Development Of Chronic Inflammatory Disorders Research Articles

Targeting TREM1 augments antitumor T cell immunity by inhibiting myeloid-derived suppressor cells and restraining anti-PD-1 resistance.

The triggering receptor expressed on myeloid cell 1 (TREM1) plays a critical role in development of chronic inflammatory disorders and the inflamed tumor microenvironment (TME) associated with most solid tumors. We examined whether loss of TREM1 signaling can abrogate the immunosuppressive TME and enhance cancer immunity. To investigate the therapeutic potential of TREM1 in cancer, we used mice deficient in Trem1 and developed a novel small molecule TREM1 inhibitor, VJDT. We demonstrated that genetic or pharmacological TREM1 silencing significantly delayed tumor growth in murine melanoma (B16F10) and fibrosarcoma (MCA205) models. Single-cell RNA-Seq combined with functional assays during TREM1 deficiency revealed decreased immunosuppressive capacity of myeloid-derived suppressor cells (MDSCs) accompanied by expansion in cytotoxic CD8+ T cells and increased PD-1 expression. Furthermore, TREM1 inhibition enhanced the antitumorigenic effect of anti-PD-1 treatment, in part, by limiting MDSC frequency and abrogating T cell exhaustion. In patient-derived melanoma xenograft tumors, treatment with VJDT downregulated key oncogenic signaling pathways involved in cell proliferation, migration, and survival. Our work highlights the role of TREM1 in cancer progression, both intrinsically expressed in cancer cells and extrinsically in the TME. Thus, targeting TREM1 to modify an immunosuppressive TME and improve efficacy of immune checkpoint therapy represents what we believe to be a promising therapeutic approach to cancer.

NF-κB perturbation reveals unique immunomodulatory functions in Prx1+ fibroblasts that promote development of atopic dermatitis.

Skin is composed of diverse cell populations that cooperatively maintain homeostasis. Up-regulation of the nuclear factor κB (NF-κB) pathway may lead to the development of chronic inflammatory disorders of the skin, but its role during the early events remains unclear. Through analysis of single-cell RNA sequencing data via iterative random forest leave one out prediction, an explainable artificial intelligence method, we identified an immunoregulatory role for a unique paired related homeobox-1 (Prx1)+ fibroblast subpopulation. Disruption of Ikkb-NF-κB under homeostatic conditions in these fibroblasts paradoxically induced skin inflammation due to the overexpression of C-C motif chemokine ligand 11 (CCL11; or eotaxin-1) characterized by eosinophil infiltration and a subsequent TH2 immune response. Because the inflammatory phenotype resembled that seen in human atopic dermatitis (AD), we examined human AD skin samples and found that human AD fibroblasts also overexpressed CCL11 and that perturbation of Ikkb-NF-κB in primary human dermal fibroblasts up-regulated CCL11. Monoclonal antibody treatment against CCL11 was effective in reducing the eosinophilia and TH2 inflammation in a mouse model. Together, the murine model and human AD specimens point to dysregulated Prx1+ fibroblasts as a previously unrecognized etiologic factor that may contribute to the pathogenesis of AD and suggest that targeting CCL11 may be a way to treat AD-like skin lesions.

Regulation of macrophage-associated inflammatory responses by species-specific lactoferricin peptides.

Inflammation is the body's response to injury or infection and is important for healing and eliminating pathogens; however, prolonged inflammation is damaging and may lead to the development of chronic inflammatory disorders. Recently, there has been interest in exploiting antimicrobial peptides (AMPs) that exhibit immunoregulatory activities to treat inflammatory diseases. In this study, we investigated the immunomodulatory effects of lactoferrin-derived lactoferricin AMPs from three different species (bovine, mouse, and human) with subtle differences in their amino acid sequences that alter their antimicrobial action; to our knowledge, no other studies have compared their immunomodulatory effects. Macrophages, key players in the induction and propagation of inflammation, were used to investigate the effects of species-specific lactoferricin peptides on inflammatory processes. Bovine lactoferricin was the only one of the three peptides studied that downregulated lipopolysaccharide (LPS)-induced pro-inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-6, in both human and mouse macrophages. Lactoferricin regulated inflammation through targeting LPS-activated nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) signaling pathways. Although the immunoregulatory role of lactoferricin during an inflammatory response in vivo is yet to be elucidated, further investigation with the use of animal models is warranted by the current findings. The ability of lactoferricin, especially that of bovine origin, to downregulate macrophage-mediated inflammatory responses suggests potential for the development of this peptide as a novel immunotherapeutic agent in the treatment of chronic inflammatory conditions.

Cannabinoids as Key Regulators of Inflammasome Signaling: A Current Perspective.

Inflammasomes are cytoplasmic inflammatory signaling protein complexes that detect microbial materials, sterile inflammatory insults, and certain host-derived elements. Inflammasomes, once activated, promote caspase-1–mediated maturation and secretion of pro-inflammatory cytokines, interleukin (IL)-1β and IL-18, leading to pyroptosis. Current advances in inflammasome research support their involvement in the development of chronic inflammatory disorders in contrast to their role in regulating innate immunity. Cannabis (marijuana) is a natural product obtained from the Cannabis sativa plant, and pharmacologically active ingredients of the plant are referred to as cannabinoids. Cannabinoids and cannabis extracts have recently emerged as promising novel drugs for chronic medical conditions. Growing evidence indicates the potent anti-inflammatory potential of cannabinoids, especially Δ9-tetrahydrocannabinol (Δ9-THC), cannabidiol (CBD), and synthetic cannabinoids; however, the mechanisms remain unclear. Several attempts have been made to decipher the role of cannabinoids in modulating inflammasome signaling in the etiology of chronic inflammatory diseases. In this review, we discuss recently published evidence on the effect of cannabinoids on inflammasome signaling. We also discuss the contribution of various cannabinoids in human diseases concerning inflammasome regulation. Lastly, in the milieu of coronavirus disease-2019 (COVID-19) pandemic, we confer available evidence linking inflammasome activation to the pathophysiology of COVID-19 suggesting overall, the importance of cannabinoids as possible drugs to target inflammasome activation in or to support the treatment of a variety of human disorders including COVID-19.

Cytokine-targeted therapy in severely ill COVID-19 patients: Options and cautions

Dear Editor, The understanding of the cytokine storm mechanism(s) and its profile are crucial to developing effective therapeutic interventions in COVID-19. In this line, cytokine storm blockers and immune-host modulators are currently being applied in severely ill COVID-19 patients to cope with the overwhelming inflammation. However, most of the current reports highlighted different elevated cytokine patterns among severely ill COVID-19 patients, suggesting that more care should be taken before immunosuppressive therapy by cytokine blockers in COVID-19. Here, we summarize the more common cytokine profiles and cytokine-targeted therapy approaches that have been reported for severe COVID-19 patients. Finally, we underscore the urgent need to identify a precise cytokine panel before the administration of selective immunosuppressive therapy. Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS?CoV-2) with the symptoms including fever, dry cough and shortness of breath [1, 2]. Most COVID-19 patients will develop mild to moderate symptoms, while some infected people may face to hyper-inflammation induced by massive cytokines/chemokines production, called as cytokine storm, which may lead to fatal pneumonia and acute respiratory distress syndrome [1, 2]. Although, there is no specific antiviral therapy for COVID-19, understanding of cytokine storm mechanism in this disease can help to speculate possible therapeutic interventions [3]. Current reports have presented different cytokine profiles in patients with severe COVID-19 [1, 4-9]. For example, the higher levels of interleukin (IL)-2, IL-7, IL-10, tumor necrosis factor (TNF), granulocyte-colony stimulating factor (G-CSF), interferon gamma-induced protein 10 (IP-10; CXCL10), MCP-1 (CCL2) and MIP-1A (CCL3), but not IL-6, have been first shown in intensive care unit (ICU) patients compared to non-ICU patients [1]. Subsequent studies revealed the contribution of other cytokines, including IL-1?, IL-1ra, IL-2R, IL-6, IL-8 (CXCL8), IL-17, interferon (IFN)-? and GM-CSF (granulocyte-macrophage colony-stimulating factor), during severe COVID-19 infections [4, 5, 8, 9]. Figure 1 displays the protein-protein interaction between these cytokines/chemokines. In most existing reports, the elevated levels of several cytokines/chemokine (ie., IL-6, IL-10, IFN-?, TNF and IP-10), have been greater emphasized in severely ill (ICU) COVID-19 patients than mild to moderate (non-ICU) group [1, 4-7]. Involvement of the T helper 2 cytokine IL-10, that suppresses inflammation, is a prominent feature of all reports, and an imbalance and/or exhaustion of T cells may be also involved. [1, 10]. Several approaches, including global targeting of the inflammation or neutralizing a single key inflammatory mediator, are being employed to cope with cytokine storm in COVID-19. Among key cytokines, IL-6 has attracted high levels of interest and antibodies that block the IL-6 receptor (tocilizumab and sarilumab) are currently under phase 2/3 clinical trials for the potential treatment of COVID-19 [2]. Targeting IFN-? is another promising approach, which has been highlighted by launching a clinical trial for JAK–STAT inhibitor (ruxolitinib) for controlling COVID-19 severity. [11] TNF acts upstream of IL-6 and anti-TNF therapies previously revealed protective effects in lethal SARS-CoV infection [12]. Several TNF-blocking antibodies (eg., adalimumab, etanercept, and golimumab) are successfully used to treat inflammatory diseases, and these therapies have been urgently recommended for the hospitalized COVID-19 patients [13]. IL-10 is likely upregulated to counter overwhelming infection during SARS-CoV-2 infection, but it may be also involved in the infiltration of inflammatory cells and lung fibrosis [14]. IL-10 blocking, alone or in combination with programmed cell death protein 1 (PD-1), is promising for reinvigorating exhausted T cells and may control COVID-19 pathogenesis [10]. Despite the benefits, there are still disadvantages, such as the development of chronic inflammatory disorders, thus more experimental studies should be done to clarify whether overactivation or ablation of IL-10 could be helpful for severe COVID-19. In some countries, including Iran and Turkey, tocilizumab is a recommended therapeutic strategy for ICU patients with severe COVID-19 [15]. However, it should be note that the elevated IL-6 levels, in common with other cytokines such as TNF, have no specific pattern in all severe COVID-19 patients, so that their levels were not associated with the disease severity in some patients [1, 4, 5]. Therefore, as patients with severe COVID-19 represent the differential cytokine patterns, more care should be taken before immunosuppressive therapy by cytokine blockers in COVID-19. This is important that the doctors evaluate a cytokine panel, at least including IL-6, IFN-?, and TNF-?, to precisely identify the needs of each patient before administration of selective immunosuppressive therapy. Obviously, a combination of immunosuppressive therapy with antiviral therapies that diminish virus titer should be also into account. Declaration of interests The authors declare no conflict of interest. Keywords: Covid-19 , SARS-CoV-2 , cytokine storm

Topical applications of an emollient reduce circulating pro-inflammatory cytokine levels in chronically aged humans: a pilot clinical study.

While increased levels of circulating inflammatory cytokines in chronologically aged humans have been linked to the development of ageing-associated chronic disorders (e.g., cardiovascular disease, type II diabetes, osteoporosis and Alzheimer's disease), approaches that reduce circulating cytokines are not yet available. In chronologically aged mice, we recently demonstrated that epidermal dysfunction largely accounts for age-associated elevations in circulating cytokine levels, and that improving epidermal function reduced circulating cytokine levels. We performed a pilot study to determine whether improving epidermal function reduces circulating pro-inflammatory cytokine levels in aged humans. Thirty-three aged humans were topically treated twice-daily for 30days, with≈3mL of an emollient, previously shown to improve epidermal function, while untreated, aged humans and a cohort of young volunteers served as controls. Changes in epidermal function and levels of three key, age-related, plasma cytokines (IL-1β, IL-6 and TNFα) were measured at baseline and after treatment, using Luminex 200™ system. We also found significantly higher baseline levels of IL-1β, IL-6 and TNFα in aged vs. young humans (P<0.001), as previously reported. Topical applications of the barrier repair emollient significantly enhanced epidermal permeability barrier function (P<0.01) and stratum corneum hydration (P<0.05). In parallel, circulating levels of IL-1β and IL-6 normalized, while TNFα levels declined substantially. The results of this preliminary study suggest that a larger clinical trial should be performed to confirm whether improving epidermal function also can reduce circulating pro-inflammatory cytokine levels in aged humans, while also possibly attenuating the downstream development of chronic inflammatory disorders in the aged humans.

Protection Against Arthritis by the Parasitic Worm Product ES-62, and Its Drug-Like Small Molecule Analogues, Is Associated With Inhibition of Osteoclastogenesis.

The immunomodulatory actions of parasitic helminth excretory-secretory (ES) products that serendipitously protect against development of chronic inflammatory disorders are well established: however, knowledge of the interaction between ES products and the host musculoskeletal system in such diseases is limited. In this study, we have focused on ES-62, a glycoprotein secreted by the rodent filarial nematode Acanthocheilonema viteae that is immunomodulatory by virtue of covalently attached phosphorylcholine (PC) moieties, and also two synthetic drug-like PC-based small molecule analogues (SMAs) that mimic ES-62’s immunomodulatory activity. We have previously shown that each of these molecules prevents development of pathology in collagen-induced arthritis (CIA), a model of the musculoskeletal disease rheumatoid arthritis (RA) and reflecting this, we now report that ES-62 and its SMAs, modify bone remodeling by altering bone marrow progenitors and thus impacting on osteoclastogenesis. Consistent with this, we find that these molecules inhibit functional osteoclast differentiation in vitro. Furthermore, this appears to be achieved by induction of anti-oxidant response gene expression, thereby resulting in reduction of the reactive oxygen species production that is necessary for the increased osteoclastogenesis witnessed in musculoskeletal diseases like RA.

Fetal exposure to maternal inflammation does not affect postnatal development of genetically-driven ileitis and colitis.

Background: Chronic inflammatory disorders have been increasing in incidence over the past decades following geographical patterns of industrialization. Fetal exposure to maternal inflammation may alter organ functions and the offspring's disease risk. We studied the development of genetically-driven ileitis and colitis in response to maternal inflammation using mouse models. Methods: Disease susceptible (Tnf ΔARE/+ and IL10−/−) and disease-free (Tnf +/+ and IL10−/+) offspring were raised in inflamed and non-inflamed dams. Ileal, caecal and colonic pathology was evaluated in the offspring at 8 or 12 weeks of age. Ly6G-positive cells in inflamed sections from the distal ileum and distal colon were analysed by immunofluorescence microscopy. Gene expression of pro-inflammatory cytokines was measured in whole tissue specimens by quantitative PCR. Microarray analyses were performed on laser microdissected intestinal epithelium. Caecal bacterial communities were assessed by Illumina sequencing of 16S rRNA amplicons. Results: Disease severity, the number of infiltrated neutrophils as well as Tnf and Il12p40 mRNA expression were independent of maternal inflammation in the offspring of mouse models for ileitis (Tnf ΔARE/+) and colitis (IL10−/−). Although TNF-driven maternal inflammation regulated 2,174 (wild type) and 3,345 (Tnf ΔARE/+) genes in the fetal epithelium, prenatal gene expression patterns were completely overwritten after birth. In addition, co-housing experiments revealed no change in phylogenetic diversity of the offspring's caecal microbiota in response to maternal inflammation. This is independent of the offspring's genotype before and after the onset of tissue pathology. Conclusions: Disease risk and activity in mouse models of chronic ileitis and colitis was independent of the fetal exposure to maternal inflammation. Likewise, maternal inflammation did not alter the diversity and composition of offspring's caecal microbiota, clearly demonstrating that changes of the gene expression program in the fetal gut epithelium were not relevant for the development of chronic inflammatory disorders in the gut.

Rectal Administration of Lactobacillus casei DG Modifies Flora Composition and Toll-Like Receptor Expression in Colonic Mucosa of Patients with Mild Ulcerative Colitis

An imbalance in gut microbiota seems to contribute to the development of chronic inflammatory disorders of the gastrointestinal tract, such as ulcerative colitis (UC). Although it has been suggested that probiotic supplementation is an effective approach to colitis, its effects on intestinal flora and on mucosal cytokine balance have never been explored. To evaluate the effect of Lactobacillus casei (L.casei) DG, a probiotic strain, on colonic-associated microbiota, mucosal cytokine balance, and toll-like receptor (TLR) expression. Twenty-six patients with mild left-sided UC were randomly allocated to one of three groups for an 8-week treatment period: the first group of 7 patients received oral 5-aminosalicylic acid (5-ASA) alone, the second group of 8 patients received oral 5-ASA plus oral L.casei DG, and the third group of 11 patients received oral 5-ASA and rectal L.casei DG. Biopsies were collected from the sigmoid region to culture mucosal-associated microbes and to assess cytokine and TLR messenger RNA (mRNA) levels by quantitative real-time polymerase chain reaction (RT-PCR). 5-ASA alone or together with oral L.casei DG failed to affect colonic flora and TLR expression in a significant manner, but when coupled with rectally administered L.casei DG, it modified colonic microbiota by increasing Lactobacillus spp. and reducing Enterobacteriaceae. It also significantly reduced TLR-4 and interleukin (IL)-1β mRNA levels and significantly increased mucosal IL-10. Manipulation of mucosal microbiota by L.casei DG and its effects on the mucosal immune system seem to be required to mediate the beneficial activities of probiotics in UC patients.

Abstract no.: 10 DNA fragmentation, but not caspase‐3 activation or PARP‐1 cleavage, combined with macrophage immunostaining as a tool to study phagocytosis of apoptotic cells in situ

Efficient phagocytosis of cells undergoing apoptosis by macrophages is important to prevent immunological responses and development of chronic inflammatory disorders, such as systemic lupus erythematosus, cystic fibrosis or atherosclerosis. To study phagocytosis of apoptotic cells (AC) by macrophages in tissue, we validated different apoptosis markers (DNA fragmentation, caspase‐3 activation and cleavage of its substrate poly (ADP‐ribose) polymerase‐1) in combination with macrophage immunostaining. Human tonsils were used as a model because they show a high apoptosis frequency under physiological conditions as well as efficient phagocytosis of AC by macrophages. On the other hand, advanced human atherosclerotic plaques were examined since phagocytosis of AC in a plaque is severely impaired. Our results demonstrate that the presence of non‐phagocytized TUNEL‐positive AC represents a suitable marker for poor phagocytosis by macrophages in situ. Other markers for apoptosis, such as cleavage of caspase‐3 or PARP‐1, should not be used to assess phagocytosis efficiency, because activation of the caspase cascade and cleavage of their substrates can occur in AC when they have not yet been phagocytized by macrophages.

Molecular mechanisms of sulfasalazine-induced T-cell apoptosis.

Impaired apoptosis of T-lymphocytes is involved in the development of chronic inflammatory disorders. Previously we have shown that the anti-inflammatory drug sulfasalazine induces apoptosis in a murine T-lymphocyte cell line. The aims of the present study were to expand these observations to human systems and to analyse the molecular basis for sulfasalazine-induced apoptosis. Sulfasalazine induces apoptosis both in Jurkat cells, a human T-leukaemia cell line (ED50 value approximately 1.0 mM), and in primary human peripheral blood T-lymphocytes (ED50 value approximately 0.5 mM). In contrast SW620 colon carcinoma cells or primary human synoviocytes are not affected at these concentrations suggesting a cell type-specific sensitivity to sulfasalazine. Sulfasalazine triggers the mitochondrial accumulation of Bax and induces a collapse of the mitochondrial transmembrane potential (deltapsi(m)). Sulfasalazine causes cytochrome c release from mitochondria and subsequent activation of caspase-3 and downstream substrates. However, the pan-caspase inhibitor Z-VAD.fmk fails to inhibit sulfasalazine-induced apoptosis. Sulfasalazine stimulates mitochondrio-nuclear translocation of the novel apoptogenic factor apoptosis-inducing factor (AIF) and triggers large-scale DNA fragmentation, a characteristic feature of AIF-mediated apoptosis. Sulfasalazine-induced DeltaPsi(m) loss, AIF redistribution, and cell death are fully prevented by overexpression of Bcl-2. In conclusion, our data suggest that sulfasalazine-induced apoptosis of T-lymphocytes is mediated by mitochondrio-nuclear translocation of AIF and occurs in a caspase-independent fashion. Sulfasalazine-induced apoptosis by AIF and subsequent clearance of T-lymphocytes might thus provide the molecular basis for the beneficial therapeutic effects of sulfasalazine in the treatment of chronic inflammatory diseases.

Aspirin-tolerant asthmatics generate more lipoxins than aspirin-intolerant asthmatics.

Asthma is characterized by chronic airway inflammation resulting from overproduction of pro-inflammatory mediators, such as leukotrienes (LT). The authors questioned the biosynthetic capacity of asthmatic patients for lipoxins (LX) and 15-epimer lipoxins (15-epi-LX), endogenous regulators of inflammatory responses that inhibit pro-inflammatory events. Levels of LXA4, 15-epi-LXA4 and LTC4 were determined in 14 clinically characterized aspirin-intolerant asthmatics (AIA), 11 aspirin-tolerant asthmatics (ATA) and eight healthy volunteers using a stimulated whole blood protocol. Both LXA4 and 15-epi-LXA4 were generated in whole blood activated by the divalent cation ionophore, A23187. Higher levels of LXA4 were produced in ATA than either AIA or healthy volunteers. Exposure of AIA whole blood to interleukin-3 prior to A23187 did not elevate their reduced capacity to generate LXA4. Generation of a bronchoconstrictor, LTC4, was similar in both AIA and ATA. Consequently, the ratio of LXA4:LTC4 quantitatively favoured the bronchoconstrictor for AIA and differed from both ATA and healthy subjects. In addition, the capacity for 15-epi-LXA4 generation was also diminished in AIA, since whole blood stimulated in the presence of aspirin gave increased levels only in samples from ATA. The present results indicate that asthmatics possess the capacity to generate both lipoxins and 15-epimer-lipoxins, but aspirin-intolerant asthmatics display a lower biosynthetic capacity than aspirin-tolerant asthmatics for these potentially protective lipid mediators. This previously unappreciated, diminished capacity for lipoxin formation by aspirin-intolerant asthmatic patients may contribute to their more severe clinical phenotype, and represents a novel paradigm for the development of chronic inflammatory disorders.