Impact of neutrophil-secreted myeloid related proteins 8 and 14 (MRP 8/14) on leishmaniasis progression

Global Remodeling of Host Proteome in Response to Leishmania Infection

The protozoan parasite Leishmania possesses an intrinsic ability to modulate a multitude of pathways in the host, toward aiding its own proliferation. In response, the host reprograms its cellular, immunological, and metabolic machinery to evade the parasite's lethal impact. Besides inducing various antioxidant signaling pathways to counter the elevated stress response proteins like heme oxygenase-1 (HO-1), Leishmania also attempts to delay host cell apoptosis by promoting anti-apoptotic proteins like Bcl-2. The downstream modulation of apoptotic proteins is regulated by effector pathways, including the PI3K/Akt survival pathway, the mitogen-activated protein kinases (MAPKs) signaling pathway, and STAT phosphorylation. In addition, Leishmania assists in its infection in a time-dependent manner by modulating the level of various proteins of autophagic machinery. Immune effector cells, such as mast cells and neutrophils, entrap and kill the pathogen by secreting various granular proteins. In contrast, the host macrophages exert their leishmanicidal effect by secreting various cytokines, such as IL-2, IL-12, etc. An interplay of various signaling pathways occurs in an organized network that is highly specific to both pathogen and host species. This Review analyzes the modulation of expression of proteins, including the cytokines, providing a realistic approach toward understanding the pathophysiology of disease and predicting some prominent markers for disease intervention and vaccine support strategies.

Co-expression analysis of lncRNA and mRNA suggests a role for ncRNA-mediated regulation of host-parasite interactions in primary skin lesions of patients with American tegumentary leishmaniasis

Leishmaniasis, caused by different Leishmania species, manifests as cutaneous or visceral forms. In the American continent, the cutaneous form is called American tegumentary leishmaniasis (ATL) and is primarily caused by Leishmania (Viannia) braziliensis. Mucosal leishmaniasis (ML), the most severe form of ATL, arises in approximately 20% of patients from a primary cutaneous lesion. Evidence indicates changes in overall expression patterns of mRNAs and lncRNAs of the host in response to Leishmania infection, with the parasite capable of modulating host immune response, which may contribute to disease progression. We evaluated whether the co-expression of lncRNAs and their putative target mRNAs in primary cutaneous lesions of patients with ATL could be associated with the development of ML. Previously available public RNA-Seq data from primary skin lesions of patients infected with L. braziliensis was employed. We identified 579 mRNAs and 46 lncRNAs differentially expressed in the primary lesion that subsequently progressed to mucosal disease. Co-expression analysis revealed 1,324 significantly correlated lncRNA-mRNA pairs. Among these, we highlight the positive correlation and trans-action between lncRNA SNHG29 and mRNA S100A8, both upregulated in the ML group. S100A8 and its heterodimeric partner S100A9 form a pro-inflammatory complex expressed by immune cells and seems to participate in host innate immune response processes of infection. These findings expand the knowledge of the Leishmania-host interaction and indicate that the expression of lncRNAs in the primary cutaneous lesion could regulate mRNAs and play roles in disease progression.

Pathological roles of macrophages in Leishmania infections

Macrophages are the major host cells for Leishmania parasites, and determine the fate of infection by either limiting or allowing growth of the parasites, resulting in development or control of leishmaniasis, respectively. They also play important roles in causing pathological outcomes during Leishmania infection. The pathophysiology is complex and include a wide variety of molecular and cellular responses including enhancement of inflammatory responses by releasing cytokines, causing damages to surrounding cells by reactive oxygen species, or disordered phagocytosis of other cells. It is of note that disease severity in leishmaniasis sometimes does not correlate with parasite burdens, indicating that pathological roles of macrophages are not necessarily linked to their parasite-killing activities that are often defined by M1/M2 status. Here, we review the roles of macrophages in leishmaniasis with a focus on their pathological mechanisms in disease development.

Calprotectin in Lung Diseases

Calprotectin (CLP) is a heterodimer formed by two S-100 calcium-binding cytosolic proteins, S100A8 and S100A9. It is a multifunctional protein expressed mainly by neutrophils and released extracellularly by activated or damaged cells mediating a broad range of physiological and pathological responses. It has been more than 20 years since the implication of S100A8/A9 in the inflammatory process was shown; however, the evaluation of its role in the pathogenesis of respiratory diseases or its usefulness as a biomarker for the appropriate diagnosis and prognosis of lung diseases have only gained attention in recent years. This review aimed to provide current knowledge regarding the potential role of CLP in the pathophysiology of lung diseases and describe how this knowledge is, up until now, translated into daily clinical practice. CLP is involved in numerous cellular processes in lung health and disease. In addition to its anti-microbial functions, CLP also serves as a molecule with pro- and anti-tumor properties related to cell survival and growth, angiogenesis, DNA damage response, and the remodeling of the extracellular matrix. The findings of this review potentially introduce CLP in daily clinical practice within the spectrum of respiratory diseases.

Pathological roles of MRP14 in anemia and splenomegaly during experimental visceral leishmaniasis

Myeloid-related protein 14 (MRP14) belongs to the S100 calcium-binding protein family and is expressed in neutrophils and inflammatory macrophages. Increase in the number of MRP14+ cells or serum level of MRP14 is associated with various diseases such as autoimmune diseases and infectious diseases, suggesting the involvement of the molecule in pathogenesis of those diseases. In this study, to examine the pathological involvement of MRP14 during cutaneous and visceral leishmaniasis, wild-type (WT) and MRP14 knockout (MRP14KO) mice were infected with Leishmania major and L. donovani. Increase in the number of MRP14+ cells at the infection sites in wild-type mice was commonly found in the skin during L. major infection as well as the spleen and liver during L. donovani infection. In contrast, the influence of MRP14 to the pathology seemed different between the two infections. MRP14 depletion exacerbated the lesion development and ulcer formation in L. major infection. On the other hand, the depletion improved anemia and splenomegaly but not hepatomegaly at 24 weeks of L. donovani infection. These results suggest that, distinct from its protective role in CL, MRP14 is involved in exacerbation of some symptoms during VL.

Platelet-neutrophil interaction aggravates vascular inflammation and promotes the progression of atherosclerosis by activating the TLR4/NF-κB pathway

Platelet-neutrophil interaction is well known for its role in inflammatory diseases; however, its biological role in atherosclerosis (AS) progression remains unclear. Human peripheral blood neutrophils were obtained to compare toll-like receptor 4 (TLR4), tumor necrosis factor α (TNF-α), interleukin (IL)-1β and myeloid-related proteins 8/14 (Mrp8/14) levels in 22 AS patients with those in 18 healthy controls using quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). Meanwhile, mouse marrow neutrophils subjected to different treatment were collected for the ELISA assay, cell apoptosis, and Western blot analysis. Normal diet or high-fat diet ApoE^-/- mice with or without administration of Mrp8/14 antagonist paquinimod were used for plasma collection to measure total cholesterol, triglycerides, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol, TNF-α, IL-1β, Mrp8/14, TLR4, and nuclear factor (NF)-κB p65 levels. The results showed that Mrp8/14 and TLR4-mediated inflammatory pathway was activated in neutrophils of AS patients. In vitro experiments demonstrated that platelet-neutrophil interaction promoted the Mrp8/14 release and inhibited neutrophil apoptosis via P-selectin. Furthermore, platelet-neutrophil interaction upregulated TLR4/myeloid differentiation factor 88/NF-κB pathway. Conversely, Mrp8/14/TLR4/NF-κB interference alleviated AS progression. In conclusion, Mrp8/14/TLR4/NF-κB activated by platelet-neutrophil interaction is an important inflammatory signaling pathway for AS pathogenesis.

Calprotectin protects against experimental colonic inflammation in mice

BACKGROUND AND PURPOSE

Calprotectin is a heterodimer composed of two myeloid-related proteins, S100A8 and S100A9, that is abundant in neutrophils and monocytes/macrophages. Faecal levels of calprotectin are used routinely to monitor inflammatory bowel disease activity.

EXPERIMENTAL APPROACH

We aimed to assess the role of calprotectin in intestinal inflammation, using the dextran sulfate sodium model of colitis in mice. Calprotectin was administered (50 or 100 μg·day-1 ) by the intrarectal or by i.p. injection (50 μg·day-1 only). The condition of the mice was characterized by morphological and biochemical methods.

KEY RESULTS

Intrarectal calprotectin protected significantly against colitis, as shown by lower levels of macroscopic and microscopic damage, colonic myeloperoxidase activity and decreased expression of TNFα and toll-like receptor 4. IL-17 production by spleen and mesenteric lymph node cells was reduced. Calprotectin had no effect on body weight loss or colonic thickening. There were no effects of calprotectin after i.p. injection. Calprotectin had virtually no effects in control, non-colitic mice. Calprotectin had almost no effect on the colonic microbiota but enhanced barrier function. Treatment of rat IEC18 intestinal epithelial cells in vitro with calprotectin induced output of the chemokines CXL1 and CCL2, involving the receptor for advanced glycation end products- and NFκB.

CONCLUSION AND IMPLICATIONS

Calprotectin exerted protective effects in experimental colitis when given by the intrarectal route, by actions that appear to involve effects on the epithelium.

Deficiency of myeloid-related proteins 8 and 14 (Mrp8/Mrp14) does not block inflammaging but prevents steatosis

The Mrp8 and Mrp14 proteins (calprotectin) accumulate within tissues during aging and may contribute to chronic inflammation. To address this possibility, we evaluated female calprotectin-deficient Mrp14-KO and wild-type (WT) mice at 5 and 24 months of age. However, there was no evidence that age-related inflammation is blunted in KO mice. Inflammation markers were in fact elevated in livers from old KO mice, and microarray analysis revealed more consistent elevation of genes specifically expressed by B-cells and T-cells. Adipose-specific genes, however, were less consistently elevated in aged KO mice, suggesting an anti-steatosis effect of Mrp8/14 deficiency. Consistent with this, genes decreased by the anti-steatosis agent SRT1720 were decreased in old KO compared to old WT mice. Expression of lipid metabolism genes was altered in KO mice at 5 months of age, along with genes associated with development, biosynthesis and immunity. These early-age effects of Mrp8/14 deficiency, in the absence of any external stressor, were unexpected. Taken together, our findings demonstrate a pro-steatosis rather than pro-inflammatory role of calprotectin within the aging liver. This appears to reflect a developmental-metabolic phenotype of Mrp14-KO mice that is manifest at a young age in the absence of pro-inflammatory stimuli.

A Proteomic Investigation of Hepatic Resistance to Ascaris in a Murine Model

The helminth Ascaris causes ascariasis in both humans and pigs. Humans, especially children, experience significant morbidity including respiratory complications, growth deficits and intestinal obstruction. Given that 800 million people worldwide are infected by Ascaris, this represents a significant global public health concern. The severity of the symptoms and associated morbidity are related to the parasite burden and not all hosts are infected equally. While the pathology of the disease has been extensively examined, our understanding of the molecular mechanisms underlying resistance and susceptibility to this nematode infection is poor. In order to investigate host differences associated with heavy and light parasite burden, an experimental murine model was developed utilising Ascaris-susceptible and -resistant mice strains, C57BL/6J and CBA/Ca, respectively, which experience differential burdens of migratory Ascaris larvae in the host lungs. Previous studies identified the liver as the site where this difference in susceptibility occurs. Using a label free quantitative proteomic approach, we analysed the hepatic proteomes of day four post infection C57BL/6J and CBA/Ca mice with and without Ascaris infection to identify proteins changes potentially linked to both resistance and susceptibility amongst the two strains, respectively. Over 3000 proteins were identified in total and clear intrinsic differences were elucidated between the two strains. These included a higher abundance of mitochondrial proteins, particularly those associated with the oxidative phosphorylation pathway and reactive oxygen species (ROS) production in the relatively resistant CBA/Ca mice. We hypothesise that the increased ROS levels associated with higher levels of mitochondrial activity results in a highly oxidative cellular environment that has a dramatic effect on the nematode’s ability to successfully sustain a parasitic association with its resistant host. Under infection, both strains had increased abundances in proteins associated with the oxidative phosphorylation pathway, as well as the tricarboxylic acid cycle, with respect to their controls, indicating a general stress response to Ascaris infection. Despite the early stage of infection, some immune-associated proteins were identified to be differentially abundant, providing a novel insight into the host response to Ascaris. In general, the susceptible C57BL/6J mice displayed higher abundances in immune-associated proteins, most likely signifying a more active nematode cohort with respect to their CBA/Ca counterparts. The complement component C8a and S100 proteins, S100a8 and S100a9, were highly differentially abundant in both infected strains, signifying a potential innate immune response and the importance of the complement pathway in defence against macroparasite infection. In addition, the signatures of an early adaptive immune response were observed through the presence of proteins, such as plastin-2 and dipeptidyl peptidase 1. A marked decrease in proteins associated with translation was also observed in both C57BL/6J and CBA/Ca mice under infection, indicative of either a general response to Ascaris or a modulatory effect by the nematode itself. Our research provides novel insights into the in vivo host-Ascaris relationship on the molecular level and provides new research perspectives in the development of Ascaris control and treatment strategies.

Ascaris infection is a significant burden on the people who live in developing countries with infection being linked to poor hygiene and low socio-economic status. The parasite causes a range of symptoms, especially in children, which include both chronic morbidity, such as growth retardation, and acute outcomes, such as intestinal obstruction. Certain people tend to be more heavily infected than others, with those individuals experiencing worse morbidity. The understanding of the difference between susceptible and resistant people is an essential first step in the development of new therapies in order to eliminate this neglected parasitic disease. Using an established mouse model involving a susceptible and resistant strain, we aimed to gain insight into the host-Ascaris interaction at the hepatic interface and elucidate some of the molecular mechanisms potentially involved in resistance. A number of key intrinsic differences were determined between both strains including major differences in mitochondrial and ROS associated processes which may present the nematodes with differing oxidative conditions and explain the failure of the nematode to establish a successful parasitism in the resistant strain. In addition, we resolved signatures of the innate and early adaptive immune response and a major reduction in the proteins associated with translation in both strains under infection. Our findings need to be further explored, but could be the foundation for a better understanding of the mechanisms behind the differential parasite burden and in the future, potential new therapies for control.

Calprotectin induces cell death in human prostate cancer cell (LNCaP) through survivin protein alteration

Calprotectin (CP), an abundant heterodimeric cytosolic protein of neutrophils, conveys a variety of functions such as tumor cell growth arrest and antimicrobial activity. We investigated CP activity and its possible apoptosis-inducing mechanism of action against an antiandrogen therapy-resistance prostate cancer cell line LNCaP. Cell viability and Annexin V FITC assays were performed in order to investigate its cell death activity and apoptosis, respectively. In order to address cell death inducing mechanism(s), immunocytochemistry and immunobloting analysis, reactive oxygen species (ROS) and nitric oxide (NO) measurements were performed. The effective concentration of CP against LNCaP promoting LNCaP cell death was 200 µg/mL. ROS and NO levels of cells remarkably were enhanced following treatment with 50 and 100 µg/mL of CP, respectively. Protein expression of anti-apoptotic protein survivin was significantly decreased after administration of tumor cells with CP. Our data indicate that CP regulates the LNCaP cells viability via survivin-mediated pathway and ROS and NO enhancement. Thus, inhibition of survivin expression, enhancement of ROS and NO level by CP or other similar pharmaceutical agents might be effective in lowering the malignant proliferation of human prostate cancer cells.