an early warning system for potential adverse effects.

Organ Transplant Specificity of Tolerance to Skin Grafts with Heart or Kidney Grafts Plus Nondepleting Anti-CD4 Monoclonal Antibody (RIB 5/2) and Intravenous Donor Alloantigen Administration

BACKGROUND

CD4+ T cells play an essential role in allograft rejection. Monoclonal anti-rat CD4 antibody, RIB 5/2, has been shown to modulate the CD4 glycoprotein without eliminating recipient T cells. A single dose of monoclonal anti-rat CD4 antibody RIB 5/2 plus donor splenocytes results in donor-specific unresponsiveness to heart and kidney allografts, but not skin allografts. This study examined whether tolerance to the more resistant skin graft could also be achieved with RIB 5/2.

METHODS

Buffalo (RT1(b)) recipients were given a single dose (20 mg/kg) of monoclonal antibody RIB 5/2 IP plus IV Lewis (RT1(l)) splenocytes (25 x 10(6)) 21 days before Lewis heart, kidney, or skin grafts. In addition, Lewis skin was grafted either simultaneously with or after long- term Lewis heart or kidney allograft acceptance (>50 days).

RESULTS

While IV alloantigen plus RIB 5/2 results in long-term acceptance of both heart and kidney, skin allografts are rejected when transplanted alone. Simultaneous transplantation with a Lewis kidney, but not with a Lewis heart, resulted in long-term Lewis skin graft acceptance. However, recipients tolerant to Lewis kidney or heart alone will not accept subsequent Lewis skin grafts, while recipients of simultaneous Lewis skin and kidney grafts subsequently accept a second Lewis, but not third-party Brown Norway (RT1(n)), skin graft.

CONCLUSION

RIB 5/2 plus Lewis donor splenocytes tolerize for donor-specific heart and kidney but not skin grafts. However, Lewis skin grafted simultaneously with a Lewis kidney, but not Lewis heart, is accepted and protects a subsequent donor-specific Lewis skin graft.

Potential biologic agents for treating rheumatoid arthritis

The encouraging clinical results observed in trials using anti-TNF therapy clearly warrant further studies to determine whether TNF inhibitors are capable of modifying the destructive component of this disease in long-term follow-up studies as well as to assess the safety of long-term use (see the article by Keystone in this issue). It is also reasonable to propose that interfering with the cytokine cascade earlier in the course of disease may be of even greater therapeutic benefit. As the pathogenetic mechanisms in RA are more clearly defined, especially in early disease and in those individuals destined to develop severe disease, the potential of other biologic agents to specifically inhibit these critical pathways may provide better treatments for our patients. Many potential targets in the immune-mediated process of RA are currently being rigorously evaluated in clinical trials. Use of combinations of biologic therapies, perhaps in human patients with RA, should be of considerable interest in future trials.

Current treatment practice in immunosuppression

New drugs have recently been added that may eventually replace the two-decade dominance of cyclosporin in solid organ transplantation. This cornerstone of immunosuppression was introduced by Borel [1] and Calne [2] in the mid-70s. In 1989, Starzl et al., after 2 years of preclinical experimentation, introduced tacrolimus (originally designated as FK506 by the Fujisawa Pharmaceutical Company of Japan) as a potent immunosuppressant for liver transplants [3]. Also, in recent years, a variety of novel purine and pyrimidine biosynthesis inhibitors have been tested for transplantation therapy. The leading agent which appears to be replacing the 35-year position occupied by azathioprine is the semi-synthetic morpholinoethyl ester of mycophenolic acid (MPA), mycophenolate mofetil (MMF), introduced by Allison [4] and Sollinger [5], and developed by the Syntex Corporation (now Roche Pharmaceuticals). Others, affecting different intra- or intercellular messages amplifying immunity, are in the pipeline.

Pharmacokinetic, pharmacodynamic and clinical effects of a humanized IgG1 anti-CD4 monoclonal antibody in the peripheral blood and synovial fluid of rheumatoid arthritis patients

BACKGROUND

CD4(+) T cells are important mediators in the pathogenesis of rheumatoid arthritis (RA). In this open-label, dose-escalating study, we examined the pharmacokinetic (PK), clinical, biological and immunological effects of a humanized IgG1 anti-CD4 monoclonal antibody (mAb), 4162W94, in the peripheral blood (PB) and synovial fluid (SF) of RA patients.

METHOD

Twenty-four patients in four cohorts (six patients in each cohort) were allocated to be treated with five consecutive daily doses of 4162W94 (10, 30, 100 or 300 mg i.v.). Disease activity was measured by the American College of Rheumatology (ACR) criteria and disease activity score (DAS). We also measured 4162W94 concentration, the percentage of 4162W94-coated CD4(+) lymphocytes, percentage down-modulation of CD4, interleukin-6 (IL-6) and tumour necrosis factor alpha (TNFalpha) levels in the PB and SF.

RESULTS

A direct relationship between 4162W94 dose, biological response and clinical outcome was seen. Treatment with 10 and 30 mg of 4162W94 for 5 consecutive days resulted in transient coating and down-modulation of CD4(+) lymphocytes, with little effect observed beyond the final dose. However, treatment with 100 and 300 mg resulted in sustained coating and/or down-modulation for 3 weeks and 4 weeks, respectively, in PB and >4 weeks in SF in one patient from the 300 mg cohort. There was a dose-related moderate but transient depression in the CD4(+) lymphocyte count in most patients, with all but three returning to >0.40 x 10(9)/l or >75% baseline by the end of the study period. Significant clinical improvement (ACR 20%) was seen in only 1/6 patients in each of the 10- and 30-mg cohorts; however, 3/6 and 5/5 patients in the 100 and 300-mg cohorts, respectively, were ACR 20% responders. In addition, there were significant reductions in PB acute phase reactants as well as SF IL-6 and TNFalpha concentrations in parallel to clinical improvement.

CONCLUSION

Data from this pilot study suggest that 4162W94 is a clinically active novel immunotherapeutic agent that may suppress inflammation in RA.

Anti-CD4 monoclonal antibody treatment of moderate to severe psoriasis vulgaris: results of a pilot, multicenter, multiple-dose, placebo-controlled study

BACKGROUND

OKTcdr4a (IMUCLONE) is a humanized anti-CD4 IgG4 monoclonal antibody that retains the binding and in vitro immunosuppressive properties of the parent murine antibody. Psoriasis is a chronic disease for which treatment with multiple doses of monoclonal antibodies is likely to be required for adequate control.

OBJECTIVE

This study was performed to test the efficacy and safety of OKTcdr4a, given in sequential courses over a period of several weeks, in the treatment of moderate to severe psoriasis vulgaris.

METHODS

Twenty-eight patients (45.6 +/- 10.1 years of age) were studied, with a mean pretreatment Psoriasis Area and Severity Index (PASI) score of 18.3. In the first double-blind phase of the study, patients were randomized to receive OKTcdr4a as a 225 mg/course (low dose), 750 mg/course (high dose), or placebo divided into 3 identical infusions over a 5-day period. After 42 days, patients who met the criteria for re-treatment with OKTcdr4a were re-treated with the 750 mg/course in an open phase of the study.

RESULTS

After the double-blind course of treatment, the mean PASI decreased by 11% in the placebo group, by 4% in the low-dose group, and by 17% in the high-dose group at 15 days. Twenty patients met the criteria for re-treatment (ie, did not experience a decrease in PASI score of 50% at 42 days). They were re-treated with OKTcdr4a at 43 days with the 750 mg/course in the open phase of the study. By day 99, the mean PASI score decreased from 19.9 at baseline to 17 in those patients who had received either placebo or low-dose OKTcdr4a followed by high-dose OKTcdr4a. In contrast, the mean PASI score decreased from 17.4 at baseline to only 7.7 in those patients who had received high-dose OKTcdr4a for both courses. Sustained CD4 saturation was not necessary for sustained clinical response. No patients had significant changes in circulating CD4(+) T-cell counts. The infusions were well tolerated.

CONCLUSION

Targeting CD4 using sequential treatments with a humanized monoclonal antibody (OKTcdr4a) may offer another therapeutic option for the treatment of moderate to severe psoriasis.

The kinetics of tolerance induction by nondepleting anti-CD4 monoclonal antibody (RIB 5/2) plus intravenous donor alloantigen administration

BACKGROUND

CD4+ T cells play an essential role in allograft rejection. The monoclonal anti-rat CD4 antibody, RIB 5/2, has been shown to modulate the CD4 glycoprotein without eliminating the recipient T cells. We have successfully induced tolerance to rat heart allografts by recipient pretreatment with a single dose of RIB 5/2 plus intravenous administration of donor splenocytes. In this study, we explored whether this potent regimen could induce tolerance to the more resistant kidney and skin allografts. Furthermore, we examined the kinetics and requirements for tolerance to be met by a single dose of RIB 5/2 plus i.v. alloantigen.

METHODS

The efficacy of a single i.p. dose of 20 mg/kg RIB 5/2 plus i.v. donor antigen (25x10(6) splenocyte) pretreatment 0, 21, or 40 days before receipt of an MHC-mismatched Lewis (RT1l) to Buffalo (RT1b) rat cardiac, renal, or skin allograft was studied. Another group of Buffalo recipients treated with RIB 5/2 plus an i.v. alloantigen +/-thymectomy received kidney transplants after 40 days. Attempts to prevent tolerance used interleukin-2 or prior sensitization. Mixed lymphocyte cultures, cytotoxic assays, and precursor frequencies of helper and cytotoxic cells, by limiting dilution analysis, serially measured in vitro cell-mediated immunity.

RESULTS

RIB 5/2 administration combined with i.v. alloantigen 21 days before induced tolerance to heart and kidney allografts but did not prolong skin graft survival. In contrast, kidney allografts delayed for 40 days after pretreatment were acutely rejected and survival was not affected by the thymectomy. MLC, CTL, and pTH, and pCTL precursor frequencies from recipients of long-term grafts were specifically suppressed to donor, but not third party, alloantigen.

CONCLUSION

A single dose of the nondepleting anti-CD4 monoclonal antibody, RIB 5/2, plus i.v. alloantigen is a potent inducer of tolerance to heart and kidney, but not skin, allografts. The RIB 5/2-induced donor unresponsiveness to a delayed kidney or cardiac allograft is time dependent but can be prolonged if specific alloantigen is present. Suppression of cell-mediated allo-immune responsiveness correlates with allograft acceptance.

Management of therapy-resistant rheumatoid arthritis

During the last two decades, newly introduced therapeutic strategies have resulted in satisfactory modification of the disease course in the majority of the patients with rheumatoid arthritis (RA). Nevertheless, a definite number of RA patients remain therapy-resistant, and for this group more aggressive treatment may be required for preventing permanent disability and progressive joint damage necessitating surgical procedures. Therefore, management of therapy-resistant RA is one of the major challenges in modern rheumatology. RA patients who have not responded to conventional disease-modifying antirheumatic drug (DMARD) therapy are defined as refractory RA patients. However, a uniform description or definition for 'refractory' RA does not appear to be available. In this article we will deal with, and discuss, the term 'refractory RA' based on a MEDLINE database search using this term, currently available therapeutic options, data on therapy-resistant RA patients from an inception cohort of RA patients attending the Nijmegen University Hospital, management of extra-articular manifestations and future management strategies.

Suppression of systemic lupus erythematosus disease in mice by oral administration of kidney extract

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the increased production of antibodies reactive with a variety of self and non-self antigens. A number of immunomodulatory therapies have been investigated for the disease process. Intragastric administration of low dose kidney extract (KE) three times weekly for 5 weeks and then weekly until 6 months of age in SLE mice, showed decreased anti-dsDNA antibody levels, less kidney damage and significantly prolonged survival compared with control phosphate buffered saline (PBS)-fed mice. The KE-fed mice also exhibited reduced T cell proliferative response to KE in comparison with PBS-fed controls. Serum isotype distribution of the anti-dsDNA antibodies revealed a marked reduction of IgG1 and IgG3 responses in the KE-fed mice. While the renal inflammatory cell infiltration and expression of interleukin-4 (IL-4) and IL-10 were markedly suppressed, no local enhancement of transforming growth factor-beta (TGF-beta) was detected. Oral administration of low dose KE, however, upregulated expression of IL-2, IFN-gamma and TNF-alpha in the kidneys and suppressed glomerulonephritis. These findings suggest that oral KE affects the disease process in SLE and raise the possibility that oral administration of KE or other potential autoantigens may provide a new approach for the treatment of SLE.

Treatment with monoclonal anti-tumor necrosis factor alpha antibody results in an accumulation of Th1 CD4+ T cells in the peripheral blood of patients with rheumatoid arthritis

OBJECTIVE

In rheumatoid arthritis (RA), treatment with tumor necrosis factor alpha (TNFalpha) binding agents has proven to be highly effective. Downregulation of the proinflammatory cytokine cascade and a reduced migration of leukocytes into the joints have been proposed as modes of action of TNFalpha blockade. We investigated whether alterations in the number of circulating pro- and antiinflammatory T cell subsets contribute to the therapeutic effect of monoclonal antibodies (mAb) against TNFalpha in RA patients.

METHODS

Phenotypic analysis of peripheral blood T cell subsets was performed on blood from RA patients before and after treatment with an anti-TNFalpha mAb.

RESULTS

An accumulation of primed CD45RA- T cells of both the CD4+ and the CD8+ T cell population was seen shortly after treatment. Most notably, within the CD4+,CD45RA- T cell subset, the number of interferon-gamma-producing T cells was significantly increased after anti-TNFalpha mAb treatment, resulting in a significant rise in the Th1:Th2 ratio. In addition, an increase in the number of CD4+ T cells expressing the homing receptor CD49d in high density was observed after treatment, which correlated positively with the increase in the Th1:Th2 ratio. Conclusion. We show that the Th1:Th2 ratio in the peripheral blood is raised by anti-TNFalpha mAb treatment.

Differential effects of administration of a human anti-CD4 monoclonal antibody, HM6G, in nonhuman primates

A human sequence IgGkappa anti-CD4 monoclonal antibody (mAb), HM6G, originally isolated from a human immunoglobulin transgenic mouse was specific for and bound with high binding avidity to the CD4 antigen expressed on human, chimpanzee, and cynomolgus monkey T cells. Prior to testing this mAb in human clinical trials, a number of preclinical primate studies were performed. In chimpanzees, HM6G did not deplete circulating CD4(+) T cells and was cleared in a dose-dependent manner. In contrast, this mAb administered to cynomolgus monkeys depleted CD4(+) T cells (albeit only at high doses) and its clearance, which had reached saturation even at very low doses, was much slower. These differences were most likely due to the additional and rather substantial expression of the CD4 antigen on chimpanzee monocytes. In monkeys, the T cell depletion was mitigated by infusing the mAb over 30 min or longer (as opposed to 30 s) while only slightly altering the clearance. As expected, the human mAb did not induce an immune response in chimpanzees, although it did induce a low titer response in monkeys. These disparate pharmacokinetic and pharmacodynamic results suggest prudence when extrapolating results obtained in nonhuman models to humans.

Initial increase in blood CD4(+) lymphocytes after HIV antiretroviral therapy reflects redistribution from lymphoid tissues

Previous studies proposed a dynamic, steady-state relationship between HIV-mediated cell killing and T-cell proliferation, whereby highly active antiretroviral therapy (HAART) blocks viral replication and tips the balance toward CD4(+) cell repopulation. In this report, we have analyzed blood and lymph node tissues obtained concurrently from HIV-infected patients before and after initiation of HAART. Activated T cells were significantly more frequent in lymph node tissue compared with blood at both time points. Ten weeks after HAART, the absolute number of lymphocytes per excised lymph node decreased, whereas the number of lymphocytes in the blood tended to increase. The relative proportions of lymphoid subsets were not significantly changed in tissue or blood by HAART. The expression levels of mRNA for several proinflammatory cytokines (IFN-gamma, IL-1beta, IL-6, and macrophage inflammatory protein-1alpha) were lower after HAART. After therapy, the expression of VCAM-1 and ICAM-1 -- adhesion molecules known to mediate lymphocyte sequestration in lymphoid tissue -- was also dramatically reduced. These data provide evidence suggesting that initial increases in blood CD4(+) cell counts on HAART are due to redistribution and that this redistribution is mediated by resolution of the immune activation that had sequestered T cells within lymphoid tissues.

New therapeutic targets for rheumatoid arthritis

New insights into the pathogenesis of rheumatoid arthritis (RA) and consequently new targets of therapy are covered in a broad overview fashion. Short-term significant beneficial effect on RA disease activity has been established in a small but rapidly growing number of double-blind placebo-controlled trials now including recombinant human IL-1 receptor antagonist, chimeric (mouse/human) monoclonal antibodies (mAb) against TNF alpha (cA2), humanised (human/mouse) anti-TNF alpha mAb (CDP571) and recombinant human TNF-receptor-Fc fusion protein (TNFR:Fc). Placebo-controlled trials of anti-T cells agents such as chimeric anti-CD4 mAb (cM-T412) and anti-CD5 immunoconjugate, did not demonstrate clinical benefit. A placebo-controlled study of the anti-T cell derived cytokine IL-2 (DAB486IL-2) showed only modes clinical improvement. Other anti-T cell approaches such as autologous T cell vaccination and induction of tolerance by oral type II collagen have been unsuccessful. The one controlled trial with an anti-inflammatory cytokine, recombinant human IFN-gamma, showed modest clinical benefits. Controlled trials with IL-4 and IL-10 and with anti-adhesion molecules are awaited.

Adenoviral Transfer of the Viral IL-10 Gene Periarticularly to Mouse Paws Suppresses Development of Collagen-Induced Arthritis in Both Injected and Uninjected Paws

Gene therapy is a promising new approach in the treatment of rheumatoid arthritis. Gene delivery to diseased joints offers the prospect of achieving high, local concentrations of a therapeutic gene product in a sustained manner, while minimizing exposure of nontarget organs. We report that a single administration of a modified adenovirus encoding the Epstein-Barr-derived homologue of IL-10 can suppress the development of disease for extended periods of time when injected locally within the periarticular tissue surrounding the ankle joints of mice with collagen type II-induced arthritis. Furthermore, we show that injection of an adenoviral vector carrying the IL-10 gene into a single paw can suppress development of arthritis in other, noninjected paws of the same individual. The systemic protection resulting from local gene therapy occurred in the absence of detectable levels of viral IL-10 in the serum. Circulating Ab levels to heterologous collagen were unaffected; however, treatment with viral IL-10 significantly suppressed the development of Abs to autologous mouse type II collagen. Thus, the treatment of a single joint by local delivery of the vIL-10 gene may protect multiple joints of the same individual while avoiding deleterious side effects often associated with systemic therapy.

Early recovery of CD4+ T lymphocytes in children on highly active antiretroviral therapy. Dutch study group for children with HIV infections

INTRODUCTION

Regeneration of CD4+ T lymphocytes has been shown to be thymus-dependent in bone marrow transplant recipients and after intensive chemotherapy. The rate of CD4+ T cell regeneration is correlated positively with enlargement of the thymus, as shown on radiographs, and higher rates of CD4+ T lymphocyte regeneration were observed in children as compared with adults, consistent with thymic function diminishing with age. We hypothesized that in HIV infected patients CD4+ T cell recovery during highly active antiretroviral therapy (HAART) may also be thymus dependent. Therefore, repopulation of naive (CD45RA+), memory (CD45RO+) and total CD4+ T lymphocytes and total CD8+ T lymphocytes in peripheral blood was assessed in 13 HIV infected children during the initial 3 months of HAART.

RESULTS

Significantly higher recovery rates of naive, memory and total CD4+ T cells were observed in children below the age of 3 years as compared with older children. Kinetics of total CD8+ T cells showed no relation to age. Moreover, recovery rates of naive CD4+ T cells in patients below 3 years of age were 10-40 fold higher as compared with previously reported naive CD4+ T cell recovery rates in adults on HAART.

CONCLUSIONS

High recovery rates of naive, memory and total CD4+ T cells can be achieved in children below 3 years of age. Changes in CD8 counts did not correlate with age. These results indicate that regeneration of CD4+ T cells during HAART may be a thymus-dependent process.

STCP-1 (MDC) CC Chemokine Acts Specifically on Chronically Activated Th2 Lymphocytes and Is Produced by Monocytes on Stimulation with Th2 Cytokines IL-4 and IL-13

STCP-1 stimulated T cell chemoattractant protein-1 (STCP-1) (macrophage-derived chemokine; MDC), a recently described CC chemokine for chronically activated T lymphocytes, was found to act specifically on a subset of memory CD4 lymphocytes that displayed a Th2 cytokine profile. Also, STCP-1, thymus and activation regulated chemokine (TARC), eotaxin, and eotaxin-2 acted specifically on in vitro derived Th2 lymphocytes, while IP-10 (IFN-γ-inducible 10-kDa protein) showed some preference for Th1 lymphocytes. The corresponding receptors for eotaxin, TARC, and IP-10 are also differentially expressed on Th1 and Th2 lymphocytes. In desensitization Ca flux experiments, TARC and STCP-1 bound to a common receptor and therefore at least one chemokine receptor for STCP-1 is CCR4. STCP-1 expression is restricted to immune cells. Dendritic cells, B cells, and macrophages produce STCP-1 constitutively, while NK cells, monocytes, and CD4 lymphocytes produce STCP-1 upon appropriate stimulation. Production of STCP-1 is positively modulated by Th2 cytokines IL-4 and IL-13 but inhibited by IL-10.

Randomised, dose-ranging, placebo-controlled study of chimeric antibody to CD4 (keliximab) in chronic severe asthma

BACKGROUND

There is substantial circumstantial evidence that CD4 lymphocytes have a role in the pathogenesis of chronic asthma. We investigated the efficacy and safety in severe corticosteroid-dependent asthma of a single intravenous infusion of keliximab (IDEC CE9.1), a chimeric monoclonal antibody to CD4.

METHODS

22 patients were recruited from two asthma clinics. In an ascending-dose design, the first eight patients were assigned 0.5 mg/kg keliximab (six) or placebo (two); the next seven were assigned 1.5 mg/kg (five) or placebo (two); and the last seven were assigned 3.0 mg/kg (five) or placebo (two). Masked data on safety for each dose group were assessed before progression to the next dose. Patients kept a daily symptom diary and measured morning and evening peak expiratory flow (PEF) at home. PEF and forced expiratory volume in 1 s (FEV1) were measured at follow-up clinic visits.

FINDINGS

Patients given 0.5 mg/kg or 1.5 mg/kg keliximab and placebo recipients did not differ in change from baseline of PEF, FEV1, or symptom score. Those given 3.0 mg/kg keliximab differed significantly from placebo recipients in change in morning PEF (median area under curve [AUC] 445 vs -82.5, p=0.005) and evening PEF (median AUC 548 vs -85, p=0.014). Symptom score showed the same pattern (though differences did not achieve significance), but there was no difference in clinic FEV1. There were no serious adverse effects related to treatment. Two patients had mild exacerbations of eczema and one developed a transient maculopapular rash. All doses of keliximab were associated with a reduction from baseline in CD4 count.

INTERPRETATION

Our findings raise the possibility that T-cell-directed treatment may be an alternative approach to the treatment of severe asthma.

Monoclonal antibodies to CD4

Animal models of human autoimmune disease suggest that it should be possible to reinduce self-tolerance in these conditions by the use of T-cell directed therapies, in particular with anti-CD4 monoclonal antibodies (CD4-mAb). Many studies have shown that CD4-mAb can prevent and in a treatment setting suppress activity of these disease models, including collagen-induced arthritis.

Opportunities for future biological therapy in SLE

The development of monoclonal antibodies and the emergence of recombinant DNA technology has made it possible to identify and selectively inhibit distinct cell subsets, surface molecules and secreted products that contribute to normal and pathological immune responses. These advances have helped to clarify the mechanisms that promote autoimmune diseases. As a result, it is now possible to contemplate rational strategies for the treatment of these diseases. Some of these strategies are designed to influence the cell surface interactions that determine whether potentially autoreactive T cells become activated or tolerant following antigen stimulation. Other strategies are designed to augment or inhibit distinct cytokines that regulate autoimmunity. All of these strategies have shown promise in animal models for systemic lupus erythematosus, and they may soon be translated into effective new therapies for people.

Treatment of recalcitrant plaque psoriasis with a humanized non-depleting antibody to CD4

The presence of activated CD4(+) T lymphocytes in psoriatic skin plaques suggests an immune-mediated pathogenesis for the disease. Six patients with recalcitrant plaque psoriasis (PASI>12) received a humanized non-depleting monoclonal antibody to CD4 (ORTHOCLONE OKT(R)cdr4a). The antibody was well tolerated. Four weeks from treatment, the mean decrease in PASI score was 46%. In three patients disease remission was prolonged for up to 6 months and, in one case, up to 1 year post-treatment. In all patients, circulating CD4+ T-cell counts remained normal and peripheral OKTcdr4a-coated CD4+ lymphocytes were detected up to 10 days after antibody infusion. These results point to the relevance of CD4+ lymphocytes in psoriasis. They also emphasize that depletion of CD4+ cells is not mandatory to achieve therapeutic effectiveness.