CD11b-bearing mononuclear leucocytes and IgA levels in the staging of human immunodeficiency virus infection

Certain immunological parameters (i.e. low CD4+ T cell numbers, high serum soluble CD8) have been described as prognostic factors for the progression of human immunodeficiency virus (HIV) infection to later clinical stages. In the present study we have found in one hundred HIV-infected Spanish patients (81% drug abusers, 7% homosexuals, 6% heterosexuals, and 6% other or unknown risk groups) that CD11b+ peripheral blood mononuclear cells are increased in those with persistent lymphadenopathy as compared to other clinical stages (asymptomatic, AIDS-related complex and AIDS). Serum IgA was significantly increased in AIDS patients, and in patients at any other clinical stage who had concomitant infections (mainly mycobacterial and fungal). CD11b (an integrin with complement receptor functions) may thus be of clinical interest for the staging of HIV-infected patients, and reflect stage-selective immunological changes in mononuclear cell biology during HIV infection. High IgA on the other hand, would be a marker of concomitant infection as well as of disease progression. The results concern mostly drug addicts (the main risk group in Spain), but may apply to the other risk groups because no significant differences were detected between drug addicts (n=81) and non-drug addicts (n=19) for the studied variables (p>0.05).     

CD11b-bearing mononuclear leucocytes and IgA levels in the staging of human immunodeficiency virus infection.

Certain immunological parameters (i.e. low CD4+ T cell numbers, high serum soluble CD8) have been described as prognostic factors for the progression of human immunodeficiency virus (HIV) infection to later clinical stages. In the present study we have found in one hundred HIV-infected Spanish patients (81% drug abusers, 7% homosexuals, 6% heterosexuals, and 6% other or unknown risk groups) that CD11b+ peripheral blood mononuclear cells are increased in those with persistent lymphadenopathy as compared to other clinical stages (asymptomatic, AIDS-related complex and AIDS). Serum IgA was significantly increased in AIDS patients, and in patients at any other clinical stage who had concomitant infections (mainly mycobacterial and fungal). CD11b (an integrin with complement receptor functions) may thus be of clinical interest for the staging of HIV-infected patients, and reflect stage-selective immunological changes in mononuclear cell biology during HIV infection. High IgA on the other hand, would be a marker of concomitant infection as well as of disease progression. The results concern mostly drug addicts (the main risk group in Spain), but may apply to the other risk groups because no significant differences were detected between drug addicts (n = 81) and non-drug addicts (n = 19) for the studied variables (p greater than 0.05).     

Elektronenmikroskopische Beobachtungen bei experimenteller Poliomyelitis

Summary The lumbar motor columns of a cynomolgus monkey which had become tetraplegic after infection with a highly virulent strain of type 3 poliovirus were examined by electron microscopy. Within the cytoplasm of many endothelial cells of intraspinal blood vessels, as well as within the perikarya of numerous mononuclear inflammatory cells, there occurred regular arrays of dense particles which, on the basis of morphological evidence, could be identified as poliovirus crystals. The possible significance of virual replication by endothelial and mononuclear cells for poliovirus spread within the central nervous system is briefly discussed.     

Potassium and sodium transport in non-animal cells: the Trk/Ktr/HKT transporter family

Bacterial Trk and Ktr, fungal Trk and plant HKT form a family of membrane transporters permeable to K⁺ and/or Na⁺ and characterized by a common structure probably derived from an ancestral K⁺ channel subunit. This transporter family, specific of non-animal cells, displays a large diversity in terms of ionic permeability, affinity and energetic coupling (H⁺–K⁺ or Na⁺–K⁺ symport, K⁺ or Na⁺ uniport), which might reflect a high need for adaptation in organisms living in fluctuating or dilute environments. Trk/Ktr/HKT transporters are involved in diverse functions, from K⁺ or Na⁺ uptake to membrane potential control, adaptation to osmotic or salt stress, or Na⁺ recirculation from shoots to roots in plants. Structural analyses of bacterial Ktr point to multimeric structures physically interacting with regulatory subunits. Elucidation of Trk/Ktr/HKT protein structures along with characterization of mutated transporters could highlight functional and evolutionary relationships between ion channels and transporters displaying channel-like features.     

Ionic currents in morphogenesis

Summary Morphogenetic fields must be generated by mechanisms based on known physical forces which include gravitational forces, mechanical forces, electrical forces, or some combination of these. While it is unrealistic to expect a single force, such as a voltage gradient, to be the sole cause of a morphogenetic event, spatial and temporal information about the electrical fields and ion concentration gradients in and around a cell or embryo undergoing morphogenesis can take us one step further toward understanding the entire morphogenetic mechanism. This is especially true because one of the handful of identified morphogens is Ca²⁺, an ion that will not only generate a current as it moves, but which is known to directly influence the plasma membrane's permeability to other ions, leading to other transcellular currents. It would be expected that movements of this morphogen across the plasma membrane might generate ionic currents and gradients of both electrical potential and intracellular concentration. Such ionic currents have been found to be integral components of the morphogenetic mechanism in some cases and only secondary components in other cases. My goal in this review is to discuss examples of both of these levels of involvement that have resulted from investigations conducted during the past several years, and to point to areas that are ripe for future investigation. This will include the history and theory of ionic current measurements, and a discussion of examples in both plant and animal systems in which ionic currents and intracellular concentration gradients are integral components of morphogenesis as well as cases in which they play only a secondary role. By far the strongest cases for a direct role of ionic currents in morphogenesis is the polarizing fucoid egg where the current is carried in part by Ca²⁺ and generates an intracellular concentration gradient of this ion that orients the outgrowth, and the insect follicle in which an intracellular voltage gradient is responsible for the polarized transport from nurse cell to oocyte. However, in most of the systems studied, the experiments to determine if the observed ionic currents are directly involved in the morphogenetic mechanism are yet to be done. Our experience with the fucoid egg and the fungal hypha ofAchlya suggest that it is the change in the intracellular ion concentration resulting from the ionic current that is critical for morphogenesis.     

Host recognition by toxigenic plant pathogens

Certain fungal pathogens release host-selective (or host-specific) toxins (HST) as a host recognition factor during spore germination at the infection site on plants. Prior to penetration of the pathogen into its host, the released toxin specifically binds to a putative receptor on the host cells and initiates signaling mechanisms leading to pleiotropic effects on cells. Of these, the crucial one negates the general and inducible defense reactions of the cells. This is accomplished by a signal from the HSt, which is transduced through a path way at or near the step of plasma membrane modulation, which is directly or indirectly triggered by the HST. This mechanism operates even though the toxin may affect mitochondria or chloroplasts as the primary target organelle. The fungal spore is able to penetrate the so-called narcotized cell and completes the initial colonization of the host. The host recognition process may take place without necessitating host cell death, even in the case of perthophytic parasites. At the molecular level, HST-mediated recognition of the host by a pathogen requires strict stereochemical precision like a lock and key.     

<Emphasis Type="Italic">Yersinia pseudotuberculosis</Emphasis> supports Th17 differentiation and limits de novo regulatory T cell induction by directly interfering with T cell receptor signaling

Adaptive immunity critically contributes to control acute infection with enteropathogenic Yersinia pseudotuberculosis; however, the role of CD4⁺ T cell subsets in establishing infection and allowing pathogen persistence remains elusive. Here, we assessed the modulatory capacity of Y. pseudotuberculosis on CD4⁺ T cell differentiation. Using in vivo assays, we report that infection with Y. pseudotuberculosis resulted in enhanced priming of IL-17-producing T cells (Th17 cells), whereas induction of Foxp3⁺ regulatory T cells (Tregs) was severely disrupted in gut-draining mesenteric lymph nodes (mLNs), in line with altered frequencies of tolerogenic and proinflammatory dendritic cell (DC) subsets within mLNs. Additionally, by using a DC-free in vitro system, we could demonstrate that Y. pseudotuberculosis can directly modulate T cell receptor (TCR) downstream signaling within naïve CD4⁺ T cells and Tregs via injection of effector molecules through the type III secretion system, thereby affecting their functional properties. Importantly, modulation of naïve CD4⁺ T cells by Y. pseudotuberculosis resulted in an enhanced Th17 differentiation and decreased induction of Foxp3⁺ Tregs in vitro. These findings shed light to the adjustment of the Th17-Treg axis in response to acute Y. pseudotuberculosis infection and highlight the direct modulation of CD4⁺ T cell subsets by altering their TCR downstream signaling.     

Generation of MHC class I ligands in the secretory and vesicular pathways

CD8⁺ T lymphocytes screen the surface of all cells in the body to detect pathogen infection or oncogenic transformation. They recognize peptides derived from cellular proteins displayed at the plasma membrane by major histocompatibility complex (MHC) class I molecules. Peptides are mostly by-products of cytosolic proteolytic enzymes. Peptidic ligands of MHC class I molecules are also generated in the secretory and vesicular pathways. Features of protein substrates, of proteases and of available MHC class I molecules for loading peptides in these compartments shape a singular collection of ligands that also contain different, longer, and lower affinity peptides than ligands produced in the cytosol. Especially in individuals who lack the transporters associated with antigen processing, TAP, and in infected and tumor cells where TAP is blocked, which thus have no supply of peptides derived from the cytosol, MHC class I ligands generated in the secretory and vesicular pathways contribute to shaping the CD8⁺ T lymphocyte response.     

Leishmania donovani in hamsters: Stimulation of non-specific resistance by some novel glycopeptides and impact on therapeutic efficacy

Summary Several glycopeptides structurally related to muramyl dipeptide (MDP) have been synthesized and evaluated for their ability to stimulate the non-specific resistance of hamsters againstL. donovani infection. These compounds have been named CDRI compounds. The synthetic procedure used for compounds 86/448 and 84/212 is described.MDP and its synthetic congeners were administered as immunostimulants at a prophylactic dose of 3 mg/kg at two weeks interval. The challenge infection (1×10⁷ amastigotes i.c./hamster) was given in between two doses of the compounds. One of the glycopeptides, CDRI comp. 86/448, has been found to be significantly more potent than MDP, effecting 92% inhibition of the challenge dose, whereas MDP produced only 26.5% inhibition. The effect of comp. 86/448 lasted until day 7 of challenge. The efficacy of sodium stibogluconate was appreciably improved in hamsters treated with comp. 86/448.     

Host recognition by toxigenic plant pathogens

Certain fungal pathogens release host-selective (or host-specific) toxins (HST) as a host recognition factor during spore germination at the infection site on plants. Prior to penetration of the pathogen into its host, the released toxin specifically binds to a putative receptor on the host cells and initiates signaling mechanisms leading to pleiotropic effects on cells. Of these, the crucial one negates the general and inducible defense reactions of the cells. This is accomplished by a signal from the HST, which is transduced through a path way at or near the step of plasma membrane modulation, which is directly or indirectly triggered by the HST. This mechanism operates even though the toxin may affect mitochondria or chloroplasts as the primary target organelle. The fungal spore is able to penetrate the so-called 'narcotized cell' and completes the initial colonization of the host. The host recognition process may take place without necessitating host cell death, even in the case of perthophytic parasites. At the molecular level, HST-mediated recognition of the host by a pathogen requires strict stereochemical precision like a lock and key.     

Nanobody-induced perturbation of LFA-1/L-plastin phosphorylation impairs MTOC docking, immune synapse formation and T cell activation

The T cell integrin receptor LFA-1 orchestrates adhesion between T cells and antigen-presenting cells (APCs), resulting in formation of a contact zone known as the immune synapse (IS) which is supported by the cytoskeleton. L-plastin is a leukocyte-specific actin bundling protein that rapidly redistributes to the immune synapse following T cell–APC engagement. We used single domain antibodies (nanobodies, derived from camelid heavy-chain only antibodies) directed against functional and structural modules of L-plastin to investigate its contribution to formation of an immune synapse between Raji cells and human peripheral blood mononuclear cells or Jurkat T cells. Nanobodies that interact either with the EF hands or the actin binding domains of L-plastin both trapped L-plastin in an inactive conformation, causing perturbation of IS formation, MTOC docking towards the plasma membrane, T cell proliferation and IL-2 secretion. Both nanobodies delayed Ser⁵ phosphorylation of L-plastin which is required for enhanced bundling activity. Moreover, one nanobody delayed LFA-1 phosphorylation, reduced the association between LFA-1 and L-plastin and prevented LFA-1 enrichment at the IS. Our findings reveal subtle mechanistic details that are difficult to attain by conventional means and show that L-plastin contributes to immune synapse formation at distinct echelons.     

High frequency of human cytomegalovirus (HCMV)-specific CD8+-T cells detected in a healthy CMV-seropositive donor

Human cytomegalovirus (HCMV) persists after infection but is controlled by cellular immune responses, particularly by CD8⁺ T cells. If infected individuals are immunosuppressed, HCMV can be reactivated. Upon testing the blood of healthy donors with human lymphocyte antigen tetramers, we found one individual with about 50 % of his CD8⁺ T cells being specific for the immunodominant pp65 epitope NLVPMVATV. Over a period of 2 years the high level of HCMV-specific T cells was maintained, and no HCMV DNA could be detected. At one timepoint, however, HCMV-specific DNA was detected, while 65 % of CD8⁺ T cells were specific for HCMV. When virus was detectable, a lower percentage of HCMV-specific CD8⁺ T cells showed interferon γ (IFN-γ) production after peptide stimulation in vitro. These data suggest that HCMV reactivation may also occur in immunocompetent persons, accompanied by the presence of HCMV-specific CD8⁺ T cells which are not producing IFNγ, and therefore potentially anergic or in vivo exhausted. Received 6 March 2002; received after revision 15 April 2002; accepted 17 April 2002     

2-Carboxyethylgermanium sesquioxide,a synthetic organogermanium compound,as an inducer of contrasuppressor T cells

2-Carboxyethylgermanium sesquioxide (Ge-132), a synthesized organogermanium compound with immunomodulaing activities, was shown to be an inducer of anti-suppressor T cells in normal mice. The suppressor cell activity of T6S cells, a clone of burn-induced CD8⁺ IL-4-producing suppressor T cells, was clearly inhibited when a mixed lymphocyte-tumor cell reaction of the clone was conducted with splenic mononuclear cells from mice treated orally with a 100 mg/kg dose of Ge-132. The activity of anti-suppressor cells was demonstrated in spleens of mice 2 days after treatment with Ge-132 and reached its peak on day 3. The anti-suppressor cells induced by the compound were of a contrasuppressor T cell-linage, because they were characterized as CD4⁺ CD28⁺ TCR/⁺ Vicia villosa lectin-adherent T cells. These cells produced IFN- but did not produce IL-2, IL-4, IL-6 or IL-10 in their culture fluids. CD4⁺ anti-suppressor T cells induced by Ge-132 may be different from other subsets of CD4⁺ T cells because Th1 and Th2 cells generated in our laboratory did not adhere toVicia villosa lectin-coated petri dishes, and each produced specific cytokines. Th1 cells produced IFN- and IL-2 while Th2 cells produce IL-4 and IL-10 in vitro. These results suggest that Ge-132 may be useful as an inducer of contrasuppressor T cells in immunocompromised individuals bearing suppressor T cells. To eliminate suppressor T cells from immunocompromised hosts may result in improved resistance from various opportunistic infections.     

The cephalopod heart: The evolution of a high-performance invertebrate pump

Cephalopods typically have high metabolic rates. They have blood in which the oxygen carrier is haemocyanin, a pigment that is found only in solution and which never seems to be present in concentrations that will transport more than 4–5 vols % of oxygen. Their hearts must in consequence have very high cardiac outputs. In this account the performance of the heart ofNautilus, the only surviving ectocochleate, is contrasted with the performance of the hearts of coleoids,Octopus which has a relatively low metabolic rate (for a coleoid) and squids which have very high oxygen uptakes by any standards. In all these animals, heartbeat frequency is temperature-dependent and the additional oxygen demand in exercise is met very largely by a 2–3-fold increase in stroke volume. With the exception ofNautilus, cephalopods tend to utilise nearly all of the oxygen transported in the blood even at rest; they show very limited factorial scopes. Specific power output has, however, increased dramatically from 2.7 mWg^–1 in an activeNautilus to 5.5 mWg^–1 inOctopus and up to 20 or 30 mWg^–1 in species ofLoligo. The increase is almost entirely due to a 10-fold increase in heartbeat frequency. It is argued that frequency cannot be used as a means of responding to extra demand in an animal that must also carry automatic compensation for changes in metabolic rate dependent upon the ambient temperature, and that the use of frequency in some squid may be associated with a reduced temperature tolerance. Cephalopod systemic hearts do not scale directly with body mass, like the hearts of fish and the higher vertebrates. Smaller cephalopods have relatively larger hearts (as Mass^0.9). A typical 100-g coleoid would have a heart mass of 0.15 g. Oegopsid squids appear to be exceptional with hearts twice as large.     

Anti-Candida activity of 1–18 fragment of the frog skin peptide esculentin-1b: in vitro and in vivo studies in a Caenorhabditis elegans infection model

Candida albicans represents one of the most prevalent species causing life-threatening fungal infections. Current treatments to defeat Candida albicans have become quite difficult, due to their toxic side effects and the emergence of resistant strains. Antimicrobial peptides (AMPs) are fascinating molecules with a potential role as novel anti-infective agents. However, only a few studies have been performed on their efficacy towards the most virulent hyphal phenotype of this pathogen. The purpose of this work is to evaluate the anti-Candida activity of the N-terminal 1–18 fragment of the frog skin AMP esculentin-1b, Esc(1–18), under both in vitro and in vivo conditions using Caenorhabditis elegans as a simple host model for microbial infections. Our results demonstrate that Esc(1–18) caused a rapid reduction in the number of viable yeast cells and killing of the hyphal population. Esc(1–18) revealed a membrane perturbing effect which is likely the basis of its mode of action. To the best of our knowledge, this is the first report showing the ability of a frog skin AMP-derived peptide (1) to kill both growing stages of Candida; (2) to promote survival of Candida-infected living organisms and (3) to inhibit transition of these fungal cells from the roundish yeast shape to the more dangerous hyphal form at sub-inhibitory concentrations.     

Toxic substances produced byFusarium VI. Anti-F. oxysporum f. sp.carthami effect of 2,2′,4-trihydroxybenzophenone

Summary Anti-Fusarium oxysporum f. sp.carthami activity of 2,2,4-tri-hydroxybenzophenone was evaluated. Pretreatment with the benzophenone offered complete protection to safflower seeds and seedlings, and recovery of the latter from the fungal infection.     

Attività enolasica del plasma e del fegato nell'epatite sperimentale de virus MHV-3 Craig

Summary In experimental hepatitis from MHV-3 Craig strain, the enolase activity of plasma increases significatively from 48^th h of the infection, reaching the highest values at 72–96^th h.The same activity in the liver decreases only after 72^th h, while in the precocious stages of the infection it is unmodified.The physiopathological significance of the enzymatic modification in the plasma is related to the liver necrosis (enzymo-plasmatic syndrome of virus hepatitis).     

Mesenchymal stem cells or cardiac progenitors for cardiac repair? A comparative study

In the past, clinical trials transplanting bone marrow–derived mononuclear cells reported a limited improvement in cardiac function. Therefore, the search for stem cells leading to more successful stem cell therapies continues. Good candidates are the so-called cardiac stem cells (CSCs). To date, there is no clear evidence to show if these cells are intrinsic stem cells from the heart or mobilized cells from bone marrow. In this study we performed a comparative study between human mesenchymal stem cells (hMSCs), purified c-kit⁺ CSCs, and cardiosphere-derived cells (CDCs). Our results showed that hMSCs can be discriminated from CSCs by their differentiation capacity towards adipocytes and osteocytes and the expression of CD140b. On the other hand, cardiac progenitors display a greater cardiomyogenic differentiation capacity. Despite a different isolation protocol, no distinction could be made between c-kit⁺ CSCs and CDCs, indicating that they probably derive from the same precursor or even are the same cells.     

Protective effect of Shigyaku-to,a traditional Chinese herbal medicine,on the infection of herpes simplex virus type 1 (HSV-1) in mice

The antiviral activity of Shigyaku-to (TJS-109), a traditional Chinese herbal medicine, was investigated in mice infected with herpes simplex virus type 1 (HSV-1). TJS-109 is a combination of the medicinal plant extracts fromZingiberis siccatum rhizoma,Aconiti tuber andGlycyrrhizae radix in a specific proportion. Mice infected with a 10 LD₅₀ dose of HSV-1 were treated with TJS-109 orally at doses of 1.25 to 20 mg/kg 2 days before, and 1 and 4 days after the infection. The treated groups had 80% (1.25 mg/kg), 40% (5 mg/kg) and 23% (20 mg/kg) mortality rates 25 days after the infection as compared with a 100% mortality rate in control mice treated with saline. When HSV-1 infected mice (recipients) received CD8⁺T cell fractions derived from spleens of mice treated with TJS-109 (donors), 70% of recipients survived, as compared with 0% survivors in the groups of mice treated with saline, B cell fractions, CD4⁺ T cell fractions or macrophage-enriched fractions prepared from the same donors. TJS-109 did not show any virucidal activities against HSV-1 or any virostatic activities on the growth of HSV-1 in Vero cells. These results suggest that TJS-109 protected mice exposed to lethal amounts of HSV-1 through the activation of CD8⁺ T cells.     

Organization and expression of the poxvirus genome

Summary Poxviruses comprise a large group of very complex animal DNA viruses which replicate in the cytoplasm of infected cells. Vaccinia virus, the most studied poxvirus, has a linear, double stranded DNA genome with an approximate molecular weight of 120×10⁶ (180 kilobase pairs). The two strands of the DNA molecule are naturally cross-linked at both termini. In addition, the vaccinia virus genome contains very long inverted terminal repetitions of approximately 10 kilobase pairs which are further characterized by the presence of direct tandem repeats of a 70-base-pair sequence arranged in two blocks of 13 and 17 copies, respectively. A central region of the genome is highly conserved between different orthopoxviruses. In contrast, the ends are hypervariable and may contain extensive deletions and complex, symmetrical sequences rearrangements. Vaccinia virus gene expression is divided into two stages. Early in infection, RNA complementary to one half of one strand-equivalent of the genome is transcribed within subviral particles by the virion-associated RNA polymerase. Later in infection, after DNA replication, RNA complementary to one entire strand-equivalent is transcribed. RNA made late in infection is very heterogeneous in length and a large fraction of it contains self-complementary sequences. Late genes are clustered near the central region of the genome. Vaccinia virus mRNAs do not appear to be synthesized by a splicing mechanism.