Masoud Manjili

Background / Purpose: Follicular dendritic cells (FDCs) multimerize monomeric antigens and present them polyvalently in an array fit for simultaneous engagement of multiple B cell receptors (BCRs) leading to a strong BCR-mediated signal. In addition, FDCs provide B cell co-stimulatory signals including BAFF, C4bBP, IL-6 and CD21L. In the presence of FDC-derived co-stimulatory signals; self-Ag presentation by FDCs can break B cell tolerance and induce autoreactive GCs and autoantibody secretion in a T cell-independent manner. Main conclusion: Our preliminary data indicate that B cell tolerance to TNF-α, IgE, and HEL can be broken by presenting these auto/neo-auto-Ags in the form of ICs by FDCs to B cells. Deliberate breakage of B cell tolerance and induction of high affinity self-regulated auto-Abs provide a potential novel therapy targeting endogenous mediators of chronic debilitating autoimmune and hypersensitivity diseases.This approach can also be applied for other disease condit...

Background and objectivesAutoimmune disorders frequently display autoreactive germinal centres (GCs) with immune complex (IC)-bearing follicular dendritic cells (FDCs) suggesting that FDCs are involved in the pathogenesis of autoimmune diseases. The authors recently described induction of T cell-independent (TI) antibody (Ab) responses to T dependent (TD) antigens (Ags) by presenting the TD Ags on FDCs. Rather than presenting peptide fragments, FDCs

Women classified as having triple-negative tumors have a poor prognosis. The importance of CD44(+)/CD24(-/low) (stem/progenitor cell-phenotype) in breast cancer patients has also been appreciated. However, correlation between triple negativity and CD44(+)/CD24(-/low) with tumor recurrence remains elusive. In the present study, we evaluated tumor specimens of 50 breast cancer patients with known hormone receptor status for whom we had follow-up information and outcome data available, and performed immunohistochemistry analysis to determine CD44 and CD24 expression. Gene expression arrays were also independently performed on 52 breast cancer specimens with banked frozen tissue. Lastly, we used FVBN202 transgenic mouse model of breast carcinoma and determined the hormone receptor status, the proportion of CD44(+)/CD24(-/low) breast cancer stem-like cells, and the behavior of the tumor. We determined that patients with triple-negative tumors had significantly higher incidence of recurre...

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effe...

An increasing number of studies suggest an important role of host immunity as a barrier to tumor formation and progression. Complex mechanisms and multiple pathways are involved in evading innate and adaptive immune responses, with a broad spectrum of chemicals displaying the potential to adversely influence immunosurveillance. The evaluation of the cumulative effects of low-dose exposures from the occupational and natural environment, especially if multiple chemicals target the same gene(s) or pathway(s), is a challenge. We reviewed common environmental chemicals and discussed their potential effects on immunosurveillance. Our overarching objective was to review related signaling pathways influencing immune surveillance such as the pathways involving PI3K/Akt, chemokines, TGF-β, FAK, IGF-1, HIF-1α, IL-6, IL-1α, CTLA-4 and PD-1/PDL-1 could individually or collectively impact immunosurveillance. A number of chemicals that are common in the anthropogenic environment such as fungicides...

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effe...

Several studies have shown that when purified from a tumor, certain heat shock proteins (HSPs) can function as effective vaccines against the same tumor by virtue of their ability to bind tumor-specific peptides. However, only a small fraction of the associated peptides would be expected to be immunogenic, in addition to which, the clinical application of this vaccine requires the availability of a surgical specimen of sufficient quantity for purification of the HSP. The present study describes a new approach for the development of natural HSP vaccines that do not have these limitations. This approach uses a recombinant HSP that is noncovalently bound to a recombinant tumor protein antigen by heat shock. HSP110 has been selected for this purpose, because it has been shown to be a highly efficient molecular chaperone in binding to large protein substrates. We show that a "natural chaperone complex" between HSP110 and the intracellular domain (ICD) of human epidermal growth ...

This report defines a novel approach to heat shock protein vaccine formulation that takes advantage of the chaperoning property of heat shock protein hsp110 to efficiently bind a large protein substrate (specifically, human melanoma-associated antigen gp100) during heat shock. We demonstrate that hsp110 can form chaperone complexes with gp100 and prevent heat-induced aggregation of gp100. The resultant natural hsp110-gp100 complexes are strongly immunogenic as determined by their ability to elicit an antigen-specific IFN-gamma production and a cytotoxic T-cell response. Immunization with the hsp110-gp100 complex protected mice against subsequent challenge with human gp100-transduced B16 melanoma, which involves both CD4(+) and CD8(+) T-cell populations. Administration of the hsp110-gp100 vaccine also significantly suppressed the growth of established tumors in a therapeutic model. Furthermore, the hsp110-gp100 chaperone complex exhibited inhibitory effects on the progression of wild...

We employed a grp170-secreting tumour cell system to determine whether tumour cells engineered to secrete grp170 generate an antitumour-specific immune response. Further, we examine the possibility that secreted grp170 can bind to and co-transport out of tumour cells full-length tumour antigens that may play a role in the anti-tumour immune response. Wild type Colon-26 and Colon-26 engineered to secrete grp170 were subcutaneously inoculated into BALB/c mice. Tumour growth was monitored, and variations in immunoregulatory mechanisms were evaluated using immunohistochemistry, lymphocyte depletion, ELISpot assays, and Western blot analysis. Immunisation of animals with grp170-secreting tumour cells results in rejection of the tumour by induction of antigen-specific, CD8-dependent immune responses. The secreted grp170 is able to deliver full-length tumour antigens to the tumour microenvironment, thus making them available for uptake by antigen presenting cells (APCs) to initiate tumour-specific immune responses. These data parallel our studies showing that hsp110 or grp170 are able to chaperone full-length proteins, and when complexed with protein antigens and used as vaccines, these complexes elicit immune responses in vivo against the protein antigens. This cell-based approach has the potential to be utilised as a tumour-specific vaccine in tumours of various histological origins.

Tumor-derived heat shock proteins have shown promise as anti-cancer vaccines in clinical trials. Heat shock proteins (HSPs) can generate potent anti-tumor immunity and elicit antigen-specific CD8+ T cell responses in murine studies. Antigen presenting cells (APC), such as macrophages and dendritic cells (DCs), can elicit antigen-specific CD8+ T cell responses mediated by HSPs. CD91 was the first identified endocytic scavenger receptor for HSPs on APC that can facilitate the process of cross-presentation. Other scavenger receptors may also play a similar role in this process. The present review critically evaluates the identified HSP endocytic receptors on APCs that may generate adaptive immune responses. A better understanding of this interaction between HSPs and APCs may further unravel mechanisms of immunoadjuvant function of HSPs.

HSP110 is a large molecular weight heat shock protein highly capable of chaperoning large proteins. When chaperoning tumour antigens, HSP110 is capable of eliciting effective anti-tumour immune responses. In the present study, we have determined whether such immunoadjuvant properties of HSP110 stem from its ability to induce "danger signals" through interaction with antigen presenting cells (APCs) and with tumour cells. In the previous studies, endotoxin contamination of HSP preparations was always a matter of concern and controversy. Therefore, we prepared recombinant HSP110 with low endotoxin concentration at which LPS did not have any effect on dendritic cells (DCs). We then evaluated the ability of the HSP110 to induce "danger signals" while interacting with APCs or mouse mammary carcinoma cell line (MMC), as evaluated by modulation of cell surface receptors and cytokines involved in innate and adaptive immune responses. We also performed competition studies in order to rule out contribution of endotoxin in HSP110 preparations while interacting with DCs and MMC. We showed that low endotoxin HSP110 induced DCs to up-regulate the expression of MHC class II, CD40 and CD86 molecules, and to secrete pro-inflammatory cytokines IL-6, IL-12 and TNF-alpha. Importantly, HSP110 induced MMC to secrete IL-12 and elevate secretion of IL-6 and expression of CD40 molecule. These findings demonstrate that HSP110 acts as a "danger signal" through its interaction with DCs and tumour cells, regardless of its endotoxin component. These immunoadjuvant properties of HSP110 suggest that pre-existing immunity in tumour-bearing individuals,may be due to the release of HSPs from tumours upon necrosis alerting the immune system against the tumours.

Tumor derived heat shock protein (hsp)-peptide complexes (particularly hsp70 and grp94/gp96) have been demonstrated to serve as effective vaccines, producing anti-tumor immune responses in animals and in man. This approach utilizes the peptide binding properties of stress proteins which are responsible for their functions as molecular chaperones in numerous cellular processes. The present review briefly introduces the reader to the basic stress protein families, i.e. heat shock and glucose regulated proteins, their regulation, compartmentalization and family members. It then introduces the reader to aspects of hsps/grp function and interactions with the host's immune system. An overview of the conventional uses of hsp/grp vaccines as autologous vaccines derived from cancers is presented. We then discuss other stress protein related vaccination approaches. This includes the use of recombinant antigens, both proteins and peptides, naturally complexed to hsp/grps; hsp/grp DNA vaccines, hsp/grp fusion proteins and cell based hsp/grp vaccines. The advantages and disadvantages of each vaccination approach are discussed. Lastly, means of further enhancing the already potent activity of stress protein vaccines are presented, specifically the use of hyperthermia or CTLA-4 blockade as adjuvants.

Recent mechanistic studies on the role of heat-shock proteins (HSPs) to induce innate and adaptive immune responses have resulted in conflicting reports. Whereas some groups reported that HSPs have direct immunological function, others emphasised the endotoxin contamination of HSP preparations and questioned the antigen-specificity of HSP vaccines. The present review will discuss these issues and suggest that HSPs have diverse and distinct immunological functions that could be superimposed on effects resulting from endotoxin contamination or misunderstood by using experimental procedures with inadequate controls. To understand the actual function of HSPs in their interaction with the immune system, methods and procedures need to be optimised and appropriate controls need to be used. These points should also clarify the conflicting findings about HSPs and promote our knowledge about other immuologically important components that may be present in HSP preparations.