IL-23 compensates for the absence of IL-12p70 and is essential for the IL-17 response during tuberculosis but is dispensable for protection and antigen-specific IFN-gamma responses if IL-12p70 is available

Safety of interleukin-17A inhibitors in 306 patients with psoriasis with or without latent tuberculosis: a dual-centre retrospective study in China

BACKGROUND

New interleukin (IL)-17A inhibitors seem to demonstrate smaller effects on tuberculosis (TB) reactivation than expected.

OBJECTIVES

To evaluate the risk of TB reactivation, to assess serial interferon (IFN)-γ levels, and to weigh up the risks and benefits of TB chemoprophylaxis in patients with psoriasis treated with IL-17A inhibitors.

METHODS

This dual-centre study included patients with psoriasis who were treated with IL-17A inhibitors. The incidence of active TB, serial IFN-γ levels tested by IFN-γ release assays (IGRAs), adverse events (AEs) and effectiveness were evaluated through 1 year in patients with psoriasis treated with IL-17A inhibitors. According to the chemoprophylaxis treatment regimen, patients with latent TB infection (LTBI) were classified into three groups: a complete chemoprophylaxis dose regimen (CCP), an incomplete chemoprophylaxis (ICCP) or no chemoprophylaxis (NCP).

RESULTS

In 220 IGRA-negative patients, 17 of 220 (7.3%) became IGRA positive after receiving a mean of 69.1 weeks of IL-17A inhibitor treatment. Only one case of new-onset TB was observed after 52 weeks of ixekizumab therapy. Significant changes in IFN-γ levels were observed in IGRA-negative patients. Similarly, IFN-γ levels [listed as the mean (SD)] significantly increased at 1 year compared with baseline among IGRA-positive patients in the NCP [105 (68.7) vs. 236 (80.8) pg mL-1, P < 0.01] and ICCP [75.3 (48.3) vs. 608 (249) pg mL-1, P < 0.001] groups, whereas the changes were not significant [125 (26.6) vs. 131 (21.7) pg mL-1, P = 0.70] in the CCP group.

CONCLUSIONS

During IL-17A inhibitor therapy, there is a need for increased awareness of annual screening and assessment of individual risk for early detection of TB infection. LTBI treatment is generally well tolerated and is effective in preventing increased IFN-γ responses in patients with psoriasis treated with IL-17A inhibitors.

Bacterial vaginosis associates with dysfunctional T cells and altered soluble immune factors in the cervicovaginal tract

BACKGROUNDBacterial vaginosis (BV) is a dysbiosis of the vaginal microbiome that is prevalent among reproductive-age females worldwide. Adverse health outcomes associated with BV include an increased risk of sexually acquired HIV, yet the immunological mechanisms underlying this association are not well understood.METHODSTo investigate BV-driven changes to cervicovaginal tract (CVT) and circulating T cell phenotypes, Kinga Study participants with or without BV provided vaginal tract (VT) and ectocervical (CX) tissue biopsies and PBMC samples.RESULTSHigh-parameter flow cytometry revealed an increased frequency of cervical CD4+ conventional T (Tconv) cells expressing CCR5 in BR+ versus BR- women. However, we found no difference in the number of CD3+CD4+CCR5+ cells in the CX or VT of BV+ versus BV- individuals, suggesting that BV-driven increased HIV susceptibility may not be solely attributed to increased CVT HIV target cell abundance. Flow cytometry also revealed that individuals with BV had an increased frequency of dysfunctional CX and VT CD39+ Tconv and CX tissue-resident CD69+CD103+ Tconv cells, reported to be implicated in HIV acquisition risk and replication. Many soluble immune factor differences in the CVT further support that BV elicits diverse and complex CVT immune alterations.CONCLUSIONOur comprehensive analysis expands on potential immunological mechanisms that may underlie the adverse health outcomes associated with BV, including increased HIV susceptibility.TRIAL REGISTRATIONClinicalTrials.gov NCT03701802.FUNDINGThis work was supported by National Institutes of Health grants R01AI131914, R01AI141435, and R01AI129715.

Safety of Interleukin Inhibitors in Psoriatic Patients with Latent Tuberculosis Infection Without Chemoprophylaxis: A Systematic Review

Current guidelines recommend psoriatic patients with latent tuberculosis infection undergo chemoprophylaxis prior to initiating any biologic. However, clinical studies indicate that interleukin (IL) inhibitors may not increase the risk of tuberculosis reactivation. This review evaluates the safety in psoriatic patients with latent tuberculosis infection using IL inhibitors without chemoprophylaxis. PubMed and EMBASE were searched up to 1 November 2024 in accordance with PRISMA. Fifteen studies, including one safety analysis of a clinical trial, 2 case series, and 12 retrospective studies were analysed. The included studies reported a total of 837 cases: 179 patients were treated with secukinumab, 69 with ixekizumab, 8 with brodalumab, 539 with risankizumab, 22 with guselkumab, and 20 with tildrakizumab. Psoriatic patients with latent tuberculosis infection using an IL-12/23 inhibitor without chemoprophylaxis were not found in this review. Three of the 837 cases exhibited reactivation of tuberculosis. The reactivation rate is 0.78% among psoriatic patients with latent tuberculosis infection using IL-17 inhibitors, and 0.17% among those using IL-23 inhibitors. Our analysis shows that IL-17 and IL-23 inhibitors do not increase the risk of tuberculosis activation in psoriatic patients with latent tuberculosis infection. The impact of IL-12/23 inhibitors on tuberculosis reactivation among psoriatic patients with latent tuberculosis infection remains uncertain and requires further investigation.

Bacterial vaginosis-driven changes in cervicovaginal immunity that expand the immunological hypothesis for increased HIV susceptibility

Bacterial vaginosis (BV) is a dysbiosis of the vaginal microbiome that is prevalent among reproductive-age females worldwide. Adverse health outcomes associated with BV include an increased risk of sexually-acquired HIV, yet the immunological mechanisms underlying this association are not well understood. To investigate BV-driven changes to cervicovaginal tract (CVT) and circulating T cell phenotypes, participants with or without BV provided vaginal tract (VT) and ectocervical (CX) tissue biopsies and PBMC samples. High-parameter flow cytometry revealed an increased frequency of cervical conventional CD4+ T cells (Tconv) expressing CCR5. However, we found no difference in number of CD3+CD4+CCR5+ cells in the CX or VT of BV+ vs BV- individuals, suggesting that BV-driven increased HIV susceptibility may not be solely attributed to increased CVT HIV target cell abundance. Flow cytometry also revealed that individuals with BV have an increased frequency of dysfunctional CX and VT CD39+ Tconv and CX tissue-resident CD69+CD103+ Tconv, reported to be implicated in HIV acquisition risk and replication. Many soluble immune factor differences in the CVT further support that BV elicits diverse and complex CVT immune alterations. Our comprehensive analysis expands on potential immunological mechanisms that may underlie the adverse health outcomes associated with BV including increased HIV susceptibility.

Treatment of psoriasis with biologic and non-biologic targeted therapies in patients with latent tuberculosis infection or at risk for tuberculosis disease progression: Recommendations from a SPIN-FRT expert consensus

Tuberculosis (TB), caused by Mycobacterium tuberculosis, is a significant global health problem. In immunocompetent individuals, the microorganism can remain in a latent, non-contagious form, however, it may become active under conditions of immunosuppression. Tumour necrosis factor (TNF) inhibitors, which are frequently used for the management of immune-mediated disorders like psoriasis, have been associated with a significantly increased risk of reactivating latent TB. Consequently, international guidelines recommend TB screening and preventive treatment before starting anti-TNF therapy. These recommendations have extended to IL-12/23, IL-17, IL-23 and TYK2 inhibitors under a caution principle, despite their different mechanisms of action. However, current evidence suggests that some of these agents are arguably not associated with an increased risk of TB reactivation or development of TB disease after infection, which calls for a critical reassessment of these guidelines. We have conducted a literature search evaluating the risk of TB reactivation associated with these innovative therapies, integrating findings from both randomized clinical trials and real-world evidence. The identified evidence is limited but the low number of identified cases of reactivation with IL-17 and IL-23 inhibitors prompts reconsidering the need for preventive treatment for latent TB in all cases, regardless of biologic class or individual patient's risk of TB reactivation or drug toxicity. This review, along with the clinical insight of a panel of experts on behalf of the SPIN-FRT, led to the development of these consensus recommendations for managing psoriasis treatment in patients with latent TB infection or at risk of TB infection, who are receiving or are intended to receive biologic and non-biologic targeted therapies. These recommendations highlight the need for updates to the existing guidelines, aiming to provide a more differentiated approach that reflects the evolving landscape of psoriasis treatment and its implications for TB management.

An intranasal nanoparticle vaccine elicits protective immunity against Mycobacterium tuberculosis

Mucosal vaccines have the potential to elicit protective immune responses at the point of entry of respiratory pathogens, thus preventing even the initial seed infection. Unlike licensed injectable vaccines, mucosal vaccines comprising protein subunits are only in development. One of the primary challenges associated with mucosal vaccines has been identifying and characterizing safe yet effective mucosal adjuvants that can effectively prime multi-factorial mucosal immunity. In this study, we tested NanoSTING, a liposomal formulation of the endogenous activator of the stimulator of interferon genes (STING) pathway, cyclic guanosine adenosine monophosphate (cGAMP), as a mucosal adjuvant. We formulated a vaccine based on the H1 antigen (fusion protein of Ag85b and ESAT-6) adjuvanted with NanoSTING. Intranasal immunization of NanoSTING-H1 elicited a strong T-cell response in the lung of vaccinated animals characterized by (a) CXCR3+ KLRG1- lung resident T cells that are known to be essential for controlling bacterial infection, (b) IFNγ-secreting CD4+ T cells which is necessary for intracellular bactericidal activity, and (c) IL17-secreting CD4+ T cells that can confer protective immunity against multiple clinically relevant strains of Mtb. Upon challenge with aerosolized Mycobacterium tuberculosis Erdman strain, intranasal NanoSTING-H1 provides protection comparable to subcutaneous administration of the live attenuated Mycobacterium bovis vaccine strain Bacille-Calmette-Guérin (BCG). Our results indicate that NanoSTING adjuvanted protein vaccines can elicit a multi-factorial immune response that protects from infection by M. tuberculosis.

Effect of IL-17A on the immune response to pulmonary tuberculosis induced by high- and low-virulence strains of Mycobacterium bovis

Tuberculosis (TB) is an infectious, chronic, and progressive disease occurring globally. Human TB is caused mainly by Mycobacterium tuberculosis (M. tuberculosis), while the main causative agent of bovine TB is Mycobacterium bovis (M. bovis). The latter is one of the most important cattle pathogens and is considered the main cause of zoonotic TB worldwide. The mechanisms responsible for tissue damage (necrosis) during post-primary TB remain elusive. Recently, IL-17A was reported to be important for protection against M. tuberculosis infection, but it is also related to the production of an intense inflammatory response associated with necrosis. We used two M. bovis isolates with different levels of virulence and high IL-17A production to study this important cytokine's contrasting functions in a BALB/c mouse model of pulmonary TB. In the first part of the study, the gene expression kinetics and cellular sources of IL-17A were determined by real time PCR and immunohistochemistry respectively. Non-infected lungs showed low production of IL-17A, particularly by the bronchial epithelium, while lungs infected with the low-virulence 534 strain showed high IL-17A expression on Day 3 post-infection, followed by a decrease in expression in the early stage of the infection and another increase during late infection, on Day 60, when very low bacillary burdens were found. In contrast, infection with the highly virulent strain 04-303 induced a peak of IL-17A expression on Day 14 of infection, 1 week before extensive pulmonary necrosis was seen, being lymphocytes and macrophages the most important sources. In the second part of the study, the contribution of IL-17A to immune protection and pulmonary necrosis was evaluated by suppressing IL-17A via the administration of specific blocking antibodies. Infection with M. bovis strain 534 and treatment with IL-17A neutralizing antibodies did not affect mouse survival but produced a significant increase in bacillary load and a non-significant decrease in inflammatory infiltrate and granuloma area. In contrast, mice infected with the highly virulent 04-303 strain and treated with IL-17A blocking antibodies showed a significant decrease in survival, an increase in bacillary loads on Day 24 post-infection, and significantly more and earlier necrosis. Our results suggest that high expression of IL-17A is more related to protection than necrosis in a mouse model of pulmonary TB induced by M. bovis strains.

Treatment of Psoriasis Patients with Latent Tuberculosis Using IL-17 and IL-23 Inhibitors: A Retrospective, Multinational, Multicentre Study

BACKGROUND

Tuberculosis has a major global impact. Immunocompetent hosts usually control this disease, resulting in an asymptomatic latent tuberculosis infection (LTBI). Because TNF inhibitors increase the risk of tuberculosis reactivation, current guidelines recommend tuberculosis screening before starting any biologic drug, and chemoprophylaxis if LTBI is diagnosed. Available evidence from clinical trials and real-world studies suggests that IL-17 and IL-23 inhibitors do not increase the risk of tuberculosis reactivation.

OBJECTIVE

To evaluate psoriasis patients with treated or untreated newly diagnosed LTBI who received IL-17 and IL-23 inhibitors and the tolerability/safety of tuberculosis chemoprophylaxis.

METHODS

This is a retrospective, observational, multinational study from a series of 14 dermatology centres based in Portugal, Spain, Italy, Greece and Brazil, which included adult patients with moderate-to-severe chronic plaque psoriasis and newly diagnosed LTBI who were treated with IL-23 or IL-17 inhibitors between January 2015 and March 2022. LTBI was diagnosed in the case of tuberculin skin test and/or interferon gamma release assay positivity, according to local guideline, prior to initiating IL-23 or IL-17 inhibitor. Patients with prior diagnosis of LTBI (treated or untreated) or treated active infection were excluded.

RESULTS

A total of 405 patients were included; complete/incomplete/no chemoprophylaxis was administered in 62.2, 10.1 and 27.7% of patients, respectively. The main reason for not receiving or interrupting chemoprophylaxis was perceived heightened risk of liver toxicity and hepatotoxicity, respectively. The mean duration of biological treatment was 32.87 ± 20.95 months, and only one case of active tuberculosis infection (ATBI) was observed, after 14 months of treatment with ixekizumab. The proportion of ATBI associated with ixekizumab was 1.64% [95% confidence interval (CI): 0-5.43%] and 0% for all other agents and 0.46% (95% CI 0-1.06%) and 0% for IL-17 and IL-23 inhibitors, respectively (not statistically significant).

CONCLUSIONS

The risk of tuberculosis reactivation in patients with psoriasis and LTBI does not seem to increase with IL-17 or IL-23 inhibitors. IL-17 or IL-23 inhibitors should be preferred over TNF antagonists when concerns regarding tuberculosis reactivation exists. In patients with LTBI considered at high risk for developing complications related to chemoprophylaxis, this preventive strategy may be waived before initiating treatment with IL-17 inhibitors and especially IL-23 inhibitors.

Innate Lymphoid Cells and Their Role in the Immune Response to Infections

Over the past decade, a group of lymphocyte-like cells called innate lymphoid cells (ILCs) has gained considerable attention due to their crucial role in regulating immunity and tissue homeostasis. ILCs, lacking antigen-specific receptors, are a group of functionally differentiated effector cells that act as tissue-resident sentinels against infections. Numerous studies have elucidated the characteristics of ILC subgroups, but the mechanisms controlling protective or pathological responses to pathogens still need to be better understood. This review summarizes the functions of ILCs in the immunology of infections caused by different intracellular and extracellular pathogens and discusses their possible therapeutic potential.

Helper T cell bias following tuberculosis chemotherapy identifies opportunities for therapeutic vaccination to prevent relapse

Therapeutic vaccines have promise as adjunctive treatment for tuberculosis (TB) or as preventives against TB relapse. An important development challenge is the limited understanding of T helper (Th) cell roles during these stages of disease. A murine model of TB relapse was used to identify changes in Th populations and cytokine microenvironment. Active TB promoted expansion of Th1, Th2, Th17, and Th22 cells and cytokines in the lung. Following drug therapy, pulmonary Th17 and Th22 cells contracted, Th1 cells remained elevated, while Th cells producing IL-4 or IL-10 expanded. At relapse, Th22 cells failed to re-expand in the lung despite a moderate re-expansion of Th1 and Th17 cells and an increase in Th cytokine polyfunctionality. The dynamics of Th populations further differed by tissue compartment and disease presentation. These outcomes identify immune bias by Th subpopulations during TB relapse as candidate mechanisms for pathogenesis and targets for therapeutic vaccination.

Mycobacteria modulate SUMOylation to suppresses protective responses in dendritic cells

Post translational modifications (PTMs) are exploited by various pathogens in order to escape host immune responses. SUMOylation is one of the PTMs which is involved in regulation of a variety of cellular responses. However, the effects of host SUMOylation on pathogenic bacteria largely remain elusive. We, therefore, investigated the role of SUMOylation in regulating defense responses in dendritic cells (DCs) during mycobacterial infection. Dendritic Cells of female BALB/c mice and THP-1 macrophages were used. Western blotting was performed to measure the expression of level of SUMO1, pSTAT1, pp38, pERK, Beclin-1, LC3, Bax and Cytochrome C. For bacterial burden confocal microscopy and CFU (Colony Forming Unit) were used. Flow cytometry was used for ROS and co-stimulatory molecules measurement. Cytokine level were measured using ELISA. We show that stimulation of Bone Marrow Derived Dendritic Cells (BMDCs) with mycobacterial antigen Rv3416 or live infection with Mycobacterium bovis BCG increases the SUMOylation of host proteins. Inhibition of SUMOylation significantly decreased intracellular bacterial loads in DCs. Additionally, inhibiting SUMOylation, induces protective immune responses by increasing oxidative burst, pro-inflammatory cytokine expression and surface expression of T cell co-stimulatory molecules, and activation of pSTAT1 and Mitogen Activated Protein Kinases (MAPK) proteins- pp38 and pERK. SUMOylation inhibition also increased apoptosis and autophagy in BMDCs. Intriguingly, mycobacteria increased SUMOylation of many of the above molecules. Furthermore, inhibiting SUMOylation in DCs primed T cells that in turn attenuated bacterial burden in infected macrophages. These findings demonstrate that SUMOylation pathway is exploited by mycobacteria to thwart protective host immune responses.

Mechanisms of lung damage in tuberculosis: implications for chronic obstructive pulmonary disease

Pulmonary tuberculosis is increasingly recognized as a risk factor for COPD. Severe lung function impairment has been reported in post-TB patients. Despite increasing evidence to support the association between TB and COPD, only a few studies describe the immunological basis of COPD among TB patients following successful treatment completion. In this review, we draw on well-elaborated Mycobacterium tuberculosis-induced immune mechanisms in the lungs to highlight shared mechanisms for COPD pathogenesis in the setting of tuberculosis disease. We further examine how such mechanisms could be exploited to guide COPD therapeutics.

Systemic Levels of Pro-Inflammatory Cytokines and Post-Treatment Modulation in Tuberculous Lymphadenitis

Pro-inflammatory cytokines are potent stimulators of inflammation and immunity and markers of infection severity and bacteriological burden in pulmonary tuberculosis (PTB). Interferons could have both host-protective and detrimental effects on tuberculosis disease. However, their role has not been studied in tuberculous lymphadenitis (TBL). Thus, we evaluated the systemic pro-inflammatory (interleukin (IL)-12, IL-23, interferon (IFN)α, and IFNβ) cytokine levels in TBL, latent tuberculosis (LTBI), and healthy control (HC) individuals. In addition, we also measured the baseline (BL) and post-treatment (PT) systemic levels in TBL individuals. We demonstrate that TBL individuals are characterized by increased pro-inflammatory (IL-12, IL-23, IFNα, IFNβ) cytokines when compared to LTBI and HC individuals. We also show that after anti-tuberculosis treatment (ATT) completion, the systemic levels of pro-inflammatory cytokines were significantly modulated in TBL individuals. A receiver operating characteristic (ROC) analysis revealed IL-23, IFNα, and IFNβ significantly discriminated TBL disease from LTBI and/or HC individuals. Hence, our study demonstrates the altered systemic levels of pro-inflammatory cytokines and their reversal after ATT, suggesting that they are markers of disease pathogenesis/severity and altered immune regulation in TBL disease.

Active pulmonary tuberculosis in a patient with secukinumab treatment

Numerous investigations have documented active tuberculosis (TB) infection following biologic treatment. One of the most secure biologic medications for infections is secukinumab. Additionally, no cases of active TB while receiving secukinumab therapy were recorded. Secukinumab 150 mg per month has been administered for a 19-year-old man with spondyloarthritis since May 2020. A diagnosis of pulmonary TB was made when the patient complained of a moderate fever, a productive cough, and weight loss after 2 years. His fever and respiratory symptoms were relieved after 6 weeks of treatment by stopping secukinumab and utilizing 4 antibiotics: isoniazid, rifampicin, pyrazinamide, and ethambutol, while non-steroidal anti-inflammatory drugs reduced his joint and back discomfort. During biological therapy, even with secukinumab, annual screening for latent and active TB is crucial. We require additional study on secukinumab-treated patients with active TB in nations with high TB burdens, including Vietnam.

The Double Game Played by Th17 Cells in Infection: Host Defense and Immunopathology

T-helper 17 (Th17) cells represent a subpopulation of CD4+ T lymphocytes that play an essential role in defense against pathogens. Th17 cells are distinguished from Th1 and Th2 cells by their ability to produce members of the interleukin-17 (IL-17) family, namely IL-17A and IL-17F. IL-17 in turn induces several target cells to synthesize and release cytokines, chemokines, and metalloproteinases, thereby amplifying the inflammatory cascade. Th17 cells reside predominantly in the lamina propria of the mucosa. Their main physiological function is to maintain the integrity of the mucosal barrier against the aggression of infectious agents. However, in an appropriate inflammatory microenvironment, Th17 cells can transform into immunopathogenic cells, giving rise to inflammatory and autoimmune diseases. This review aims to analyze the complex mechanisms through which the interaction between Th17 and pathogens can be on the one hand favorable to the host by protecting it from infectious agents, and on the other hand harmful, potentially generating autoimmune reactions and tissue damage.

Risk of Reactivation of Latent Tuberculosis in Psoriasis Patients on Biologic Therapies: A Retrospective Cohort from a Tertiary Care Centre in Northern Italy

Psoriatic patients with latent tuberculosis infection and properly treated active tuberculosis need careful management when prescribing modern biological drugs. Although data and guidelines regarding tumour necrosis factor-α inhibitors advise caution and initiation of prophylactic therapy in patients with latent tuberculosis infection, the same indications do not seem to find equal force for interleukin (IL)-23 and IL-17 inhibitors. In order to evaluate the risk of reactivation in patients with latent tuberculosis infection or properly treated active tuberculosis, an observational retrospective study was conducted on the population referred to our centre at Dermatologic Clinic of University of Turin, Italy. In the last 10 years at the clinic 19 psoriatic patients were found to be at risk of tuberculosis reactivation: 10 patients were QuantiFERON- TB-positive at baseline, 2 became positive during treatment, 6 reported prior tuberculous infection, and 1 was QuantiFERON-TB-negative at baseline and developed disseminated tuberculosis during treatment with anti-tumour necrosis factor-α. Overall, 10.5% of this group of patients developed active tuberculosis; however, stratifying by biologic therapy, zero cases were observed among patients treated with anti-IL-17, -23, or -12/23 over a relatively long follow-up (48.1 months) A review of the available literature following our experience confirms the increased risk of tuberculosis reactivation with tumour necrosis factor-α inhibitors. Concerning anti-IL-23 and IL-17 drugs, available data showed high safety in patients at risk of tuberculosis reactivation. Screening of patients who should be taking IL-17 and IL-23 inhibitors is recommended for public health purposes. In case of a positive result with these therapies, consulting with an infectious diseases specialist is suggested in order to weigh up the risks and benefits of prophylactic treatment.

An intranasal stringent response vaccine targeting dendritic cells as a novel adjunctive therapy against tuberculosis

Lengthy tuberculosis (TB) treatment is required to overcome the ability of a subpopulation of persistent Mycobacterium tuberculosis (Mtb) to remain in a non-replicating, antibiotic-tolerant state characterized by metabolic remodeling, including induction of the RelMtb-mediated stringent response. We developed a novel therapeutic DNA vaccine containing a fusion of the relMtb gene with the gene encoding the immature dendritic cell-targeting chemokine, MIP-3α/CCL20. To augment mucosal immune responses, intranasal delivery was also evaluated. We found that intramuscular delivery of the MIP-3α/relMtb (fusion) vaccine or intranasal delivery of the relMtb (non-fusion) vaccine potentiate isoniazid activity more than intramuscular delivery of the DNA vaccine expressing relMtb alone in a chronic TB mouse model (absolute reduction of Mtb burden: 0.63 log10 and 0.5 log10 colony-forming units, respectively; P=0.0002 and P=0.0052), inducing pronounced Mtb-protective immune signatures. The combined approach involving intranasal delivery of the DNA MIP-3α/relMtb fusion vaccine demonstrated the greatest mycobactericidal activity together with isoniazid when compared to each approach alone (absolute reduction of Mtb burden: 1.13 log10, when compared to the intramuscular vaccine targeting relMtb alone; P<0.0001), as well as robust systemic and local Th1 and Th17 responses. This DNA vaccination strategy may be a promising adjunctive approach combined with standard therapy to shorten curative TB treatment, and also serves as proof of concept for treating other chronic bacterial infections.

High-Dose Mycobacterium tuberculosis H37rv Infection in IL-17A- and IL-17A/F-Deficient Mice

During experimental tuberculosis (TB), interleukin (IL)-17A appears to be involved in the formation of lung granulomas, possibly through the attraction of neutrophils to the sites of infection. However, the protective impact of cytokine appears to depend on the degree of its induction. Hence, robust production of IL-17A in mice infected with the hypervirulent isolate Mycobacterium tuberculosis (Mtb) HN878 mediates protection, while the cytokine is dispensable for protective immune responses against low-dose infection with the less virulent strain H37rv. Here, we show that after experimental infection with high doses of Mtb H37rv, IL-17A-deficient (^−/−) mice exhibited high susceptibility to the infection, which was mediated by the strong accumulation of neutrophils in the infected lung tissue. Accordingly, we observed nearly unrestricted bacterial replication within the neutrophils, indicating that they may serve as a survival niche for Mtb. By use of IL-17A/IL-17F-double-deficient mice, we demonstrated that the susceptibility in the absence of IL-17A is mediated by a compensatory expression of IL-17F, which, however, appeared not to be dependent on neutrophils. Together, our results illustrate the compensatory potential of the Th17-secreted cytokines IL-17A and IL-17F in the context of experimental TB and once again emphasize the detrimental effect of excessive neutrophil infiltration in response to Mtb.

Dendritic cells Trigger IFN-γ secretion by NK cells independent of IL-12 and IL-18

It is commonly believed that IL-12 produced by DCs in response to pathogens is the first signal that stimulates the production of IFN-γ by NK cells. However, IL-12 production by DCs in response to bacterial LPS depends on either engagement of CD40 by CD40L on activated T cells or IFN-γ from NK cells. This suggests that during the primary immune response, NK cells produce IFN-γ before IL-12 production by DCs. Here, using single-cell measurements, cell sorting and mouse lines deficient in IL-12, IL-23, type I IFN receptor and the IL-18 receptor, we show that a subset of BM-derived DCs characterized by low expression of MHC class II (MHCIIlow ) stimulates IFN-γ production by NK cells. The expression of Toll-like Receptor (TLR) 4 on DCs but not NK cells was required for such NK-derived IFN-γ. In addition, soluble factor(s) produced by LPS-activated MHCIIlow DCs were sufficient to induce IFN-γ production by NK cells independent of IL-12, IL-23, and IL-18. This response was enhanced in the presence of a low dose of IL-2. These results delineate a previously unknown pathway of DC-mediated IFN-γ production by NK cells, which is independent of commonly known cytokines.

IL12RB1 allele bias in human TH cells is regulated by functional SNPs in its 3'UTR

Allele bias is an epigenetic mechanism wherein only the maternal- or paternal-derived allele of a gene is preferentially expressed. Allele bias is used by T cells to regulate expression of numerous genes, including those which govern their development and response to cytokines. Here we demonstrate that human T_H cell expression of the cytokine receptor gene IL12RB1 is subject to allele bias, and the extent to which this bias occurs is influenced by cells' differentiation status and two polymorphic sites in the IL12RB1 3'UTR. The single nucleotide polymorphisms (SNPs) at these sites, rs3746190 and rs404733, function to increase expression of their encoding allele. Modeling suggests this is due to a stabilizing effect of these SNPs on the predicted mRNA secondary structure. The SNP rs3746190 is also proximal to the predicted binding site of microRNA miR-1277, raising the possibility that miR-1277 cannot exert suppression in the presence of rs3746190. Functional experiments demonstrate, however, that miR-1277 suppression of IL12RB1 3'UTR expression-which itself has not been previously reported-is nevertheless independent of rs3746190. Collectively, these data demonstrate that rs3746190 and rs404733 are functional SNPs which regulate IL12RB1 allele bias in human T_H cells.

The relapse of psoriasis: what’s the veil of mystery?

Over the past decades, tremendous success in the treatment of psoriasis has been achieved using biologics, such as neutralizing antibodies against TNF/TNFR, IL-23, and IL-17A/IL-17RA. Although psoriatic skin lesions appear to resolve after treatment with these biologics, lesions often recur after therapy is discontinued or during therapy. Memory T cells residing in the skin have been considered as the major driver of psoriasis relapse. However, whether structural cells in the skin such as keratinocytes and fibroblasts are involved in the relapse of psoriasis is unknown. In this review, we outline the therapeutic rationale of biologics used in the treatment of psoriasis, summarize different clinical features of psoriasis relapse on the basis of preclinical and clinical data, and specifically discuss how memory T cells and structural cells in the skin are involved in psoriasis relapse. Finally, we discuss the future challenges in the basic or clinical research on psoriasis.

The Tuberculous Granuloma and Preexisting Immunity

Pulmonary granulomas are widely considered the epicenters of the immune response to Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB). Recent animal studies have revealed factors that either promote or restrict TB immunity within granulomas. These models, however, typically ignore the impact of preexisting immunity on cellular organization and function, an important consideration because most TB probably occurs through reinfection of previously exposed individuals. Human postmortem research from the pre-antibiotic era showed that infections in Mtb-naïve individuals (primary TB) versus those with prior Mtb exposure (postprimary TB) have distinct pathologic features. We review recent animal findings in TB granuloma biology, which largely reflect primary TB. We also discuss our current understanding of postprimary TB lesions, about which much less is known. Many knowledge gaps remain, particularly regarding how preexisting immunity shapes granuloma structure and local immune responses at Mtb infection sites.

Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Advancing Adjuvants for Mycobacterium tuberculosis Therapeutics

Tuberculosis (TB) remains one of the leading causes of death worldwide due to a single infectious disease agent. BCG, the only licensed vaccine against TB, offers limited protection against pulmonary disease in children and adults. TB vaccine research has recently been reinvigorated by new data suggesting alternative administration of BCG induces protection and a subunit/adjuvant vaccine that provides close to 50% protection. These results demonstrate the need for generating adjuvants in order to develop the next generation of TB vaccines. However, development of TB-targeted adjuvants is lacking. To help meet this need, NIAID convened a workshop in 2020 titled “Advancing Vaccine Adjuvants for Mycobacterium tuberculosis Therapeutics”. In this review, we present the four areas identified in the workshop as necessary for advancing TB adjuvants: 1) correlates of protective immunity, 2) targeting specific immune cells, 3) immune evasion mechanisms, and 4) animal models. We will discuss each of these four areas in detail and summarize what is known and what we can advance on in order to help develop more efficacious TB vaccines.

Interleukin-23 instructs protective multifunctional CD4 T cell responses after immunization with the Mycobacterium tuberculosis subunit vaccine H1 DDA/TDB independently of interleukin-17A

Interleukin (IL)-17A-producing T helper (Th)17 cells are increasingly being acknowledged to be associated with protective immunity to Mycobacterium tuberculosis (Mtb). Subunit vaccines potently promote protective immune responses against Mtb infection that correlate with an expansion of IL-23-dependent Th17 cells. Previous studies revealed that after vaccination, IL-23 is required for protection against challenge with Mtb but the underlying IL-23-dependent-and possibly IL-17A-mediated-mechanisms remain elusive. Therefore, we here analyzed the early outcome of Mtb infection in C57BL/6, IL-23p19-deficient (-/-), and IL-17A-/- mice after vaccination with the subunit vaccine H1-DDA/TDB to investigate the role of the IL-23-Th17 immune axis for the instruction of vaccine-induced protection. While in IL-23p19-/- mice the protective effect was reduced, protection after vaccination was maintained in IL-17A-/- animals for the course of infection of 6 weeks, indicating that after vaccination with H1-DDA/TDB early protection against Mtb is-although dependent on IL-23-not mediated by IL-17A. In contrast, IL-17A deficiency appears to have an impact on maintaining long-term protection. In fact, IL-23 instructed the vaccine-induced memory immunity in the lung, in particular the sustained expansion of tumor necrosis factor (TNF)+IL-2+ multifunctional T cells, independently of IL-17A. Altogether, a targeted induction of IL-23 during vaccination against Mtb might improve the magnitude and quality of vaccine-induced memory immune responses. KEY MESSAGES: After subunit Mtb vaccination with H1-DDA/TDB, IL-23 but not IL-17A contributes to vaccine-induced early protection against infection with Mtb. IL-17F does not compensate for IL-17A deficiency in terms of H1-DDA/TDB-induced protection against Mtb infection. IL 23 promotes the H1-DDA/TDB-induced accumulation of effector memory T cells independently of IL 17A. IL-23 arbitrates the induction of H1-specific IFN-γ-TNF+IL-2+ double-positive multifunctional CD4 T cells after subunit Mtb vaccination in an IL-17A-independent manner.

Innate lymphoid cells exhibited IL-17-expressing phenotype in active tuberculosis disease

BACKGROUND

Innate lymphoid cells (ILCs), as an important group of innate immunity, could respond rapidly to Mycobacterium tuberculosis (Mtb) infection. In this research, we studied the phenotypic changes of circulatory ILCs in active tuberculosis (TB) disease.

METHODS

We recruited 40 patients with active Mtb infection (TB group) and 41 healthy subjects (NC group), and collected their clinical information and peripheral blood. Circulating ILCs, ILC subsets, dendritic cells (DCs), macrophages, and the production of cytokines in ILCs were tested by flow cytometry (FCM). Enzyme-linked immunosorbent assay (ELISA) was used to detect plasma IL-23.

RESULTS

Compared with healthy control, total ILCs (0.73% vs. 0.42%, P = 0.0019), ILC1 (0.55% vs. 0.31%, P = 0.0024) and CD117⁺ ILC2 (0.02% vs. 0.01%, P = 0.0267) were upregulated in TB group. The total IL-17⁺ lymphocytes were elevated (3.83% vs. 1.76%, P = 0.0006) while the IL-22⁺ lymphocytes remained unchanged. Within ILC subsets, ILC3, CD117⁺ ILC2 and ILC1 in TB group all expressed increased IL-17 (15.15% vs. 4.55%, 19.01% vs. 4.57%, 8.79% vs. 3.87%, P < 0.0001) but similar IL-22 comparing with healthy control. TB group had more plasma IL-23 than NC group (7.551 vs. 5.564 pg/mL, P = 0.0557). Plasma IL-23 in TB group was positively correlated to IL-17⁺ ILC3 (r = 0.4435, P = 0.0141), IL-17⁺CD117⁺ ILC2 (r = 0.5385, P = 0.0021) and IL-17⁺ ILC1(r = 0.3719, P = 0.0430). TB group also had elevated DCs (9.35% vs. 6.49%, P < 0.0001) while macrophages remained unchanged. Within TB group, higher proportion of IL-17⁺ ILCs was related to severer inflammatory status and poorer clinical condition.

CONCLUSIONS

In active TB disease, circulatory ILCs were upregulated and exhibited IL-17-expressing phenotype. This may expand the understanding of immune reaction to Mtb infection.

Albumin fusion with granulocyte-macrophage colony-stimulating factor acts as an immunotherapy against chronic tuberculosis

A long duration of treatment and emerging drug resistance pose significant challenges for global tuberculosis (TB) eradication efforts. Therefore, there is an urgent need to develop novel strategies to shorten TB treatment regimens and to treat drug-resistant TB. Using an albumin-fusion strategy, we created a novel albumin-fused granulocyte-macrophage colony-stimulating factor (albGM-CSF) molecule that harnesses albumin's long half-life and targeting abilities to enhance the biostability of GM-CSF and direct it to the lymph nodes, where the effects of GM-CSF can increase dendritic cell populations crucial for eliciting a potent immune response. In this study, we demonstrate that albGM-CSF serves as a novel immunotherapy for chronic Mycobacterium tuberculosis (Mtb) infections by enhancing GM-CSF biostability in serum. Specifically, albumin is very safe, stable, and has a long half-life, thereby enhancing the biostability of GM-CSF. In the lungs and draining lymph nodes, albGM-CSF is able to increase the numbers of dendritic cells, which are crucial for the activation of naive T cells and for eliciting potent immune responses. Subcutaneous administration of albGM-CSF alone reduced the mean lung bacillary burden in mice with chronic tuberculosis infection. While GM-CSF administration was associated with IL-1β release from Mtb-infected dendritic cells and macrophages, higher IL-1β levels were observed in albGM-CSF-treated mice with chronic tuberculosis infection than in mice receiving GM-CSF. Albumin fusion with GM-CSF represents a promising strategy for the control of chronic lung tuberculosis infections and serves as a novel therapeutic vaccination platform for other infectious diseases and malignancies.

Understanding the Reciprocal Interplay Between Antibiotics and Host Immune System: How Can We Improve the Anti-Mycobacterial Activity of Current Drugs to Better Control Tuberculosis?

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) infection, remains a global health threat despite recent advances and insights into host-pathogen interactions and the identification of diverse pathways that may be novel therapeutic targets for TB treatment. In addition, the emergence and spread of multidrug-resistant Mtb strains led to a low success rate of TB treatments. Thus, novel strategies involving the host immune system that boost the effectiveness of existing antibiotics have been recently suggested to better control TB. However, the lack of comprehensive understanding of the immunomodulatory effects of anti-TB drugs, including first-line drugs and newly introduced antibiotics, on bystander and effector immune cells curtailed the development of effective therapeutic strategies to combat Mtb infection. In this review, we focus on the influence of host immune-mediated stresses, such as lysosomal activation, metabolic changes, oxidative stress, mitochondrial damage, and immune mediators, on the activities of anti-TB drugs. In addition, we discuss how anti-TB drugs facilitate the generation of Mtb populations that are resistant to host immune response or disrupt host immunity. Thus, further understanding the interplay between anti-TB drugs and host immune responses may enhance effective host antimicrobial activities and prevent Mtb tolerance to antibiotic and immune attacks. Finally, this review highlights novel adjunctive therapeutic approaches against Mtb infection for better disease outcomes, shorter treatment duration, and improved treatment efficacy based on reciprocal interactions between current TB antibiotics and host immune cells.

Immunogenicity of HspX/EsxS fusion protein of Mycobacterium tuberculosis along with ISCOMATRIX and PLUSCOM nano-adjuvants after subcutaneous administration in animal model

BACKGROUND

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tuberculosis), is one of the most common and dangerous infectious diseases in the world. Despite vaccination with BCG, it is still considered as a major health problem. Therefore, design and production of an effective novel vaccine against TB is necessary. Our aim was to evaluate immunogenicity of HspX/EsxS fusion protein of M. tuberculosis along with ISCOMATRIX, PLUSCOM nano-adjuvants and MPLA through the subcutaneous route in mice model.

METHODS

HspX/EsxS fused protein of M. tuberculosis was cloned, expressed and purified in the prokaryotic system. ISCOMATRIX and PLUSCOM nano-adjuvants were prepared by film hydration method. Subcutaneous immunization of BALB/c mice was performed by different formulations. IFN-γ, IL-4, IL-17 and TGF-β cytokines levels as well as serum IgG1, IgG2a.

RESULTS

Our results showed that subcutaneous administration of mice with HspX/EsxS along with three adjuvants, ISCOMATRIX, PLUSCOM and MPLA increased immunogenicity of multi-stage fusion protein of M. tuberculosis. Additionally, HspX/EsxS protein + ISCOMATRIX or + PLUSCOM nano-adjuvants induced stronger Th1, IgG2a and IgG1 immune responses compared to MPLA adjuvant. Totally, HspX/EsxS/ISCOMATRIX/MPLA, HspX/EsxS/PLUSCOM/MPLA and two BCG booster groups could significantly induce higher Th1 and IgG2a immune responses.

CONCLUSION

With regard to ability of ISCOMATRIX, PLUSCOM and MPLA adjuvants to increase immunogenicity of HspX/EsxS protein through induction of IFN-γ and IgG2a immune responses, it seems that these adjuvants and especially ISCOMATRIX and PLUSCOM, could also improve BCG efficacy as a BCG booster.

Urinary metabolomic analysis to identify potential markers for the diagnosis of tuberculosis and latent tuberculosis

Tuberculosis (TB) is a serious infectious disease with high infection and mortality rates. 5%-10% of the latent tuberculosis infections (LTBI) are likely to develop into active TB, and there are currently no clinical biomarkers that can distinguish between LTBI, active TB and other non-tuberculosis populations. Therefore, it is necessary to develop rapid diagnostic methods for active TB and LTBI. In this study, urinary metabolome of 30 active TB samples and the same number of LTBI and non-TB control samples were identified and analyzed by UPLC-Q Exactive MS. In total, 3744 metabolite components were obtained in ESI- mode and 4086 in ESI + mode. Orthogonal partial least square discriminant analysis (OPLS-DA) and hierarchical cluster analysis (HCA) showed that there were significant differences among LTBI, active TB and non-TB. Six differential metabolites were screened in positive and negative mode, 3-hexenoic acid, glutathione (GSH), glycochenodeoxycholate-3-sulfate, N-[4'-hydroxy-(E)-cinnamoyl]-l-aspartic acid, deoxyribose 5-phosphate and histamine. The overlapping pathways differential metabolites involved were mainly related to immune regulation and urea cycle. The results showed that the urine metabolism of TB patients was disordered and many metabolic pathways changed. Multivariate statistical analysis revealed that GSH and histamine were selected as potential molecular markers, with area under curve of receiver operating characteristic curve over 0.75. Among the multiple differential metabolites, GSH and histamine changed to varying degrees in active TB, LTBI and the non-TB control group. The levels of GSH and histamine in 48 urinary samples were measured by ELISA in validation phase, and the result in our study provided the potential for non-invasive biomarkers of TB.

Monocyte dysregulation: consequences for hepatic infections

Liver disorders due to infections are a substantial health concern in underdeveloped and industrialized countries. This includes not only hepatotropic viruses (e.g., hepatitis B, hepatitis C) but also bacterial and parasitic infections such as amebiasis, leishmaniasis, schistosomiasis, or echinococcosis. Recent studies of the immune mechanisms underlying liver disease show that monocytes play an essential role in determining patient outcomes. Monocytes are derived from the mononuclear phagocyte lineage in the bone marrow and are present in nearly all tissues of the body; these cells function as part of the early innate immune response that reacts to challenge by external pathogens. Due to their special ability to develop into tissue macrophages and dendritic cells and to change from an inflammatory to an anti-inflammatory phenotype, monocytes play a pivotal role in infectious and non-infectious liver diseases: they can maintain inflammation and support resolution of inflammation. Therefore, tight regulation of monocyte recruitment and termination of monocyte-driven immune responses in the liver is prerequisite to appropriate healing of organ damage. In this review, we discuss monocyte-dependent immune mechanisms underlying hepatic infectious disorders. Better understanding of these immune mechanisms may lead to development of new interventions to treat acute liver disease and prevent progression to organ failure.

Saponin-adjuvanted recombinant vaccines containing rCP00660, rCP09720 or rCP01850 proteins against Corynebacterium pseudotuberculosis infection in mice

PURPOSE

rCP01850, rCP09729 and rCP00660 proteins from Corynebacterium pseudotuberculosis, predicted as the three best targets to be used in vaccines against Caseous Lymphadenitis in mature epitope density (MED) analysis were tested as vaccinal targets in association to saponin as adjuvant.

METHODOLOGY

rCP00660, rCP09720 and rCP01850 were expressed in E. coli and purified for immunization assay. Balb/c mice were divided into five groups of sixteen animals each. G1 was injected with saline solution (0.9% NaCl), G2 with saponin, G3, G4 and G5 with, respectively, rCP00660, rCP09720 and rCP01850 added by saponin. Two doses were administered within a 21-days interval, and blood samples were collected for IgG quantification. Twenty-one days after the last immunization, ten mice in each group were challenged with virulent C. pseudotuberculosis MIC-6 strain, and mortality was recorded for 40 days. Meanwhile six mice in each group were used for cytokine quantification by qPCR.

RESULTS

G2, G3, G4 and G5 presented protection rates of 10, 30, 40 and 60%, respectively. In spite of levels of total IgG were higher in G4 and G5, production of IgG2a was higher than IgG1 for G5. G3, G4 and G5 presented significant high IFN-γ levels, however, only G5 showed high TNF-α while G3 and G4 showed high IL-17.

CONCLUSION

rCP01850 added by saponin was able to protect efficiently mice against C. pseudotuberculosis challenge, and to induce high IgG, IFN-γ and TNF-α levels. In spite of rCP00660 and rCP09720 had not same adequate protection levels, significant IgG, IFN-γ, and IL-17 levels and further studies aiming to improve protection rates should be conducted.

The emerging role of exosomal miRNAs as a diagnostic and therapeutic biomarker in Mycobacterium tuberculosis infection

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), has been the world's driving fatal bacterial contagious disease globally. It continues a public health emergency, and around one-third of the global community has been affected by latent TB infection (LTBI). This is mostly due to the difficulty in diagnosing and treating patients with TB and LTBI. Exosomes are nanovesicles (40-100 nm) released from different cell types, containing proteins, lipids, mRNA, and miRNA, and they allow the transfer of one's cargo to other cells. The functional and diagnostic potential of exosomal miRNAs has been demonstrated in bacterial infections, including TB. Besides, it has been recognized that cells infected by intracellular pathogens such as Mtb can be secreting an exosome, which is implicated in the infection's fate. Exosomes, therefore, open a unique viewpoint on the investigative process of TB pathogenicity. This study explores the possible function of exosomal miRNAs as a diagnostic biomarker. Moreover, we include the latest data on the pathogenic and therapeutic role of exosomal miRNAs in TB.

Association of Secukinumab Treatment With Tuberculosis Reactivation in Patients With Psoriasis, Psoriatic Arthritis, or Ankylosing Spondylitis

Question

What is the association of secukinumab with active tuberculosis (TB) development, TB reactivation, and latent tuberculosis infection (LTBI) activation?

Findings

In this pooled cohort study of 12 319 patients with psoriasis, psoriatic arthritis, or ankylosing spondylitis, spontaneous reporting of new LTBI while undergoing secukinumab treatment was rare. No active cases of TB or LTBI reactivation were reported.

Meaning

The findings of this study provide a broader understanding of the safety of secukinumab and appear to support its long-term use in chronic systemic inflammatory conditions.

Importance

Approximately one-quarter of the global population have latent tuberculosis infection (LTBI), and tuberculosis (TB) is accountable for more than 1.5 million deaths annually. Methotrexate, cyclosporine, and tumor necrosis factor inhibitors may be associated with increased risk of TB and LTBI reactivation, although data are limited on the risks of TB with use of newer biologics.

Objective

To assess the association of secukinumab with reporting of active TB development, TB reactivation, and LTBI activation as an adverse event (AE) in patients with psoriasis, psoriatic arthritis, or ankylosing spondylitis.

Design, Setting, and Participants

This pooled cohort study pooled data from 28 clinical trials of secukinumab used in psoriasis (17 phase 3 or 3b and 2 phase 4 trials), psoriatic arthritis (5 phase 3 trials), and ankylosing spondylitis (4 phase 3 trials). A search of the Novartis Secukinumab Compound Pool Database was conducted for the 28 trials. All trial participants who had received at least 1 approved subcutaneous dose of secukinumab (150 mg or 300 mg) were included. Before randomization in these trials, patients underwent screening for TB. Patients with active TB were excluded, and patients with LTBI were treated according to local guidelines. Data were analyzed from the start of treatment in the individual studies through December 25, 2018.

Main Outcomes and Measures

Reporting of active TB or LTBI as an AE over a 5-year period using exposure-adjusted incidence rates (EAIR; incidence rates per 100 patient-years).

Results

A total of 12 319 patients were included, of whom 8819 patients had psoriasis (71.6%; 5930 men [67.2%]; mean [SD] age, of 44.9 [13.5] years), 2523 had psoriatic arthritis (20.5%; 1323 women [52.4%]; mean [SD] age, 48.8 [12.1] years), and 977 had ankylosing spondylitis (7.3%; 658 men [67.3%]; mean [SD] age, 42.3 [11.9] years). In the total population, 684 patients (5.6%) had tested positive for LTBI at screening. Over 5 years, LTBI as an AE during secukinumab treatment was reported in 13 patients (0.1% of 12 319). Of these 13 patients, 6 had a prior positive LTBI test result, and 7 were newly diagnosed as having LTBI. Four of the 7 patients had psoriasis (EAIR, 0.03; 95% CI, 0.01-0.07), 1 had psoriatic arthritis (EAIR, 0.02; 95% CI, 0.00-0.11), and 2 had ankylosing spondylitis (EAIR, 0.08; 95% CI, 0.01-0.28). No cases of active TB were reported.

Conclusions and Relevance

This study found that LTBI reported as an AE after secukinumab treatment was uncommon and appeared to support the use of secukinumab in chronic systemic inflammatory conditions.

Susceptibility and resistance in leprosy: Studies in the mouse model

Leprosy is a chronic granulomatous infectious disease caused by the pathogen, Mycobacterium leprae, and the more recently discovered, M. lepromatosis. Described in 1873, M. leprae was among the first microorganisms to be proposed as a cause of a human infectious disease. As an obligate intracellular bacterium, it has still not thus far been reproducibly cultivated in axenic medium or cell cultures. Shepard's mouse footpad assay, therefore, was truly a breakthrough in leprosy research. The generation of immunosuppressed and genetically engineered mice, along with advances in molecular and cellular techniques, has since offered more tools for the study of the M. leprae–induced granuloma. While far from perfect, these new mouse models have provided insights into the immunoregulatory mechanisms responsible for the spectrum of this complex disease.

Tissue-resident memory Th17 cells maintain stable fungal commensalism in the oral mucosa

Keeping a stable equilibrium between the host and commensal microbes to which we are constantly exposed, poses a major challenge for the immune system. The host mechanisms that regulate homeostasis of the microbiota to prevent infection and inflammatory disorders are not fully understood. Here, we provide evidence that CD4+ tissue-resident memory T (TRM) cells act as central players in this process. Using a murine model of C. albicans commensalism we show that IL-17 producing CD69+CD103+CD4+ memory T cells persist in the colonized tissue long-term and independently of circulatory supplies. Consistent with the requirement of Th17 cells for limiting fungal growth, IL-17-producing TRM cells in the mucosa were sufficient to maintain prolonged colonization, while circulatory T cells were dispensable. Although TRM cells were first proposed to protect from pathogens causing recurrent acute infections, our results support a central function of TRM cells in the maintenance of commensalism.

Maternal HIV status skews transcriptomic response in infant cord blood monocytes exposed to Bacillus Calmette--Guerín

OBJECTIVES

HIV-exposed uninfected (HEU) infants exhibit altered vaccine responses and an increased mortality compared with HIV-unexposed infants. Here, vaccine responses in HEU and HIV-unexposed cord blood monocytes (CBMs) were assessed following Bacillus Calmette--Guerín (BCG) treatment.

DESIGN

Innate responses to in-vitro BCG treatment were assessed through transcriptional profiling using CBMs obtained from a Nigerian cohort of HIV-infected and uninfected women.

METHODS

HIV-unexposed (n = 9) and HEU (n = 10) infant CBMs were treated with BCG and transcriptionally profiled with the Nanostring nCounter platform. Differential expression and pathway enrichment analyses were performed, and transcripts were identified with enhanced or dampened BCG responses.

RESULTS

Following BCG stimulation, several pathways associated with inflammatory gene expression were upregulated irrespective of HIV exposure status. Both HIV-unexposed and HEU monocytes increased expression of several cytokines characteristic of innate BCG responses, including IL1β, TNFα, and IL-6. Using differential expression analysis, we identified genes significantly upregulated in HEU compared with HIV-unexposed monocytes including monocyte chemokine CCL7 and anti-inflammatory cytokine TNFAIP6. In contrast, genes significantly upregulated in HIV-unexposed compared with HEU monocytes include chemokine CCL3 and cytokine IL23A, both of which influence anti-mycobacterial T-cell responses. Finally, two genes, which regulate prostaglandin production, CSF2 and PTGS2, were also more significantly upregulated in the HIV-unexposed cord blood indicating that inflammatory mediators are suppressed in the HEU infants.

CONCLUSION

HEU monocytes exhibit altered induction of several key innate immune responses, providing mechanistic insights into dysregulated innate response pathways that can be therapeutically targeted to improve vaccine responses in HEU infants.

IL-6 is not Absolutely Essential for the Development of a TH17 Immune Response after an Aerosol Infection with Mycobacterium Tuberculosis H37rv

Anti-inflammatory treatment of chronic inflammatory diseases often increases susceptibility to infectious diseases such as tuberculosis (TB). Since numerous chronic inflammatory and autoimmune diseases are mediated by interleukin (IL)-6-induced T helper (TH) 17 cells, a TH17-directed anti-inflammatory therapy may be preferable to an IL-12-dependent TH1 inhibition in order to avoid reactivation of latent infections. To assess, however, the risk of inhibition of IL-6-dependent TH17-mediated inflammation, we examined the TH17 immune response and the course of experimental TB in IL-6- and T-cell-specific gp130-deficient mice. Our study revealed that the absence of IL-6 or gp130 on T cells has only a minor effect on the development of antigen-specific TH1 and TH17 cells. Importantly, these gene-deficient mice were as capable as wild type mice to control mycobacterial infection. Together, in contrast to its key function for TH17 development in other inflammatory diseases, IL-6 plays an inferior role for the generation of TH17 immune responses during experimental TB.

The Role of gp130 Cytokines in Tuberculosis

Protective immune responses to Mycobacterium tuberculosis (Mtb) infection substantially depend on a delicate balance within cytokine networks. Thus, immunosuppressive therapy by cytokine blockers, as successfully used in the management of various chronic inflammatory diseases, is often connected with an increased risk for tuberculosis (TB) reactivation. Hence, identification of alternative therapeutics which allow the treatment of inflammatory diseases without compromising anti-mycobacterial immunity remains an important issue. On the other hand, in the context of novel therapeutic approaches for the management of TB, host-directed adjunct therapies, which combine administration of antibiotics with immunomodulatory drugs, play an increasingly important role, particularly to reduce the duration of treatment. In both respects, cytokines/cytokine receptors related to the common receptor subunit gp130 may serve as promising target candidates. Within the gp130 cytokine family, interleukin (IL)-6, IL-11 and IL-27 are most explored in the context of TB. This review summarizes the differential roles of these cytokines in protection and immunopathology during Mtb infection and discusses potential therapeutic implementations with respect to the aforementioned approaches.

Antiviral properties of placental growth factors: A novel therapeutic approach for COVID-19 treatment

The current challenge of the COVID-19 pandemic is complicated by the limited therapeutic options against the virus, with many being anecdotal or still undergoing confirmatory trials, underlining the urgent need for novel strategies targeting the virus. The pulmotropic virus causes loss of oxygenation in severe cases with acute respiratory distress syndrome (ARDS) and need for mechanical ventilation. This work seeks to introduce placental extract-derived biologically active components as a therapeutic option and highlights their mechanism of action relevant to COVID-19 virus. Human placenta has been used in clinical practice for over a century and there is substantial experience in clinical applications of placental extract for different indications. Aqueous extract of human placentacontains growth factors, cytokines/chemokines, natural metabolic and other compounds, anti-oxidants, amino acids, vitamins, trace elements and biomolecules, which individually or in combination show accelerated cellular metabolism, immunomodulatory and anti-inflammatory effects, cellular proliferation and stimulation of tissue regeneration processes. Placental extract treatment is proposed as a suitable therapeutic approach consideringthe above properties which could protect against initial viral entry and acute inflammation of alveolar epithelial cells, reconstitute pulmonary microenvironment and regenerate the lung. We reviewed useful therapeutic information of placental biomolecules in relation to COVID-19 treatment. We propose the new approach of using placental growth factors, chemokines and cytokine which will execute antiviral activity in coordination with innate and humoral immunity and improve patient's immunological responses to COVID-19. Executing a clinical trial using placental extract as preventive, protective and/or therapeutic approach for COVID-19treatment could advance the development of a most promising therapeutic candidate that can join the armamentaria against the COVID-19 virus.

Risk of tuberculosis reactivation with interleukin (IL)-17 and IL-23 inhibitors in psoriasis - time for a paradigm change

Tuberculosis is an infectious disease with a major global impact, ranked in the top 10 mortality causes worldwide. In an immunocompetent individual, the host defence mechanisms control Mycobacterium tuberculosis infection and induce the latent form of the disease. However, in the presence of diseases or therapies, which exert an immunosuppressive effect, latent tuberculosis can be re-activated. Psoriasis is an immune-mediated, inflammatory disease, and its treatment has rapidly evolved over the last few years. It has long been recognized that the tumour necrosis factor (TNF)-α inhibitors are associated with increased risk of reactivation of latent tuberculosis infection. Thus, international guidelines have been suggesting tuberculosis screening before starting the treatment with all biological agents since then. In addition, the institution of chemoprophylaxis in the presence of latent tuberculosis and the annual screening for tuberculosis thereafter have also been indicated. However, anti-tuberculosis treatments can have significant side-effects and there are currently several contraindications to their use. The risk benefit of starting anti-tuberculous treatment should be carefully weighed up. The emergence of new biological drugs for the treatment of psoriasis, such as interleukin (IL)-17 and IL-23 inhibitors, has reignited the subject of tuberculosis reactivation as it is possible that IL-17 and 23 blockade do not carry the same risk of TB reactivation as TNF-α inhibitors. Although preclinical studies have shown that cytokines IL-17 and IL-23 have a possible role against infection with M. tuberculosis, data from clinical trials and post-marketing surveillance with drugs that inhibit these cytokines appear to suggest that they are not crucial to this response. In this article, we review the available data on tuberculosis reactivation after the treatment of psoriasis with IL-17 and IL-23 inhibitors, and its possible impact on the way we currently manage latent tuberculosis infection before or after starting treatment with these new drugs.

T Cell Immunity to Bacterial Pathogens: Mechanisms of Immune Control and Bacterial Evasion

The human body frequently encounters harmful bacterial pathogens and employs immune defense mechanisms designed to counteract such pathogenic assault. In the adaptive immune system, major histocompatibility complex (MHC)-restricted αβ T cells, along with unconventional αβ or γδ T cells, respond to bacterial antigens to orchestrate persisting protective immune responses and generate immunological memory. Research in the past ten years accelerated our knowledge of how T cells recognize bacterial antigens and how many bacterial species have evolved mechanisms to evade host antimicrobial immune responses. Such escape mechanisms act to corrupt the crosstalk between innate and adaptive immunity, potentially tipping the balance of host immune responses toward pathological rather than protective. This review examines the latest developments in our knowledge of how T cell immunity responds to bacterial pathogens and evaluates some of the mechanisms that pathogenic bacteria use to evade such T cell immunosurveillance, to promote virulence and survival in the host.

Targeting Unconventional Host Components for Vaccination-Induced Protection Against TB

The current tuberculosis (TB) vaccine, Bacille Calmette-Guerin (BCG), is effective in preventing TB in young children but was developed without a basic understanding of human immunology. Most modern TB vaccine candidates have targeted CD4⁺ T cell responses, thought to be important for protection against TB disease, but not known to be sufficient or critical for protection. Advances in knowledge of host responses to TB afford opportunities for developing TB vaccines that target immune components not conventionally considered. Here, we describe the potential of targeting NK cells, innate immune training, B cells and antibodies, and Th17 cells in novel TB vaccine development. We also discuss attempts to target vaccine immunity specifically to the lung, the primary disease site in humans.

Interleukin 23p19 inhibitors in chronic plaque psoriasis with focus on mirikizumab: A narrative review

Psoriasis, a T-cell mediated chronic dermatosis, has a complex etiopathogenesis. There has been extensive research into the aberrant immune response, which leads to the formation of clinical lesions, and the need for developing better and safer drugs has been unrelenting. The past two decades of research has opened up new areas of the immune pathway that can be targeted in order to control the disease. Therefore, we have seen the emergence of biologics which either target T-cell receptors or inhibit Tumor Necrosis Factor-alpha (TNF-α) or inhibit interleukins (IL) like IL-12, IL-17, IL-17 receptor, and more recently IL-23. Drugs specifically targeting the p19 subunit of IL-23 have shown promising results in the management of chronic plaque psoriasis. This has given way to the development of a new class of biologics, that is, the IL-23p19 inhibitors that have a better safety profile as compared to its predecessors. In this review, we shall scrutinize the role of IL-23 and Th17 cell signaling in the evolution of the psoriatic lesions and summarize the clinical experience with IL-23p19 inhibitors especially mirikizumab in the treatment of chronic plaque psoriasis.

NB-UVB irradiation attenuates inflammatory response in psoriasis

Psoriasis is a chronic inflammatory disease characterized by immunological imbalance and vasodilation. Many triggering factors for psoriasis initiate inflammation via the activation of NF-κB. Narrow-band ultraviolet B (NB-UVB) irradiation can be used as a general treatment for psoriasis, although the molecular mechanism has not yet been determined. The aim of this study was to elucidate the potential molecular mechanism of NB-UVB irradiation therapy on psoriasis. We collected serum samples from patients with psoriasis and healthy control, and detected the expression of inflammatory factors by ELISA. In addition, we established mouse model of psoriasis. After different doses of NB-UVB irradiation, the proportion of CD4+ , CD8+ , and CD11c+ cells in mouse spleen was detected by flow cytometry. Meanwhile, the expression of inflammatory factors in the damaged skin of mice was detected by RT-PCR and Western blot analysis, and mouse serum levels of inflammatory factors were detected by ELISA. Our results showed that NB-UVB irradiation regulated the expression of inflammatory factors in psoriasis patients. In mice, high-dose NB-UVB irradiation effectively eliminated IMQ-induced psoriasis-like dermatitis and inhibited the expression of pro-inflammatory factors. In conclusion, our results indicate that NB-UVB irradiation could regulate the expression of inflammatory factors and attenuate psoriasis plaques.

Antigen-Specific IFN-γ/IL-17-Co-Producing CD4+ T-Cells Are the Determinants for Protective Efficacy of Tuberculosis Subunit Vaccine

The antigen-specific Th17 responses in the lungs for improved immunity against Mycobacterium tuberculosis (Mtb) infection are incompletely understood. Tuberculosis (TB) vaccine candidate HSP90-ESAT-6 (E6), given as a Bacillus Calmette-Guérin (BCG)-prime boost regimen, confers superior long-term protection against the hypervirulent Mtb HN878 infection, compared to BCG or BCG-E6. Taking advantage of protective efficacy lead-out, we found that ESAT-6-specific multifunctional CD4⁺IFN-γ⁺IL-17⁺ T-cells optimally correlated with protection level against Mtb infection both pre-and post-challenge. Macrophages treated with the supernatant of re-stimulated lung cells from HSP90-E6-immunised mice significantly restricted Mtb growth, and this phenomenon was abrogated by neutralising anti-IFN-γ and/or anti-IL-17 antibodies. We identified a previously unrecognised role for IFN-γ/IL-17 synergism in linking anti-mycobacterial phagosomal activity to enhance host control against Mtb infection. The implications of our findings highlight the fundamental rationale for why and how Th17 responses are essential in the control of Mtb, and for the development of novel anti-TB subunit vaccines.

Mycobacterium smegmatis Vaccine Vector Elicits CD4+ Th17 and CD8+ Tc17 T Cells With Therapeutic Potential to Infections With Mycobacterium avium

Mycobacterium avium (Mav) complex is increasingly reported to cause non-tuberculous infections in individuals with a compromised immune system. Treatment is complicated and no vaccines are available. Previous studies have shown some potential of using genetically modified Mycobacterium smegmatis (Msm) as a vaccine vector to tuberculosis since it is non-pathogenic and thus would be tolerated by immunocompromised individuals. In this study, we used a mutant strain of Msm disrupted in EspG₃, a component of the ESX-3 secretion system. Infection of macrophages and dendritic cells with Msm ΔespG₃ showed increased antigen presentation compared to cells infected with wild-type Msm. Vaccination of mice with Msm ΔespG₃, expressing the Mav antigen MPT64, provided equal protection against Mav infection as the tuberculosis vaccine, Mycobacterium bovis BCG. However, upon challenge with Mav, we observed a high frequency of IL-17-producing CD4+ (Th17 cells) and CD8+ (Tc17 cells) T cells in mice vaccinated with Msm ΔespG₃::mpt64 that was not seen in BCG-vaccinated mice. Adoptive transfer of cells from Msm ΔespG₃-vaccinated mice showed that cells from the T cell compartment contributed to protection from Mav infection. Further experiments revealed Tc17-enriched T cells did not provide prophylactic protection against subsequent Mav infection, but a therapeutic effect was observed when Tc17-enriched cells were transferred to mice already infected with Mav. These initial findings are important, as they suggest a previously unknown role of Tc17 cells in mycobacterial infections. Taken together, Msm ΔespG₃ shows promise as a vaccine vector against Mav and possibly other (myco)bacterial infections.

Granulocyte/Macrophage Colony-Stimulating Factor-Derived Macrophages Exhibit Distinctive Early Immune Response to Lymphocytic Choriomeningitis Virus Infection

Granulocyte/macrophage colony-stimulating factor (GM-CSF) and macrophage CSF (M-CSF) modulate differentiation and immune functions of macrophages (MΦ). Our aim was to evaluate how different MΦ differentiation conditions influence the MΦ response to virus infection. To address this, we differentiated bone marrow-derived MΦ in either GM-CSF or M-CSF and measured the cytokine responses to two different strains of lymphocytic choriomeningitis virus (LCMV) (clone 13; Cl13 or Armstrong; ARM). GM-CSF MΦ infected with either LCMV-ARM or -Cl13 produced more IL-6 than M-CSF MΦ, whereas M-CSF MΦ generated more IL-10 than GM-CSF MΦ. Interestingly, in M-CSF MΦ, LCMV-ARM induced more IL-10 production than Cl13. However, we could not detect any IL-12p70 or IL-23 after infection from either cell types. We also observed that GM-CSF MΦ was more efficient than M-CSF MΦ in supporting antigen-specific CD8⁺ T cell proliferation. Taken together, our data demonstrate that GM-CSF and M-CSF MΦ differ in how they respond to viral infection by their production of different cytokines, and their support for CD8⁺ T cell proliferation.

The current state of animal models and genomic approaches towards identifying and validating molecular determinants of Mycobacterium tuberculosis infection and tuberculosis disease

Animal models are important in understanding both the pathogenesis of and immunity to tuberculosis (TB). Unfortunately, we are beginning to understand that no animal model perfectly recapitulates the human TB syndrome, which encompasses numerous different stages. Furthermore, Mycobacterium tuberculosis infection is a very heterogeneous event at both the levels of pathogenesis and immunity. This review seeks to establish the current understanding of TB pathogenesis and immunity, as validated in the animal models of TB in active use today. We especially focus on the use of modern genomic approaches in these models to determine the mechanism and the role of specific molecular pathways. Animal models have significantly enhanced our understanding of TB. Incorporation of contemporary technologies such as single cell transcriptomics, high-parameter flow cytometric immune profiling, proteomics, proteomic flow cytometry and immunocytometry into the animal models in use will further enhance our understanding of TB and facilitate the development of treatment and vaccination strategies.

Genetic polymorphism rs8193036 of IL17A is associated with increased susceptibility to pulmonary tuberculosis in Chinese Han population

Th17 cells play a key role in immunity against Mycobacterium tuberculosis, our previous research showed that reduced Th17 responses were associated with the severe outcome of Mtb infection. The associations between IL17A polymorphisms and susceptibility of TB has been reported, but the results are inconsistent and the underlying mechanisms is unknown. In this study, we identified a genetic variation (rs8193036) in the promoter region of IL17A is associated with susceptibility to TB. The minor allele T frequency of rs8193036 was significantly different between patients with active TB (29.7%) and healthy controls (32.3%) (OR = 0.81; 95%CI, 0.71-0.93; P = 0.0026). Peripheral blood mononuclear cells from individuals carrying rs8193036CC genotypes produced significantly lower amount of IL17A upon CD3/28 stimulation compared to the individuals carrying rs8193036TT genotypes. Functional assay by reporter luciferase activity and EMSA demonstrated that rs8193036C exhibited significantly lower promotor transcription activities. In conclusion, our study confirmed that IL17A (rs8193036) is a functional SNP that could regulate gene expression though influencing transcription factor binding activity.

STING-Activating Adjuvants Elicit a Th17 Immune Response and Protect against Mycobacterium tuberculosis Infection

There are a limited number of adjuvants that elicit effective cell-based immunity required for protection against intracellular bacterial pathogens. Here, we report that STING-activating cyclic dinucleotides (CDNs) formulated in a protein subunit vaccine elicit long-lasting protective immunity to Mycobacterium tuberculosis in the mouse model. Subcutaneous administration of this vaccine provides equivalent protection to that of the live attenuated vaccine strain Bacille Calmette-Guérin (BCG). Protection is STING dependent but type I IFN independent and correlates with an increased frequency of a recently described subset of CXCR3-expressing T cells that localize to the lung parenchyma. Intranasal delivery results in superior protection compared with BCG, significantly boosts BCG-based immunity, and elicits both Th1 and Th17 immune responses, the latter of which correlates with enhanced protection. Thus, a CDN-adjuvanted protein subunit vaccine has the capability of eliciting a multi-faceted immune response that results in protection from infection by an intracellular pathogen.