Gene Expression Profile of Human Cytokines in Response to Burkholderia pseudomallei Infection

Melioidosis is an underreported infectious disease, caused by the Gram-negative bacterium Burkholderia pseudomallei. Understanding the disease susceptibility and pathogenesis is crucial for developing newer diagnostic and therapeutic strategies for this life-threatening infection. In this study, we aimed to analyze the gene expression levels of important cytokines in melioidosis patients and establish useful correlates with disease biomarkers compared to cases of sepsis infection caused by other pathogens and healthy individuals. A Qiagen common human cytokines array profiling the gene expression of 84 important cytokines by real-time quantitative PCR (RT-qPCR) was used. We analyzed 26 melioidosis cases, 5 healthy controls, and 10 cases of sepsis infection caused by other pathogens. Our results showed consistently upregulated expression of interleukins (IL) interleukin-4 (IL-4), interleukin-17 alpha (IL-17A), IL-23A, and IL-24, interferons (IFN) interferon alpha 1 (IFNA1) and interferon beta 1 (IFNB1), tumor necrosis factor (TNF) superfamily 4 (TNFSF4), transforming growth factor (TGF) superfamily, bone morphogenetic proteins 3 and 6 (BMP3 and BMP6), transforming growth factor beta 1 (TGFB1), and other growth factors, including macrophage colony-stimulating factor (M-CSF), C-fos-induced growth factor (FIGF), and platelet-derived growth factor alpha (PDGFA) polypeptide, in melioidosis patients compared to their expression in other sepsis cases, irrespective of comorbidities, duration of fever/clinical symptoms, and antibiotic treatment. Our findings indicate a dominant Th2- and Th17-type-cytokine response, suggesting that their dysregulation at initial stages of infection may play an important role in disease pathogenesis. IL-1A, interleukin-1 beta (IL-1B), and IL-8 were significantly downregulated in septicemic melioidosis patients compared to their expression in other sepsis cases. These differentially expressed genes may serve as biomarkers for melioidosis diagnosis and targets for therapeutic intervention and may help us understand immune response mechanisms

Preexisting Neutralizing Antibody Responses Distinguish Clinically Inapparent and Apparent Dengue Virus Infections in a Sri Lankan Pediatric Cohort

Dengue viruses (DENVs) are mosquito-borne flaviviruses that infect humans. The clinical presentation of DENV infection ranges from inapparent infection to dengue hemorrhagic fever and dengue shock syndrome. We analyzed samples from a pediatric dengue cohort study in Sri Lanka to explore whether antibody responses differentiated clinically apparent infections from clinically inapparent infections. In DENV-naive individuals exposed to primary DENV infections, we observed no difference in the quantity or quality of acquired antibodies between inapparent and apparent infections. Children who experienced primary infections had broad, serotype–cross-neutralizing antibody responses that narrowed in breadth to a single serotype over a 12-month period after infection. In DENV immune children who were experiencing a repeat infection, we observed a strong association between preexisting neutralizing antibodies and clinical outcome. Notably, children with preexisting monospecific neutralizing antibody responses were more likely to develop fever than children with cross-neutralizing responses. Preexisting DENV neutralizing antibodies are correlated with protection from dengue disease

Whole-genome sequences of eight clinical isolates of Burkholderia pseudomallei from melioidosis patients in Eastern Sri Lanka

Here, we report whole-genome sequences (WGS) of eight clinical isolates of Burkholderia pseudomallei obtained from melioidosis patients with sepsis in eastern Sri Lanka

HLA Class I and Class II Associations in Dengue Viral Infections in a Sri Lankan Population

BACKGROUND: HLA class I and class II alleles have been shown to be associated with the development of dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS) in different populations. However, the majority of studies have been based on limited numbers of patients. In this study we aimed to investigate the HLA-class I and class II alleles that are positively and negatively associated with the development of DSS in a cohort of patients with DHF and also the alleles associated with development of DHF during primary dengue infections in a Sri Lankan population. METHODOLOGY/PRINCIPAL FINDINGS: The allele frequencies of HLA class I and class II alleles were compared in 110 patients with DHF and 119 individuals from the population who had never reported a symptomatic dengue infection at the time of recruitment. We found that HLA-A*31 (corrected P = 0.01) and DRB1*08 (corrected P = 0.009) were associated with susceptibility to DSS when infected with the dengue virus, during secondary dengue infection. The frequency of DRB1*08 allele was 28.7 times higher than in the normal population in patients with DSS. HLA-A*31 allele was increased 16.6 fold in DHF who developed shock when compared to those who did not develop shock. A*24 (corrected P = 0.03) and DRB1*12 (corrected P = 0.041) were strongly associated with the development of DHF during primary dengue infection. CONCLUSIONS/SIGNIFICANCE: These data suggest that certain HLA alleles confer susceptibility/protection to severe dengue infections. As T cell epitope recognition depend on the HLA type of an individual, it would be now important to investigate how epitope specific T cells associate with primary and secondary dengue infections and in severe dengue infections

Melioidosis in Sri Lanka

Until recently, Sri Lanka was not considered a country with endemic melioidosis. However, an increasing number of cases is being reported. National surveillance for melioidosis was instituted after 2008. A total of 250 culture-positive cases was recorded between 2006 and May 2017. Males predominated (71.6%). The age range was wide (2–92 years) reflecting a ubiquity of exposure. The majority (201/250, 80%) lived in rural areas. All provinces were affected. Case load increased during the two monsoonal periods (67%). There was representation of every population group including farmers (n = 44), housewives (n = 24), school children (n = 10), professionals (n = 5), businesspersons (n = 6), white-collar workers (n = 10) and blue-collar workers (n = 8). Diabetes was the predominant risk factor (n = 163, 65.2%). Clinical presentations included community-acquired sepsis and pneumonia, superficial and deep abscesses, and septic arthritis. Mortality was 20.4% (51/250). A majority (n = 212) of isolates belonged to the YLF (Yersinia-like fimbrial) clade but 38 were BTFC (B. thailandensis-like flagellum and chemotaxis). A total of 108 isolates was genotyped and 46 sequence types (STs) were identified, 40 being novel. It is clear that melioidosis is endemic in Sri Lanka with a wide geographic and demographic distribution. There is an urgent need to extend surveillance of melioidosis to under-resourced parts of the country and to populations at high risk

Polymorphisms of transporter associated with antigen presentation, tumor necrosis factor-α and interleukin-10 and their implications for protection and susceptibility to severe forms of dengue fever in patients in Sri Lanka

Context: To date, a clear understanding of dengue disease pathogenesis remains elusive. Some infected individuals display no symptoms while others develop severe life-threatening forms of the disease. It is widely believed that host genetic factors influence dengue severity. Aims: This study evaluates the relationship between certain polymorphisms and dengue severity in Sri Lankan patients. Settings and Design: Polymorphism studies are carried out on genes for; transporter associated with antigen presentation (TAP), promoter of tumor necrosis factor-α (TNF-α), and promoter of interleukin-10 (IL-10). In other populations, TAP1 (333), TAP2 (379), TNF-α (−308), and IL-10 (−1082, −819, −592) have been associated with dengue and a number of different diseases. Data have not been collected previously for these polymorphisms for dengue patients in Sri Lanka. Materials and Methods: The polymorphisms were typed by amplification refractory mutation system polymerase chain reaction in 107 dengue hemorrhagic fever (DHF) patients together with 62 healthy controls. Statistical Analysis Used: Pearson′s Chi-square contingency table analysis with Yates′ correction. Results: Neither the TAP nor the IL-10 polymorphisms considered individually can define dengue disease outcome with regard to severity. However, the genotype combination, IL-10 (−592/−819/−1082) CCA/ATA was significantly associated with development of severe dengue in these patients, suggesting a risk factor to developing DHF. Also, identified is the genotype combination IL-10 (−592/−819/−1082) ATA/ATG which suggested a possibility for protection from DHF. The TNF-α (−308) GG genotype was also significantly associated with severe dengue, suggesting a significant risk factor. Conclusions: The results reported here are specific to the Sri Lankan population. Comparisons with previous reports imply that data may vary from population to population

Ratio of dengue infections to notified cases by age in Colombo Municipal Council, 2009.

<p>Blue line: Model 1 (constant force of infection); Red line: Model 2 (different forces of infection above and below 6 years).</p

Observed prevalence by age (with 95% CIs) and model-predicted values.

<p>Blue line: Model 1 (constant force of infection); Red line: Model 2 (different forces of infection above and below 6 years).</p

Is Total Serum Nitrite and Nitrate (NOx) Level in Dengue Patients a Potential Prognostic Marker of Dengue Hemorrhagic Fever?

Potential use of total nitrite plus nitrate (NOx) and nitrite (NO2−) separately as surrogate markers for serum nitric oxide in severe dengue and their longitudinal changes along with the progression of infection was studied. Deproteinized sera from confirmed dengue fever (DF, n=145) and dengue hemorrhagic fever (DHF, n=74) patients on admission—A, critical—C, discharge—D, and convalescence—CON stages and from age-gender matched healthy individuals (HC, n=77) were taken to assess NO2− and NOx levels using Griess and modified Griess assays. Serum NOx in DHFA was significantly lower compared to DFA (p<0.001). HC had the lowest NOx and NO2− compared to all patient categories (p<0.001) except NO2− in DF-CON and DHF-CON and NOx in DHF-CON. Serum NOx and NO2− in DHF patients admitted on fever day 3 (DHFA-3) was significantly lower compared to DFA-3 (p<0.05). Cut-off values of 4.46 μM for NOx (91.3% sensitivity and 80.1% specificity) and 1.25 μM for NO2− (75.0% sensitivity and 73.3% specificity) were obtained for day 3 of fever. Serum NOx may be used as potential prognostic marker of DHF in patients presenting with DF in the early stage (on day 3 of fever) of the disease

Host gene expression analysis in Sri Lankan melioidosis patients

<div><p>Background</p><p>Melioidosis is a life threatening infectious disease caused by the gram-negative bacillus <i>Burkholderia pseudomallei</i> predominantly found in southeast Asia and northern Australia. Studying the host transcription profiles in response to infection is crucial for understanding disease pathogenesis and correlates of disease severity, which may help improve therapeutic intervention and survival. The aim of this study was to analyze gene expression levels of human host factors in melioidosis patients and establish useful correlation with disease biomarkers, compared to healthy individuals and patients with sepsis caused by other pathogens.</p><p>Methods</p><p>The study population consisted of 30 melioidosis cases, 10 healthy controls and 10 sepsis cases caused by other pathogens. Total RNA was extracted from peripheral blood mononuclear cells (PBMC’s) of study subjects. Gene expression profiles of 25 gene targets including 19 immune response genes and 6 epigenetic factors were analyzed by real time quantitative polymerase chain reaction (RT-qPCR).</p><p>Principal findings</p><p>Inflammatory response genes; TLR4, late onset inflammatory mediator HMGB1, genes associated with antigen presentation; MICB, PSMB2, PSMB8, PSME2, epigenetic regulators; DNMT3B, HDAC1, HDAC2 were significantly down regulated, whereas the anti-inflammatory gene; IL4 was up regulated in melioidosis patients compared to sepsis cases caused by other pathogens. Septicaemic melioidosis cases showed significant down regulation of IL8 compared to sepsis cases caused by other pathogens. HMGB1, MICB, PSMB8, PSMB2, PSME2, HDAC1, HDAC2 and DNMT3B showed consistent down regulation of gene expression in melioidosis patients compared to other sepsis infection, irrespective of comorbidities such as diabetes, duration of clinical symptoms and antibiotic treatment.</p><p>Significance</p><p>Specific immune response genes and epigenetic regulators are differentially expressed among melioidosis patients and patients with sepsis caused by other pathogens. Therefore, these genes may serve as biomarkers for disease diagnosis to distinguish melioidosis from cases of sepsis due to other infections and therapeutic intervention for melioidosis.</p></div