Impact of immune checkpoint molecules on FoxP3+ Treg cells and related cytokines in patients with acute and chronic brucellosis

Investigation of IL-35 and IL-39, New Members of the IL-12 Family, in Different Clinical Presentations of Brucellosis

Brucellosis is significantly influenced by the interactions between the causative Brucella bacteria and host immunity. Recently identified cytokines have been described for their immunomodulatory effects in numerous inflammatory, autoimmune and infectious diseases. Some of them are new members of cytokine superfamilies, including several members of the IL-12 superfamily (IL-35, IL-39). The major purpose of the present study was to investigate the role of these new immunomodulatory cytokines in Brucella infections. The levels of IL-35 and IL-39 in the serum of 40 acute and 40 chronic brucellosis patients and 40 healthy controls were measured by ELISA. The mRNA levels of IL-35 and IL-39 in PBMCs were detected by RT-qPCR. Both IL-35 and IL-39 serum concentrations were significantly higher in healthy control subjects than in brucellosis patients, and IL-35 and IL-39 serum levels of chronic brucellosis patients were higher than those of acute cases. It was also found that the expression of Ebi3/IL-12A (IL-35 genes) and Ebi3/IL-23A (IL-39 genes) was upregulated in chronic brucellosis patients compared to healthy controls. Moreover, the expression of the Ebi3/IL-12A and Ebi3/IL-23A genes was lower in patients with acute brucellosis than in patients with chronic brucellosis. Overall, this study showed that IL-35 and IL-39 are positively correlated in brucellosis and significantly decreased during the disease. Significantly lower levels of IL-35 and IL-39 in acute brucellosis than in chronic brucellosis and healthy controls suggest that these cytokines may play a key role in suppressing the immune response to brucellosis and its progression to chronicity.

PRRSV-1 induced lung lesion is associated with an imbalance between costimulatory and coinhibitory immune checkpoints

Porcine reproductive and respiratory syndrome virus (PRRSV) induces a dysregulation on the innate and adaptive immune responses. T-cell activation requires a proper interaction and precise balance between costimulatory and coinhibitory molecules, commonly known as immune checkpoints. This study aims to evaluate the expression of immune checkpoints in lung and tracheobronchial lymph node from piglets infected with two PRRSV-1 strains of different virulence during the early stage of infection. Seventy 4-week-old piglets were grouped into three experimental groups: (i) control, (ii) 3249-infected group (low virulent strain), and (iii) Lena-infected group (virulent strain) and were euthanized at 1, 3, 6, 8, and 13 days post-infection (dpi). Lung and tracheobronchial lymph node were collected to evaluate histopathological findings, PRRSV viral load and mRNA expression of costimulatory (CD28, CD226, TNFRSF9, SELL, ICOS, and CD40) and coinhibitory (CTLA4, TIGIT, PD1/PDL1, TIM3, LAG3, and IDO1) molecules through RT-qPCR. Our findings highlight a mild increase of costimulatory molecules together with an earlier and stronger up-regulation of coinhibitory molecules in both organs from PRRSV-1-infected animals, especially in the lung from virulent Lena-infected animals. The simultaneous expression of coinhibitory immune checkpoints could work in synergy to control and limit the inflammation-induced tissue damage. Further studies should be addressed to determine the role of these molecules in later stages of PRRSV infection.

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.

Serum Levels of Seven General Cytokines in Acute Brucellosis Before and After Treatment

Purpose

Human brucellosis is the most common bacterial zoonosis globally that poses a severe health threat. Despite the availability of antibiotic therapy for human brucellosis, its tendencies of chronicity and persistence may lead to severe debilitating and disabling conditions in patients. Comprehensive understanding of the immune response in brucellosis will be helpful in improving the treatment strategies. In this study, we measured serum levels of T helper cell type 1 (Th1), Th2, and Th17 cytokines in patients with acute brucellosis before and after treatment.

Patients and Methods

Overall, 30 patients with acute brucellosis from the Beijing Di Tan Hospital and 26 healthy controls were enrolled in this study. All the patients received a 6-week therapy regimen comprising ceftriaxone, doxycycline, and rifampicin. Serum samples were collected from patients with acute Brucella infection and healthy controls before and after treatment. Serum seven cytokine levels of Th1 (IL-2, IFN-γ, and TNF-α), Th2 (IL-4, IL-6, IL-10), and Th17 (IL-17A) were measured using cytometric bead array.

Results

In patients with acute infection, the IL-2, IFN-γ, and IL-10 levels were significantly increased compared with those in healthy controls (P < 0.001). After treatment, IL-2, IFN-γ, and IL-10 levels significantly decreased (P < 0.05) and the TNF-α level significantly increased compared with the corresponding baseline levels and those in healthy controls (P < 0.05). Furthermore, the IFN-γ, IL-4, and IL-10 levels were higher in patients after treatment than in healthy controls (P < 0.05). IL-2 and IL-6 levels exhibited a positive correlation with the C-reactive protein (CRP) level in acute brucellosis (P < 0.05).

Conclusion

Levels of most serum Th1 and Th2 cytokines were simultaneously increased in acute infection, followed by reduction in the corresponding cytokine levels and residual cytokine response during treatment. This residual immune response could represent a therapeutic opportunity that may improve the long-term clinical outcomes in patients with acute brucellosis after treatment.