LPS Response Is Impaired by Urban Fine Particulate Matter.

Fine particulate matter (PM2.5) is a complex mixture of components with diverse chemical and physical characteristics associated with increased respiratory and cardiovascular diseases mortality. Our study aimed to investigate the effects of exposure to concentrated PM2.5 on LPS-induced lung injury onset. BALB/c male mice were exposed to either filtered air or ambient fine PM2.5 in an ambient particle concentrator for 5 weeks. Then, an acute lung injury was induced with nebulized LPS. The animals were euthanized 24 h after the nebulization to either LPS or saline. Inflammatory cells and cytokines (IL-1ß, IL-4, IL-5, IL-6, IL-10, IL-17, TNF) were assessed in the blood, bronchoalveolar lavage fluid (BALF), and lung tissue. In addition, lung morphology was assessed by stereological methods. Our results showed that the PM+LPS group showed histological evidence of injury, leukocytosis with increased neutrophils and macrophages, and a mixed inflammatory response profile, with increased KC, IL-6, IL-1ß, IL-4, and IL-17. Our analysis shows that there is an interaction between the LPS nebulization and PM2.5 exposure, differently modulating the inflammatory response, with a distinct response pattern as compared to LPS or PM2.5 exposure alone. Further studies are required to explain the mechanism of immune modulation caused by PM2.5 exposure.

A promiscuous T cell epitope-based HIV vaccine providing redundant population coverage of the HLA class II elicits broad, polyfunctional T cell responses in nonhuman primates

Over the last few decades, several emerging or reemerging viral diseases with no readily available vaccines have ravaged the world. A platform to fastly generate vaccines inducing potent and durable neutralizing antibody and T cell responses is sorely needed. Bioinformatically identified epitope-based vaccines can focus on immunodominant T cell epitopes and induce more potent immune responses than a whole antigen vaccine and may be deployed more rapidly and less costly than whole-gene vaccines. Increasing evidence has shown the importance of the CD4+ T cell response in protection against HIV and other viral infections. The previously described DNA vaccine HIVBr18 encodes 18 conserved, promiscuous epitopes binding to multiple HLA-DR-binding HIV epitopes amply recognized by HIV-1-infected patients. HIVBr18 elicited broad, polyfunctional, and durable CD4+ and CD8+ T cell responses in BALB/c and mice transgenic to HLA class II alleles, showing cross-species promiscuity. To fully delineate the promiscuity of the HLA class II vaccine epitopes, we assessed their binding to 34 human class II (HLA-DR, DQ, and -DP) molecules, and immunized nonhuman primates. Results ascertained redundant 100% coverage of the human population for multiple peptides. We then immunized Rhesus macaques with HIVBr18 under in vivo electroporation. The immunization induced strong, predominantly polyfunctional CD4+ T cell responses in all animals to 13 out of the 18 epitopes; T cells from each animal recognized 7–11 epitopes. Our results provide a preliminary proof of concept that immunization with a vaccine encoding epitopes with high and redundant coverage of the human population can elicit potent T cell responses to multiple epitopes, across species and MHC barriers. This approach may facilitate the rapid deployment of immunogens eliciting cellular immunity against emerging infectious diseases, such as COVID-19.

Air pollution impairs recovery and tissue remodeling in a murine model of acute lung injury.

Evidence regarding the impact of air pollution on acute respiratory distress syndrome (ARDS) is limited, and most studies focus on ARDS onset. Our study aimed to evaluate whether exposure to fine particulate matter interferes with lung recovery and remodeling in a murine model of acute lung injury. Forty-eight mice received nebulized LPS or the vehicle (controls). Blood, BALF, lungs and spleen were collected after 5 weeks of exposure to either PM2.5 (PM and LPS + PM group) or filtered air (control and LPS5w groups). Inflammatory cells and cytokines were assessed in the blood, BALF, lungs and spleen. Stereological analyses and remodeling assessments were performed by histology. The LPS + PM group showed increased BALF leukocytes, characterized by increased macrophages, increased IL-1ß and IL-6 levels, anemia and thrombocytopenia. Moreover, we also observed septal thickening, decreased alveolar air space total volume and, septa surface density. Finally, regarding tissue remodeling, we observed elastosis of the lung parenchyma, and unlike in the LPS5w group, we did not observe fibrosis in the LPS + PM group. In conclusion, the delayed inflammation resolution due to subchronic exposure to PM2.5 could be influenced by low systemic and local lymphocyte counts, which lead to impaired lung injury recovery and tissue remodeling.

Ethnopharmacology Study of Plants from Atlantic Forest with Leishmanicidal Activity.

Leishmaniasis is an infectious disease caused by a protozoan belonging to Leishmania genus. Different clinical outcomes can be observed depending on the parasite species and patient's health condition. The outcomes can range from single cutaneous lesions to lethal visceral form. The treatment of all forms of leishmaniasis is based on pentavalent antimonials, and, in some cases, the second-line drug, amphotericin B, is used. Beside the toxicity of both classes of drugs, in some areas of the world, parasites are resistant to antimonial. These detrimental features make fundamental the discovery and characterization of new drugs or plant extracts with leishmanicidal effects. Brazil is a well-known country for its biodiversity. Additionally, the common knowledge inherited for generations in small villages makes Brazil a source of new information and resources for the discovery and development of new drugs. Based on ethnopharmacology, elderlies were interviewed about plants they commonly used for skin diseases and infections. Five native plants from Atlantic forest were indicated; EtOH and n-hexane extracts were prepared with the vegetative organs of the plants and assayed against promastigote and amastigote forms of L. (L.) amazonensis. The major molecules of each extract were detected using qualitative nuclear magnetic resonance. Among all tested extracts, the n-hexane extract from the leave of Eugenia uniflora (Myrtaceae), enriched in myricitrin and quercitrin flavonoids, was the most effective against L. (L.) amazonensis amastigotes. This data supports the ethnopharmacology approach as a successful tool for the discovery of new drugs with leishmanicidal effects.

Activity of Fenticonazole, Tioconazole and Nystatin on New World Leishmania Species.

Leishmaniasis is an infectious disease caused by protozoal parasites belonging to Leishmania genus. Different clinical outcomes can be observed depending on the parasite species and health condition of patients. It can range from single cutaneous lesion until deadly visceral form. The treatment of all forms of leishmaniasis is based on pentavalent antimonials, and in some cases, the second-line drug, amphotericin B is used. Beside the toxicity of both drugs, parasites can be resistant to antimonial in some areas of the world. This makes fundamental the characterization of new drugs with leishmanicidal effect. Thus, the aim of the present work was to study the leishmanicidal activity of drugs able to interfere with ergosterol pathway (fenticonazole, tioconazole, nystatin, rosuvastatin and voriconazole) against promastigote and amastigote forms of L.(L.) amazonensis, L.(V.) braziliensis and L.(L.) infantum, and its impact on morphological and physiological changes in L.(L.) amazonensis or in host macrophages. We observed that fenticonazole, tioconazole and nystatin drugs eliminated promastigote and intracellular amastigotes, being fenticonazole and nystatin the most selective towards amastigote forms. Rosuvastatin and voriconazole did not present activity against amastigote forms of Leishmania sp. In addition, the drugs with leishmanicidal activity interfered with parasite mitochondrion. Although drugs did not stimulate NO and H2O2, specially fenticonazole was able to alkalize infected host macrophages. These results suggest well established and non-toxic antifungal drugs can be repurposed and used in leishmaniasis.

Effect of phospholipase A2 inhibitors during infection caused by Leishmania (Leishmania) amazonensis.

BACKGROUND: Lipid metabolites play an important role in parasite differentiation and virulence. Studies have revealed that Leishmania sp. uses prostaglandins to evade innate barriers, thus enabling the parasites to survive inside immune cells. Despite the role of the enzyme Phospholipase A2 (PLA2) in prostaglandins production, few studies have investigated the role of parasite PLA2 during the interaction between L. (L.) amazonensis and the host (in vitro and in vivo) immune cells. METHODS: In the present work, the leishmanicidal effect of PLA2 inhibitors, methyl arachidonyl fluorophosphonate (MAFP), bromoenol lactone (BEL) and aristolochic acid (AA) were investigated in vitro (promastigote and intracellular amastigote forms of L. (L.) amazonensis) and during in vivo infection using BALB/c mice. RESULTS: The aforementioned inhibitors were deleterious to promastigote and amastigote forms of the L. (L.) amazonensis and were non-toxic to peritoneal macrophages from BALB/c mice. L. (L.) amazonensis-infected BALB/c mice treated with the inhibitor BEL presented decreased lesion size and skin parasitism; however, BEL treatment induced hepatotoxicity in BALB/c mice. CONCLUSIONS: Results presented herein suggested that PLA2 inhibitors altered L. (L.) amazonensis viability. In spite of liver toxicity, treatment with BEL was the most selective compound in vitro, as well in vivo, resulting in lower skin parasitism in the infected mice. These findings corroborate the role of PLA2 in parasite virulence and maintenance in vertebrate hosts, and suggest that molecules structurally related to BEL should be considered when planning compounds against Leishmania sp.

Effect of phospholipase A2 inhibitors during infection caused by Leishmania (Leishmania) amazonensis

Lipid metabolites play an important role in parasite differentiation and virulence. Studies have revealed that Leishmania sp. uses prostaglandins to evade innate barriers, thus enabling the parasites to survive inside immune cells. Despite the role of the enzyme Phospholipase A2 (PLA2) in prostaglandins production, few studies have investigated the role of parasite PLA2 during the interaction between L. (L.) amazonensis and the host (in vitro and in vivo) immune cells. Methods: In the present work, the leishmanicidal effect of PLA2 inhibitors, methyl arachidonyl fluorophosphonate (MAFP), bromoenol lactone (BEL) and aristolochic acid (AA) were investigated in vitro (promastigote and intracellular amastigote forms of L. (L.) amazonensis) and during in vivo infection using BALB/c mice. Results: The aforementioned inhibitors were deleterious to promastigote and amastigote forms of the L. (L.) amazonensis and were non-toxic to peritoneal macrophages from BALB/c mice. L. (L.) amazonensis-infected BALB/c mice treated with the inhibitor BEL presented decreased lesion size and skin parasitism; however, BEL treatment induced hepatotoxicity in BALB/c mice. Conclusions: Results presented herein suggested that PLA2 inhibitors altered L. (L.) amazonensis viability. In spite of liver toxicity, treatment with BEL was the most selective compound in vitro, as well in vivo, resulting in lower skin parasitism in the infected mice. These findings corroborate the role of PLA2 in parasite virulence and maintenance in vertebrate hosts, and suggest that molecules structurally related to BEL should be considered when planning compounds against Leishmania sp.(AU)

Effect of phospholipase A2 inhibitors during infection caused by Leishmania (Leishmania) amazonensis

Background: Lipid metabolites play an important role in parasite differentiation and virulence. Studies have revealed that Leishmania sp. uses prostaglandins to evade innate barriers, thus enabling the parasites to survive inside immune cells. Despite the role of the enzyme Phospholipase A2 (PLA2) in prostaglandins production, few studies have investigated the role of parasite PLA2 during the interaction between L. (L.) amazonensis and the host (in vitro and in vivo) immune cells. Methods: In the present work, the leishmanicidal effect of PLA2 inhibitors, methyl arachidonyl fluorophosphonate (MAFP), bromoenol lactone (BEL) and aristolochic acid (AA) were investigated in vitro (promastigote and intracellular amastigote forms of L. (L.) amazonensis) and during in vivo infection using BALB/c mice. Results: The aforementioned inhibitors were deleterious to promastigote and amastigote forms of the L. (L.) amazonensis and were non-toxic to peritoneal macrophages from BALB/c mice. L. (L.) amazonensis-infected BALB/c mice treated with the inhibitor BEL presented decreased lesion size and skin parasitism; however, BEL treatment induced hepatotoxicity in BALB/c mice. Conclusions: Results presented herein suggested that PLA2 inhibitors altered L. (L.) amazonensis viability. In spite of liver toxicity, treatment with BEL was the most selective compound in vitro, as well in vivo, resulting in lower skin parasitism in the infected mice. These findings corroborate the role of PLA2 in parasite virulence and maintenance in vertebrate hosts, and suggest that molecules structurally related to BEL should be considered when planning compounds against Leishmania sp.

Effect of phospholipase A2 inhibitors during infection caused by Leishmania (Leishmania) amazonensis

Background: Lipid metabolites play an important role in parasite differentiation and virulence. Studies have revealed that Leishmania sp. uses prostaglandins to evade innate barriers, thus enabling the parasites to survive inside immune cells. Despite the role of the enzyme Phospholipase A2 (PLA2) in prostaglandins production, few studies have investigated the role of parasite PLA2 during the interaction between L. (L.) amazonensis and the host (in vitro and in vivo) immune cells. Methods: In the present work, the leishmanicidal effect of PLA2 inhibitors, methyl arachidonyl fluorophosphonate (MAFP), bromoenol lactone (BEL) and aristolochic acid (AA) were investigated in vitro (promastigote and intracellular amastigote forms of L. (L.) amazonensis) and during in vivo infection using BALB/c mice. Results: The aforementioned inhibitors were deleterious to promastigote and amastigote forms of the L. (L.) amazonensis and were non-toxic to peritoneal macrophages from BALB/c mice. L. (L.) amazonensis-infected BALB/c mice treated with the inhibitor BEL presented decreased lesion size and skin parasitism; however, BEL treatment induced hepatotoxicity in BALB/c mice. Conclusions: Results presented herein suggested that PLA2 inhibitors altered L. (L.) amazonensis viability. In spite of liver toxicity, treatment with BEL was the most selective compound in vitro, as well in vivo, resulting in lower skin parasitism in the infected mice. These findings corroborate the role of PLA2 in parasite virulence and maintenance in vertebrate hosts, and suggest that molecules structurally related to BEL should be considered when planning compounds against Leishmania sp.(AU)

Early and late pulmonary effects of nebulized LPS in mice: An acute lung injury model.

BACKGROUND AND OBJECTIVE: Acute respiratory distress syndrome (ARDS) has a high mortality rate of 35-46% depending on its severity. Animal models are crucial to better understand the pathophysiology of diseases, including ARDS. This study presents a feasible animal model of acute lung injury (ALI) using nebulized lipopolysaccharide (LPS) in a non-invasive approach, focusing on its short and long-term effects. METHODS: Mice received nebulized LPS or vehicle only (control group). Blood, BALF and lung tissue were collected 24 hours (LPS 24h) or 5 weeks (LPS 5w) after the nebulized LPS-induced lung injury. Inflammatory cytokines were assessed in the blood serum, BALF and lung tissue. Stereological analyses and remodeling changes were assessed by histology and immunohistochemistry at the specified time points. RESULTS: The LPS 24h group showed increased pro-inflammatory cytokine levels, intense cell influx, increased total septal volume, septal thickening and decreased surface density of the alveolar septa. The LPS 5w group showed persistent lung inflammation, septal thickening, increased total lung volume, accentuated collagen deposition, especially of collagen type I, and decreased MMP-2 protein expression. CONCLUSION: We present a feasible, reproducible and non-invasive nebulized-LPS animal model that allows the assessment of both the acute and late phases of acute lung injury. The presence of lung remodeling with collagen deposition after 5 weeks makes it useful to study the pathophysiology, complications, and possible therapeutic intervention studies that aim to understand and reduce pulmonary fibrosis in the late phases of ALI.

p16INK4a Expression and Immunologic Aging in Chronic HIV Infection.

Chronic HIV infection is characterized by increased immune activation and immunosenescence. p16 INK4a (p16) is a member of the cyclin-dependent kinase antagonist family that inhibits cellular proliferation, and its protein expression increases during normal chronological aging. However, some infectious diseases can increase the expression of this anti-proliferative protein, potentially accelerating immunological aging and dysfunction. In order to investigate the immunological aging in HIV patients, p16 protein expression was evaluated by flow cytometry, in T cell subsets in a cohort of chronically HIV-infected patients on and off ART as well as age-matched healthy controls. Results showed that untreated HIV-infected subjects exhibited increased per-cell p16 protein expression that was discordant with chronological aging. ART restored p16 protein expression to levels comparable with HIV-negative subjects in the CD4 compartment, but not in CD8 T cells, which can be an indicative of an irreversible activation/exhaustion status on these cells. Additionally, the frequency of activated CD4+ and CD8+ T cells was positively correlated with p16 expression in CD4+ and CD8+ T cells in untreated subjects. In contrast to healthy controls, untreated HIV-infected individuals had increased p16 levels within the effector memory (TEM) subset, indicating a possible role for this marker in impaired clonal expansion during antiviral effector function. Taken together, these data demonstrate that chronic HIV infection is associated with elevated expression of the cellular aging marker p16 in T cells. ART restored normal p16 levels in the CD4+ T cell compartment, indicating that use of therapy can be of fundamental importance to normal cell cycling and maintaining immune homeostasis.

The antifungal compound butenafine eliminates promastigote and amastigote forms of Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis.

The production of ergosterol lipid, important for the Leishmania membrane homeostasis, involves different enzymes. This pathway can be blocked to azoles and allylamines drugs, such as Butenafine. The aim of the present work was to evaluate the anti-leishmanicidal activity of this drug in 2 major species of Leishmania responsible for causing the American tegumentar leishmaniasis (L. (L.) amazonensis and L. (V.) braziliensis). Butenafine eliminated promastigote forms of L. amazonensis and L. braziliensis with efficacy similar to miltefosine, a standard anti-leishmania drug. In addition, butenafine induced alterations in promastigote forms of L. amazonensis that resemble programmed cell death. Butenafine as well as miltefosine presented mild toxicity in peritoneal macrophages, however, butenafine was more effective to eliminate intracellular amastigotes of both L. amazonensis and L. braziliensis, and this effect was not associated with elevated levels of nitric oxide or hydrogen peroxide. Taken together, data presented herein suggests that butenafine can be considered as a prototype drug able to eliminate L. amazonensis and L. braziliensis, etiological agents of anergic diffuse and mucocutaneous leishmaniasis, respectively.

Increase in cholinergic modulation with pyridostigmine induces anti-inflammatory cell recruitment soon after acute myocardial infarction in rats.

We tested the hypothesis that an increase in the anti-inflammatory cholinergic pathway, when induced by pyridostigmine (PY), may modulate subtypes of lymphocytes (CD4+, CD8+, FOXP3+) and macrophages (M1/M2) soon after myocardial infarction (MI) in rats. Wistar rats, randomly allocated to receive PY (40 mg·kg(-1)·day(-1)) in drinking water or to stay without treatment, were followed for 4 days and then were subjected to ligation of the left coronary artery. The groups-denominated as the pyridostigmine-treated infarcted (IP) and infarcted control (I) groups-were submitted to euthanasia 3 days after MI; the heart was removed for immunohistochemistry, and the peripheral blood and spleen were collected for flow cytometry analysis. Noninfarcted and untreated rats were used as controls (C Group). Echocardiographic measurements were registered on the second day after MI, and heart rate variability was measured on the third day after MI. The infarcted groups had similar MI areas, degrees of systolic dysfunction, blood pressures, and heart rates. Compared with the I Group, the IP Group showed a significant higher parasympathetic modulation and a lower sympathetic modulation, which were associated with a small, but significant, increase in diastolic function. The IP Group showed a significant increase in M2 macrophages and FOXP3(+)cells in the infarcted and peri-infarcted areas, a significantly higher frequency of circulating Treg cells (CD4(+)CD25(+)FOXP3(+)), and a less extreme decrease in conventional T cells (CD25(+)FOXP3(-)) compared with the I Group. Therefore, increasing cholinergic modulation with PY induces greater anti-inflammatory cell recruitment soon after MY in rats.

The Effect of Ursolic Acid on Leishmania (Leishmania) amazonensis Is Related to Programed Cell Death and Presents Therapeutic Potential in Experimental Cutaneous Leishmaniasis.

Among neglected tropical diseases, leishmaniasis is one of the most important ones, affecting more than 12 million people worldwide. The available treatments are not well tolerated, and present diverse side effects, justifying the search for new therapeutic compounds. In the present study, the activity of ursolic acid (UA) and oleanolic acid (OA) were assayed in experimental cutaneous leishmaniasis (in vitro and in vivo). Promastigote forms of L. amazonensis were incubated with OA and UA for 24h, and effective concentration 50% (EC50) was estimated. Ultraestructural alterations in Leishmania amazonensis promastigotes after UA treatment were evaluated by transmission electron microscopy, and the possible mode of action was assayed through Annexin V and propidium iodide staining, caspase 3/7 activity, DNA fragmentation and transmembrane mitochondrial potential. The UA potential was evaluated in intracellular amastigotes, and its therapeutic potential was evaluated in L. amazonensis infected BALB/c mice. UA eliminated L. amazonensis promastigotes with an EC50 of 6.4 µg/mL, comparable with miltefosine, while OA presented only a marginal effect on promastigote forms at 100 µg/mL. The possible mechanism by which promastigotes were eliminated by UA was programmed cell death, independent of caspase 3/7, but it was highly dependent on mitochondria activity. UA was not toxic for peritoneal macrophages from BALB/c mice, and it was able to eliminate intracellular amastigotes, associated with nitric oxide (NO) production. OA did not eliminate amastigotes nor trigger NO. L. amazonensis infected BALB/c mice submitted to UA treatment presented lesser lesion size and parasitism compared to control. This study showed, for the first time, that UA eliminate promastigote forms through a mechanism associated with programed cell death, and importantly, was effective in vivo. Therefore, UA can be considered an interesting candidate for future tests as a prototype drug for the treatment of cutaneous leishmaniasis.

Co-administration of plasmid-encoded granulocyte-macrophage colony-stimulating factor increases human immunodeficiency virus-1 DNA vaccine-induced polyfunctional CD4+ T-cell responses

T-cell based vaccines against human immunodeficiency virus (HIV) generate specific responses that may limit both transmission and disease progression by controlling viral load. Broad, polyfunctional, and cytotoxic CD4+T-cell responses have been associated with control of simian immunodeficiency virus/HIV-1 replication, supporting the inclusion of CD4+ T-cell epitopes in vaccine formulations. Plasmid-encoded granulocyte-macrophage colony-stimulating factor (pGM-CSF) co-administration has been shown to induce potent CD4+ T-cell responses and to promote accelerated priming and increased migration of antigen-specific CD4+ T-cells. However, no study has shown whether co-immunisation with pGM-CSF enhances the number of vaccine-induced polyfunctional CD4+ T-cells. Our group has previously developed a DNA vaccine encoding conserved, multiple human leukocyte antigen (HLA)-DR binding HIV-1 subtype B peptides, which elicited broad, polyfunctional and long-lived CD4+ T-cell responses. Here, we show that pGM-CSF co-immunisation improved both magnitude and quality of vaccine-induced T-cell responses, particularly by increasing proliferating CD4+ T-cells that produce simultaneously interferon-γ, tumour necrosis factor-α and interleukin-2. Thus, we believe that the use of pGM-CSF may be helpful for vaccine strategies focused on the activation of anti-HIV CD4+ T-cell immunity.

Co-administration of plasmid-encoded granulocyte-macrophage colony-stimulating factor increases human immunodeficiency virus-1 DNA vaccine-induced polyfunctional CD4+ T-cell responses.

T-cell based vaccines against human immunodeficiency virus (HIV) generate specific responses that may limit both transmission and disease progression by controlling viral load. Broad, polyfunctional, and cytotoxic CD4+T-cell responses have been associated with control of simian immunodeficiency virus/HIV-1 replication, supporting the inclusion of CD4+ T-cell epitopes in vaccine formulations. Plasmid-encoded granulocyte-macrophage colony-stimulating factor (pGM-CSF) co-administration has been shown to induce potent CD4+ T-cell responses and to promote accelerated priming and increased migration of antigen-specific CD4+ T-cells. However, no study has shown whether co-immunisation with pGM-CSF enhances the number of vaccine-induced polyfunctional CD4+ T-cells. Our group has previously developed a DNA vaccine encoding conserved, multiple human leukocyte antigen (HLA)-DR binding HIV-1 subtype B peptides, which elicited broad, polyfunctional and long-lived CD4+ T-cell responses. Here, we show that pGM-CSF co-immunisation improved both magnitude and quality of vaccine-induced T-cell responses, particularly by increasing proliferating CD4+ T-cells that produce simultaneously interferon-γ, tumour necrosis factor-α and interleukin-2. Thus, we believe that the use of pGM-CSF may be helpful for vaccine strategies focused on the activation of anti-HIV CD4+ T-cell immunity.

Multiple Approaches for Increasing the Immunogenicity of an Epitope-Based Anti-HIV Vaccine.

The development of a highly effective vaccine against the human immunodeficiency virus (HIV) will likely be based on rational vaccine design, since traditional vaccine approaches have failed so far. In recent years, an understanding of what type of immune response is protective against infection and/or disease facilitated vaccine design. T cell-based vaccines against HIV have the goal of limiting both transmission and disease progression by inducing broad and functionally relevant T cell responses. In this context, CD4(+) T cells play a direct cytotoxic role and are also important for the generation and maintenance of functional CD8(+) T and B cell responses. The use of MHC-binding algorithms has allowed the identification of novel CD4(+) T cell epitopes that could be used in vaccine design, the so-called epitope-driven vaccine design. Epitope-based vaccines have the ability to focus the immune response on highly antigenic, conserved epitopes that are fully recognized by the target population. We have recently mapped a set of conserved multiple HLA-DR-binding HIV-1 CD4 epitopes and observed interferon (IFN)-γ-producing CD4(+) T cells when we tested these peptides in peripheral blood mononuclear cells (PBMCs) from HIV-infected individuals. We then designed multiepitopic DNA vaccines that induced broad and polyfunctional T cell responses in immunized mice. In this review we will focus on alternative strategies to increase the immunogenicity of an epitope-based vaccine against HIV infection.

Plasma cytokine profile in tropical endomyocardial fibrosis: predominance of TNF-a, IL-4 and IL-10.

BACKGROUND: The participation of immune/inflammatory mechanisms in the pathogenesis of tropical endomyocardial fibrosis (EMF) has been suggested by the finding of early blood and myocardial eosinophilia. However, the inflammatory activation status of late-stage EMF patients is still unknown. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated pro- and anti-inflammatory cytokine levels in plasma samples from late stage EMF patients. Cytokine levels of Tumor Necrosis Factor (TNF)-α, Interferon (IFN)-γ, Interleukin (IL)-2, IL-4, IL-6, and IL-10 were assayed in plasma samples from 27 EMF patients and compared with those of healthy control subjects. All EMF patients displayed detectable plasma levels of at least one of the cytokines tested. We found that TNF-α, IL-6, IL-4, and IL-10 were each detected in at least 74% of tested sera, and plasma levels of IL-10, IL-4, and TNF-α were significantly higher than those of controls. Plasma levels of such cytokines positively correlated with each other. CONCLUSIONS/SIGNIFICANCE: The mixed pro- and anti-inflammatory/Th2circulating cytokine profile in EMF is consistent with the presence of a persistent inflammatory stimulus. On the other hand, the detection of increased levels of TNF-α may be secondary to the cardiovascular involvement observed in these patients, whereas IL-4 and IL-10 may have been upregulated as a homeostatic mechanism to buffer both production and deleterious cardiovascular effects of pro-inflammatory cytokines. Further studies might establish whether these findings play a role in disease pathogenesis.

The CD8⁺ memory stem T cell (T(SCM)) subset is associated with improved prognosis in chronic HIV-1 infection.

UNLABELLED: Memory stem T cells (T(SCM)) constitute a long-lived, self-renewing lymphocyte population essential for the maintenance of functional immunity. The hallmarks of HIV-1 pathogenesis are CD4(+) T cell depletion and abnormal cellular activation. We investigated the impact of HIV-1 infection on the T(SCM) compartment, as well as any protective role these cells may have in disease progression, by characterizing this subset in a cohort of 113 subjects with various degrees of viral control on and off highly active antiretroviral therapy (HAART). We observed that the frequency of CD8(+) T(SCM) was decreased in all individuals with chronic, untreated HIV-1 infection and that HAART had a restorative effect on this subset. In contrast, natural controllers of HIV-1 had the highest absolute number of CD4(+) T(SCM) cells among all of the infected groups. The frequency of CD4(+) T(SCM) predicted higher CD8(+) T(SCM) frequencies, consistent with a role for the CD4(+) subset in helping to maintain CD8(+) memory T cells. In addition, T(SCM) appeared to be progenitors for effector T cells (TEM), as these two compartments were inversely correlated. Increased frequencies of CD8(+) T(SCM) predicted lower viral loads, higher CD4(+) counts, and less CD8(+) T cell activation. Finally, we found that T(SCM) express the mucosal homing integrin α4ß7 and can be identified in gut-associated lymphoid tissue (GALT). The frequency of mucosal CD4(+) T(SCM) was inversely correlated with that in the blood, potentially reflecting the ability of these self-renewing cells to migrate to a crucial site of ongoing viral replication and CD4(+) T cell depletion. IMPORTANCE: HIV-1 infection leads to profound impairment of the immune system. T(SCM) constitute a recently identified lymphocyte subset with stem cell-like qualities, including the ability to generate other memory T cell subtypes, and are therefore likely to play an important role in controlling viral infection. We investigated the relationship between the size of the CD8(+) T(SCM) compartment and HIV-1 disease progression in a cohort of chronically infected individuals. Our results suggest that HAART restores a normal frequency of CD8(+) T(SCM) and that the natural preservation of this subset in the setting of untreated HIV-1 infection is associated with improved viral control and immunity. Therefore, the CD8(+) T(SCM) population may represent a correlate of protection in chronic HIV-1 infection that is directly relevant to the design of T cell-based vaccines, adoptive immunotherapy approaches, or the pharmacologic induction of T(SCM).

Short communication: HIV type 1 subtype BF leads to faster CD4+ T cell loss compared to subtype B.

Although it has been suggested that biological differences among HIV-1 subtypes exist, their possible influence on disease progression has not been fully revealed. In particular, the increasing emergence of recombinants stresses the need to characterize disease presentation in persons infected by these diverse HIV-1 forms. We explored this issue among 83 Brazilian subjects infected with either HIV-1 subtype B or recombinant subtype BF, all followed since incident infection in a cohort study. Viral subtypes were assigned by full length sequencing of HIV-1 genomes. We observed that the baseline measures for CD4(+) T cells and viral load did not differ between the groups. However, longitudinal analysis revealed that subtype BF was clearly associated with a faster CD4(+) T cell decline compared to infection with subtype B, in spite of a similar plasma HIV-1 load. While subtype B-infected subjects presented a loss of 3.6 CD4(+) T cells/µl per month, subtype BF-infected individuals showed a monthly decay of 6.3 CD4(+) T cells/µl (p<0.01). The time to reach 350 CD4(+) T cells/µl and the time to start antiretroviral treatment were also shorter in subtype BF-infected persons. The elucidation of an accelerated CD4(+) T cell loss associated with subtype BF suggests that this HIV-1 genetic form could be more pathogenic than subtype B.