Effects of quercetin and extracts from Phyllanthus emblica, Morus alba, and Ginkgo biloba on platelet recovery in a rat model of chemotherapy-induced thrombocytopenia

Background

Chemotherapy-induced thrombocytopenia (CIT) is a major reason for chemotherapy delays, dose reduction, or even treatment discontinuation, which may impact oncologic outcomes. We investigated the effects of quercetin and extracts of Phyllanthus emblica fruit (PEE), Morus alba leaf (MAE), and Ginkgo biloba leaf (GBE) on platelet recovery in a rat model of chemotherapy-induced thrombocytopenia.

Methods

The total phenolic content (TPC), total flavonoid content (TFC), quercetin content, and antioxidant activities of all the extracts were determined. Sixty male Sprague Dawley rats were categorized into healthy controls and CIT groups. The CIT groups was administered a cyclophosphamide solution, while the control group received a saline solution. Each group was then subdivided into five subgroups of six animals which were administered with PEE, MAE, GBE, quercetin, or a vehicle for 15 days.

Results

The highest quercetin content was found in PEE, followed by MAE and GBE, which correlated with their antioxidant properties. Administration of these extracts and quercetin did not significantly change the platelet counts in healthy rats. Thrombocytopenic rats treated with PEE, MAE, and GBE also were not associated with significant changes in platelet counts. However, more rapid platelet count recovery was observed in all groups receiving extracts. On day 11, platelet counts in the PEE, MAE, and GBE groups returned to near baseline levels with a mean of 4.29 %, -40.77 %, and -14.24 %, respectively, compared to -71 % in the CIT group. In thrombocytopenic rats treated with quercetin, there was a significant increase in platelet counts on days 9 and 11, with a mean decrease of 5.41 % from baseline on day 11.

Conclusion

Quercetin improved platelet recovery in the animal model of CIT. This finding merits for further investigation to better elucidate the health benefits of quercetin and quercetin-rich plants and potential pharmacokinetics underpinning their activity in thrombocytopenia.

In-vitro antimalarial activity of methanolic leaf- and stem-derived extracts from four Annonaceae plants

OBJECTIVE

Plants in the Annonaceae family are known for having abundant biologically active secondary metabolites. They have been used in alternative drugs for various diseases in several countries, for instance, the bark of Cananga odorata (Lam.) Hook and Thomson is used for Ophthalmic inflammation and wound healing in Malaysia. Extracts from the leaves and stems of four Annonaceae plants, namely Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Dasymaschalon sp., Artabotrys burmanicus A.DC, and Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders were investigated for growth inhibitory activity against blood-stage Plasmodium falciparum growth in vitro and for non-specific cytotoxicity against normal peripheral blood mononuclear cells (PBMCs). Antimalarial activity was assessed by invasion inhibition assay and the percentage of infected red blood cells on blood smears were determined. Cytotoxicity was tested by culturing PBMCs with the extracts, and viabilities were determined by Annexin V/propidium iodide staining.

RESULTS

A. burmanicus stem extract and M. modestum leaf extract were capable of inhibiting growth of P. falciparum when used at 200 µg/mL compared to chloroquine. The extracts at effective concentrations, did not affect the viability of PBMCs. These results support further need for characterization of active compounds from specific Annonaceae plants in order to exploit their components for potential malaria treatment.

Safety and immunogenicity of the third and fourth doses of vaccine against SARS-CoV-2 following a 2-dose regimen of inactivated whole-virion SARS-CoV-2 vaccine

This study followed healthcare personnel (HCP) who had completed a primary series of CoronaVac and then received the third and fourth doses of COVID-19 vaccine. The primary objective was to determine the seroconversion rate of neutralizing antibodies against wild-type SARS-CoV-2 and VOCs at day 28 after the third dose of vaccine and day 28 after the fourth dose of vaccine. This prospective cohort study was conducted at Maharaj Nakorn Chiang Mai Hospital, a tertiary care hospital affiliated to Chiang Mai University from July 2021 to February 2022. Two hundred and eighty-three participants were assessed for eligibility; 142 had received AZD1222 and 141 BNT162b2 as the third dose. Seroconversion rates using a 30% inhibition cutoff value against wild-type SARS-CoV-2 were 57.2%, 98.6%, 97.8%, and 98.9% at points before and after the third dose, before and after the fourth dose, respectively among those receiving AZD1222 as the third dose. Frequencies were 31.9%, 99.3%, 98.9%, and 100% among those receiving BNT162b2 as the third dose, respectively. The seroconversion rates against B.1.1.529 [Omicron] were 76.1% and 90.2% (p-value 0.010) at 4 weeks after the third dose in those receiving AZD1222 and BNT162b2 as the third dose, respectively. After a booster with the mRNA vaccine, the seroconversion rates increased from 21.7 to 91.3% and from 30.4 to 91.3% in those receiving AZD1222 and BNT162b2 as the third dose, respectively. No serious safety concerns were found in this study. In conclusion, antibody responses waned over time regardless of the vaccine regimen. The booster dose of the vaccine elicited a humoral immune response against SARS-CoV-2 including SARS-CoV-2 variants of concern, including B.1.1.529 [Omicron], which was circulating during the study period. However, the results might not be extrapolated to other Omicron sublineages.

Comparison of antibody responses following natural infection with Severe Acute Respiratory Syndrome Coronavirus 2 or receipt of CoronaVac or ChAdOx1 (AZD1222) vaccination in Chiang Mai, Thailand

Background

In Thailand, early vaccination initiatives for SARS-CoV-2 relied on CoronaVac (Sinovac Life Sciences) and ChAdOx1 (Oxford-AstraZeneca) vaccines. However, the data of immunogenicity of these two vaccines in Thai populations is limited. This real time, head-to-head comparative study was conducted to investigate antibody (Ab) responses to SARS-CoV-2 following infection or receipt of either CoronaVac or ChAdOx1 vaccination in Chiang Mai, Thailand.

Methods

Sera was collected within two months from participants having a history of documented SARS-CoV-2 infection or at one month after the second dose of CoronaVac vaccine. Sera from participants with a history of receiving one dose of ChAdOx1 vaccination was collected twice, at one month following each vaccine dose. Neutralizing antibodies (NAbs) were assessed using the surrogate neutralization test and anti-spike protein antibodies were assessed using an in-house enzyme-linked immunosorbent assay.

Results

The prevalence of NAbs against SARS-CoV-2 was 92.1 %, 95.7 %, 64.1 % and 100 % in the infection group, CoronaVac group, ChAdOx1 group after 1st dose, and ChAdOx1 group after 2nd dose, respectively. The inhibition rate in individuals receiving two doses of ChAdOx1 vaccine (90.8%) was significantly higher than individuals who had recovered from natural infection (71.7%) or individuals who had received two doses of CoronaVac vaccine (66.7%). The prevalence of anti-spike Abs was 97.4 %, 97.8 %, 97.4 % and 100 % in the infection group, CoronaVac group, ChAdOx1 group after 1st dose, and ChAdOx1 group after 2nd dose, respectively. Significantly higher levels of anti-spike Abs were observed in the ChAdOx1 group after two doses of vaccination (1975 AU/mL) compared to those who had recovered from natural infection (468.5 AU/mL) and individuals who had received CoronaVac (554.4 AU/mL). Neutralizing activity had a statistically significant positive correlation with levels of anti-spike Abs.

Conclusions

ChAdOx1 vaccine may provide superior immunogenicity than CoronaVac and natural infection.

A preliminary study on the effectiveness of maternal to neonatal transfer of antibodies against SARS-CoV-2 in the women vaccinated with heterologous CoronaVac-ChAdOx1

The objective is to evaluate the effectiveness of placental transfer of maternally derived SARS-CoV-2 IgG antibodies after the vaccination of pregnant women with heterologous CoronaVac-ChAdOx1. Thirty pregnant women were vaccinated with CoronaVac as the first dose, followed by ChAdOx1 3 weeks later. The antibody levels in the maternal blood and in the umbilical cord blood at the time of delivery were determined. The results showed that the vaccination effectively increased antibody levels in both mothers and newborns. The antibody levels in the mothers were strongly correlated with those in the newborns (P < .001). The high levels of passive immunity in the newborns were achieved when the first and second doses of vaccination were given more than 40 and 20 d before delivery, respectively. After 1 month of the second dose, the immune levels seemed to decline in the mothers but increase in the newborns. The antibody levels in the newborns appear to be higher than those in the mothers in cases of delivery after 20 d of the second dose (1419 ± 699 vs 1222 ± 593 BAU/L; p < .05). In conclusion, heterologous CoronaVac-ChAdOx1-S schedule can increase antibody levels in a short time during pregnancy. Also, the regimen effectively increases immunity in the newborns. The antibody levels in the newborns appear to be higher than that in the mothers in most cases, if receiving the second dose more than 3 weeks before delivery. Therefore, the regimen should be considered as an effective regimen for pregnant women, especially in settings where mRNA vaccine is not available.

Comparison of Immunogenicity and Reactogenicity of Five Primary Series of COVID-19 Vaccine Regimens against Circulating SARS-CoV-2 Variants of Concern among Healthy Thai Populations

To compare immunogenicity and reactogenicity of five COVID-19 vaccine regimens against wild-type SARS-CoV-2 and variants of concern (VoCs) among Thai populations, a prospective cohort study was conducted among healthy participants aged ≥18 years who had never been infected with COVID-19 and were scheduled to get one of the five primary series of COVID-19 vaccine regimens, including CoronaVac/CoronaVac, AZD1222/AZD1222, CoronaVac/AZD1222, AZD1222/BNT162b2, and BNT162b2/BNT162b2. Anti-receptor binding domain (anti-RBD-WT) IgG and neutralizing antibody (NAb-WT) against wild-type SARS-CoV-2 were measured at pre-prime, post-prime, and post-boost visits. NAb against VoCs (NAb-Alpha, NAb-Beta, NAb-Delta, and NAb-Omicron) were assessed at the post-boost visit. Adverse events (AEs) following vaccination were recorded. A total of 901 participants (CoronaVac/CoronaVac: 332, AZD1222/AZD1222: 221, CoronaVac/AZD1222: 110, AZD1222/BNT162b2: 128, and BNT162b2/BNT162b2: 110) were enrolled. Anti-RBD-WT IgG and NAb-WT levels increased substantially after each vaccine dose. At the post-boost visit, BNT162b2/BNT162b2 induced the highest GMC of anti-RBD-WT IgG level (1698 BAU/mL), whereas AZD1222/BNT162b2 induced the highest median NAb-WT level (99% inhibition). NAb levels against VoCs, particularly the Omicron strain, were markedly attenuated for all vaccine regimens (p < 0.001). Overall, no serious AEs following vaccination were observed. All five primary series of COVID-19 vaccine regimens were well-tolerated and elicited robust antibody responses against wild-type SARS-CoV-2 but had attenuated responses against VoCs, particularly the Omicron strain, among healthy Thai populations.

Placental Transfer Immunity to the Newborns in a Twin Pregnant Women Vaccinated with Heterologous CoronaVac-ChAdOx1

Pregnant women who receive the COVID-19 vaccine develop anti-SARS-CoV-2 antibodies, which can be transferred to the fetus. However, the effectiveness of placental transfer has not been evaluated in twin pregnancy, especially in cases vaccinated with heterologous CoronaVac (Sinovac)-ChAdOx1 (Oxford-AstraZeneca) regimen, which was commonly used in many countries. Case: A 34-year-old Thai woman with a twin pregnancy attended our antenatal care clinic at 21 + 2 weeks of gestation and requested COVID-19 vaccination. Her medical history and physical examination were unremarkable. She had not received COVID-19 vaccination before. Ultrasound screening for fetal anomaly revealed a dichorion diamnion twin pregnancy. Both twins showed no structural anomaly. She received the CoronaVac vaccine at 21 + 2 weeks of gestation without serious side effects and the ChAdOx1 vaccine at 24 + 2 weeks of gestation. Cesarean delivery was performed at 36 + 5 weeks of gestation, giving birth to the two healthy babies. The levels of anti-spike protein IgG levels (BAU/mL) in maternal blood just before delivery and umbilical cord blood of the two newborns were 313.349, 678.219, and 874.853, respectively. The levels of % inhibition (wild-type and delta) in the two newborns were also higher than those in the mother. In conclusion, heterologous CoronaVac-ChAdOx1-S vaccination in a twin pregnancy could effectively provide protective immunity to both twin newborns. The antibody levels in both were approximately two times higher than those in the mothers. This case report may serve as a reference in counseling couples with a twin pregnancy, while the studies on placental transfer of vaccine-derived antibodies in twin pregnancy are currently not available, especially in countries experiencing a vaccine shortage or unavailability of mRNA vaccines.

Minireview: Insights into anti-interferon-γ autoantibodies

The association between the presence of anti-interferon-γ autoantibodies and the onset of immunodeficiency with intracellular infections has been clearly established. No standard regimen to control the production of these pathogenic autoantibodies, apart from antimicrobial therapy to eliminate infections, contributes to the medical burden of this syndrome, which sometimes has a fatal outcome. In this review, we summarize the findings on anti-interferon-γ autoantibodies to facilitate further research and to provide guidance for treatment strategies.

Neutralizing Activity of Anti-interferon-γ Autoantibodies in Adult-Onset Immunodeficiency Is Associated With Their Binding Domains

Adult-onset immunodeficiency (AOID) with anti-interferon-γ (IFN-γ) autoantibodies (autoAbs) is an emerging immunodeficiency syndrome in Asian countries. The presence of neutralizing anti-IFN-γ autoAbs are significantly associated with severe disseminated opportunistic infections. However, the characteristics of the neutralizing antibodies in patients are poorly defined. To better understand the properties of the anti-IFN-γ autoAbs in patients with opportunistic infections, a simplified competitive-binding ELISA was developed. The domains recognized by anti-IFN-γ autoAbs were assessed based on their competition with commercial neutralizing mouse anti-IFN-γ monoclonal antibodies (mAbs). First, the binding affinity and neutralizing capacity of these mAbs (clones B27, B133.5, and MD-1) were characterized. Kinetic analysis and epitope binning using bio-layer interferometry showed the comparable binding affinity of these mAbs to full-length IFN-γ and to the adjacent binding region. These mAbs did not recognize the synthetic 20-mer peptides and inhibited IFN-γ-mediated functions differently. In a competitive-binding ELISA, the anti-IFN-γ autoAbs in AOID serum blocked B27, B133.5, and MD-1 mAb binding. This evidence suggested that the autoAbs that competed with neutralizing mouse anti-IFN-γ mAbs recognized a discontinuous epitope of homodimeric IFN-γ as these mAbs. The patient autoAbs that recognized the B27 epitope exhibited strong neutralizing activity that was determined by the functional analysis. Our results demonstrated the heterogeneity of the autoAbs against IFN-γ in AOID patients and the different patterns among individuals. These data expand upon the fundamental knowledge of neutralizing anti-IFN-γ autoAbs in AOID patients.

Dot enzyme-linked immunosorbent assay strip as a screening tool for detection of autoantibody to interferon gamma in sera of suspected cases of adult-onset immunodeficiency

BACKGROUND

Being able to detect the presence of autoantibodies to interferon (IFN)-γ in serum is essential for evaluating patients with suspected adult-onset immunodeficiency (AOID) with unusual intracellular infections. Most reported patients with AOID have been Asian, although the exact prevalence of this illness is unknown. To date, no standard assay exists to detect autoantibodies to IFN-γ. An easy-to-use, low-cost assay that can be performed in any laboratory would be a valuable tool for clinical management of AOID, as well as better reveal its prevalence.

METHODS

Our experimental study exploited a dot enzyme-linked immunosorbent assay (Dot-ELISA) strip to detect autoantibodies to IFN-γ. Sera from 66 HIV-negative patients having autoantibodies to IFN-γ as determined by indirect ELISA were tested.

RESULTS

Dot enzyme-linked immunosorbent assay was sensitive (100%) and specific (94.5%), with a positive predictive value of 97.6% and a negative predictive value of 100%.

CONCLUSION

This simple method provides prompt qualitative results that can be read visually and used in facilities with limited testing capabilities.

Characterization of anti-interferon-γ antibodies in HIV-negative immunodeficient patients infected with unusual intracellular microorganisms

A major characteristic of immunodeficiency associated with life-threatening intracellular infection in adults is the presence of anti-interferon-γ antibodies. Although little is known about the mechanism underlying this syndrome, it is believed that the antibodies inhibit the activity of downstream signaling pathway of interferon-γ. In this study, the characteristics of these antibodies in patients who presented, or have a history of, intracellular infection and were positive to anti-interferon-γ antibodies were investigated. The antibodies exhibited mainly the IgG1 and the IgG4 subtypes and recognized the C-terminal of the interferon-γ linear epitope containing the KRKR motif, which is required for the biological activity of interferon-γ. The antibodies bound to recombinant interferon-γ with significantly lower avidity than antibodies to a recall antigen, tetanus toxoid, suggesting that the antibodies might have not undergone affinity maturation. The data from this study may provide fundamental information to better understand the properties of anti-interferon-γ antibodies, which can be useful for future studies. Impact statement An increase in the number of immunodeficient patients related to autoantibodies to interferon (IFN)-γ has been observed particularly in East Asian adults. These patients are often presented with opportunistic infections caused by intracellular pathogens, including non-tuberculous mycobacteria (NTM), Cryptococcus neoformans, Penicillium marneffei (now called Talaromyces marneffei), and non-typhoidal Salmonella spp. The mortality rate for this syndrome is relatively high with 32% patients dying at the median time of 25 months after diagnosis. Characterization of these autoantibodies may promote better understanding of the syndrome, an emerging health problem affecting East Asia populations and impeding their welfare and economic development.

Cell cycle arrest and apoptosis induction by methanolic leaves extracts of four Annonaceae plants

Background

Uvaria longipes (Craib) L.L.Zhou, Y.C.F.Su & R.M.K.Saunders, Artabotrys burmanicus A.DC, Marsypopetalum modestum (Pierre) B.Xue & R.M.K.Saunders and Dasymaschalon sp. have been used for traditional medicine to treat cancer-like symptoms in some ethnic groups of Thailand and Laos.

Methods

We evaluated the anti-cancer activity of these Annonaceae plants against several human cancer cell lines. The apoptosis induction was detected by Annexin/propidium iodide (PI) staining. Phytochemical screening was tested by standard protocols and bioactive compounds were determined by HPLC.

Results

The crude extracts from leaves of U. longipes, Dasymaschalon sp., A. burmanicus, and M. modestum showed particular effects that were found to vary depending on the cancer cell line, suggesting that the effect was in a cell-type specific manner. Interestingly, the induction of apoptotic cell death was prominent by the leaves-derived crude extract of M. modestum. This crude was, therefore, subjected to cell cycle analysis by PI staining. Results showed that this crude extract arrested cell cycle and increased the percentage of cells in the SubG1 phase in some cancer cell lines. The phytochemical screening tests indicated that all crude extracts contained tannins and flavonoids. HPLC of flavonoids using standards identified rutin as an active compound in U. longipes and Dasymaschalon sp., whereas quercetin was found in U. longipes and M. modestum.

Conclusions

These crude extracts provide a new source for rutin and quercetin, which might be capable of inducing cancer cell apoptotic death in a cell-type specific manner. This suggests, by analyzing the major bioactive compounds, the potential use of these crudes for chemotherapy in the future.

Hemoglobin E Prevalence among Ethnic Groups Residing in Malaria-Endemic Areas of Northern Thailand and Its Lack of Association with Plasmodium falciparum Invasion In Vitro

Hemoglobin E (HbE) is one of the most common hemoglobin variants caused by a mutation in the β-globin gene, and found at high frequencies in various Southeast Asian groups. We surveyed HbE prevalence among 8 ethnic groups residing in 5 villages selected for their high period malaria endemicity, and 5 for low endemicity in northern Thailand, in order to uncover factors which may affect genetic persistence of HbE in these groups. We found the overall HbE prevalence 6.7%, with differing frequencies from 0% in the Pwo Karen, the Lawa, and the Skaw Karen to 24% in the Mon. All HbE genes were heterozygous (AE). Differences in HbE prevalence among the studied ethnic groups indirectly documents that ancestries and evolutionary forces, such as drift and admixture, are the important factors in the persistence of HbE distribution in northern Thailand. Furthermore, the presence of HbE in groups of northern Thailand had no effect on the in vitro infectivity and proliferation of Plasmodium falciparum, nor the production of hemozoin, a heme crystal produced by malaria parasites, when compared to normal red-blood-cell controls. Our data may contribute to a better understanding on the persistence of HbE among ethnic groups and its association with malaria.

Vaccination for 2009 pandemic H1N1 influenza A did not induce conserved epitope-specific memory CD8 T cell responses in HIV+ northern Thai children

The influenza virus causes severe illness in susceptible populations, including children and people living with human immunodeficiency virus (HIV). Here, we investigated cell-mediated immune responses (CMI) against influenza CD8 T cell conserved epitopes in HIV-infected (HIV+) northern Thai children following the 2009 pandemic H1N1 influenza A vaccination. Sixty HIV+ children were vaccinated with two doses of the 2009 pandemic influenza vaccine and their CD8T cell responses were assessed. We found no significant differences in the increase of cytokines-producing and CD107a-expressing CD8+ T cells or CD8+ memory T cells in response to pooled conserved epitopes stimulation in vitro between children with different serologic responses to the vaccine at all time points of the study. Our results suggest that the 2009 pandemic H1N1 vaccine did not induce the conserved epitope-specific immune responses in HIV+ children. Vaccine design and vaccination strategy against influenza in these populations warrant further studies.

Low expression of activation marker CD69 and chemokine receptors CCR5 and CXCR3 on memory T cells after 2009 H1N1 influenza A antigen stimulation in vitro following H1N1 vaccination of HIV-infected individuals

Unlike well-studied antibody responses to pandemic 2009 H1N1 influenza A virus vaccines in human immunodeficiency virus-infected (HIV+) individuals, less well understood are cell-mediated immune (CMI) responses to this antigen in this susceptible population. We investigated such influenza-specific CMI responses in 61 HIV+ individuals and in 20 HIV-negative (HIV-) healthy controls. Each was vaccinated with a single licensed dose of inactivated, split-virion vaccine comprised of the influenza A/California/7/2009 (H1N1) virus-like strain. Cells collected just prior to vaccination and at 1 and 3 months afterwards were stimulated in vitro with dialyzed vaccine antigen and assayed by flow cytometry for cytokines TNF-α, IFN-γ, IL-2, and IL-10, for degranulation marker CD107a, as well as phenotypes of memory T-cell subpopulations. Comparable increases of cytokine-producing and CD107a-expressing T cells were observed in both HIV+ subjects and healthy HIV-controls. However, by 3 months post-vaccination, in vitro antigen stimulation of peripheral blood mononuclear cells induced greater expansion in controls of both CD4 and CD8 central memory and effector memory T cells, as well as higher expression of the activation marker CD69 and chemokine receptors CCR5 and CXCR3 than in HIV+ subjects. We concluded CD4+ and CD8+ memory T cells produce cytokines at comparable levels in both groups, whereas the expression after in vitro stimulation of molecules critical for cell migration to infection sites are lower in the HIV+ than in comparable controls. Further immunization strategies against influenza are needed to improve the CMI responses in people living with HIV.

Cellular immune responses in HIV-negative immunodeficiency with anti-interferon-γ antibodies and opportunistic intracellular microorganisms

Background

Cell-mediated immunity plays a crucial role in resistance to intracellular infection. We previously reported antibodies against interferon-gamma (IFN-γ) in HIV− negative (HIV−) patients with acquired immunodeficiency presenting with repeated episodes of disseminated infection caused by uncommon opportunistic intracellular fungal, bacterial, and viral pathogens. This follow-up study aimed to investigate cellular immune responses in these unusual patients.

Methods

Twenty HIV− patients presenting with ≥2 episodes of culture- or histopathologic-proven opportunistic infections were enrolled along with age- and sex-matched controls comprised of 20 HIV+ patients plus 20 healthy adults. Monocyte phenotyping and intracellular cytokine production were determined by staining with specific antibodies followed by flow cytometry. Anti-interferon-γ antibodies were measured by enzyme-linked immunosorbent assay, and inducible nitric oxide synthase by reverse-transcription polymerase chain reaction.

Results

There were no differences among cases, HIV+, and healthy controls in the percentage of monocytes, or CD68 and HLA-DR expression on their surfaces. FcR1 (CD119) expression on monocytes was significantly higher in cases than in HIV+ (p<0.05) and healthy controls (p<0.01), suggesting the presence of activated monocytes in the circulation. Interleukin (IL)-2 and tumor necrosis factor (TNF)-α production in CD4 cells were significantly lower in cases than in healthy controls (p<0.01 and p<0.001, respectively). CD8 production of TNF-α among cases was significantly lower than that of healthy controls (p<0.05).

Conclusion

Immunodeficiency in HIV− individuals with repeated infections with intracellular pathogens may be associated with one or more of the abnormal immune responses reflected by the reduced production of both IL-2 by CD4 T cells and TNF-α by CD4 T cells and CD8 T cells, as well as presence of anti-IFN-γ antibody, as previously reported.

Structural analysis of a dengue cross-reactive antibody complexed with envelope domain III reveals the molecular basis of cross-reactivity

Dengue virus infections are still increasing at an alarming rate in tropical and subtropical countries, underlying the need for a dengue vaccine. Although it is relatively easy to generate Ab responses to dengue virus, low avidity or low concentrations of Ab may enhance infection of FcR-bearing cells with clinical impact, posing a challenge to vaccine production. In this article, we report the characterization of a mAb, 2H12, which is cross-reactive to all four serotypes in the dengue virus group. Crystal structures of 2H12-Fab in complex with domain III of the envelope protein from three dengue serotypes have been determined. 2H12 binds to the highly conserved AB loop of domain III of the envelope protein that is poorly accessible in the mature virion. 2H12 neutralization varied between dengue serotypes and strains; in particular, dengue serotype 2 was not neutralized. Because the 2H12-binding epitope was conserved, this variation in neutralization highlights differences between dengue serotypes and suggests that significant conformational changes in the virus must take place for Ab binding. Surprisingly, 2H12 facilitated little or no enhancement of infection. These data provide a structural basis for understanding Ab neutralization and enhancement of infection, which is crucial for the development of future dengue vaccines.

Short-lived IFN-γ effector responses, but long-lived IL-10 memory responses, to malaria in an area of low malaria endemicity

Immunity to malaria is widely believed to wane in the absence of reinfection, but direct evidence for the presence or absence of durable immunological memory to malaria is limited. Here, we analysed malaria-specific CD4+ T cell responses of individuals living in an area of low malaria transmission in northern Thailand, who had had a documented clinical attack of P. falciparum and/or P. vivax in the past 6 years. CD4+ T cell effector memory (CD45RO+) IFN-γ (24 hours ex vivo restimulation) and cultured IL-10 (6 day secretion into culture supernatant) responses to malaria schizont antigens were detected only in malaria-exposed subjects and were more prominent in subjects with long-lived antibodies or memory B cells specific to malaria antigens. The number of IFN-γ-producing effector memory T cells declined significantly over the 12 months of the study, and with time since last documented malaria infection, with an estimated half life of the response of 3.3 (95% CI 1.9-10.3) years. In sharp contrast, IL-10 responses were sustained for many years after last known malaria infection with no significant decline over at least 6 years. The observations have clear implications for understanding the immunoepidemiology of naturally acquired malaria infections and for malaria vaccine development.

Cross-reacting antibodies enhance dengue virus infection in humans

Dengue virus co-circulates as four serotypes, and sequential infections with more than one serotype are common. One hypothesis for the increased severity seen in secondary infections is antibody-dependent enhancement (ADE) leading to increased replication in Fc receptor-bearing cells. In this study, we have generated a panel of human monoclonal antibodies to dengue virus. Antibodies to the structural precursor-membrane protein (prM) form a major component of the response. These antibodies are highly cross-reactive among the dengue virus serotypes and, even at high concentrations, do not neutralize infection but potently promote ADE. We propose that the partial cleavage of prM from the viral surface reduces the density of antigen available for viral neutralization, leaving dengue viruses susceptible to ADE by antibody to prM, a finding that has implications for future vaccine design.

Investigation of the anti-inflammatory effect of Curcuma longa in Helicobacter pylori-infected patients

Helicobacter pylori infection of the lining of the stomach induces an array of inflammatory cytokine production leading to gastritis and peptic ulcer disease. The aim of this study was to investigate the effect of curcumin on the production of interleukin (IL)-8, IL-1beta, tumor necrosis factor (TNF)-alpha and cyclooxygenase (COX)-2 in gastric mucosa from H. pylori-infected gastritis patients. Patients were randomly assigned to receive either OAM (Omeprazole, Amoxicillin and Metronidazole) treatment or a course of curcumin. Gastric biopsies were collected before and after treatment and were examined for the level of inflammatory cytokines mRNA by semi-quantitative reverse transcription polymerase chain reaction. The eradication rate of H. pylori in patients that received OAM treatment was significantly higher than the patients that received curcumin (78.9% versus 5.9%). The levels of IL-8 mRNA expression in the OAM group significantly decreased after treatment, but no changes of other cytokines were found. This emphasizes an important role of IL-8 in H. pylori infection. The decreases of cytokine production were not found in the curcumin group. We concluded that curcumin alone may have limited anti-bactericidal effect on H. pylori, and on the production of inflammatory cytokines. Nevertheless, other studies have reported that patients treated with curcumin had relieved symptoms. Further investigation should be carried out as the use of curcumin in combination with therapeutic regimens may be beneficial as an alternative treatment.

Production of antibodies by single DNA immunization: comparison of various immunization routes

DNA immunization is a recent vaccination method that induces humoral and cellular immune responses in a range of hosts. Different immunization routes induce a different degree of the immune response. In the present report, we demonstrate that multiple intramuscular immunizations of plasmid DNA encoding various leukocyte surface molecules induced a specific antibody response. In contrast, a single intramuscular immunization could not induce antibody production. To study the induction of antibody response after a single immunization of plasmid DNA, mice were single-dose intramuscularly, intraperitoneally, intravenously and intrasplenically immunized, simultaneously, with the same preparation of plasmid DNA encoding CD147 membrane protein. We observed that only the intrasplenic route induced specific antibody production. The induction of antibody by intrasplenic immunization was confirmed by using plasmid DNA encoding CD54 molecule. By this single-dose DNA intrasplenic immunization, the generated antibodies could be detected in mice up to 6 months. These results suggest that the injected DNA is expressing the relevant protein antigen in the spleen for several months after injection. Our results demonstrate that direct immunization of antigen-encoding DNA into the spleen is a more effective method for induction of antibody production. This finding may support future investigations of DNA vaccination strategies that specifically promote the uptake of plasmid by splenocytes. Intrasplenic immunization may also be helpful in the understanding of the early events of the immune response to DNA vaccine and be useful as an effective route for the induction of immune responses.