PGE2 displays immunosuppressive effects during human active tuberculosis

New insights into immune cells in cancer immunotherapy: from epigenetic modification, metabolic modulation to cell communication

Cancer is one of the leading causes of death worldwide, and more effective ways of attacking cancer are being sought. Cancer immunotherapy is a new and effective therapeutic method after surgery, radiotherapy, chemotherapy, and targeted therapy. Cancer immunotherapy aims to kill tumor cells by stimulating or rebuilding the body's immune system, with specific efficiency and high safety. However, only few tumor patients respond to immunotherapy and due to the complex and variable characters of cancer immune escape, the behavior and regulatory mechanisms of immune cells need to be deeply explored from more dimensions. Epigenetic modifications, metabolic modulation, and cell-to-cell communication are key factors in immune cell adaptation and response to the complex tumor microenvironment. They collectively determine the state and function of immune cells through modulating gene expression, changing in energy and nutrient demands. In addition, immune cells engage in complex communication networks with other immune components, which are mediated by exosomes, cytokines, and chemokines, and are pivotal in shaping the tumor progression and therapeutic response. Understanding the interactions and combined effects of such multidimensions mechanisms in immune cell modulation is important for revealing the mechanisms of immunotherapy failure and developing new therapeutic targets and strategies.

The Cyclooxygenase 2 Inhibitor Etoricoxib as Adjunctive Therapy in Tuberculosis Impairs Macrophage Control of Mycobacterial Growth

BACKGROUND

Current tuberculosis treatment regimens could be improved by adjunct host-directed therapies (HDT) targeting host responses. We investigated the antimycobacterial capacity of macrophages from patients with tuberculosis in a phase 1/2 randomized clinical trial (TBCOX2) of the cyclooxygenase-2 inhibitor etoricoxib.

METHODS

Peripheral blood mononuclear cells from 15 patients with tuberculosis treated with adjunctive COX-2i and 18 controls (standard therapy) were collected on day 56 after treatment initiation. The ex vivo capacity of macrophages to control mycobacterial infection was assessed by challenge with Mycobacterium avium, using an in vitro culture model. Macrophage inflammatory responses were analyzed by gene expression signatures, and concentrations of cytokines were analyzed in supernatants by multiplex.

RESULTS

Macrophages from patients receiving adjunctive COX-2i treatment had higher M. avium loads than controls after 6 days, suggesting an impaired capacity to control mycobacterial infection compared to macrophages from the control group. Macrophages from the COX-2i group had lower gene expression of TNF, IL-1B, CCL4, CXCL9, and CXCL10 and lowered production of cytokines IFN-β and S100A8/A9 than controls.

CONCLUSIONS

Our data suggest potential unfavorable effects with impaired macrophage capacity to control mycobacterial growth in patients with tuberculosis receiving COX-2i treatment. Larger clinical trials are required to analyze the safety of COX-2i as HDT in patients with tuberculosis.

CLINICAL TRIALS REGISTRATION

NCT02503839.

Harnessing host-pathogen interactions for innovative drug discovery and host-directed therapeutics to tackle tuberculosis

Tuberculosis (TB) is a highly contagious bacterial infection caused by Mycobacterium tuberculosis (Mtb), which has been ranked as the second leading cause of death worldwide from a single infectious agent. As an intracellular pathogen, Mtb has well adapted to the phagocytic host microenvironment, influencing diverse host processes such as gene expression, trafficking, metabolism, and signaling pathways of the host to its advantage. These responses are the result of dynamic interactions of the bacteria with the host cell signaling pathways, whereby the bacteria attenuate the host cellular processes for their survival. Specific host genes and the mechanisms involved in the entry and subsequent stabilization of M. tuberculosis intracellularly have been identified in various genetic and chemical screens recently. The present understanding of the co-evolution of Mtb and macrophage system presented us the new possibilities for exploring host-directed therapeutics (HDT). Here, we discuss the host-pathogen interaction for Mtb, including the pathways adapted by Mtb to escape immunity. The review sheds light on different host-directed therapies (HDTs) such as repurposed drugs and vitamins, along with their targets such as granuloma, autophagy, extracellular matrix, lipids, and cytokines, among others. The article also examines the available clinical data on these drug molecules. In conclusion, the review presents a perspective on the current knowledge in the field of HDTs and the need for additional research to overcome the challenges associated HDTs.

Expression of Prostaglandin Genes and β-Catenin in Whole Blood as Potential Markers of Muscle Degeneration

Prostaglandin signaling pathways are closely related to inflammation, but also muscle regeneration and processes associated with frailty and sarcopenia, whereas β-catenin (CTNNB1 gene) as a part of Wnt signaling is also involved in the differentiation of muscle cells and fibrosis. The present study analyzed the association between selected prostaglandin pathway genes and clinical parameters in patients with sarcopenia and frailty syndrome. The present study was conducted on patients with sarcopenia, frailty syndrome, and control older patients (N = 25). Additionally, two healthy controls at the age of 25-30 years (N = 51) and above 50 years old (N = 42) were included. The expression of the PTRGER4, PTGES2 (COX2), PTGS2, and CTNNB1 genes in whole blood was checked by the qPCR method. The serum cytokine levels (IL-10, TNFα, IFN-y, IL-1α, IL-1β) in patients and controls were checked by the Q-Plex Human Cytokine Panel. The results showed a significant effect of age on PTGER4 gene expression (p = 0.01). A negative trend between the appendicular skeletal muscle mass parameter (ASSM) and the expression of PTGER4 has been noted (r = -0.224, p = 0.484). PTGES2 and PTGS2 expressions negatively correlated with creatine phosphokinase (r = -0.71, p = 0.009; r = -0.58, p = 0.047) and positively with the functional mobility test timed up and go scale (TUG) (r = 0.61, p = 0.04; r = 0.63, p = 0.032). In the older control group, a negative association between iron levels and the expression of PTGS2 (r = -0.47, p = 0.017) was observed. A similar tendency was noted in patients with sarcopenia (r = -0.112, p = 0.729). A negative trend between appendicular skeletal muscle mass (ASMM) and PTGER4 seems to confirm the impairment of muscle regeneration associated with sarcopenia. The expression of the studied genes revealed a trend in associations with the clinical picture of muscular dystrophy and weakening patients. Perhaps PTGS2 and PTGES2 is in opposition to the role of the PTGER4 receptor in muscle physiology. Nevertheless, further, including functional studies is needed.

Dynamics of inflammatory cytokine expression in bovine endometrial cells exposed to cow blood plasma small extracellular vesicles (sEV) may reflect high fertility

Aberrant inflammation in the endometrium impairs reproduction and leads to poor fertility. Small extracellular vesicles (sEV) are nanoparticles 30-200 nm in-size and contain transferable bioactive molecules that reflect the parent cell. Holstein-Friesian dairy cows with divergent genetic merit, high- (n = 10) and low-fertile (n = 10), were identified based on fertility breeding value (FBV), cow ovulation synchronization and postpartum anovulatory intervals (PPAI). In this study, we evaluated the effects of sEVs enriched from plasma of high-fertile (HF-EXO) and low-fertile (LF-EXO) dairy cows on inflammatory mediator expression by bovine endometrial epithelial (bEEL) and stromal (bCSC) cells. Exposure to HF-EXO in bCSC and bEEL cells yielded lower expression of PTGS1 and PTGS2 compared to the control. In bCSC cells exposed to HF-EXO, pro-inflammatory cytokine IL1-α was downregulated compared to the untreated control, IL-12α and IL-8 were downregulated compared to the LF-EXO treatment. Our findings demonstrate that sEVs interact with both endometrial epithelial and stromal cells to initiate differential gene expression, specifically genes relate to inflammation. Therefore, even subtle changes on the inflammatory gene cascade in the endometrium via sEV may affect reproductive performance and/or outcomes. Further, sEV from high-fertile animals acts in a unique direction to deactivate prostaglandin synthases in both bCSC and bEEL cells and deactivate pro-inflammatory cytokines in the endometrial stroma. The results suggest that circulating sEV may serve as a potential biomarker of fertility.

Inflammation-mediated tissue damage in pulmonary tuberculosis and host-directed therapeutic strategies

Treatment of tuberculosis (TB) involves the administration of anti-mycobacterial drugs for several months. The emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb, the causative agent) together with increased disease severity in people with co-morbidities such as diabetes mellitus and HIV have hampered efforts to reduce case fatality. In severe disease, TB pathology is largely attributable to over-exuberant host immune responses targeted at controlling bacterial replication. Non-resolving inflammation driven by host pro-inflammatory mediators in response to high bacterial load leads to pulmonary pathology including cavitation and fibrosis. The need to improve clinical outcomes and reduce treatment times has led to a two-pronged approach involving the development of novel antimicrobials as well as host-directed therapies (HDT) that favourably modulate immune responses to Mtb. HDT strategies incorporate aspects of immune modulation aimed at downregulating non-productive inflammatory responses and augmenting antimicrobial effector mechanisms to minimise pulmonary pathology and accelerate symptom resolution. HDT in combination with existing antimycobacterial agents offers a potentially promising strategy to improve the long-term outcome for TB patients. In this review, we describe components of the host immune response that contribute to inflammation and tissue damage in pulmonary TB, including cytokines, matrix metalloproteinases, lipid mediators, and neutrophil extracellular traps. We then proceed to review HDT directed at these pathways.

Effect of Dysglycemia on Urinary Lipid Mediator Profiles in Persons With Pulmonary Tuberculosis

Background

Oxidized lipid mediators such as eicosanoids play a central role in the inflammatory response associated with tuberculosis (TB) pathogenesis. Diabetes mellitus (DM) leads to marked changes in lipid mediators in persons with TB. However, the associations between diabetes-related changes in lipid mediators and clearance of M. tuberculosis (Mtb) among persons on anti-TB treatment (ATT) are unknown. Quantification of urinary eicosanoid metabolites can provide insights into the circulating lipid mediators involved in Mtb immune responses.

Methods

We conducted a multi-site prospective observational study among adults with drug-sensitive pulmonary TB and controls without active TB; both groups had sub-groups with or without dysglycemia at baseline. Participants were enrolled from RePORT-Brazil (Salvador site) and RePORT-South Africa (Durban site) and stratified according to TB status and baseline glycated hemoglobin levels: a) TB-dysglycemia (n=69); b) TB-normoglycemia (n=64); c) non-TB/dysglycemia (n=31); d) non-TB/non-dysglycemia (n=29). We evaluated the following urinary eicosanoid metabolites: 11α-hydroxy-9,15-dioxo-2,3,4,5-tetranor-prostane-1,20-dioic acid (major urinary metabolite of prostaglandin E2, PGE-M), tetranor-PGE₁ (metabolite of PGE2, TN-E), 9α-hydroxy-11,15-dioxo-2,3,4,5-tetranor-prostane-1,20-dioic acid (metabolite of PGD2, PGD-M), 11-dehydro-thromboxane B2 (11dTxB2), 2,3-dinor-6-keto-PGF₁α (prostaglandin I metabolite, PGI-M), and leukotriene E4 (LTE₄). Comparisons between the study groups were performed at three time points: before ATT and 2 and 6 months after initiating therapy.

Results

PGE-M and LTE₄ values were consistently higher at all three time-points in the TB-dysglycemia group compared to the other groups (p<0.001). In addition, there was a significant decrease in PGI-M and LTE₄ levels from baseline to month 6 in the TB-dysglycemia and TB-normoglycemia groups. Finally, TB-dysglycemia was independently associated with increased concentrations of PGD-M, PGI-M, and LTE₄ at baseline in a multivariable model adjusting for age, sex, BMI, and study site. These associations were not affected by HIV status.

Conclusion

The urinary eicosanoid metabolite profile was associated with TB-dysglycemia before and during ATT. These observations can help identify the mechanisms involved in the pathogenesis of TB-dysglycemia, and potential biomarkers of TB treatment outcomes, including among persons with dysglycemia.

Immunosuppressive Mechanisms in Brucellosis in Light of Chronic Bacterial Diseases

Brucellosis is considered one of the major zoonoses worldwide, constituting a critical livestock and human health concern with a huge socio-economic burden. Brucella genus, its etiologic agent, is composed of intracellular bacteria that have evolved a prodigious ability to elude and shape host immunity to establish chronic infection. Brucella’s intracellular lifestyle and pathogen-associated molecular patterns, such as its specific lipopolysaccharide (LPS), are key factors for hiding and hampering recognition by the immune system. Here, we will review the current knowledge of evading and immunosuppressive mechanisms elicited by Brucella species to persist stealthily in their hosts, such as those triggered by their LPS and cyclic β-1,2-d-glucan or involved in neutrophil and monocyte avoidance, antigen presentation impairment, the modulation of T cell responses and immunometabolism. Attractive strategies exploited by other successful chronic pathogenic bacteria, including Mycobacteria, Salmonella, and Chlamydia, will be also discussed, with a special emphasis on the mechanisms operating in brucellosis, such as granuloma formation, pyroptosis, and manipulation of type I and III IFNs, B cells, innate lymphoid cells, and host lipids. A better understanding of these stratagems is essential to fighting bacterial chronic infections and designing innovative treatments and vaccines.

Mycobacterium tuberculosis-Induced Upregulation of the COX-2/mPGES-1 Pathway in Human Macrophages Is Abrogated by Sulfasalazine

Macrophages are the primary human host cells of intracellular Mycobacterium tuberculosis (M.tb) infection, where the magnitude of inflammatory reactions is crucial for determining the outcome of infection. Previously, we showed that the anti-inflammatory drug sulfasalazine (SASP) significantly reduced the M.tb bactericidal burden and histopathological inflammation in mice. Here, we asked which genes in human inflammatory macrophages are affected upon infection with M.tb and how would potential changes impact the functional state of macrophages. We used a flow cytometry sorting system which can distinguish the dead and alive states of M.tb harbored in human monocyte-derived macrophages (MDM). We found that the expression of cyclooxygenase-2 and microsomal prostaglandin E₂ synthase (mPGES)-1 increased significantly in tagRFP⁺ MDM which were infected with alive M.tb. After exposure of polarized M1-MDM to M.tb (H37Rv strain)-conditioned medium (MTB-CM) or to the M.tb-derived 19-kD antigen, the production of PGE₂ and pro-inflammatory cytokines increased 3- to 4-fold. Upon treatment of M1-MDM with SASP, the MTB-CM-induced expression of COX-2 and the release of COX products and cytokines decreased. Elevation of PGE₂ in M1-MDM upon MTB-CM stimulation and modulation by SASP correlated with the activation of the NF-κB pathway. Together, infection of human macrophages by M.tb strongly induces COX-2 and mPGES-1 expression along with massive PGE₂ formation which is abrogated by the anti-inflammatory drug SASP.

Shedding Light on Autophagy During Human Tuberculosis. A Long Way to Go

Immunity against Mycobacterium tuberculosis (Mtb) is highly complex, and the outcome of the infection depends on the role of several immune mediators with particular temporal dynamics on the host microenvironment. Autophagy is a central homeostatic mechanism that plays a role on immunity against intracellular pathogens, including Mtb. Enhanced autophagy in macrophages mediates elimination of intracellular Mtb through lytic and antimicrobial properties only found in autolysosomes. Additionally, it has been demonstrated that standard anti-tuberculosis chemotherapy depends on host autophagy to coordinate successful antimicrobial responses to mycobacteria. Notably, autophagy constitutes an anti-inflammatory mechanism that protects against endomembrane damage triggered by several endogenous components or infectious agents and precludes excessive inflammation. It has also been reported that autophagy can be modulated by cytokines and other immunological signals. Most of the studies on autophagy as a defense mechanism against Mycobacterium have been performed using murine models or human cell lines. However, very limited information exists about the autophagic response in cells from tuberculosis patients. Herein, we review studies that face the autophagy process in tuberculosis patients as a component of the immune response of the human host against an intracellular microorganism such as Mtb. Interestingly, these findings might contribute to recognize new targets for the development of novel therapeutic tools to combat Mtb. Actually, either as a potential successful vaccine or a complementary immunotherapy, efforts are needed to further elucidate the role of autophagy during the immune response of the human host, which will allow to achieve protective and therapeutic benefits in human tuberculosis.