Alterations of adipokines, pancreatic hormones and incretins in acute and convalescent COVID-19 children.

BACKGROUND: The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), accountable for Coronavirus disease 2019 (COVID-19), may cause hyperglycemia and additional systemic complexity in metabolic parameters. It is unsure even if the virus itself causes type 1 or type 2 diabetes mellitus (T1DM or T2DM). Furthermore, it is still unclear whether even recuperating COVID-19 individuals have an increased chance to develop new-onset diabetes. METHODS: We wanted to determine the impact of COVID-19 on the levels of adipokines, pancreatic hormones, incretins and cytokines in acute COVID-19, convalescent COVID-19 and control children through an observational study. We performed a multiplex immune assay analysis and compared the plasma levels of adipocytokines, pancreatic hormones, incretins and cytokines of children presenting with acute COVID-19 infection and convalescent COVID-19. RESULTS: Acute COVID-19 children had significantly elevated levels of adipsin, leptin, insulin, C-peptide, glucagon and ghrelin in comparison to convalescent COVID-19 and controls. Similarly, convalescent COVID-19 children had elevated levels of adipsin, leptin, insulin, C-peptide, glucagon, ghrelin and Glucagon-like peptide-1 (GLP-1) in comparison to control children. On the other hand, acute COVID-19 children had significantly decreased levels of adiponectin and Gastric Inhibitory Peptide (GIP) in comparison to convalescent COVID-19 and controls. Similarly, convalescent COVID-19 children had decreased levels of adiponectin and GIP in comparison to control children. Acute COVID-19 children had significantly elevated levels of cytokines, (Interferon (IFN)) IFNγ, Interleukins (IL)-2, TNFα, IL-1α, IL-1ß, IFNα, IFNß, IL-6, IL-12, IL-17A and Granulocyte-Colony Stimulating Factors (G-CSF) in comparison to convalescent COVID-19 and controls. Convalescent COVID-19 children had elevated levels of IFNγ, IL-2, TNFα, IL-1α, IL-1ß, IFNα, IFNß, IL-6, IL-12, IL-17A and G-CSF in comparison to control children. Additionally, Principal component Analysis (PCA) analysis distinguishes acute COVID-19 from convalescent COVID-19 and controls. The adipokines exhibited a significant correlation with the levels of pro-inflammatory cytokines. CONCLUSION: Children with acute COVID-19 show significant glycometabolic impairment and exaggerated cytokine responses, which is different from convalescent COVID-19 infection and controls.

Enhanced Severe Acute Respiratory Syndrome Coronavirus 2 Antigen-Specific Systemic Immune Responses in Multisystem Inflammatory Syndrome in Children and Reversal After Recovery.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) presents with inflammation and pathology of multiple organs in the pediatric population in the weeks following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: We characterized the SARS-CoV-2 antigen-specific cytokine and chemokine responses in children with MIS-C, coronavirus disease 2019 (COVID-19), and other infectious diseases. RESULTS: MIS-C is characterized by elevated levels of type 1 (interferon-γ, interleukin [IL] 2), type 2 (IL-4, IL-13), type 17 (IL-17), and other proinflammatory cytokines (IL-1α, IL-6, IL-12p70, IL-18, and granulocyte-macrophage colony-stimulating factor) in comparison to COVID-19 and other infectious diseases following stimulation with SARS-CoV-2-specific antigens. Similarly, upon SARS-CoV-2 antigen stimulation, CCL2, CCL3, and CXCL10 chemokines were significantly elevated in children with MIS-C in comparison to the other 2 groups. Principal component analysis based on these cytokines and chemokines could clearly distinguish MIS-C from both COVID-19 and other infections. In addition, these responses were significantly diminished and normalized 6-9 months after recovery. CONCLUSIONS: Our data suggest that MIS-C is characterized by an enhanced production of cytokines and chemokines that may be associated with disease pathogenesis.

Heightened Microbial Translocation Is a Prognostic Biomarker of Recurrent Tuberculosis.

BACKGROUND: Microbial translocation is a known characteristic of pulmonary tuberculosis (PTB). Whether microbial translocation is also a biomarker of recurrence in PTB is not known. METHODS: We examined the presence of microbial translocation in a cohort of newly diagnosed, sputum smear, and culture positive individuals with drug-sensitive PTB. Participants were followed up for a year following the end of anti-tuberculosis treatment. They were classified as cases (in the event of recurrence, n = 30) and compared to age and gender matched controls (in the event of successful, recurrence free cure; n = 51). Plasma samples were used to measure the circulating microbial translocation markers. All the enrolled study participants were treatment naïve, HIV negative and with or without diabetes mellitus. RESULTS: Baseline levels of lipopolysaccharide (LPS) (P = .0002), sCD14 (P = .0191), and LPS-binding protein (LBP) (P < .0001) were significantly higher in recurrence than controls and were associated with increased risk for recurrence, whereas intestinal fatty acid binding protein (I-FABP) and Endocab showed no association. Receiver operating characteristic (ROC) curve analysis demonstrated the utility of these individual microbial markers in discriminating recurrence from cure with high sensitivity, specificity, and area under the curve (AUC). CONCLUSIONS: Recurrence following microbiological cure in PTB is characterized by heightened baseline microbial translocation. These markers can be used as a rapid prognostic tool for predicting recurrence in PTB.

Restoration of dendritic cell homeostasis and Type I/Type III interferon levels in convalescent COVID-19 individuals.

BACKGROUND: Plasmacytoid and myeloid dendritic cells play a vital role in the protection against viral infections. In COVID-19, there is an impairment of dendritic cell (DC) function and interferon secretion which has been correlated with disease severity. RESULTS: In this study, we described the frequency of DC subsets and the plasma levels of Type I (IFNα, IFNß) and Type III Interferons (IFNλ1), IFNλ2) and IFNλ3) in seven groups of COVID-19 individuals, classified based on days since RT-PCR confirmation of SARS-CoV2 infection. Our data shows that the frequencies of pDC and mDC increase from Days 15-30 to Days 61-90 and plateau thereafter. Similarly, the levels of IFNα, IFNß, IFNλ1, IFNλ2 and IFNλ3 increase from Days 15-30 to Days 61-90 and plateau thereafter. COVID-19 patients with severe disease exhibit diminished frequencies of pDC and mDC and decreased levels of IFNα, IFNß, IFNλ1, IFNλ2 and IFNλ3. Finally, the percentages of DC subsets positively correlated with the levels of Type I and Type III IFNs. CONCLUSION: Thus, our study provides evidence of restoration of homeostatic levels in DC subset frequencies and circulating levels of Type I and Type III IFNs in convalescent COVID-19 individuals.

Plasma chemokines as immune biomarkers for diagnosis of pediatric tuberculosis.

BACKGROUND: Diagnosing tuberculosis (TB) in children is challenging due to paucibacillary disease, and lack of ability for microbiologic confirmation. Hence, we measured the plasma chemokines as biomarkers for diagnosis of pediatric tuberculosis. METHODS: We conducted a prospective case control study using children with confirmed, unconfirmed and unlikely TB. Multiplex assay was performed to examine the plasma CC and CXC levels of chemokines. RESULTS: Baseline levels of CCL1, CCL3, CXCL1, CXCL2 and CXCL10 were significantly higher in active TB (confirmed TB and unconfirmed TB) in comparison to unlikely TB children. Receiver operating characteristics curve analysis revealed that CCL1, CXCL1 and CXCL10 could act as biomarkers distinguishing confirmed or unconfirmed TB from unlikely TB with the sensitivity and specificity of more than 80%. In addition, combiROC exhibited more than 90% sensitivity and specificity in distinguishing confirmed and unconfirmed TB from unlikely TB. Finally, classification and regression tree models also offered more than 90% sensitivity and specificity for CCL1 with a cutoff value of 28 pg/ml, which clearly classify active TB from unlikely TB. The levels of CCL1, CXCL1, CXCL2 and CXCL10 exhibited a significant reduction following anti-TB treatment. CONCLUSION: Thus, a baseline chemokine signature of CCL1/CXCL1/CXCL10 could serve as an accurate biomarker for the diagnosis of pediatric tuberculosis.

Antibody responses to the BBV152 vaccine in individuals previously infected with SARS-CoV-2: A pilot study.

Background & objectives: Vaccination against SARS-CoV-2 is a recommendation from the World Health Organization as the foremost preference in the current situation to control the COVID-19 pandemic. BBV152 is one of the approved vaccines against SARS-CoV-2 in India. In this study, we determined SARS-CoV-2-specific antibody levels at day 0 (baseline, before vaccination), day 28 ± 2 post-first dose (month 1) and day 56 ± 2 post-first dose (month 2) of BBV152 whole-virion-inactivated SARS-CoV-2 recipients, and compared the antibody responses of individuals with confirmed pre-vaccination SARS-CoV-2 infection to those individuals without prior evidence of infection. Methods: Blood samples were collected from 114 healthcare professionals and frontline workers who received BBV152 vaccine from February to May & June 2021. Prior infection with SARS-CoV-2 was determined at baseline. Serum samples were used to estimate SARS-CoV-2 nucleoprotein-specific IgG [IgG (N)], spike protein-specific IgG [IgG (S)] and neutralizing antibodies (NAb). Results: Participants with previous SARS-CoV-2 infection after a single vaccine dose elicited IgG (N) and IgG (S) antibody levels along with NAb binding inhibition responses levels were similar to infection-naïve vaccinated participants who had taken two doses of vaccine. Interpretation & conclusions: Our preliminary data suggested that a single dose of BBV152-induced humoral immunity in previously infected individuals was equivalent to two doses of the vaccine in infection-naïve individuals. However, these findings need to be confirmed with large sized cohort studies.

Host-directed therapy of tuberculosis based on interleukin-1 and type I interferon crosstalk.

Tuberculosis remains second only to HIV/AIDS as the leading cause of mortality worldwide due to a single infectious agent. Despite chemotherapy, the global tuberculosis epidemic has intensified because of HIV co-infection, the lack of an effective vaccine and the emergence of multi-drug-resistant bacteria. Alternative host-directed strategies could be exploited to improve treatment efficacy and outcome, contain drug-resistant strains and reduce disease severity and mortality. The innate inflammatory response elicited by Mycobacterium tuberculosis (Mtb) represents a logical host target. Here we demonstrate that interleukin-1 (IL-1) confers host resistance through the induction of eicosanoids that limit excessive type I interferon (IFN) production and foster bacterial containment. We further show that, in infected mice and patients, reduced IL-1 responses and/or excessive type I IFN induction are linked to an eicosanoid imbalance associated with disease exacerbation. Host-directed immunotherapy with clinically approved drugs that augment prostaglandin E2 levels in these settings prevented acute mortality of Mtb-infected mice. Thus, IL-1 and type I IFNs represent two major counter-regulatory classes of inflammatory cytokines that control the outcome of Mtb infection and are functionally linked via eicosanoids. Our findings establish proof of concept for host-directed treatment strategies that manipulate the host eicosanoid network and represent feasible alternatives to conventional chemotherapy.

Plasma levels of C-reactive protein, matrix metalloproteinase-7 and lipopolysaccharide-binding protein distinguish active pulmonary or extrapulmonary tuberculosis from uninfected controls in children.

The immune profile associated with distinct clinical forms of tuberculosis (TB) has been extensively described for adult populations. Nevertheless, studies describing immune determinants of pulmonary or extrapulmonary TB (PTB or EPTB, respectively) in children are scarce. Here, we retrospectively assessed plasma levels of several mediators of inflammation in age and sex-matched children from South India presenting with PTB (n = 14) or EPTB (n = 22) as well as uninfected healthy controls (n = 19) to identify biomarkers that could accurately distinguish different TB clinical forms. Furthermore, we performed exploratory analyses testing the influence of sex on the systemic inflammatory profile. The analyses identified a biosignature of 10 biomarkers capable of distinguishing the three clinical groups simultaneously. Machine-learning decision trees indicated that C-reactive protein (CRP), matrix metalloproteinase (MMP)-7 and lipopolysaccharide-binding protein (LBP) were the markers that, when combined, displayed the highest accuracy in identifying the clinical groups. Additional exploratory analyses suggested that the disease signatures were highly influenced by sex. Therefore, sex differentially impacted status of systemic inflammation, immune activation and tissue remodeling in children with distinct clinical forms of TB. Regardless of such nuances related to biological sex, MMP-7, CRP and LBP were strong discriminators of active TB and thus could be considered as biomarkers useful in discrimination different TB clinical forms. These observations have implications on our understanding of the immunopathology of both clinical forms of TB in pediatric patients. If validated by other studies in the future, the combination of identified biomarkers may help development of point-of-care diagnostic or prognostic tools.

Systemic RAGE ligands are upregulated in tuberculosis individuals with diabetes co-morbidity and modulated by anti-tuberculosis treatment and metformin therapy.

BACKGROUND: Ligands of the receptor for advanced glycation end products (RAGE) are key signalling molecules in the innate immune system but their role in tuberculosis-diabetes comorbidity (TB-DM) has not been investigated. METHODS: We examined the systemic levels of soluble RAGE (sRAGE), advanced glycation end products (AGE), S100A12 and high mobility group box 1 (HMGB1) in participants with either TB-DM, TB, DM or healthy controls (HC). RESULTS: Systemic levels of AGE, sRAGE and S100A12 were significantly elevated in TB-DM and DM in comparison to TB and HC. During follow up, AGE, sRAGE and S100A12 remained significantly elevated in TB-DM compared to TB at 2nd month and 6th month of anti-TB treatment (ATT). RAGE ligands were increased in TB-DM individuals with bilateral and cavitary disease. sRAGE and S100A12 correlated with glycated hemoglobin levels. Within the TB-DM group, those with known diabetes (KDM) revealed significantly increased levels of AGE and sRAGE compared to newly diagnosed DM (NDM). KDM participants on metformin treatment exhibited significantly diminished levels of AGE and sRAGE in comparison to those on non-metformin regimens. CONCLUSIONS: Our data demonstrate that RAGE ligand levels reflect disease severity and extent in TB-DM, distinguish KDM from NDM and are modulated by metformin therapy.

Heightened Systemic Levels of Neutrophil and Eosinophil Granular Proteins in Pulmonary Tuberculosis and Reversal following Treatment.

Granulocytes are activated during Mycobacterium tuberculosis infection and act as immune effector cells, and granulocyte responses are implicated in tuberculosis (TB) pathogenesis. Plasma levels of neutrophil and eosinophil granular proteins provide an indirect measure of degranulation. In this study, we wanted to examine the levels of neutrophil and eosinophil granular proteins in individuals with pulmonary tuberculosis (PTB) and to compare them with the levels in individuals with latent TB (LTB). Hence, we measured the plasma levels of myeloperoxidase (MPO), neutrophil elastase, proteinase 3, major basic protein (MBP), eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), and eosinophil peroxidase (EPX) in these individuals. Finally, we also measured the levels of all of these proteins in PTB individuals following antituberculosis treatment (ATT). Our data reveal that PTB individuals are characterized by significantly higher plasma levels of MPO, elastase, proteinase 3, as well as MBP and EDN in comparison to those in LTB individuals. Our data also reveal that ATT resulted in the reversal of all of these changes, indicating an association with TB disease. Finally, our data show that the systemic levels of MPO and proteinase 3 can significantly discriminate PTB from LTB individuals. Thus, our data suggest that neutrophil and eosinophil granular proteins could play a potential role in the innate immune response and, therefore, the pathogenesis of pulmonary TB.

Intestinal Barrier Dysfunction and Microbial Translocation in Human Immunodeficiency Virus-Infected Pregnant Women Are Associated With Preterm Birth.

Background: Preterm birth (PTB) rates are high in human immunodeficiency virus (HIV)-infected populations, even when on treatment. Still, only a subset of all births in HIV-infected pregnant women result in PTB, suggesting that risk factors other than HIV infection itself are also important. Inflammation is a known risk factor in uninfected populations, but its role in HIV-infected population have not been studied; in addition, the immune pathways involved are not clear and noninvasive immune markers with predictive value are lacking. Our objective was to determine the association of select markers of inflammation with PTB in HIV-1-infected pregnant women. Methods: Within a randomized trial of pregnant women receiving nevirapine (Six-Week Extended-Dose Nevirapine [SWEN] trial), we nested a case-control study (n = 107; 26 cases, 81 controls) to determine the association of maternal inflammation with PTB. Cases were defined as PTB (<37 weeks' gestational age). We assessed inflammation by measuring plasma levels of markers of general inflammation (C-reactive protein [CRP]), intestinal barrier dysfunction (intestinal fatty acid binding protein [I-FABP]), and microbial translocation/monocyte activation (soluble CD14 [sCD14] and CD163 [sCD163]). Multivariable logistic regression was used to determine the odds of PTB per log2 increase of each marker. Results: In multivariable models, there was increased odds of PTB per unit increase of log2 sCD14 (adjusted odds ratio [aOR], 2.45; 95% confidence interval [CI], 1.24-4.86), log2 sCD163 (aOR, 3.87; 95% CI, 1.43-10.49), and log2 I-FABP (aOR, 2.28; 95% CI, 1.18-4.41) but not log2 CRP (aOR, 0.72; 95% CI, .48-1.09). Conclusions: Our results show that select immune markers can identify women at higher risk for PTB in HIV-1-infected populations and suggest that modulating gut barrier integrity and microbial translocation may affect PTB. Clinical Trials Registration: NCT00061321.

Modulation of Th1/Tc1 and Th17/Tc17 responses in pulmonary tuberculosis by IL-20 subfamily of cytokines.

Although IL-10 is known to be an important cytokine in the immune response to TB, very little is known about the role of IL-20 subfamily of cytokines in the host response to TB. To identify the role of CD4+ T and CD8+ T cells producing IL-20 subfamily of cytokines in human TB, we enumerated the frequencies of IL-10, IL-19 and IL-24 expressing CD4+ and CD8+ T cells following Mtb-specific antigen stimulation of cells from individuals with pulmonary TB (PTB) and latent TB (LTB). We first demonstrated that Mtb-specific antigen induce an expansion of CD4+ and CD8+ T cells expressing IL-10, IL-19 and IL-24 in PTB and LTB individuals, with frequencies being significantly higher in PTB. Next, we demonstrated that IL-10, IL-19 and IL-24 play an important role in the regulation of CD4+ and CD8+ T cells expressing Th1/Tc1 and Th17/Tc17 cytokines in PTB but not LTB individuals. Thus, active PTB is characterized by an IL-10, IL-19 and IL-24 mediated down modulation of Th1/Tc1 and/or Th17/Tc17 cytokines in CD4+ and CD8+ T cell subsets. This suggests that the IL-20 subfamily of cytokines, similar to IL-10 might play a potentially crucial role in the modulation of T cell responses in active TB disease.

Diminished circulating plasma and elevated lymph node culture supernatant levels of IL-10 family cytokines in tuberculous lymphadenitis.

BACKGROUND: IL-10 family cytokines are associated with the host immune response to pulmonary tuberculosis (PTB), but their association with host response in tuberculous lymphadenitis (TBL) is not known. METHODS: Hence, we examined the circulating levels of the whole panel of IL-10 family cytokines in TBL (n = 44) and compared them to the levels in PTB (n = 44) and healthy control (HC, n = 44) individuals. We also assessed the pre and post-treatment cytokine levels in TBL individuals following the completion of anti-tuberculosis treatment (ATT). Next, we also compared the levels of IL-10 family cytokine in circulation versus lymph node (LN) culture supernatants in a subset of TBL individuals (n = 22). Finally, we also measured the levels of IL-10 family cytokines in tuberculosis antigen (purified protein derivative, PPD) stimulated and unstimulated LN culture supernatants. RESULTS: TBL individuals exhibit significantly decreased levels of IL-10, IL-19, IL-20, IL-24, IL-28B and IL-29 in the circulation when compared to PTB (except IL-10) and HC (except IL-20 and IL-28B) and significantly increased levels of IL-22 when compared to PTB individuals. Following ATT, TBL individuals exhibit significantly elevated levels of IL-10, IL-19, IL-20, IL-24, IL-28B and IL-29 and significantly diminished levels of IL-26. Similarly, TBL individuals also exhibited significantly increased levels of IL-10, IL-19, IL-20, IL-24, IL-28A and IL-29 in LN culture supernatants compared to plasma and significantly decreased levels of IL-22. This was associated with enhanced levels of IL-19, IL-20, IL-24, IL-28B and IL-29 upon PPD stimulation of LN cultures. CONCLUSIONS: Therefore, we demonstrate that TBL is associated with significantly diminished plasma and elevated LN culture supernatant levels of most of the IL-10 family cytokines. This to our knowledge is the first comprehensive examination of IL-10 family cytokines in TBL.

Influence of diabetes mellitus on immunity to human tuberculosis.

Type 2 diabetes mellitus(DM) is a major risk factor for the development of active pulmonary tuberculosis (TB), with development of DM pandemic in countries where TB is also endemic. Understanding the impact of DM on TB and the determinants of co-morbidity is essential in responding to this growing public health problem with improved therapeutic approaches. Despite the clinical and public health significance posed by the dual burden of TB and DM, little is known about the immunological and biochemical mechanisms of susceptibility. One possible mechanism is that an impaired immune response in patients with DM facilitates either primary infection with Mycobacterium tuberculosis or reactivation of latent TB. Diabetes is associated with immune dysfunction and alterations in the components of the immune system, including altered levels of specific cytokines and chemokines. Some effects of DM on adaptive immunity that are potentially relevant to TB defence have been identified in humans. In this review, we summarize current findings regarding the alterations in the innate and adaptive immune responses and immunological mechanisms of susceptibility of patients with DM to M. tuberculosis infection and disease.

Coincident diabetes mellitus modulates Th1-, Th2-, and Th17-cell responses in latent tuberculosis in an IL-10- and TGF-ß-dependent manner.

Type 2 diabetes mellitus (DM) is a risk factor for the development of active tuberculosis (TB), although its role in the TB-induced responses in latent TB (LTB) is not well understood. Since Th1, Th2, and Th17 responses are important in immunity to LTB, we postulated that coincident DM could alter the function of these CD4(+) T-cell subsets. To this end, we examined mycobacteria-induced immune responses in the whole blood of individuals with LTB-DM and compared them with responses of individuals without DM (LTB-NDM). T-cell responses from LTB-DM are characterized by diminished frequencies of mono- and dual-functional CD4(+) Th1, Th2, and Th17 cells at baseline and following stimulation with mycobacterial antigens-purified protein derivative, early secreted antigen-6, and culture filtrate protein-10. This modulation was at least partially dependent on IL-10 and TGF-ß, since neutralization of either cytokine resulted in significantly increased frequencies of Th1 and Th2 cells but not Th17 cells in LTB-DM but not LTB individuals. LTB-DM is therefore characterized by diminished frequencies of Th1, Th2, and Th17 cells, indicating that DM alters the immune response in latent TB leading to a suboptimal induction of protective CD4(+) T-cell responses, thereby providing a potential mechanism for increased susceptibility to active disease.

Impaired Cytokine but Enhanced Cytotoxic Marker Expression in Mycobacterium tuberculosis-Induced CD8+ T Cells in Individuals With Type 2 Diabetes and Latent Mycobacterium tuberculosis Infection.

Type 2 diabetes mellitus (DM) is a risk factor for tuberculosis among individuals with latent Mycobacterium tuberculosis infection. To explore the influence of DM on CD8(+) T-cell responses during latent M. tuberculosis infection, we estimated the cytokine and cytotoxic marker expression pattern in individuals with latent M. tuberculosis infection with DM and those with latent M. tuberculosis infection without DM. Among individuals with latent M. tuberculosis infection, those with DM had diminished frequencies of CD8(+) T-helper type 1 (Th1), Th2, and Th17 cells following stimulation by M. tuberculosis antigen and enhanced frequencies of CD8(+) T cells expressing cytotoxic markers, compared with those without DM. Thus, our results suggest that coincident DM modulates CD8(+) T-cell function during latent M. tuberculosis infection.

Helminth infections coincident with active pulmonary tuberculosis inhibit mono- and multifunctional CD4+ and CD8+ T cell responses in a process dependent on IL-10.

Tissue invasive helminth infections and tuberculosis (TB) are co-endemic in many parts of the world and can trigger immune responses that might antagonize each other. We have previously shown that helminth infections modulate the Th1 and Th17 responses to mycobacterial-antigens in latent TB. To determine whether helminth infections modulate antigen-specific and non-specific immune responses in active pulmonary TB, we examined CD4(+) and CD8(+) T cell responses as well as the systemic (plasma) cytokine levels in individuals with pulmonary TB with or without two distinct helminth infections-Wuchereria bancrofti and Strongyloides stercoralis infection. By analyzing the frequencies of Th1 and Th17 CD4(+) and CD8(+) T cells and their component subsets (including multifunctional cells), we report a significant diminution in the mycobacterial-specific frequencies of mono- and multi-functional CD4(+) Th1 and (to a lesser extent) Th17 cells when concomitant filarial or Strongyloides infection occurs. The impairment in CD4(+) and CD8(+) T cell cytokine responses was antigen-specific as polyclonal activated T cell frequencies were equivalent irrespective of helminth infection status. This diminution in T cell responses was also reflected in diminished circulating levels of Th1 (IFN-γ, TNF-α and IL-2)- and Th17 (IL-17A and IL-17F)-associated cytokines. Finally, we demonstrate that for the filarial co-infections at least, this diminished frequency of multifunctional CD4(+) T cell responses was partially dependent on IL-10 as IL-10 blockade significantly increased the frequencies of CD4(+) Th1 cells. Thus, co-existent helminth infection is associated with an IL-10 mediated (for filarial infection) profound inhibition of antigen-specific CD4(+) T cell responses as well as protective systemic cytokine responses in active pulmonary TB.

Mycobacterium tuberculosis dysregulates MMP/TIMP balance to drive rapid cavitation and unrestrained bacterial proliferation.

Active tuberculosis (TB) often presents with advanced pulmonary disease, including irreversible lung damage and cavities. Cavitary pathology contributes to antibiotic failure, transmission, morbidity and mortality. Matrix metalloproteinases (MMPs), in particular MMP-1, are implicated in TB pathogenesis. We explored the mechanisms relating MMP/TIMP imbalance to cavity formation in a modified rabbit model of cavitary TB. Our model resulted in consistent progression of consolidation to human-like cavities (100% by day 28), with resultant bacillary burdens (>10(7) CFU/g) far greater than those found in matched granulomatous tissue (10(5) CFU/g). Using a novel, breath-hold computed tomography (CT) scanning and image analysis protocol, we showed that cavities developed rapidly from areas of densely consolidated tissue. Radiological change correlated with a decrease in functional lung tissue, as estimated by changes in lung density during controlled pulmonary expansion (R(2) = 0.6356, p < 0.0001). We demonstrated that the expression of interstitial collagenase (MMP-1) was specifically greater in cavitary compared to granulomatous lesions (p < 0.01), and that TIMP-3 significantly decreased at the cavity surface. Our findings demonstrated that an MMP-1/TIMP imbalance is associated with the progression of consolidated regions to cavities containing very high bacterial burdens. Our model provided mechanistic insight, correlating with human disease at the pathological, microbiological and molecular levels. It also provided a strategy to investigate therapeutics in the context of complex TB pathology. We used these findings to predict a MMP/TIMP balance in active TB and confirmed this in human plasma, revealing the potential of MMP/TIMP levels as key components of a diagnostic matrix aimed at distinguishing active from latent TB (PPV = 92.9%, 95% CI 66.1-99.8%, NPV = 85.6%; 95% CI 77.0-91.9%).

Profiling leucocyte subsets in tuberculosis-diabetes co-morbidity.

The immune system plays an important role in the pathogenesis of pulmonary tuberculosis-type 2 diabetes mellitus (PTB-DM) co-morbidity. However, the phenotypic profile of leucocyte subsets at homeostasis in individuals with active or latent tuberculosis (LTB) with coincident diabetes is not known. To characterize the influence of diabetes on leucocyte phenotypes in PTB or LTB, we examined the frequency (Fo ) of leucocyte subsets in individuals with TB with (PTB-DM) or without (PTB) diabetes; individuals with latent TB with (LTB-DM) or without (LTB) diabetes and non-TB-infected individuals with (NTB-DM) or without (NTB) diabetes. Coincident DM is characterized by significantly lower Fo of effector memory CD4(+) T cells in LTB individuals. In contrast, DM is characterized by significantly lower Fo of effector memory CD8(+) T cells and significantly higher Fo of central memory CD8(+) T cells in PTB individuals. Coincident DM resulted in significantly higher Fo of classical memory B cells in PTB and significantly higher Fo of activated memory and atypical B cells in LTB individuals. Coincident DM resulted in significantly lower Fo of classical and intermediate monocytes in PTB, LTB and NTB individuals. Finally, DM resulted in significantly lower Fo of myeloid and plasmacytoid dendritic cells in PTB, LTB and NTB individuals. Our data reveal that coincident diabetes alters the cellular subset distribution of T cells, B cells, dendritic cells and monocytes in both individuals with active TB and those with latent TB, thus potentially impacting the pathogenesis of this co-morbid condition.

Diminished systemic and antigen-specific type 1, type 17, and other proinflammatory cytokines in diabetic and prediabetic individuals with latent Mycobacterium tuberculosis infection.

BACKGROUND: Diabetes mellitus type 2 (DM) is known to be a major risk factor for the development of active tuberculosis, although its influence on latent Mycobacterium tuberculosis infection (hereafter, "latent infection") remains poorly characterized. METHODS: We examined circulating plasma cytokine levels in individuals with latent infection with DM or pre-DM (ie, intermediate hyperglycemia) and compared them to levels in patients with latent infection and normal glycemic control. RESULTS: In persons with DM or pre-DM, latent infection is characterized by diminished circulating levels of type 1 (interferon γ, interleukin 2, and tumor necrosis factor α) and type 17 (interleukin 17F) cytokines. This was associated with decreased systemic levels of other proinflammatory cytokines (interleukin 1ß and interleukin 18) and the antiinflammatory cytokine interleukin 10 but not with decreased systemic levels of type 2 cytokines. Moreover, latently infected individuals with DM had diminished levels of spontaneous and M. tuberculosis antigen-specific levels of type 1 and type 17 cytokines when antigen-stimulated whole blood was examined. Finally, there was no significant correlation between the levels of any of the cytokines measured (with the exception of interleukin 22) with hemoglobin A1c levels. CONCLUSIONS: Our data reveal that latent infection in the presence of DM or pre-DM, is characterized by diminished production of cytokines, implicated in the control of M. tuberculosis activation, allowing for a potential immunological mechanism that could account for the increased risk of active tuberculosis in latently infected individuals with DM.