Human polyspecific immunoglobulin for therapeutic use induces p21/WAF-1 and Bcl-2, which may be responsible for G1 arrest and long-term survival

Intravenous immunoglobulin (IVIg) acts directly on conventional T cells to suppress T cell receptor signaling

Intravenous immunoglobulin (IVIg) therapy is widely used to treat autoimmune and infectious disorders. Despite the clinical efficacy of IVIg therapy, its precise immunosuppressive mechanisms remain unclear. Here, we provide evidence that IVIg acts directly on T cells to suppress their activation upon T cell receptor (TCR) ligation. IVIg suppressed the proliferation of murine splenocytes upon stimulation with anti-CD3 antibody and T cell-tropic mitogens. These immunosuppressive effects of IVIg were still intact against purified T cells, and the depletion of naturally-occurring regulatory T cells (nTreg) had no effect on T cell regulatory activity. Instead, we found that IVIg negatively regulated TCR signaling; IVIg co-stimulation impaired IκB degradation, nuclear translocation of the nuclear factor of activated T cells (NFAT), and the activation of mitogen-activated protein kinase (MAPK, Erk1/2). These results suggest an additional new immunosuppressive role of IVIg, which acts directly on conventional T cells to suppress the TCR signaling pathway.

The potential of intravenous immunoglobulins for cancer therapy: a road that is worth taking?

Much has been learned recently about the role of immunoglobulins as effector molecules of the adaptive immunity and as active elements in the maintenance of immune homeostasis. The increasing number of pathologies where intravenous immunoglobulins (IVIg) display a beneficial action illustrates their therapeutic relevance. Considering recent findings on the ability of IVIg to modulate macrophage polarization, herein we review evidences on the antitumoral activity of IVIg. Fragmentary and nonconclusive, available evidences are just suggestive of the potential of IVIg in antitumoral therapy, but encourage for the generation of additional evidences through well-designed clinical trials, and for additional studies to address the molecular effects of IVIg as a means to avoid the extrapolation of data gathered from animal models.

In VitroCytotoxic Effects of Stabilizing Sugars within Human Intravenous Immunoglobulin Preparations against the Human Macrophage THP-1 Cell-line

Intravenous immunoglobulin (IVIg) is a safe and effective therapy for the treatment of primary and secondary humoral immune deficiencies and autoimmune disorders. Both minor and more serious side effects may occur following IVIg administration in approximately 1-15% of infusions and stabilizing sugars found in IVIg preparations may contribute some of these. In this report, we aimed to determine the cytotoxic effects of IVIg as compared with four stabilizing sugars (glucose, sucrose, maltose and D-sorbitol) found in IVIg preparations on human monocyte-macrophages. The human THP-1 macrophage cell-line was used as a model to determine the effects of stabilizing sugars and IVIg preparations on cell viability and growth. The sugars differentially affected the viability of THP-1 cells. In experiments using doses of the sugars commonly found in IVIg preparations, cell viability and proliferation was unaffected when compared with doses of IVIg typically administered to patients (5 mg/ml). However, in an LDH-release cell lysis assay that measures changes in cell permeability, glucose (50 mg/ml) induced significant release of LDH as compared with complete IVIg (5 mg/ml, p<0.0001). Intranucleosomal DNA fragmentation was not detected at therapeutically relevant doses of IVIg. This suggested that THP-1 cell death was not due to apoptosis. We conclude that osmotic stress mediated by the sugars at high doses promoted THP-1 cell death. We propose that IVIg per se is not cytotoxic to the autonomously growing human THP-1 cell-line but rather, the stabilizing sugars used in the preparations are the cytotoxic factors. This observation was evident when preparations of IVIg were used at high concentrations but not at levels one would associate with clinically relevant doses of IVIg.

Ephrin-B3 decreases the survival of adult rat spinal cord-derived neural stem/progenitor cells in vitro and after transplantation into the injured rat spinal cord

Although transplantation of neural stem/progenitor cells (NSPC) encourages regeneration and repair after spinal cord injury (SCI), the survival of transplanted NSPC is limited. Ephrin-B3 has been shown to reduce the death of endogenous NSPC in the subventricular zone of the mouse brain without inducing uncontrolled proliferation. Due to similarities in the environment of the brain and spinal cord, we hypothesized that ephrin-B3 might reduce the death of both transplanted and endogenous spinal cord-derived NSPC. Both normal and injured (26 g clip compression) spinal cords were examined. Ephrin-B3-Fc was tested, and Fc fragments and phosphate-buffered saline (PBS) were used as controls. We found that EphA4 receptors were expressed by spinal cord-derived NSPC and expressed in the normal and injured rat spinal cord (higher expression in the latter). In vitro, ephrin-B3-Fc did not significantly reduce the survival of NSPC except at 1 μg/mL (P<0.05), but Fc fragments alone reduced NSPC survival at all doses in a dose-dependent fashion. In vivo, intrathecal infusion of ephrin-B3-Fc increased the proliferation of endogenous ependymal cells and the proportion of proliferating cells that expressed the glial fibrillary acidic protein astrocytic marker in the injured spinal cord compared with the infusion of PBS (P<0.05). However, in the injured spinal cord, the infusion of either ephrin-B3-Fc or Fc fragments alone caused a 20-fold reduction in the survival of transplanted NSPC (P<0.001). Thus, after SCI, ephrin-B3-Fc and Fc fragments are toxic to transplanted NSPC.

Treatment with HPMA copolymer-based doxorubicin conjugate containing human immunoglobulin induces long-lasting systemic anti-tumour immunity in mice

Linkage of doxorubicin (Dox) to a water-soluble synthetic N-(2-hydroxypropyl)methacrylamide copolymer (PHPMA) eliminates most of the systemic toxicity of the free drug. In EL-4 lymphoma-bearing C57BL/6 mice, a complete regression of pre-established tumours has been achieved upon treatment with Dox-PHPMA-HuIg conjugate. The treatment was effective using a range of regimens and dosages, ranging from 62.5 to 100% cured mice treated with a single dose of 10-20 mg of Dox eq./kg, respectively. Fractionated dosages producing lower levels of the conjugate for a prolonged time period had substantial curative capacity as well. The cured mice developed anti-tumour protection as they rejected subsequently re-transplanted original tumour. The proportion of tumour-protected mice inversely reflected the effectiveness of the primary treatment. The treatment protocol leading to 50% of cured mice produced only protected mice, while no mice treated with early treatment regimen (i.e. starting on day 1 after tumour transplantation) rejected the re-transplanted tumour. Exposure of the host to the cancer cells was a prerequisite for developing protection. The anti-tumour memory was long lasting and specific against the original tumour, as the cured mice did not reject another syngeneic tumour, melanoma B16-F10. The immunity was transferable to naïve recipients in in vivo neutralization assay by spleen cells or CD8(+) lymphocytes derived from cured animals. We propose an effective treatment strategy which eradicates tumours without harming the protective immune anti-cancer responses.

Pathogenesis and recent therapeutic trends in Stevens-Johnson syndrome and toxic epidermal necrolysis

OBJECTIVE

To review the current pathophysiologic mechanisms and recent therapeutic trends in Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).

DATA SOURCES

A MEDLINE search for SJS and TEN in combination with Fas, Fas ligand (FasL), cytotoxic T cells, intravenous immunoglobulin, and cyclosporine for articles published in English during 1966 to 2006.

STUDY SELECTION

Information was derived from original research articles and reviews published in peer-reviewed journals.

RESULTS

The hallmark of SJS and TEN is epidermal cell apoptosis, which may be mediated through keratinocyte Fas-FasL interaction or through cytotoxic T-cell release of perforin and granzyme B. Whereas systemic corticosteroid therapy showed contradictory results, intravenous immunoglobulin (IVIG) and cyclosporine have shown promising outcomes. IVIG contains anti-Fas antibodies that can abrogate apoptosis when preincubated with keratinocytes. Most studies on IVIG in SJS and TEN reported improvement in arresting disease progression and reduction in time to skin healing. Because of variations among studies, the findings cannot be optimally compared. In general, mortality varied from 0% to 12% in studies that supported the use of IVIG and 25% to 41.7% in those that did not demonstrate a beneficial effect. Cyclosporine inhibits CD8 activation and thus may reduce epidermal destruction. Relatively few case reports and 1 case series have been published regarding the use of cyclosporine in SJS and TEN. In general, cyclosporine was associated with a significant improvement in time to disease arrest and to complete reepithelization, with no reported fatalities.

CONCLUSIONS

Both IVIG and cyclosporine have been associated with enhanced healing and better survival through inhibition of apoptosis. Multicenter, randomized, placebo-controlled trials using a standardized design are needed to validate these findings.

Uncovering the hidden potential of intravenous immunoglobulin as an anticancer therapy

Intravenous immunoglobulin (IVIg) is a safe preparation made from human plasma. The original concept of IVIg as an anticancer drug was built up over the years, after numeral reports were accumulated indicating cancer regressions after IVIg administration. Because IVIg is basically an established remedy for immunodeficiencies and several autoimmune diseases, the association between beneficial effects in cancer patients after IVIg was first seen in patients who had both cancer and autoimmune or immunodeficiency diseases. Interestingly, cancer and autoimmunity share several common features, which together enhance the notion of using IVIg to treat cancer. Several studies tested the broad range of the antimetastatic effects of IVIg. IVIg was found to operate in many different and complex ways, among them (a) induction of interleukin-12 secretion, leading to natural-killer-cell activation; (b) inhibition of matrix metalloproteinase-9 mRNA expression; (c) suppression of tumor cell growth; (d) hindrance of nuclear factor kappaB activation and IkappaB degradation; and (e) G1 cell-cycle arrest. In conclusion, IVIg is a potential anticancer treatment for several reasons: (a) the bidirectional relationship between cancer and autoimmunity; (b) the apparent association between cancer regression and IVIg administration; (c) a variety of anticancer effects of IVIg observed; and (d) IVIg is considered to be a safe preparation with minimal side effects. Obviously, prospective controlled studies that will establish the antitumor effects of IVIg are needed.

Novel mechanisms of target cell death and survival and of therapeutic action of IVIg in Pemphigus

Pemphigus vulgaris (PV) is a potentially lethal mucocutaneous blistering disease characterized by cell-cell detachment within the stratified epithelium (acantholysis) caused by IgG autoantibodies. Intravenous immunoglobulin (IVIg) therapy effectively treats PV, but the mechanism is not fully understood. To further understand acantholysis and the efficacy of IVIg, we measured effects of IgG fractions from PV patients on keratinocyte death processes. Using IgGs from representative PV patients who improved with IVIg, we identified apoptotic and oncotic signaling pathways in in vitro and in vivo PV models. We identified two groups of PV patients, each producing autoantibodies activating predominantly either apoptotic or oncotic cell death pathway. Experimental treatments with caspase 3 or calpain inhibitors demonstrated that PV IgGs induced acantholysis through both pathways. Upstream, the apoptotic signaling involved activation of caspases 8 and 3 and up-regulation of Fas ligand mRNA, whereas calpain-mediated cell death depended on elevated intracellular free Ca(2+). IVIg reduced PV IgG-mediated acantholysis and cell death and up-regulated the caspase inhibitor FLIP and the calpain inhibitor calpastatin. These results indicate that in different PV patients, IgG-induced acantholysis proceeds predominantly via distinct, yet complementary, pathways of programmed cell death differentially mediated by apoptosis and oncosis effectors, with IVIg protecting target cells by up-regulating endogenous caspase and calpain inhibitors.

Therapeutic efficacy of high-dose intravenous immunoglobulin in Mycobacterium tuberculosis infection in mice

Intravenous immunoglobulin (IVIg) is used to treat patients with primary antibody deficiencies and, at high doses, to treat a range of autoimmune and inflammatory disorders. With high-dose IVIg (hdIVIg), immunomodulatory mechanisms act on a range of cells, including T cells, B cells, and dendritic cells. Here, we demonstrate that the treatment of M. tuberculosis-infected mice with a single cycle of hdIVIg resulted in substantially reduced bacterial loads in the spleen and lungs when administered at either an early or late stage of infection. Titration of the IVIg showed a clear dose-response effect. There was no reduction in bacterial load when mice were given equimolar doses of another human protein, human serum albumin, or maltose, the stabilizing agent in the IVIg preparation. HdIVIg in vitro had no inhibitory effect on the growth of M. tuberculosis in murine bone marrow-derived macrophages. In addition, the effect of hdIVIg on bacterial loads was not observed in nude mice, suggesting the involvement of conventional T cells. Analysis of T cells infiltrating the lungs revealed only small increases in CD8(+) but not CD4(+) T-cell numbers in hdIVIg-treated mice. The mechanism of action of hdIVIg against tuberculosis in mice remains to be determined. Nevertheless, since hdIVIg is already widely used clinically, the magnitude and long duration of the therapeutic effect seen here suggest that IVIg, or components of it, may find ready application as an adjunct to therapy of human tuberculosis.

Therapeutic intravenous immunoglobulins

Intravenous immunoglobulins (IVIg) are concentrated formulations of human IgG prepared by industrial fractionation of large pools of individual plasma donations. IVIg were developed 20 years ago for the prophylaxis support of immunodeficient patients. However, IVIg have been increasingly used since 10 years, in the treatment of many autoimmune and inflammatory diseases raising the possibility of product shortages and ever increasing costs in the near future. Surprisingly, the immunomodulatory mechanisms of action of IVIg are unclear because of the diversity and often contradictory Fc, F(ab')(2), and non-IgG-related mechanisms that have been proposed from clinical observations and from results obtained in various in vitro and in vivo experimental models. These concepts are reviewed here and we discuss in more details three areas of active research, namely the mechanisms of IVIg action in Idiopathic Thrombocytopenic Purpura (ITP), the effects of IVIg on activated B lymphocytes and the possible involvement of autoantibodies of IgG isotype (auto-IgG) in the immunomodulatory effects of IVIg. The elucidation of the mechanisms of action of IVIg is crucial for a more rationalized clinical use of IVIg and for developing substitutes for some of the immunomodulatory indications in order to ensure long-term availability of plasma-derived IVIg for immunodeficient patients.

Effets immunomodulateurs des immunoglobulines intraveineuses

Intravenous immunoglobulins (IVIg) are therapeutic preparations of normal human IgG obtained from pools of more than 1000 healthy blood donors. They are currently used in the treatment of a wide range of auto-immune diseases, whether associated with auto-antibodies or auto-reactive T lymphocytes, as well as in the treatment of systemic inflammatory diseases. Several mechanisms of action have been identified during the last 20 years, including: (i) modulation of Fc receptors expression on leukocytes and endothelial cells; (ii) interaction with complement proteins; (iii) modulation of cytokines and chemokines synthesis and release; (iv) modulation of cell proliferation and apoptosis; (v) remyelinisation; (vi) neutralisation of circulating autoantibodies; (vii) selection of repertoires of B and T lymphocytes; (viii) interaction with other cell-surface molecules on lymphocytes and monocytes; (ix) corticosteroid sparing. These mechanisms of action are multiple and often intricate. However, they are still little known and further investigations are warranted.

Intravenous immunoglobulins in the treatment of severe drug eruptions

PURPOSE OF REVIEW

To present and discuss the rationale for using high-dose intravenous human immunoglobulins in the treatment of severe drug eruptions and the clinical results of recently published series.

RECENT FINDINGS

In toxic epidermal necrolysis, intravenous human immunoglobulins were expected to inhibit the apoptosis of epidermal cells by blocking the Fas/Fas ligand pathway. Some controversies persist both on the role of Fas/Fas ligand pathway and on the anti-apoptotic effect of human immunoglobulins in vitro. The clinical results of the treatment of toxic epidermal necrolysis with intravenous immunoglobulins are also controversial, the important differences between series being difficult to explain.

SUMMARY

More evidence is needed before high-dose intravenous human immunoglobulins can be considered as standard therapy of toxic epidermal necrolysis.

Correction of the nonlinear dose response improves the viability of adenoviral vectors for gene therapy of Fabry disease

Systemic administration of recombinant adenoviral vectors for gene therapy of chronic diseases such as Fabry disease can be limited by dose-dependent toxicity. Because administration of a high dose of Ad2/CMVHI-alpha gal encoding human alpha-galactosidase A results in expression of supraphysiological levels of the enzyme, we sought to determine whether lower doses would suffice to correct the enzyme deficiency and lysosomal storage abnormality observed in Fabry mice. Reducing the dose of Ad2/CMVHI-alpha gal by 10-fold (from 10(11) to 10(10) particles/mouse) resulted in a greater than 200-fold loss in transgene expression. In Fabry mice, the reduced expression of alpha-galactosidase A, using the lower dose of Ad2/CMVHI-alpha gal, was associated with less than optimal clearance of the accumulated glycosphingolipid (GL-3) from the affected lysosomes. It was determined that this lack of linearity in dose response was not due to an inability to deliver the recombinant viral vectors to the liver but rather to sequestration, at least in part, of the viral vectors by the Kupffer cells. This lack of correlation between dose and expression levels could be obviated by supplementing the low dose of Ad2/CMVHI-alpha gal with an unrelated adenoviral vector or by depleting the Kupffer cells before administration of Ad2/CMVHI-alpha gal. Prior removal of the Kupffer cells, using clodronate liposomes, facilitated the use of a 100-fold lower dose of Ad2/CMVHI-alpha gal (10(9) particles/mouse) to effect the nearly complete clearance of GL-3 from the affected organs of Fabry mice. These results suggest that practical strategies that minimize the interaction between the recombinant adenoviral vectors and the reticuloendothelial system (RES) may improve the therapeutic window of this vector system. In this regard, we showed that pretreatment of mice with gamma globulins also resulted in significantly enhanced adenovirus-mediated transduction and expression of alpha-galactosidase A in the liver.