Dendritic cells transfected with scFv from Mab 7.B12 mimicking original antigen gp43 induces protection against experimental Paracoccidioidomycosis

Emerging trends and therapeutic applications of monoclonal antibodies

Monoclonal antibodies (mAbs) are being used to prevent, detect, and treat a broad spectrum of malignancies and infectious and autoimmune diseases. Over the past few years, the market for mAbs has grown exponentially. They have become a significant part of many pharmaceutical product lines, and more than 250 therapeutic mAbs are undergoing clinical trials. Ever since the advent of hybridoma technology, antibody-based therapeutics were realized using murine antibodies which further progressed into humanized and fully human antibodies, reducing the risk of immunogenicity. Some of the benefits of using mAbs over conventional drugs include a drastic reduction in the chances of adverse reactions, interactions between drugs, and targeting specific proteins. While antibodies are very efficient, their higher production costs impede the process of commercialization. However, their cost factor has been improved by developing biosimilar antibodies, which are affordable versions of therapeutic antibodies. Along with biosimilars, innovations in antibody engineering have helped to design bio-better antibodies with improved efficacy than the conventional ones. These novel mAb-based therapeutics are set to revolutionize existing drug therapies targeting a wide spectrum of diseases, thereby meeting several unmet medical needs. In the future, mAbs generated by applying next-generation sequencing (NGS) are expected to become a powerful tool in clinical therapeutics. This article describes the methods of mAb production, pre-clinical and clinical development of mAbs, approved indications targeted by mAbs, and novel developments in the field of mAb research.

Monoclonal Antibodies as Tools to Combat Fungal Infections

Antibodies represent an important element in the adaptive immune response and a major tool to eliminate microbial pathogens. For many bacterial and viral infections, efficient vaccines exist, but not for fungal pathogens. For a long time, antibodies have been assumed to be of minor importance for a successful clearance of fungal infections; however this perception has been challenged by a large number of studies over the last three decades. In this review, we focus on the potential therapeutic and prophylactic use of monoclonal antibodies. Since systemic mycoses normally occur in severely immunocompromised patients, a passive immunization using monoclonal antibodies is a promising approach to directly attack the fungal pathogen and/or to activate and strengthen the residual antifungal immune response in these patients.

Therapeutic treatment with scFv-PLGA nanoparticles decreases pulmonary fungal load in a murine model of paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is a systemic mycosis with lymphatic dissemination that is caused by Paracoccidioides species. Treatment of PCM consists of chemotherapeutics such as itraconazole, trimethoprim, sulfamethoxazole or amphotericin B. However, several studies are aiming to develop therapeutic alternatives for the treatment of fungal infection using new molecules as adjuvants. The single-chain variable fragments (scFv) from an antibody that mimics the main fungal component incorporated within poly(lactide-co-glycolic) acid (PLGA) nanoparticles helped treat the fungal disease. After expressing the scFv in Picchia pastoris (P. pastoris), the recombinant molecules were coupled with PLGA, and the BALB/c mice were immunized before or after infection with yeast Paracoccidioides brasiliensis (P. brasiliensis). Our results showed decreased disease progression and decreased fungal burden. Taken together, our results showed an increased of IFN-γ and IL-12 cytokine production and an increased number of macrophages and dendritic cells in the pulmonary tissue of BALB/c mice treated with a high concentration of our molecule. Our data further confirm that the scFv plays an important role in the treatment of experimental PCM.

Altered distribution of peripheral blood dendritic cell subsets in patients with pulmonary paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by fungi from the genus Paracoccidioides in Latin America. PCM-patients (PCM-p) are classified as having acute/subacute or chronic (CF) clinical forms. CF is responsible for 75%-90% of all cases, affects mainly adults over 30 years old and the clinical manifestation are associated mainly with lungs and mucosa of upper airdigestive tract. In addition, the CF patients exhibit fibrosis of the lungs, oral mucous membranes and adrenals, and pulmonary emphysema. Consequently, CF PCM-p with active disease, as well as those that have been apparently cured, seem to be an interesting model for studies aiming to understand the long-term host-fungi relationship and hypoxia. Dendritic cells (DCs) constitute a system that serve as a major link between innate and adaptive immunity composed of several subpopulations of cells including two main subsets: myeloid (mDCs) and plasmacytoid (pDCs). The present study aimed to access the distribution of PBDC subsets of CF PCM-p who were not treated (NT) or treated (apparently cured - AC). CF PCM-p were categorized into two groups, consisting of 9 NTs and 9 ACs. Twenty-one healthy individuals were used as the control group. The determination of the PBDC subsets was performed by FACS (fluorescence-activated cell sorting) and the dosage of serum TNF-α, IL1β, IL-18, CCL3, IL-10 and basic fibroblast growth factor (bFGF) by ELISA (enzyme-linked immunosorbent assay). A high count and percentage of mDCs was observed before treatment, along with a low count of pDCs in treated patients. Furthermore, the mDC:pDC ratio and serum levels of TNF-α was higher in both of the PCM-p groups than in the control group. In conclusion, our findings demonstrated that active PCM influences the distribution of mDCs and pDCs, and after treatment, PCM-p retained a lower count of pDCs associated with pro-inflammatory profile. Therefore, we identified new evidences of persistent immunological abnormalities in PCM-p after treatment. Even these patients showing fungal clearance after successful antifungal treatment; the hypoxia, triggered by the persistent pulmonary sequelae, possibly continues to interfere in the immune response.

PARACOCCIDIOIDOMYCOSIS: CHALLENGES IN THE DEVELOPMENT OF A VACCINE AGAINST AN ENDEMIC MYCOSIS IN THE AMERICAS

Paracoccidioidomycosis (PCM), caused by Paracoccidioides spp, is an important endemic mycosis in Latin America. There are two recognized Paracoccidioides species, P. brasiliensis and P. lutzii, based on phylogenetic differences; however, the pathogenesis and disease manifestations of both are indistinguishable at present. Approximately 1,853 (~51,2%) of 3,583 confirmed deaths in Brazil due to systemic mycoses from 1996-2006 were caused by PCM. Antifungal treatment is required for patients with PCM. The initial treatment lasts from two to six months and sulfa derivatives, amphotericin B, azoles and terbinafine are used in clinical practice; however, despite prolonged therapy, relapses are still a problem. An effective Th1-biased cellular immune response is essential to control the disease, which can be induced by exogenous antigens or modulated by prophylactic or therapeutic vaccines. Stimulation of B cells or passive transference of monoclonal antibodies are also important means that may be used to improve the efficacy of paracoccidioidomycosis treatment in the future. This review critically details major challenges facing the development of a vaccine to combat PCM.

Protection against Paracoccidioides brasiliensis infection in mice treated with modulated dendritic cells relies on inhibition of interleukin-10 production by CD8+ T cells

Paracoccidioidomycosis is a systemic infection prevalent in Latin American countries. Disease develops after inhalation of Paracoccidioides brasiliensis conidia followed by an improper immune activation by the host leucocytes. Dendritic cells (DCs) are antigen-presenting cells with the unique ability to direct the adaptive immune response by the time of activation of naive T cells. This study was conducted to test whether extracts of P. brasiliensis would induce maturation of DCs. We found that DCs treated with extracts acquired an inflammatory phenotype and upon adoptive transfer conferred protection to infection. Interestingly, interleukin-10 production by CD8(+) T cells was ablated following DC transfer. Further analyses showed that lymphocytes from infected mice were high producers of interleukin-10, with CD8(+) T cells being the main source. Blockage of cross-presentation to CD8(+) T cells by modulated DCs abolished the protective effect of adoptive transfer. Collectively, our data show that adoptive transfer of P. brasiliensis-modulated DCs is an interesting approach for the control of infection in paracoccidioidomycosis.

scFv from Antibody That Mimics gp43 Modulates the Cellular and Humoral Immune Responses during Experimental Paracoccidioidomycosis

Paracoccidioidomycosis (PCM), caused by Paracoccidioides species is a prevalent systemic and progressive mycosis that occurs in Latin America. It is caused by Paracoccidioides species. Immunization with dendritic cells transfected with a plasmid encoding the scFv (pMAC/PS-scFv) that mimics the main antigen of P. brasiliensis (gp43) confers protection in experimental PCM. DCs link innate and adaptive immunity by recognizing invading pathogens and selecting the type of effector T cell to mediate the immune response. Here, we showed that DC-pMAC/PS-scFv induces the activation of CD4+ and CD8+ T cells. Moreover, our results demonstrated that BALB/c mice infected with P. brasiliensis and treated with DC-pMAC/PS-scFv showed the induction of specific IgG production against gp43 and IFN-γ, IL-12 and IL-4 cytokines. Analysis of regional lymph nodes revealed increases in the expression of clec7a, myd88, tlr2, gata3 and tbx21, which are involved in the immune response. Taken together, our results indicate that the scFv modulates the humoral and cellular immune responses and presents epitopes to CD4+ and CD8+ T cells.

New advances in the development of a vaccine against paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is an endemic Latin American mycosis caused by Paracoccidioides brasiliensis and also by the recently described P. lutzii. The systemic mycosis is the 10th leading cause of death due to infectious diseases in Brazil. As published, 1,853 patients died of PCM in the 1996–2006 decade in this country. The main diagnostic antigen of P.brasiliensis is the 43 kDa glycoprotein gp43, and its 15-mer peptide QTLIAIHTLAIRYAN, known as P10, contains the T-CD4⁺ epitope that elicits an IFN-γ-mediated Th1 immune response, which effectively treats mice intratracheally infected with PCM. The association of peptide P10 with antifungal drugs rendered an additive protective effect, even in immunosuppressed animals, being the basis of a recommended treatment protocol. Other immunotherapeutic tools include a peptide carrying a B cell epitope as well as protective anti-gp43 monoclonal antibodies. New delivery systems and gene therapy have been studied in prophylactic and therapeutic protocols to improve the efficacy of the recognized antigens aiming at a future vaccine as co-adjuvant therapy in patients with PCM.