25 research outputs found
Augmented chemokine levels and chemokine receptor expression on immune cells during pulmonary tuberculosis
The systemic changes in immune mediators such as cytokine and chemokines, and their synchronized
interaction that regulates the cell trafficking during Mycobacterium tuberculosis (M. tuberculosis) infection,
were studied. Cytokines and chemokines were evaluated by cytometric bead array (CBA) and enzyme-linked
immunosorbent assay (ELISA) in 34 pulmonary tuberculosis (PTB) patients and 30 healthy subjects. The
expression of chemokine receptors was assessed by flow cytometry. A significant increase in IP-10, MIG,
interleukin-8, RANTES, and interleukin-6 levels was found, whereas a decrease in interferon-�, tumor
necrosis factor–�, and transforming growth factor–� was observed during PTB. Significant correlation within
chemokines and between cytokines was observed in PTB. All immune cells except monocytes and B cells
expressed significantly higher levels of CCR1, CCR2, and CXCR2 whereas CCR7 expression was upregulated
only on monocytes and neutrophils in PTB. Both T and B cells expressed significantly high levels of CXCR3
which also correlated well with the chemokine levels in PTB. Thus, it was found that chemokines function
coordinately and consistently during PTB. This balanced chemokine and cytokine relationship at the periphery
may aid in amplified effector immune cell trafficking and retarded monocyte migration through differential
chemokine receptor expression
Di¡erential upregulation of chemokine receptors onCD561NKcells and their transmigration tothe site of infection in tuberculous pleurisy
Chemokines and their receptors orchestrate leukocyte recruitment and confer
immunity during Mycobacterium tuberculosis infection. The immunoregulatory
and cytotoxic activities of natural killer (NK) cells are essential at the site of
infection during tuberculous pleurisy. The frequency, subtypes, and expression of
phenotype markers and chemokine receptors on NK cells were assessed by flow
cytometry in tuberculous (TB) and nontuberculous (NTB) pleural fluid (PF).
Chemotaxis was also shown in response to chemokines. A significant decrease in
CD56dim with no change in CD56bright NK cells was observed, while a significant
increase in activation markers and Toll-like receptors (TLRs) was observed on TBPF
CD56bright NK cells. Significantly increased expression of chemokine receptors
CCR1, CCR2 and CCR7 on CD56bright and CCR5 on CD56dim NK cells was
observed in the TB group. Transmigration of TB-PF NK cells was significantly high
in response to IL-8, IP-10, MCP-1 and SLC. Transmigrated TB-NK cells showed a
significant increase in CXCR2, CCR2 and CCR7 expression. The study suggests
that CD56bright NK cells may recognize M. tuberculosis directly using TLRs, HLADR
and express CD69 as an early activation marker. In addition, CC chemokines
induce activation signals in chemokine receptors mediating differential NK cell
migration to the site. Thus, NK cells act as first direct sensors and effectors in
mycobacterial infection
Phenotypic modulation in Mycobacterium tuberculosis infected neutrophil during tuberculosis
Background & objectives: Polymorphonuclear leucocytes (PMN) or neutrophils infiltrate to the
inflammatory sites and phagocytose mycobacteria thereby inhibiting the bacillary spread initially
until the accumulated macrophages get activated. The present study was carried out to highlight the
interaction of neutrophils with the two clinical isolates (S7 and S10) of Mycobacterium tuberculosis and
the subsequent morphological changes.
Methods: Dextran purified neutrophils from normal and TB patients infected with M. tuberculosis\ud
isolates were cultured for 3 and 18 h time points. At the end of termination, the cell surface expression
of CD16, CD69, CXCR2 and induction of apoptosis were analyzed using flow cytometry. Cytokines and
chemokines were estimated in supernatants by ELISA.
Results: All infected PMN showed decrease in CD16 at both time points in normals while at 18 h in TB
group. Interestingly, CD69 expression was significantly high at early time point in TB-PMN compared
to normals. The high expression of CXCR2 was sustained in infected TB-PMN at both the time points.
S7 and S10 infected neutrophils showed high phagocytic indices compared to H37Rv in both the groups.
A significant increase in apoptosis was observed at both the time points in infected TB-PMN but only
at 18 h in normals. Increased pro-inflammatory cytokine (TNF-α) and chemokine (IL-8) response was
observed in infected neutrophils at 3 h in both the groups.
Interpretation & conclusions: This study demonstrates the varying degree of modulation of neutrophil
functions in both the groups. TB-PMN was more competent in amplifying the innate immune response
and conferring protection at the early phase of infection. However, the response was not strain specific
in either of these groups
Pharmacologic exhaustion of suppressor cells with tasquinimod enhances bacterial clearance during tuberculosis
Pharmacologic Exhaustion of Suppressor Cells with Tasquinimod Enhances Bacterial Clearance during Tuberculosis
Matrix metalloproteinase inhibition in a murine model of cavitary tuberculosis paradoxically worsens pathology
Matrix metalloproteinases (MMPs) degrade extracellular matrix and are implicated in tuberculosis (TB) pathogenesis and cavitation. In particular, MMP-7 is induced by hypoxia and highly expressed around pulmonary cavities of Mycobacterium tuberculosis-infected C3HeB/FeJ mice. In this study, we evaluated whether administration of cipemastat, an orally available potent inhibitor of MMP-7, could reduce pulmonary cavitation in M. tuberculosis-infected C3HeB/FeJ mice. We demonstrate that compared to untreated controls, cipemastat treatment paradoxically increases the frequency of cavitation (32% versus 7%; P = 0.029), immunopathology andmortality. Further studies are needed to understand the role of MMP inhibitors as adjunctive treatments for pulmonary TB.<br/
Matrix metalloproteinase inhibition in a murine model of cavitary tuberculosis paradoxically worsens pathology
Matrix metalloproteinases (MMPs) degrade extracellular matrix and are implicated in tuberculosis (TB) pathogenesis and cavitation. In particular, MMP-7 is induced by hypoxia and highly expressed around pulmonary cavities of Mycobacterium tuberculosis-infected C3HeB/FeJ mice. In this study, we evaluated whether administration of cipemastat, an orally available potent inhibitor of MMP-7, could reduce pulmonary cavitation in M. tuberculosis-infected C3HeB/FeJ mice. We demonstrate that compared to untreated controls, cipemastat treatment paradoxically increases the frequency of cavitation (32% versus 7%; P = 0.029), immunopathology andmortality. Further studies are needed to understand the role of MMP inhibitors as adjunctive treatments for pulmonary TB.<br/
Lipopolysaccharide Inhibits Sindbis Virus-Induced IP-10 Release in Human Peripheral Blood Mononuclear Cells
Chemokines play a pivotal role in the innate response to both bacterial and viral infections, and in mixed infections. To determine chemokine responses to Sindbis virus (SIN) in a co-infection model, peripheral blood mononuclear cells (PBMCs) derived from healthy volunteers were exposed to SIN in the presence and absence of lipopolysaccharide (LPS). Culture supernatants recovered at 2, 24, and 72 h post-exposure were evaluated for virus replication and analyzed for chemokines by ELISA. None of the PBMC cultures showed new virus release, GFP reporter expression, or viral RNA synthesis. While SIN had little effect on the induction of IL-8 and RANTES, the chemokines MCP-1, MIP1-α (p < 0.001), and MIP1-β (p < 0.0004) were drastically upregulated by SIN as well as LPS. Both live and UV-inactivated SIN induced secretion of IP-10 and I-TAC. Although LPS did not induce release of IP-10, it sharply inhibited (p = 0.004) SIN-mediated IP-10 secretion. On the contrary, the release of SLC was blocked by SIN. The adjuvant activity of IP-10, its antiangiogenic function, and antagonism between SIN and LPS for the release of select chemokines may be useful in understanding the pathogenesis of mixed infections, cross-talk between cellular pathways, and may have applications in cancer and sepsis
Microglia activation in a pediatric rabbit model of tuberculous meningitis
Central nervous system (CNS) tuberculosis (TB) is the most severe form of extra-pulmonary TB and disproportionately affects young children where the developing brain has a unique host response. New Zealand white rabbits were infected with Mycobacterium tuberculosis via subarachnoid inoculation at postnatal day 4-8 and evaluated until 4-6 weeks post-infection. Control and infected rabbit kits were assessed for the development of neurological deficits, bacterial burden, and postmortem microbiologic and pathologic changes. The presence of meningitis and tuberculomas was demonstrated histologically and by in vivo magnetic resonance imaging (MRI). The extent of microglial activation was quantified by in vitro immunohistochemistry as well as non-invasive in vivo imaging of activated microglia/macrophages with positron emission tomography (PET). Subarachnoid infection induced characteristic leptomeningeal and perivascular inflammation and TB lesions with central necrosis, a cellular rim and numerous bacilli on pathologic examination. Meningeal and rim enhancement was visible on MRI. An intense microglial activation was noted in M. tuberculosis-infected animals in the white matter and around the TB lesions, as evidenced by a significant increase in uptake of the tracer 124I-DPA-713, which is specific for activated microglia/macrophages, and confirmed by quantification of Iba-1 immunohistochemistry. Neurobehavioral analyses demonstrated signs similar to those noted in children with delayed maturation and development of neurological deficits resulting in significantly worse composite behavior scores in M. tuberculosis-infected animals. We have established a rabbit model that mimics features of TB meningitis in young children. This model could provide a platform for evaluating novel therapies, including host-directed therapies, against TB meningitis relevant to a young child's developing brain
Mouse model of pulmonary cavitary tuberculosis and expression of matrix metalloproteinase-9
Cavitation is a key pathological feature of human tuberculosis (TB), and is a well-recognized risk factor for transmission of infection, relapse after treatment and the emergence of drug resistance. Despite intense interest in the mechanisms underlying cavitation and its negative impact on treatment outcomes, there has been limited study of this phenomenon, owing in large part to the limitations of existing animal models. Although cavitation does not occur in conventional mouse strains after infection with Mycobacterium tuberculosis, cavitary lung lesions have occasionally been observed in C3HeB/FeJ mice. However, to date, there has been no demonstration that cavitation can be produced consistently enough to support C3HeB/FeJ mice as a new and useful model of cavitary TB. We utilized serial computed tomography (CT) imaging to detect pulmonary cavitation in C3HeB/FeJ mice after aerosol infection with M. tuberculosis. Post-mortem analyses were performed to characterize lung lesions and to localize matrix metalloproteinases (MMPs) previously implicated in cavitary TB in situ. A total of 47-61% of infected mice developed cavities during primary disease or relapse after non-curative treatments. Key pathological features of human TB, including simultaneous presence of multiple pathologies, were noted in lung tissues. Optical imaging demonstrated increased MMP activity in TB lesions and MMP-9 was significantly expressed in cavitary lesions. Tissue MMP-9 activity could be abrogated by specific inhibitors. In situ, three-dimensional analyses of cavitary lesions demonstrated that 22.06% of CD11b+ signal colocalized with MMP-9. C3HeB/FeJ mice represent a reliable, economical and tractable model of cavitary TB, with key similarities to human TB. This model should provide an excellent tool to better understand the pathogenesis of cavitation and its effects on TB treatments