A compendium of single extracellular vesicle flow cytometry.

Flow cytometry (FCM) offers a multiparametric technology capable of characterizing single extracellular vesicles (EVs). However, most flow cytometers are designed to detect cells, which are larger than EVs. Whereas cells exceed the background noise, signals originating from EVs partly overlap with the background noise, thereby making EVs more difficult to detect than cells. This technical mismatch together with complexity of EV-containing fluids causes limitations and challenges with conducting, interpreting and reproducing EV FCM experiments. To address and overcome these challenges, researchers from the International Society for Extracellular Vesicles (ISEV), International Society for Advancement of Cytometry (ISAC), and the International Society on Thrombosis and Haemostasis (ISTH) joined forces and initiated the EV FCM working group. To improve the interpretation, reporting, and reproducibility of future EV FCM data, the EV FCM working group published an ISEV position manuscript outlining a framework of minimum information that should be reported about an FCM experiment on single EVs (MIFlowCyt-EV). However, the framework contains limited background information. Therefore, the goal of this compendium is to provide the background information necessary to design and conduct reproducible EV FCM experiments. This compendium contains background information on EVs, the interaction between light and EVs, FCM hardware, experimental design and preanalytical procedures, sample preparation, assay controls, instrument data acquisition and calibration, EV characterization, and data reporting. Although this compendium focuses on EVs, many concepts and explanations could also be applied to FCM detection of other particles within the EV size range, such as bacteria, lipoprotein particles, milk fat globules, and viruses.

Latent M. tuberculosis infection is associated with increased inflammatory cytokine and decreased suppressor of cytokine signalling (SOCS)-3 in the diabetic host.

Tuberculosis (TB) outcomes are worsened by type II diabetes mellitus (DM). Protective immunity against Mycobacterium tuberculosis (MTB) is driven by cytokines. Latent TB (LTBi) is common but its effect on the diabetic host is not well understood. We investigated mycobacterial antigen-stimulated responses in peripheral blood mononuclear cell (PBMC) isolated from healthy endemic controls (EC), those with LTBi, DM groups with and without LTBi, as compared with TB patients. Cytokines were measured using a Luminex-based assay. Gene expression was determined by RT-PCR. In DM-LTBi cases, PPD-stimulated proinflammatory cytokines; IFN-γ, IL-6, IL-2, TNF-α and GM-CSF and anti-inflammatory cytokines, IL-5 and IL-13 were raised as compared with EC. DM-LTBi PPD-stimulated IFN-γ, IL-6 and TNF-α mRNA titres were found raised in DM-LTBi, whilst suppressor of cytokine signalling (SOCS)-3 expression was lowered. Within DM cases, stratification based on HbA1c levels revealed raised IFN-γ but lowered IL-6 gene expression in those with controlled levels as compared with uncontrolled glycaemic levels. Further, SOCS1 expression levels were found higher in DM cases with controlled glycaemia when compared with EC. Overall, we show that diabetics with LTBi manifest raised levels of inflammatory and anti-inflammatory cytokines concomitant with reduced SOCS3 mRNA expression. Reduced glycaemic control results in further inflammatory dysregulation impacting conversing impacting IFN-γ and IL-6 activation. These results suggest that dysregulated immune activation in diabetes is exacerbated by LTBi, lack of glycaemic control may further compromise immunity against MTB infection.

Raised levels of IFN-gamma and IL-13 are associated with pre-diabetes amongst newly diagnosed patients with Tuberculosis.

OBJECTIVE: To investigate pre-diabetes and diabetes in newly-diagnosed tuberculosis patients and to assess the association of serum cytokine levels with diabetes status. METHODS: The cross-sectional study was conducted at Indus Hospital and The Aga Khan University Hospital, Karachi from May to November 2015, and included patients of either gender aged 18 years or more with a confirmed diagnosis of tuberculosis who were either newly diagnosed or had received up to 1 month of anti-tuberculosis therapy were included. Patients were enrolled from among those presenting to the clinics at Indus Hospital, Karachi, and the Department of Medicine, Aga Khan University Hospital (AKUH), Karachi. The patients were tested for glycosylated haemoglobin and random blood glucose. Diabetes was defined as HbA1c >6.5%; pre-diabetes as HbA1c=5.7-6.4%; and normoglycaemic as HbA1c <5.7%. Serum cytokines were investigated using the Bio-plex 27, Bio-Rad assay. SPSS version 19.0 was used for data analysis.. RESULTS: Of the 211 subjects, 110(52%) were females and 101(48%) were males. The overall median age of the sample was 26 years, and 100(47.3%) subjects were underweight. Of the total, 24(11.4%) had diabetes and 45(21.3%) had pre-diabetes. Of the diabetics, only 7(29%) knew their status prior to screening. Interferon-gamma and interleukin-13 were significantly different among tuberculosis patients with diabetes, pre-diabetes and normoglycaemia (p<0.05). Glycosylated haemoglobin levels showed a significant correlation with interferon-gamma levels. CONCLUSIONS: Raised interleukin-13 and interferon-gamma levels in newly-diagnosed tuberculosis patients with pre-diabetes.

Impact of diabetes on mechanisms of immunity against Mycobacterium tuberculosis.

Tuberculosis (TB), caused by infection with mycobacterium tuberculosis, is a major source of morbidity and mortality in Pakistan. Diabetes caused by imbalance in glycaemic control is also highly prevalent in the country. The coincidence of both diseases results in worsening outcomes of TB, making treatment and management more difficult. Both innate and adaptive arms of the host immune response are required for protection against M. tuberculosis infection. Host immunity is modified in diabetes mellitus type 2 where key pathways such as, the T cell driven interferon-gamma responses to M. tuberculosis antigens and other T cell and macrophage activating cytokines are suppressed. This makes diabetes with TB a more severe disease and results in worse treatment outcomes. Effective coordination between T cells and host macrophages is required for control of TB infection. Therefore, early identification of diabetes and management of hyperglycaemia during TB treatment is essential for favourable outcomes.

Late diagnosis of human immunodeficiency virus infections in high-risk groups in Karachi, Pakistan.

Human immunodeficiency virus (HIV) infection prevalence in Pakistan has been increasing in high-risk groups, including people who inject drugs (PWID) and transgender hijra sex workers (TG-HSWs) nationwide. Effective control of HIV requires early diagnosis of the infection. We investigated recency of HIV infections in newly-diagnosed cases in PWID and TG-HSWs. This was an observational study with convenience sampling. Overall, 210 HIV-positive subjects comprising an equal number of PWID and TG-HSWs were included. Antibody avidity was tested using the Maxim HIV-1 Limiting Antigen Avidity (LAg) EIA (Maxim Biomedical, Inc. Rockville, Maryland, USA). The mean age of study subjects was 29.5 years: PWID, 28.5 years and TG-HSWs, 30.4 years. Study subjects were married, 27%, or unmarried. Eighteen percent of individuals had recently-acquired HIV infections: 19% of PWID and 17% of TG-HSWs. Eighty-two percent of individuals had long-term HIV infections: 81% of PWID and 83% of TG-HSWs. This is the first study identification of recent HIV-1 infections in Pakistan. We show that most newly-diagnosed HIV patients in the high-risk groups studied had long-term infections. There is an urgent need for intervention in these groups to facilitate early diagnosis and treatment of HIV infection to reduce transmission in Pakistan.

Primary hyperoxaluria in populations of Pakistan origin: results from a literature review and two major registries.

Primary hyperoxalurias (PH) are devastating, autosomal recessive diseases causing renal stones. Undifferentiated hyperoxaluria is seen in up to 43% of Pakistani paediatric stone patients. High rates of consanguinity in Pakistan suggest significant local prevalence. There is no detailed information regarding number of cases, clinical features, and genetics in Pakistan-origin (P-o) patients. We reviewed available information on P-o PH patients recorded in the literature as well as from two major PH registries (the Rare Kidney Stone Consortium PH Registry (RKSCPHR) and the OxalEurope PH Registry (OxER); and the Aga Khan University Hospital in Pakistan. After excluding overlaps, we noted 217 P-o PH subjects (42 in OxER and 4 in RKSCPHR). Presentations were protean. Details of mutations were available for 94 patients of 201 who had genetic analyses. Unique mutations were noted. Mutation [c.508G>A (p. Gly170Arg)] (present in up to 25% in the West) was reported in only one case. In one series, only 30% had mutations on exons 1,4,7 of AGXT. Of 42 P-o patients in OxER, 52.4% were PH1, 45.2% PH2, and 2.4% PH3. Of concern is that diagnosis was made after renal transplant rejection (four cases) and on bone-marrow aspiration (in five). Lack of consideration of PH as a diagnosis, late diagnosis, and loss of transplanted kidneys mandates that PH be searched for diligently. Mutation analysis will need to extend to all exons and include PH 1,2,3. There is a need to spread awareness and identify patients through a scoring or screening system that alerts physicians to consider a diagnosis of PH.

Single nucleotide polymorphisms in efflux pumps genes in extensively drug resistant Mycobacterium tuberculosis isolates from Pakistan.

It is challenging to understand mechanisms of drug resistance in Mycobacterium tuberculosis (MTB) due to the large variability in resistance associated genes. Efflux pump genes contribute to drug resistance and thus add to this complexity. Efflux pump gene protein superfamilies have been characterized by genome analysis of drug resistant strains and through in vitro transcriptional studies. However, there is limited information regarding efflux pump genes in extensively drug resistant (XDR) tuberculosis (TB) isolates. Whole genome sequencing (WGS) based analysis of 37 extensively drug resistant (XDR) and five drug sensitive (DS) MTB clinical isolates was performed. Single nucleotide polymorphisms (SNPs) in efflux pump genes Rv0194, Rv1217, Rv1218, drrA, drrB, Rv1258, Rv1634, Rv2688, Rv1273, Rv1819, Rv1458, Rv1877 and Rv1250 were determined in the clinical isolates as compared with the H37Rv reference strain. Allele frequencies of SNPs identified in XDR strains were compared with DS strains. Gene expression of Rv0194, Rv2688, Rv1634, drrA and drrB was determined in XDR -TB isolates (n = 9), DS-TB strains (n = 4) and H37Rv. We identified SNPs in XDR-TB isolates which were either unique or present at very low frequencies in DS strains; Rv0194 G170V; Rv1217 L151R; Rv1258 P369T and G391R; Rv1273 S118G and I175T; Rv1877 I534T; Rv1250 V318X/A and S333A, and Rv2688 P156T. The expression of Rv2688 and drrB was found to be raised in XDR-TB as compared with DS-TB strains. We identified unique SNPs in efflux pump genes which may be associated with increased drug resistance in the isolates. Increased levels of Rv2688 and drrB efflux pump gene expression observed in XDR strains even in the absence of antibiotics suggests that these clinical isolates may be more refractory to treatment. Further studies are required to directly associate these mutations with increased resistance in MTB.

Increased Mycobacterium tuberculosis antigen-induced gene expression of interferon-gamma, tumor necrosis factor alpha and interleukin-6 in patients with diabetes.

INTRODUCTION: Pakistan ranks fifth in high tuberculosis (TB)-burden countries and seventh among countries with high prevalence rates of diabetes mellitus (DM). DM is a risk factor for TB and worsens disease outcomes. Furthermore, Mycobacterium tuberculosis (MTB) infection can induce glucose intolerance and worsen glycemic control in diabetes. Suppressor of cytokine signaling (SOCS)-1 and -3 molecules regulate cytokine signaling and are important in maintaining an immune balance. In TB, interleukin (IL)-6 upregulation induces SOCS3, which is also a negative regulator of insulin signaling. This research focuses on the mechanism by which SOCS1 and SOCS3 affect insulin resistance and increased susceptibility to TB. METHODS: We studied gene expression in peripheral blood cells of patients with diabetes (n=10) and healthy endemic controls (EC, n=11) both with and without MTB infection. Mycobacterial antigen (PPD) and mitogen-stimulated SOCS1, SOCS3, interferon-gamma (IFN-γ), IL-6, and tumor necrosis factor alpha (TNFα) mRNA expression levels were determined using real-time polymerase chain reaction. RESULTS: MTB antigen-stimulated mRNA levels of IFN-γ was 10-fold higher, SOCS1 was 4 times greater, TNFα was 10-fold higher, and IL-6 was 2-fold greater in patients with DM than in ECs. Overall levels of PPD-stimulated IL-6 was higher in patients with DM than in ECs (p=.036). Mitogen-induced mRNA levels of IFN-γ were 30-fold higher, SOCS3 was 20 fold higher, and SOCS1 was 4-fold higher in patients with DM than in ECs. CONCLUSION: Increased proinflammatory cytokine production in response to MTB antigens in diabetes would lead to exacerbated pathology and reduced inflammatory control at the site of MTB infection. This would in turn hamper the resolution of inflammation, resulting in unfavorable disease outcomes.