Challenging immunodominance of influenza-specific CD8+ T cell responses restricted by the risk-associated HLA-A*68:01 allomorph

Although influenza viruses lead to severe illness in high-risk populations, host genetic factors associated with severe disease are largely unknown. As the HLA-A*68:01 allele can be linked to severe pandemic 2009-H1N1 disease, we investigate a potential impairment of HLA-A*68:01-restricted CD8⁺ T cells to mount robust responses. We elucidate the HLA-A*68:01⁺CD8⁺ T cell response directed toward an extended influenza-derived nucleoprotein (NP) peptide and show that only ~35% individuals have immunodominant A68/NP₁₄₅⁺CD8⁺ T cell responses. Dissecting A68/NP₁₄₅⁺CD8⁺ T cells in low vs. medium/high responders reveals that high responding donors have A68/NP₁₄₅⁺CD8⁺ memory T cells with clonally expanded TCRαβs, while low-responders display A68/NP₁₄₅⁺CD8⁺ T cells with predominantly naïve phenotypes and non-expanded TCRαβs. Single-cell index sorting and TCRαβ analyses link expansion of A68/NP₁₄₅⁺CD8⁺ T cells to their memory potential. Our study demonstrates the immunodominance potential of influenza-specific CD8⁺ T cells presented by a risk HLA-A*68:01 molecule and advocates for priming CD8⁺ T cell compartments in HLA-A*68:01-expressing individuals for establishment of pre-existing protective memory T cell pools.

A divergent transcriptional landscape underpins the development and functional branching of MAIT cells

MR1-restricted mucosal-associated invariant T (MAIT) cells play a unique role in the immune system. These cells develop intrathymically through a three-stage process, but the events that regulate this are largely unknown. Here, using bulk and single-cell RNA sequencing-based transcriptomic analysis in mice and humans, we studied the changing transcriptional landscape that accompanies transition through each stage. Many transcripts were sharply modulated during MAIT cell development, including SLAM (signaling lymphocytic activation molecule) family members, chemokine receptors, and transcription factors. We also demonstrate that stage 3 "mature" MAIT cells comprise distinct subpopulations including newly arrived transitional stage 3 cells, interferon-γ-producing MAIT1 cells and interleukin-17-producing MAIT17 cells. Moreover, the validity and importance of several transcripts detected in this study are directly demonstrated using specific mutant mice. For example, MAIT cell intrathymic maturation was found to be halted in SLAM-associated protein (SAP)-deficient and CXCR6-deficient mouse models, providing clear evidence for their role in modulating MAIT cell development. These data underpin a model that maps the changing transcriptional landscape and identifies key factors that regulate the process of MAIT cell differentiation, with many parallels between mice and humans.

Live Attenuated Influenza Vaccines engineered to express the nucleoprotein of a recent isolate stimulate human influenza CD8+ T cells more relevant to current infections

Live attenuated influenza vaccines (LAIV) induce CD8⁺ T lymphocyte responses that play an important role in killing virus-infected cells. Despite the relative conservation of internal influenza A proteins, the epitopes recognized by T cells can undergo drift under immune pressure. The internal proteins of Russian LAIVs are derived from the master donor virus A/Leningrad/134/17/57 (Len/17) isolated 60 years ago and as such, some CD8⁺ T cell epitopes may vary between the vaccine and circulating wild-type strains. To partially overcome this issue, the nucleoprotein (NP) gene of wild-type virus can be incorporated into LAIV reassortant virus, along with the HA and NA genes. The present study compares the human CD8+ T cell memory responses to H3N2 LAIVs with the Len/17 or the wild-type NP using an in vitro model.

Oxidative stress indices in rats under immunosuppression

Immunosuppressants lead to generation of reactive oxygen species (ROS). Oxidative stress (OxS) can initiate chronic allograft nephropathy (CAN). The most active antioxidant enzymes, superoxide dysmutase (SOD) and catalase (CAT), are present in erythrocytes. Glutathione peroxidase (GPx) is produced in the proximal tubules of nephrons. Malonyldialdehyde (MDA) concentrations are a marker of OxS intensity in plasma. In vitro and animal model studies have shown increased or decreased OxS during treatment with tacrolimus (Tac) or cyclosporine (CyA). Results obtained in humans after solid organ transplantation have been contradictory, because of confounding factors such as ischemia-reperfusion injury, donor and recipient ages, endothelial injury, and comorbidity. The aim of this study was to assess the intensity of OxS among rats under chronic immunosuppression (IS) without a transplantation. We examined 49 male Wistar rats. IS started at 12 weeks of age was continued for 6 months: group I were controls (n=7); group II, Tac+sirolimus (Rapamycin [Rapa])+corticosteroids (CS; n=6); group III, CyA+Rapa+CS (n=4 of which 2 died); group IV, Rapa+mycophenolate mofetil (MMF)+CS (n=6); group V, CyA+MMF+CS (n=6); group VI, CsA+MMF+CS for 3 months followed by conversion to Rapa (n=6); group VII, Tac+MMF+CS (n=6 rats); and group VIII, Tac+MMF+CS for 3 months followed by conversion to Rapa (n=6). The drug doses were as follows: Tac 4 mg/kg/d; MMF 20 mg/kg/d; CyA 5mg/kg/d; Rapa 0.5 mg/kg/d; and CS 4 mg/kg/d. Multiple regression analysis revealed that all IS drugs decreased GPx activity (P<.001) except CS, which increased it (P<.0001). Multiple regression analysis showed that CsA and Tac decreased plasma MDA concentrations (P<.01), whereas CS increased them (P<.05). In conclusion, all IS drugs except CS damage proximal tubules of nephrons.

The activity of erythrocyte sodium-proton exchanger in women with pregnancy- induced hypertension

BACKGROUND

Hypertension that develops after 20 gestational weeks and is defined as pregnancy-induced hypertension (PIH). The main cause of PIH is vasoconstriction and the thickening of vascular media, which decreases vascular capacity and increases peripheral resistance. One of the theories postulated to explain this phenomenon is that a transmembrane sodium transport disorder causes an increase in intracellular sodium concentration. In the latest literature, special attention is paid to the role of the increased intracellular sodium concentration in the pathogenesis of essential hypertension (EH). One of the best documented phenotypes for EH is the increased activity of the sodium-proton exchanger (NHE). The aim of this study was to assess if increased NHE activity could be the mechanism responsible for the development of PIH.

SUBJECTS AND METHODS

The study included 30 women: 10 pregnant women with PIH after gestational week 30, 10 women with physiological pregnancy after 30 gestational weeks, and 10 healthy non-pregnant women. NHE activity was determined according to Orlov's method as amiloride-sensitive H(+) efflux from acid-loaded cells.

RESULTS

The NHE activity in the group of women with PIH was significantly higher than that in women with physiological pregnancy: 10.09 +/- 1.65 vs. 6.81 +/- 2.3 mmol/L RBC/h (p < 0.049) and in the group of non-pregnant women: 10.09 +/- 1.65 vs. 7.56 +/- 1.66 mmol/L RBC/h (p < 0.029). Erythrocyte NHE activity did not differ in the group of women with physiological pregnancy and in the group of non-pregnant women.

CONCLUSION

These results seem to suggest that erythrocyte NHE activity is elevated in PIH pregnancies.

Activity of CuZn-superoxide dismutase, catalase and glutathione peroxidase in erythrocytes in kidney allografts during reperfusion in patients with and without delayed graft function

BACKGROUND

Generation of reactive oxygen species (ROS) is the main mechanism involved in the ischemic/reperfusion damage of the transplanted organ. Oxygen burst is a trigger for complex biochemical events leading to generation of oxygenated lipids and changes in microcirculation. Many markers have been researched to prove the presence of ROS in the transplanted tissue. Some of them, like superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) are considered to play a major role in graft protection against oxygen stress during reperfusion.

METHODS

The aim of this study was to examine the changes of SOD1, CAT and GPx activity in erythrocytes during the first minutes after total graft reperfusion. Forty patients undergoing kidney transplantation at our center were assigned to two groups: with or without delayed graft function (DGF). Before anastomosing kidney vessels with recipient's iliac vessels, the '0' blood sample was taken from the iliac vein. Next blood samples I, II and III were taken from the graft's renal vein. The reperfusion of the transplanted kidney was evaluated precisely with the thermovision camera. Erythrocyte SOD1, CAT and GPx activity was measured with a spectrophotometric method.

RESULTS

We did not observe statistically significant changes in SOD1, CAT and GPx activity in erythrocytes during the early phase of reperfusion in patients with and without DGF.

CONCLUSIONS

Erythrocyte-antioxidative system in graft's vein remain stable during the early phase of reperfusion. The results of the study suggest that further studies on extracellular enzymes are required for the assessment of antioxidant system in the conditions of ischemia/reperfusion.

The Influence of Angiotensin-Converting Enzyme Gene of Donor and Recipient on the Function of Transplanted Kidney

One of the genes that is supposed to influence renal graft function is the one encoding angiotensin I-converting enzyme (ACE). It shows polymorphism in the presence (I allele) or absence (D allele) of a 287-base pair fragment. The question arises whether ACE gene polymorphism of the recipient and donor influences renal graft survival. This prospective study included 94 recipients who underwent ACE genotyping (DD, DI, II) and measured their creatinine clearance after cimetidine administration. These factors were correlated with the occurrence of acute or chronic rejection and of pharmacologic treatment of hypertension. In 27 recipients it was possible to obtain the ACE genotype of the donor. Among the recipients, 36 proved to be DD genotype, 38 ID, and 20 II. Among the donors, 10 proved to be DD genotype, 10 ID, and 7 II. The changes in creatinine clearance after cimetidine administration were not significantly different among any of the genotype subgroups. Significantly higher creatinine concentrations were found among recipients with II genotype compared to the combined group of ID and DD among patients not treated with ACE inhibitors, but not among those receiving ACE I after kidney transplantation. No differences were found in the frequency of rejection episodes among the subgroups with different ACE genotypes. No significant influence of donor ACE genotype on renal graft function was observed. In summary, the I/D genotype was not an independent prognostic factor for renal graft survival in the first 4 years after transplantation. Possibly the use of ACE I alters the influence of genotype on some parameters.

The influence of oxidative stress on permeability of capillary vessels in the cheek pouch of hamsters with alloxan-induced diabetes

Background: The aim of the study was to assess the influence of oxidative stress on the increase of permeability of capillary vessels in animals with alloxan-induced diabetes. Material and methods: The studies were performed in microcirculation system of hamster cheek pouch. After the blockade of histamine receptors and administration of diamine oxidase (DAO) and histamine into circulation fluorescein angiography was done. In addition, the influence of superoxide dismutase, aminoguanidine (DAO inhibitor) and trascolan (protease inhibitor) on vascular permeability caused by superoxide radical generation in DAO/histamine system was assessed. Results: The number of extravasal leakages in the group receiving HA and DAO was significantly higher (p < 0.001) than in the groups receiving potential vascular "sealers", e.g. SOD, aminoguanidine or trascolan. In the group receiving aminoguanidine the number of leakages was significantly lower (p < 0.05) compared to the group receiving SOD or trascolan. Conclusions: The protective effect of aminoguanidine, superoxide dismutase or trascolan decreasing the vascular permeability, suggests that the increased vascular permeability is a result of superoxide radical generation by diamine oxidase.

Chronic hypokalaemia--how to establish a diagnosis?

We present three cases of patients with symptomatic, chronic, diagnosis-resistant hypokalaemia. Differential diagnosis of renal potassium loss between Gitelman's syndrome, Bartter's syndrome and loop diuretic abuse was made. Key elements in differential diagnosis of chronic hypokalaemia are blood pressure assessment, acid base equilibrium, serum calcium concentration, 24-hour urine potassium and calcium excretion.

Quantifying complement-mediated phagocytosis by human monocyte-derived macrophages

The present study demonstrates that SRBC can be opsonized with untreated human serum such that lysis by active complement components is minimal but sufficient opsonization occurs to permit high rates of complement-mediated phagocytosis. Phagocytosis of SRBC opsonized with 2% whole human serum by human monocyte-derived macrophages was quantified in a colourimetric assay. Ingestion of SRBC was shown to occur solely via complement receptors because no phagocytosis was observed when SRBC were coated with heat- inactivated human serum, phagocytosis was augmented by the phorbol ester, PMA, and phagocytosis was inhibited by a protein kinase C (PKC)-specific inhibitor RO 31-8220. This method was used to demonstrate directly that HIV-1 infection of human monocyte-derived macrophages inhibits complement-mediated phagocytosis and will provide a useful tool for pharmacological investigations on complement-mediated phagocytosis by adherent macrophages.

FcgammaR-mediated phagocytosis by human macrophages involves Hck, Syk, and Pyk2 and is augmented by GM-CSF

The receptors for the constant region of immunoglobulin G (FcgammaR) are widely expressed on cells of hemopoietic lineage and plays an important role in host defense. We investigated the signaling pathways during FcgammaR-mediated phagocytosis in human monocyte-derived macrophages (MDMs) and examined the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on these events. FcgammaR-mediated phagocytosis resulted in enhanced tyrosine phosphorylation of a wide range of cellular proteins and activation of tyrosine kinases Hck, Syk, and Pyk2, as well as the multidomain adapter protein paxillin. Stimulation of MDMs with GM-CSF augmented FcgammaR-mediated phagocytosis and increased the levels of tyrosine phosphorylation in phagocytosing MDM cultures, indicating tyrosine kinase-mediated activation. GM-CSF treatment of MDMs without a phagocytic stimulus did not activate Syk, suggesting that GM-CSF may act either distally to Syk in the FcgammaR-mediated signaling cascade or on a parallel pathway activated by the FcgammaR. This study shows that early signaling events during FcgammaR-mediated phagocytosis in human MDMs involve activation of Syk, Hck, and paxillin. It also provides the first evidence for Pyk2 activation during phagocytosis and a baseline for further studies on the effect of GM-CSF on FcgammaR-mediated phagocytosis.

[Pseudo-Gitelman's syndrome as consequence of loop diuretics abuse]

We describe a case of 40-year old patient with chronic, resistant to treatment hypokalaemia. Differential diagnosis of renal potassium loss among Gitelman's syndrome, Bartter's syndrome and loop diuretic abuse was made.

nef-deleted HIV-1 inhibits phagocytosis by monocyte-derived macrophages in vitro but not by peripheral blood monocytes in vivo

OBJECTIVE

HIV-1 infection impairs a number of macrophage effector functions, but the mechanism is unknown. We studied the role of HIV-1 Nef in modulating phagocytosis by human monocytes and monocyte-derived macrophages (MDM).

DESIGN AND METHODS

Using a flow cytometric assay, phagocytosis of Mycobacterium avium complex (MAC) by monocytes in whole blood of Sydney Blood Bank Cohort (SBBC) members infected with a nef-deleted (Delta nef) strain of HIV-1 was compared with that of monocytes from uninfected or wild-type (WT) HIV-infected subjects. The specific impact of Nef on phagocytosis by MDM was determined by either infecting cells in vitro with Delta nef strains of HIV-1 or electroporating Nef into uninfected MDM.

RESULTS

MAC phagocytic capacity of monocytes from SBBC members was equivalent to that of cells from uninfected individuals (P = 0.81); it was greater than that of cells from individuals infected with WT HIV-1 (P < 0.0001), irrespective of CD4 counts and HIV viral load. In contrast, in vitro infection of MDM with either Delta nef or WT strains of HIV-1 resulted in similar levels of HIV replication and equivalent impairment of phagocytosis via Fc gamma and complement receptors. Electroporation of Nef into MDM did not alter phagocytic capacity.

CONCLUSIONS

This study provides evidence demonstrating the complex indirect effect of Nef on phagocytosis by peripheral blood monocytes (infrequently infected with HIV-1) in vivo. Conversely, the fact that MDM infected with either Delta nef or WT HIV-1 in vitro (high multiplicity of infection) show comparably impaired phagocytosis, indicates that HIV-1 infection of macrophages can directly impair function, independent of Nef.

Cytokines and HIV-1: interactions and clinical implications

Cytokines play an important role in controlling the homoeostasis of the immune system. Infection with HIV results in dysregulation of the cytokine profile in vivo and in vitro. During the course of HIV-1 infection secretion of T-helper type 1 (Th1) cytokines, such as interleukin (IL)-2, and antiviral interferon (IFN)-gamma, is generally decreased, whereas production of T helper type 2 (Th2) cytokines, IL-4, IL-10, proinflammatory cytokines (IL-1, IL-6, IL-8) and tumour necrosis factor (TNF)-alpha, is increased. Such abnormal cytokine production contributes to the pathogenesis of the disease by impairing cell-mediated immunity. A number of cytokines have been shown to modulate in vitro HIV-1 infection and replication in both CD4 T lymphocytes and cells of macrophage lineage. HIV-inductive cytokines include: TNF-alpha, TNF-beta, IL-1 and IL-6, which stimulate HIV-1 replication in T cells and monocyte-derived macrophages (MDM), IL-2, IL-7 and IL-15, which upregulate HIV-1 in T cells, and macrophage-colony stimulating factor, which stimulates HIV-1 in MDM. HIV-suppressive cytokines include: IFN-alpha, IFN-beta and IL-16, which inhibit HIV-1 replication in T cells and MDM, and IL-10 and IL-13, which inhibit HIV-1 in MDM. Bifunctional cytokines such as IFN-gamma, IL-4 and granulocyte-macrophage colony-stimulating factor have been shown to have both inhibitory and stimulatory effects on HIV-1. The beta-chemokines, macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta and RANTES are important inhibitors of macrophage-tropic strains of HIV-1, whereas the alpha-chemokine stromal-derived factor-1 suppresses infection of T-tropic strains of HIV-1. This review outlines the interactions between cytokines and HIV-1, and presents clinical applications of cytokine therapy combined with highly active antiretroviral therapy or vaccines.

Granulocyte-macrophage colony-stimulating factor inhibits HIV-1 replication in monocyte-derived macrophages

BACKGROUND

Previous studies of the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on HIV-1 replication in macrophages have had inconsistent results, variously reporting no effect, augmentation or inhibition of viral replication.

OBJECTIVE

To investigate the regulation of HIV-1 in monocyte-derived macrophages (MDM) by GM-CSF in vitro.

METHODS

The role of GM-CSF on HIV-1 replication was assessed as supernatant and intracellular p24 antigen concentrations and by HIV-1 DNA and mRNA production under different culture conditions. Expression of CD4 and CCR5 receptors was examined. The effect of GM-CSF with an E21R mutation, which binds only to the alpha-chain of GM-CSF receptor, was used as an additional control.

RESULTS

GM-CSF consistently suppressed HIV-1 replication in human MDM in vitro, as assessed by supernatant and intracellular p24 antigen concentrations and HIV-1 gag mRNA expression. The inhibitory effect of GM-CSF on HIV-1 replication was observed regardless of HIV-1 strain, source of GM-CSF, stage of MDM maturation or timing of GM-CSF exposure in relation to HIV-1 infection. The effect was dose dependent and reversed by addition of a neutralizing monoclonal antibody (4D4). Flow cytometric analysis of surface expression of CD4 and CCR5 indicates that GM-CSF does not affect HIV-1 entry into MDM. Analysis of intracellular HIV-1 DNA and mRNA suggests that HIV-1 replication is inhibited at or before transcription. E21R GM-CSF had no effect on HIV-1 replication in MDM.

CONCLUSIONS

GM-CSF regulates HIV-1 replication in MDM, inhibiting HIV-1 replication through binding to the beta-chain of the GM-CSF receptor.

Granulocyte-macrophage colony-stimulating factor augments phagocytosis of Mycobacterium avium complex by human immunodeficiency virus type 1-infected monocytes/macrophages in vitro and in vivo

The role of human immunodeficiency virus type 1 (HIV-1) infection on the ability of human monocytes/macrophages to phagocytose Mycobacterium avium complex (MAC) in vivo and in vitro and the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on this function were investigated. By use of a flow cytometric assay to quantify phagocytosis, HIV-1 infection was found to impair the ability of monocyte-derived macrophages to phagocytose MAC in vitro, whereas GM-CSF significantly improved this defect. Phagocytosis was not altered by exposure to a mutant form of GM-CSF (E21R) binding only to the alpha chain of the GM-CSF receptor, suggesting that signaling by GM-CSF that leads to augmentation of phagocytosis is via the beta chain of the receptor. In a patient with AIDS and disseminated multidrug-resistant MAC infection, GM-CSF treatment improved phagocytosis of MAC by peripheral blood monocytes and reduced bacteremia. These results imply that GM-CSF therapy may be useful in restoring antimycobacterial function by human monocytes/macrophages.

CYP2D6 and GSTM1 genotypes in a Polish population

OBJECTIVE

The aim of the present study was to investigate the distribution of the CYP2D6 and GSTM1 genotypes in a Polish population.

METHODS

One hundred and forty-five unrelated healthy individuals from the western region of Poland were studied. The CYP2D6 genotype was analysed by means of polymerase chain reaction (PCR) amplification for the CYP2D6*3 and CYP2D6*4 alleles. The GSTM1 genotype was also analysed by means of a PCR assay to determine two genotypes: GSTM1-1 (positive) and GSTM1-0 (negative).

RESULTS

Fourteen subjects (9.6%) were classified as poor metabolisers. The frequency of CYP2D6*4 and CYP2D6*3 was 23.1% and 2.1%, respectively. The frequency of GSTM1 nulled genotype in a Polish population came to 49%.

CONCLUSION

The frequencies of poor metabolisers for CYP2D6 and GSTM1 nulled genotype among a Polish population were similar to those observed in other Caucasian populations.

Effect of GM-CSF on HIV-1 replication in monocytes/macrophages in vivo and in vitro: a review

Cells of macrophage lineage constitute the main cellular target of Human Immunodeficiency Virus type 1 (HIV-1). Replication of HIV-1 in monocyte/macrophages is generally augmented by factors promoting their differentiation. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a key regular of the differentiation of cells of macrophage lineage. The effects of GM-CSF on HIV-1 replication in vitro are still controversial. Most of the published studies suggest that GM-CSF upregulates HIV-1 expression in both primary cultured macrophages and promonocytic cell lines. There have also been reports demonstrating that GM-CSF does not affect HIV-1 replication in cells of macrophage lineage or that GM-CSF can actually suppress HIV-1 expression. In vivo, GM-CSF administrated to HIV-positive patients at any stage of disease, without any antiretroviral therapy, appears to increase HIV-1 activity. The possible mechanism by which GM-CSF might affect HIV-1 replication in macrophages remains unclear.