Algal and cyanobacterial lectins and their antimicrobial properties

Lectins are proteins with a remarkably high affinity and specificity for carbohydrates. Many organisms naturally produce them, including animals, plants, fungi, protists, bacteria, archaea, and viruses. The present report focuses on lectins produced by marine or freshwater organisms, in particular algae and cyanobacteria. We explore their structure, function, classification, and antimicrobial properties. Furthermore, we look at the expression of lectins in heterologous systems and the current research on the preclinical and clinical evaluation of these fascinating molecules. The further development of these molecules might positively impact human health, particularly the prevention or treatment of diseases caused by pathogens such as human immunodeficiency virus, influenza, and severe acute respiratory coronaviruses, among others.Fil: Fernández Romero, José Abel. City University of New York. The City College of New York; Estados Unidos. Center for Biomedical Research; Estados UnidosFil: Paglini, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; ArgentinaFil: Priano, Christine. City University of New York. The City College of New York; Estados UnidosFil: Koroch, Adolfina. City University of New York. The City College of New York; Estados UnidosFil: Rodríguez, Yoel. City University of New York. The City College of New York; Estados UnidosFil: Sailer, James. Center for Biomedical Research; Estados UnidosFil: Teleshova, Natalia. Center for Biomedical Research; Estados Unido

Results of a phase 1, randomized, placebocontrolled first-in-human trial of griffithsin formulated in a carrageenan vaginal gel

HIV pre-exposure prophylaxis (PrEP) is dominated by clinical therapeutic antiretroviral (ARV) drugs. Griffithsin (GRFT) is a non-ARV lectin with potent anti-HIV activity. GRFT’s preclinical safety, lack of systemic absorption after vaginal administration in animal studies, and lack of cross-resistance with existing ARV drugs prompted its development for topical HIV PrEP. We investigated safety, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of PC-6500 (0.1% GRFT in a carrageenan (CG) gel) in healthy women after vaginal administration. This randomized, placebo-controlled, parallel group, double-blind first-in-human phase 1 study enrolled healthy, HIV-negative, non-pregnant women aged 24–45 years. In the open label period, all participants (n = 7) received single dose of PC- 6500. In the randomized period, participants (n = 13) were instructed to self-administer 14 doses of PC-6500 or its matching CG placebo (PC-535) once daily for 14 days. The primary outcomes were safety and PK after single dose, and then after 14 days of dosing. Exploratory outcomes were GRFT concentrations in cervicovaginal fluids, PD, inflammatory mediators and gene expression in ectocervical biopsies. This trial is registered with ClinicalTrials. gov, number NCT02875119. No significant adverse events were recorded in clinical or laboratory results or histopathological evaluations in cervicovaginal mucosa, and no anti-drug (GRFT) antibodies were detected in serum. No cervicovaginal proinflammatory responses and no changes in the ectocervical transcriptome were evident. Decreased levels of proinflammatory chemokines (CXCL8, CCL5 and CCL20) were observed. GRFT was not detected in plasma. GRFT and GRFT/CG in cervicovaginal lavage samples inhibited HIV and HPV, respectively, in vitro in a dose-dependent fashion. These data suggest GRFT formulated in a CG gel is a safe and promising on-demand multipurpose prevention technology product that warrants further investigation

Studies on co-stimulatory molecules, chemokines and chemokine receptors in neuroimmunologicaln diseases

Background. Multiple sclerosis (MS) and myasthenia gravis (MG) are characterised by activation of T cells directed against self antigens. Such autoreactive T cells are considered to play a central role in destruction of myelin in MS and in damage of neuromuscular junctions in MG. Two groups of molecules are involved in function of autoreactive T cells: (1) co-stimulatory molecules provide essential signals for T cell activation; (2) once activated, T cells are directed to target organs by chemokine and chemokine receptor interactions. Antigen presenting cells, such as dendritic cells (DC), can also be attracted by chemokines to inflammatory foci and contribute to T cell activation in situ. The aim of this thesis was to study expression of co-stimulatory molecules, chemokines and chemokine receptors in MS and MG, and to evaluate the functional importance of chemokine receptors for migration of DC in MS. Specific aims of the study: (1) To study expression of CD40/CD40L co-stimulatory molecules in MS; (2) To evaluate expression of co-stimulatory molecules (CD40/CD40L, CD28/CD80-CD86) in MG; (3) To analyse expression of inflammatory chemokines (MCP-1, RANTES, IP-10) and chemokine receptors (CCR5, CXCR3) in MS; (4) To study expression of inflammatory chemokine receptors (CCR1, CCR5, CXCR1, CXCR4) by immature monocyte-derived dendritic cells (moDC) in MS and its functional importance; (5) To evaluate effects of IFN-beta, a cytokine that beneficially modulates the course of MS, on these immunological variables. Materials. Blood and CSF MNC were obtained from patients with untreated MS, IFN-beta treated MS, optic neuritis (ON), other inflammatory neurological diseases (OIND), other non-inflammatory neurological diseases (OND), MG and healthy controls (HQ. Methods. (1) Flow cytometry to detect MNC expressing co-stimulatory molecules in blood and chemokine receptors in blood and CSF; (2) In situ hybridization to detect MCP-1 and RANTES mRNA expression by blood and CSF MNC; (3) ELISA to determine concentrations of RANTES and IP-10 in plasma and CSF; (4) In vitro generation of moDC in the presence of GM-CSF and IL-4; (5) Chemotaxis assay to study chemotactic ability of moDC. Results. MS patients had elevated numbers of CD40L+ blood T cells compared to OND and healthy subjects. Patients with MG had increased numbers of T cells expressing CD80 and CD86, and monocytes expressing CD80, in blood compared to healthy subjects. Elevated expression of co- stimulatory molecules in MS and MG may suggest continuous T cell activation in both diseases. MS and ON patients, representing early MS, had elevated numbers of CCR5+ (receptor for RANTES) and CXCR3+ (receptor for IP-10) T cells vs. healthy subjects in blood, and vs. OND patients in CSF, indicating that expression of CCR5 and CXCR3 is altered already at the early stage of the disease. MS patients also had elevated numbers of CCR5+moDC compared to healthy subjects, resulting in increased chemotaxis in response to RANTES. Elevated expression of chemokine receptors by T cells and moDC in MS may lead to their active recruitment to the MS lesions in response to inflammatory chemokines. IFN-beta in vivo and in vitro modulated expression of CD40L and chemokine receptors. Augmented levels of CD40L+, CCR5+ and CXCR3+ T cells were confined to untreated MS patients, and not observed in patiens treated with IFN-beta. Follow-up study of patients with MS before and during treatment with IFN-beta showed decreasing numbers of CD40L+ T cells. IFN-beta in vitro reduced CCR1 and CXCR1 chemokine receptor expression by moDC and chemotactic responses. Conclusion. (1) NIS is associated with augmented expression of co-stimulatory molecules and chemokine receptors, which may indicate their role in initiation and progression of immune responses in MS. IFN-beta treatment in vivo is associated with decreased co-stimulatory molecule expression. IFN-beta treatment both in vivo and in vitro is also associated with decrease of chemokine receptor expression. (2) Elevated expression of co-stimulatory molecules may have an implication for immune cell activation and tolerance breakdown in MG

Dendritic cells and HIV infection: Activating dendritic cells to boost immunity

Dendritic cells (DCs) are white blood cells that coordinate innate and adaptive immunity. They are distributed within epithelia and mucosal-associated lymphoid tissues, positioned to entrap incoming pathogens or vaccines. Human immunodeficiency virus (HIV) and the non-human primate equivalent (SIV) exploit DCs to amplify infection, underscoring the need to harness strategies that promote presentation of virus by DCs to stimulate potent anti-viral immunity instead of virus transmission. Two main subsets of DCs need to be considered: myeloid (MDC) and plasmacytoid (PDC) subsets. Using the SIV-macaque system to advance oral vaccine research, we examined macaque PDC and MDC biology, identifying ways to activate DCs and boost antiviral immunity. Immunostimulatory oligodeoxyribonucleotides (ISS-ODNs) stimulated PDC/MDC mixtures to up-regulate co-stimulatory molecule expression and to secrete both IFN-alpha and IL-12. Additionally, ISS-ODNs augmented SIV-specific IFN-gamma responses induced by virus-bearing DCs. ISS-ODN-driven DC activation is being pursued to improve oral/nasopharyngeal mucosal vaccines and therapies against HIV

Immunodeficiency virus exploitation of dendritic cells in the early steps of infection

The unique capacity of dendritic cells (DCs) to capture and process pathogens for presentation to the immune system, combined with their capacity to express costimulatory and adhesion molecules as well as cytokines and chemokines, renders them powerful antigen-presenting cells. However, immunodeficiency viruses hijack DCs to facilitate virus dissemination while subverting effective immune activation. Depending on the activation level of the DC subset, human immunodeficiency virus can use different receptors (CD4, chemokine, and C-type lectin receptors) to bind to DCs. These aspects likely impact whether a DC is productively infected by or simply carries virus for transmission to more permissive targets. DCs efficiently transmit virus to CD4+ T cells, driving virus growth as well as providing signals to trigger virus expansion in virus-bearing CD4+ T cells. There is accumulating evidence that viral determinants (nef, tat) selectively modulate immature DC biology, fostering DC-T cell interactions and virus replication without up-regulating costimulatory molecules for effective immune function. In addition, virus-loaded, immature DCs activate CD4+ virus-specific T cells, and mature DCs stimulate CD4+ and CD8+ T cells. Thus, even if immature DCs entrap virus as it crosses the mucosae and initiate a CD4+ T cell response, this is likely insufficient to control infection. Appreciating how virus modulates DC function and what determines whether virus is processed for immune stimulation or transmitted between cells will unveil the exact role of these cells in the onset of infection and advance preventative microbicide and vaccine/therapeutic approaches

Preclinical assessments of vaginal microbicide candidate safety and efficacy

Sexually transmitted infections like HIV, HPV, and HSV-2, as well as unplanned pregnancy, take a huge toll on women worldwide. Woman-initiated multipurpose prevention technologies that contain antiviral/antibacterial drugs (microbicides) and a contraceptive to simultaneously target sexually transmitted infections and unplanned pregnancy are being developed to reduce these burdens. This review will consider products that are applied topically to the vagina. Rectally administered topical microbicides in development for receptive anal intercourse are outside the scope of this review. Microbicide and microbicide/contraceptive candidates must be rigorously evaluated in preclinical models of safety and efficacy to ensure that only candidates with favorable risk benefit ratios are advanced into human clinical trials. This review describes the comprehensive set of in vitro, ex vivo, and in vivo models used to evaluate the preclinical safety and antiviral efficacy of microbicide and microbicide/contraceptive candidates

Inhibitory Effect of PRO 2000, a Candidate Microbicide, on Dendritic Cell-Mediated Human Immunodeficiency Virus Transfer▿

Without an effective vaccine against human immunodeficiency virus (HIV) infection, topical microbicide development has become a priority. The sulfonated polyanion PRO 2000, a candidate topical microbicide now in phase II/III clinical trials, blocks HIV infection of cervical tissue in vitro. Dendritic cells (DC) are among the first cell types to contact HIV in the genital tract and facilitate the spread of the virus. Thus, interfering with virus-DC interactions is a desirable characteristic of topical microbicides as long as that does not interfere with the normal function of DC. PRO 2000 present during capture of the replication-defective HIVJRFL reporter virus or replication-competent HIVBaL by monocyte-derived DC (MDDC) inhibited subsequent HIV transfer to target cells. Continuous exposure to PRO 2000 during MDDC-target cell coculture effectively inhibited HIV infection of target cells. PRO 2000 inhibited HIV capture by MDDC. In addition, the compound blocked R5 and X4 HIV envelope-mediated cell-cell fusion. Interestingly, simultaneous exposure to PRO 2000 and lipopolysaccharide attenuated the cytokine production in response to stimulation, suggesting that the compound altered DC function. While efficient blocking of MDDC-mediated virus transfer and infection in the highly permissive MDDC-T-cell environment reinforces the potential value of PRO 2000 as a topical microbicide against HIV, the impact of PRO 2000 on immune cell functions warrants careful evaluation

Estradiol inhibits HIV-1BaL infection and induces CFL1 expression in peripheral blood mononuclear cells and endocervical mucosa

An inhibitory effect of estradiol (E2) on HIV-1 infection was suggested by several reports. We previously identified increased gene expression of actin-binding protein cofilin 1 (CFL1) in endocervix in the E2-dominated proliferative phase of the menstrual cycle. Actin cytoskeleton has an integral role in establishing and spreading HIV-1 infection. Herein, we studied in vitro effects of E2 on HIV-1 infection and on CFL1 expression to gain insight into the mechanism of HIV-1 inhibition by E2. E2 dose-dependently inhibited HIV-1BaL infection in peripheral blood mononuclear cells (PBMCs) and endocervix. In PBMCs and endocervix, E2 increased protein expression of total CFL1 and phosphorylated CFL1 (pCFL1) and pCFL1/CFL1 ratios. LIMKi3, a LIM kinase 1 and 2 inhibitor, abrogated the phenotype and restored infection in both PBMCs and endocervix; inhibited E2-induced expression of total CFL1, pCFL1; and decreased pCFL1/CFL1 ratios. Knockdown of CFL1 in PBMCs also abrogated the phenotype and partially restored infection. Additional analysis of soluble mediators revealed decreased concentrations of pro-inflammatory chemokines CXCL10 and CCL5 in infected tissues incubated with E2. Our results suggest a link between E2-mediated anti-HIV-1 activity and expression of CFL1 in PBMCs and endocervical mucosa. The data support exploration of cytoskeletal signaling pathway targets for the development of prevention strategies against HIV-1

Simian immunodeficiency virus interactions with macaque dendritic cells

This chapter summarizes advances in the following areas: (1) dendritic cell (DC)-mediated simian immunodeficiency virus (SIV) transmission, (2) role of DCs in innate and adaptive immunity against SIV, and (3) approaches to harness DC function to induce anti-SIV responses. The nonhuman primate (NHP) model of human immunodeficiency virus (HIV) infection in rhesus macaques and other Asian NHP species is highly relevant to advance the understanding of virus–host interactions critical for transmission and disease pathogenesis. HIV infection is associated with changes in frequency, phenotype, and function of the two principal subsets of DCs, myeloid DCs and plasmacytoid DCs. DC biology during pathogenic SIV infection is strikingly similar to that observed in HIV-infected patients. The NHP models provide an opportunity to dissect the requirements for DC-driven SIV infection and to understand how SIV distorts the DC system to its advantage. Furthermore, the SIV model of mucosal transmission enables the study of the earliest events of infection at the portal of entry that cannot be studied in humans, and, importantly, the involvement of DCs. Nonpathogenic infection in African NHP hosts allows investigations into the role of DCs in disease control. Understanding how DCs are altered during SIV infection is critical to the design of therapeutic and preventative strategies against HIV

Multiple sclerosis: Pro- and anti-inflammatory cytokines and metalloproteinases are affected differentially by treatment with IFN-β

Interferon-beta (IFN-β) has a beneficial influence on the course of multiple sclerosis (MS) and has become standard treatment of this disease, though its mechanisms of action are incompletely understood. This study examines the effect of IFN-β treatment on the cytokines IL-6, TNF-α, IFN-γ and IL-10; the metalloproteinases MMP-3, -7 and -9 and the tissue inhibitor of metalloproteinase-1 (TIMP-1). IFN-β treatment resulted in decreased numbers of mononuclear cells (MNC) secreting IL-6 and TNF-α and expressing mRNA of MMP-3 and MMP-9 compared to pretreatment levels. On the contrary, numbers of IL-10 secreting MNC and TIMP-1 mRNA expressing were augmented during IFN-β therapy. Whether the down-regulatory effects on pro-inflammatory and upregulatory effects on anti-inflammatory molecules are a direct result of IFN-β on the immune system or secondary to clinical stabilization of MS pathology induced by IFN-β remains to be evaluated. Copyright (C) 2000 Elsevier Science B.V