Current data on IL-17 and Th17 cells and implications for graft versus host disease

The Th1/Th2 paradigm: A misrepresentation of helper T cell plasticity

For decades, the Th1/2 paradigm has been used to classify immune responses as either Th1 or Th2-biased. However, in recent years, a staggering amount of evidence has emerged to support rejection of the classical Th1/Th2 paradigm, such as the discoveries of new helper T cell subsets, helper T cell plasticity and protective mixed-Th1/Th2 responses. This opinion piece investigates the shortcomings of classical Th1/Th2 paradigm in the context of recent works, with the goal of facilitating the development of newer models to represent the diversity of Th cells.

Skin transcriptomic analysis reveals candidate genes and pathways associated with thermotolerance in hair sheep

The skin plays an important role in thermoregulation. Identification of genes on the skin that contribute to increased heat tolerance can be used to select animals with the best performance in warm environments. Our objective was to identify candidate genes associated with the heat stress response in the skin of Santa Ines sheep. A group of 80 sheep assessed for thermotolerance was kept in a climatic chamber for 8 days at a stress level temperature of 36 °C (10 am to 04 pm) and a maintenance temperature of 28 °C (04 pm to 10 am). Two divergent groups, with seven animals each, were formed after ranking them by thermotolerance using rectal temperature. From skin biopsy samples, total RNA was extracted, quantified, and used for RNA-seq analysis. 15,989 genes were expressed in sheep skin samples, of which 4 genes were differentially expressed (DE; FDR < 0.05) and 11 DE (FDR 0.05-0.177) between the two divergent groups. These genes are involved in cellular protection against stress (HSPA1A and HSPA6), ribosome assembly (28S, 18S, and 5S ribosomal RNA), and immune response (IGHG4, GNLY, CXCL1, CAPN14, and SAA-4). The candidate genes and main pathways related to heat tolerance in Santa Ines sheep require further investigation to understand their response to heat stress in different climatic conditions and under solar radiation. It is essential to verify whether these genes and pathways are present in different breeds and to understand the relationship between heat stress and other genes identified in this study.

Elucidating the role played by bone marrow in visceral leishmaniasis

Leishmaniasis is a widespread group of infectious diseases that significantly impact global health. Despite high prevalence, leishmaniasis often receives inadequate attention in the prioritization of measures targeting tropical diseases. The causative agents of leishmaniasis are protozoan parasites of the Leishmania genus, which give rise to a diverse range of clinical manifestations, including cutaneous and visceral forms. Visceral leishmaniasis (VL), the most severe form, can be life-threatening if left untreated. Parasites can spread systemically within the body, infecting a range of organs, such as the liver, spleen, bone marrow and lymph nodes. Natural reservoirs for these protozoa include rodents, dogs, foxes, jackals, and wolves, with dogs serving as the primary urban reservoir for Leishmania infantum. Dogs exhibit clinical and pathological similarities to human VL and are valuable models for studying disease progression. Both human and canine VL provoke clinical symptoms, such as organ enlargement, fever, weight loss and abnormal gamma globulin levels. Hematologic abnormalities have also been observed, including anemia, leukopenia with lymphocytosis, neutropenia, and thrombocytopenia. Studies in dogs have linked these hematologic changes in peripheral blood to alterations in the bone marrow. Mouse models of VL have also contributed significantly to our understanding of the mechanisms underlying these hematologic and bone marrow abnormalities. This review consolidates information on hematological and immunological changes in the bone marrow of humans, dogs, and mice infected with Leishmania species causing VL. It includes findings on the role of bone marrow as a source of parasite persistence in internal organs and VL development. Highlighting gaps in current knowledge, the review emphasizes the need for future research to enhance our understanding of VL and identify potential targets for novel diagnostic and therapeutic approaches.

Inhibition of Bromodomain and Extra Terminal (BET) Domain Activity Modulates the IL-23R/IL-17 Axis and Suppresses Acute Graft-Versus-Host Disease

Acute graft-versus-host disease (GVHD) is the leading cause of non-relapse mortality following allogeneic hematopoietic cell transplantation. The majority of patients non-responsive to front line treatment with steroids have an estimated overall 2-year survival rate of only 10%. Bromodomain and extra-terminal domain (BET) proteins influence inflammatory gene transcription, and therefore represent a potential target to mitigate inflammation central to acute GVHD pathogenesis. Using potent and selective BET inhibitors Plexxikon-51107 and -2853 (PLX51107 and PLX2853), we show that BET inhibition significantly improves survival and reduces disease progression in murine models of acute GVHD without sacrificing the beneficial graft-versus-leukemia response. BET inhibition reduces T cell alloreactive proliferation, decreases inflammatory cytokine production, and impairs dendritic cell maturation both in vitro and in vivo. RNA sequencing studies in human T cells revealed that BET inhibition impacts inflammatory IL-17 and IL-12 gene expression signatures, and Chromatin Immunoprecipitation (ChIP)-sequencing revealed that BRD4 binds directly to the IL-23R gene locus. BET inhibition results in decreased IL-23R expression and function as demonstrated by decreased phosphorylation of STAT3 in response to IL-23 stimulation in human T cells in vitro as well as in mouse donor T cells in vivo. Furthermore, PLX2853 significantly reduced IL-23R+ and pathogenic CD4+ IFNγ+ IL-17+ double positive T cell infiltration in gastrointestinal tissues in an acute GVHD murine model. Our findings identify a role for BET proteins in regulating the IL-23R/STAT3/IL-17 pathway. Based on our preclinical data presented here, PLX51107 will enter clinical trial for refractory acute GVHD in a Phase 1 safety, biological efficacy trial.

Effect of systemic photobiomodulation in the course of acute lung injury in rats

Acute lung injury (ALI) is a severe, multifactorial lung pathology characterized by diffuse alveolar injury, inflammatory cell infiltration, alveolar epithelial barrier rupture, alveolar edema, and impaired pulmonary gas exchange, with a high rate of mortality; and sepsis is its most common cause. The mechanisms underlying ALI due to systemic inflammation were investigated experimentally by systemic lipopolysaccharide (LPS) administration. Photobiomodulation (PBM) has been showing good results for several inflammatory diseases, but there are not enough studies to support the real benefits of its use, especially systemically. Considering that ALI is a pathology with high morbidity and mortality, we studied the effect of systemic PBM with red light-emitting diode (LED) (wavelength 660 nm; potency 100 mW; energy density 5 J/cm; total energy 15 J; time 150 s) in the management of inflammatory parameters of this disease. For this, 54 male Wistar rats were submitted to ALI by LPS injection (IP) and treated or not with PBM systemically in the tail 2 and 6 h after LPS injection. Data were analyzed by one-way ANOVA followed by Student's Newman-Keuls. Our results point to the beneficial effects of systemic PBM on the LPS-induced ALI, as it reduced the number of neutrophils recruited into the bronchoalveolar lavage, myeloperoxidase activity, and also reduced interleukins (IL) 1β, IL-6, and IL-17 in the lung. Even considering the promising results, we highlight the importance of further studies to understand the mechanisms involved, and especially the dosimetry, so that in near future, we can apply this knowledge in clinical practice.

Th17 lymphocytes in atypical cutaneous leishmaniasis caused by Leishmania (L.) infantum chagasi in Central America

Skin lesions in nonulcerated cutaneous leishmaniasis (NUCL) caused by Leishmania (L.) infantum chagasi are characterized by a mononuclear inflammatory infiltrate in the dermis, which is composed mainly of lymphocytes, followed by macrophages, few plasma cells and epithelioid granulomas with mild tissue parasitism. Previous studies have shown that the main population of lymphocytes present in the dermal infiltrate is CD8⁺ T cells, followed by CD4⁺ T cells, which are correlated with IFN-γ⁺ cells. To improve the knowledge of cellular immune responses in NUCL, skin biopsies were submitted to immunohistochemistry using anti-ROR-γt, anti-IL-17, anti-IL-6, anti-TGF-β, and anti-IL-23 antibodies to characterize the involvement of Th17 cells in the skin lesions of patients affected by NUCL. ROR-γt⁺ , IL-17⁺ , IL-6⁺ , TGF-β⁺ and IL-23⁺ cells were observed in the dermal inflammatory infiltrate of NUCL skin lesions. A positive correlation between CD4⁺ T-lymphocytes and ROR-γt⁺ and IL-17⁺ cells suggests that some of the CD4⁺ T-lymphocytes in NUCL could be Th17 lymphocytes. Moreover, a positive correlation between ROR-γt⁺ cells and TGF-β⁺ , IL-6⁺ , IL-17⁺ and IL-23⁺ cells could indicate the role of these cytokines in the differentiation and maintenance of Th17 lymphocytes. Our findings improve knowledge of the pathogenesis of this rare and atypical clinical form of leishmaniasis.

Donor-derived IL-17A and IL-17F deficiency triggers Th1 allo-responses and increases gut leakage during acute GVHD

IL-17A and IL-17F cytokines are important regulators of acute graft-versus-host-disease (GVHD). However, contrary effects of these cytokines in inflammatory diseases have been reported. To investigate the effects of donor-derived IL-17A and IL-17F on GVHD, we made use of single (Il17a^-/- or Il17f^-/-) and double deficient (Il17af^-/-) allogeneic donor CD4⁺ T cells. We could demonstrate that transplantation of Il17af^-/- CD4⁺ donor T cells led to aggravated GVHD. However, this phenotype was not observed after transplantation of single, Il17a^-/- or Il17f^-/-, deficient CD4⁺ T cells, suggesting redundant effects of IL-17A and IL-17F. Moreover, Il17af^-/- cell recipients showed an increase of systemic IFNγ, indicating a heightened pro-inflammatory state, as well as infiltration of IFNγ-secreting CD4⁺ T cells in the recipients’ intestinal tract. These recipients exhibited significant gut leakage, and markedly macrophage infiltration in the gastrointestinal epithelial layer. Moreover, we saw evidence of impaired recovery of gut epithelial cells in recipients of Il17af^-/- CD4⁺ T cells. In this study, we show that IL-17A/F double deficiency of donor CD4⁺ T cells leads to accelerated GVHD and therefore highlight the importance of these cytokines. Together, IL-17 cytokines might serve as a brake to an intensified Th1 response, leading to the exacerbated gut damage in acute GVHD.

COMPARATIVE ANALYSIS OF IMMUNOLOGICAL PROFILES IN WOMEN UNDERGOING CONVENTIONAL AND SINGLE-PORT LAPAROSCOPIC CHOLECYSTECTOMY

Background

Surgical trauma triggers an important postoperative stress response characterized by significantly elevated levels of cytokines, an event that can favor the emergence of immune disorders which lead to disturbances in the patient's body defense. The magnitude of postoperative stress is related to the degree of surgical trauma.

Aim

To evaluate the expression of pro-inflammatory (TNF-α, IFN-γ, IL-1β, and IL-17) and anti-inflammatory (IL-4) cytokines in patients submitted to conventional and single-port laparoscopic cholecystectomy before and 24 h after surgery.

Methods

Forty women with symptomatic cholelithiasis, ranging in age from 18 to 70 years, participated in the study. The patients were divided into two groups: 21 submitted to conventional laparoscopic cholecystectomy and 19 to single-port laparoscopic cholecystectomy.

Results

Evaluation of the immune response showed no significant difference in IFN-γ and IL-1β levels between the groups or time points analyzed. With respect to TNF-α and IL-4, serum levels below the detection limit (10 pg/ml) were observed in the two groups and at the time points analyzed. Significantly higher postoperative expression of IL-17A was detected in patients submitted to single-port laparoscopic cholecystectomy when compared to preoperative levels (p=0.0094).

Conclusions

Significant postoperative expression of IL-17 was observed in the group submitted to single-port laparoscopic cholecystectomy when compared to preoperative levels, indicating that surgical stress in this group was higher compared to the conventional laparoscopic cholecystectomy.

Cellular and molecular mechanisms in graft-versus-host disease

Graft-versus-host disease is a complication in patients undergoing hematopoietic stem cell transplantation. Graft-versus-host disease includes acute graft-versus-host disease and chronic graft-versus-host disease. Host APCs (e.g., dendritic cells and macrophages), effector T cells (e.g., Th1, Th17, and abnormal Th17:regulatory T cell ratio), B cells, and NK cells are implicated in graft-versus-host disease physiopathology. Proinflammation cytokines (e.g., IL-17, IL-1β, and TNF-α) are increased in graft-versus-host disease . Costimulatory molecules play an important role in inducing graft-versus-host disease . Pattern-recognition receptors, such as TLRs and nucleotide-binding oligomerization domain-like receptors, are critically involved in the pathogenesis of graft-versus-host disease . Complement system C3 mediates Th1/Th17 polarization in human T cell activation and skin graft-versus-host disease. Accumulation of CD26 T cells in graft-versus-host disease target organs was found. As a therapeutic target, soluble CD83 molecules or antibodies have been demonstrated to have therapeutic effects against graft-versus-host disease, and signaling molecules promote the inflammatory and immune process of graft-versus-host disease . These immune cells and molecules could be the predictors of graft-versus-host disease development and the drug targets of the treatments for graft-versus-host disease. This article focuses on major advances on cellular and molecular mechanisms in graft-versus-host disease.

Inhibition of the interleukin-6 signaling pathway: a strategy to induce immune tolerance

Interleukin-6 (IL-6) is a proinflammatory cytokine that is multifunctional, with multifaceted effects. IL-6 signaling plays a vital role in the control of the differentiation and activation of T lymphocytes by inducing different pathways. In particular, IL-6 controls the balance between Th17 cells and regulatory T (Treg) cells. An imbalance between Treg and Th17 cells is thought to play a pathological role in various immune-mediated diseases. Deregulated IL-6 production and signaling are associated with immune tolerance. Therefore, methods of inhibiting IL-6 production, receptors, and signaling pathways are strategies that are currently being widely pursued to develop novel therapies that induce immune tolerance. This survey aims to provide an updated account of why IL-6 inhibitors are becoming a vital class of drugs that are potentially useful for inducing immune tolerance as a treatment for autoimmune diseases and transplant rejection. In addition, we discuss the effect of targeting IL-6 in recent experimental and clinical studies on autoimmune diseases and transplant rejection.

Interleukin 7 plays a role in T lymphocyte apoptosis inhibition driven by mesenchymal stem cell without favoring proliferation and cytokines secretion

Since 2004, when a case report describing the use of human mesenchymal stem cells (hMSCs) infusion as a therapy for GVHD after bone marrow transplantation, a new perspective in MSC function emerged. Since then hMSCs immunomodulatory potential became the target of several studies. Although great progress has been made in our understanding of hMSCs, their effect on T cell remains obscure. Our study has confirmed the already described effect of hMSCs on lymphocytes proliferation and survival. We also show that the impairment of lymphocyte proliferation and apoptosis is contact-independent and occurs in a prostaglandin-independent manner. A potential correlation between IL-7 and hMSCs effect is suggested, as we observed an increase in IL-7 receptors (CD127) on lymphocyte membrane in MSC presence. Additionally, blocking IL-7 in hMSCs-lymphocytes co-cultures increased lymphocytes apoptosis and we also have demonstrated that hMSCs are able to produce this interleukin. Moreover, we found that during Th1/Th17 differentiation in vitro, hMSCs presence leads to Th1/Th17 cells with reduced capacity of INF-y and IL-17 secretion respectively, regardless of having several pro-inflammatory cytokines in culture. We did not confirm an increment of Treg in these cultures, but a reduced percentage of INF-y/IL-17 secreting cells was observed, suggesting that the ratio between anti and pro-inflammatory cells changed. This changed ratio is very important to GvHD therapy and links hMSCs to an anti-inflammatory role. Taken together, our findings provide important preliminary results on the lymphocyte pathway modulated by MSCs and may contribute for developing novel treatments and therapeutic targets for GvHD and others autoimmune diseases.

Oral complications in hematopoietic stem cell recipients: the role of inflammation

Hematopoietic stem cell transplantation (HSCT) is widely used as a potentially curative treatment for patients with various hematological malignancies, bone marrow failure syndromes, and congenital immune deficiencies. The prevalence of oral complications in both autologous and allogeneic HSCT recipients remains high, despite advances in transplant medicine and in supportive care. Frequently encountered oral complications include mucositis, infections, oral dryness, taste changes, and graft versus host disease in allogeneic HSCT. Oral complications are associated with substantial morbidity and in some cases with increased mortality and may significantly affect quality of life, even many years after HSCT. Inflammatory processes are key in the pathobiology of most oral complications in HSCT recipients. This review article will discuss frequently encountered oral complications associated with HSCT focusing on the inflammatory pathways and inflammatory mediators involved in their pathogenesis.