Cystatin C regulates major histocompatibility complex-II-peptide presentation and extracellular signal-regulated kinase-dependent polarizing cytokine production by bone marrow-derived dendritic cells

Kidney manifestations of sarcoidosis

Renal involvement is a clinically relevant organ manifestation of sarcoidosis, leading to increased morbidity and complications. Although the exact incidence remains unknown, renal disease is likely to occur in up to one third of all sarcoidosis patients. Every patient with newly diagnosed sarcoidosis should receive a renal work-up and screening for disrupted calcium metabolism. Amid various forms of glomerulonephritis, granulomatous interstitial nephritis is the most common one, but it rarely leads to renal impairment. Histologically, granulomas can be absent. Nephrocalcinosis and nephrolithiasis are frequent forms when hypercalcaemia or hypercalciuria occur. Drugs used for treatment of systemic sarcoidosis can also cause renal damage. Due to its high heterogeneity, renal sarcoidosis can be difficult to treat. Glucocorticoids and various immunosuppressive treatments have been proven to be effective based on case series, but clinical trials are lacking. A treatment guideline for renal sarcoidosis is urgently needed. In this review article, we present an overview of the different forms of renal sarcoidosis and the diagnostic steps to confirm renal involvement; in addition, we provide insights on the management and available treatments. A better understanding regarding the pathogenesis of sarcoidosis is the key for the development of more specific, targeted therapies.

Cystatin from the helminth Ascaris lumbricoides upregulates mevalonate and cholesterol biosynthesis pathways and immunomodulatory genes in human monocyte-derived dendritic cells

Background

Ascaris lumbricoides cystatin (Al-CPI) prevents the development of allergic airway inflammation and dextran-induced colitis in mice models. It has been suggested that helminth-derived cystatins inhibit cathepsins in dendritic cells (DC), but their immunomodulatory mechanisms are unclear. We aimed to analyze the transcriptional profile of human monocyte-derived DC (moDC) upon stimulation with Al-CPI to elucidate target genes and pathways of parasite immunomodulation.

Methods

moDC were generated from peripheral blood monocytes from six healthy human donors of Denmark, stimulated with 1 µM of Al-CPI, and cultured for 5 hours at 37°C. RNA was sequenced using TrueSeq RNA libraries and the NextSeq 550 v2.5 (75 cycles) sequencing kit (Illumina, Inc). After QC, reads were aligned to the human GRCh38 genome using Spliced Transcripts Alignment to a Reference (STAR) software. Differential expression was calculated by DESEq2 and expressed in fold changes (FC). Cell surface markers and cytokine production by moDC were evaluated by flow cytometry.

Results

Compared to unstimulated cells, Al-CPI stimulated moDC showed differential expression of 444 transcripts (|FC| ≥1.3). The top significant differences were in Kruppel-like factor 10 (KLF10, FC 3.3, PBH = 3 x 10-136), palladin (FC 2, PBH = 3 x 10-41), and the low-density lipoprotein receptor (LDLR, FC 2.6, PBH = 5 x 10-41). Upregulated genes were enriched in regulation of cholesterol biosynthesis by sterol regulatory element-binding proteins (SREBP) signaling pathways and immune pathways. Several genes in the cholesterol biosynthetic pathway showed significantly increased expression upon Al-CPI stimulation, even in the presence of lipopolysaccharide (LPS). Regarding the pathway of negative regulation of immune response, we found a significant decrease in the cell surface expression of CD86, HLA-DR, and PD-L1 upon stimulation with 1 µM Al-CPI.

Conclusion

Al-CPI modifies the transcriptome of moDC, increasing several transcripts encoding enzymes involved in cholesterol biosynthesis and SREBP signaling. Moreover, Al-CPI target several transcripts in the TNF-alpha signaling pathway influencing cytokine release by moDC. In addition, mRNA levels of genes encoding KLF10 and other members of the TGF beta and the IL-10 families were also modified by Al-CPI stimulation. The regulation of the mevalonate pathway and cholesterol biosynthesis suggests new mechanisms involved in DC responses to helminth immunomodulatory molecules.

Optimizing the generation of mature bone marrow-derived dendritic cells in vitro: a factorial study design

BACKGROUND

Factorial design is a simple, yet elegant method to investigate the effect of multiple factors and their interaction on a specific response simultaneously. Hence, this type of study design reaches the best optimization conditions of a process. Although the interaction between the variables is widely prevalent in cell culture procedures, factorial design per se is infrequently utilized in improving cell culture output. Therefore, we aim to optimize the experimental conditions for generating mature bone marrow-derived dendritic cells (BMDCs). Two different variables were investigated, including the concentrations of the inducing factors and the starting density of the bone marrow mononuclear cells. In the current study, we utilized the design of experiments (DoE), a statistical approach, to systematically assess the impact of factors with varying levels on cell culture outcomes. Herein, we apply a two-factor, two-level (22) factorial experiment resulting in four conditions that are run in triplicate. The two variables investigated here are cytokines combinations with two levels, granulocyte-macrophage colony-stimulating factor (GM-CSF) alone or with interleukin-4 (IL4). The other parameter is cell density with two different concentrations, 2 × 106 and 4 × 106 cells/mL. Then, we measured cell viability using the trypan blue exclusion method, and a flow cytometer was used to detect the BMDCs expressing the markers FITC-CD80, CD86, CD83, and CD14. BMDC marker expression levels were calculated using arbitrary units (AU) of the mean fluorescence intensity (MFI).

RESULTS

The current study showed that the highest total viable cells and cells yield obtained were in cell group seeded at 2 × 106 cells/mL and treated with GM-CSF and IL-4. Importantly, the expression of the co-stimulatory molecules CD83 and CD80/CD86 were statistically significant for cell density of 2 × 106 cells/mL (P < 0.01, two-way ANOVA). Bone marrow mononuclear cells seeded at 4 × 106 in the presence of the cytokine mix less efficiently differentiated and matured into BMDCs. Statistical analysis via two-way ANOVA revealed an interaction between cell density and cytokine combinations.

CONCLUSION

The analysis of this study indicates a substantial interaction between cytokines combinations and cell densities on BMDC maturation. However, higher cell density is not associated with optimizing DC maturation. Notably, applying DoE in bioprocess designs increases experimental efficacy and reliability while minimizing experiments, time, and process costs.

Transcriptome Analysis Reveals the Immunoregulatory Activity of Rice Seed-Derived Peptide PEP1 on Dendritic Cells

Some food-derived bioactive peptides exhibit prominent immunoregulatory activity. We previously demonstrated that the rice-derived PEP1 peptide, GIAASPFLQSAAFQLR, has strong immunological activity. However, the mechanism of this action is still unclear. In the present study, full-length transcripts of mouse dendritic cells (DC2.4) treated with PEP1 were sequenced using the PacBio sequencing platform, and the transcriptomes were compared via RNA sequencing (RNA-Seq). The characteristic markers of mature DCs, the cluster of differentiation CD86, and the major histocompatibility complex (MHC-II), were significantly upregulated after the PEP1 treatment. The molecular docking suggested that hydrogen bonding and electrostatic interactions played important roles in the binding between PEP1, MHC-II, and the T-cell receptor (TCR). In addition, the PEP1 peptide increased the release of anti-inflammatory factors (interleukin-4 and interleukin-10) and decreased the release of pro-inflammatory factors (interleukin-6 and tumor necrosis factor-α). Furthermore, the RNA-seq results showed the expression of genes involved in several signaling pathways, such as the NF-κB, MAPK, JAK-STAT, and TGF-β pathways, were regulated by the PEP1 treatment, and the changes confirmed the immunomodulatory effect of PEP1 on DC2.4 cells. This findings revealed that the PEP1 peptide, derived from the byproduct of rice processing, is a potential natural immunoregulatory alternative for the treatment of inflammation.

Cystatin C as a Potential Blood Biomarker for Sarcoidosis: A Case Report

Sarcoidosis is a multi-organ medical condition that is characterized by the formation of granulomas. We aimed to identify a correlation between each sarcoidosis blood biomarker and cystatin C (Cys-C) in sarcoidosis patients. We report a case of a 60-year-old man with sarcoidosis. The correlation between his Cys-C and each blood biomarker level and that between each blood biomarker and serum creatinine levels were determined using linear regression. Serum Cys-C correlated with each blood biomarker of sarcoidosis, while creatinine did not. These findings suggest that Cys-C is a potential blood biomarker for sarcoidosis.

OX40L enhances the immunogenicity of dendritic cells and inhibits tumor metastasis in mice

A well preserved immune system is a powerful tool to prevent foreign invasion or to suppress internal mutation, which must be tightly controlled by co-stimulatory molecules in different pathophysiological conditions. One such critical molecule is OX40L expressed on activated antigen-presenting cells (APCs). Consistently, its abnormality is associated with various immunological disorders such as autoinflammatory diseases and allergy. However, a comprehensive analysis of the immune-moderating role of OX40L in dendritic cells (DCs), the most powerful APCs to initiate immune responses in vivo, and investigation of its anti-tumor efficacy in the disease setting have not been performed properly. In this study, genetic approaches for both gain-of-function and reduction-of-function were employed to reveal that OX40L was required for the efficient presentation, but not uptake, of antigens by DCs to stimulate CD4⁺ , as well as CD8⁺ T cells in vivo. As a result, CD4⁺ T cells were promoted towards Th1, but inhibited on Treg differentiation, by the LPS-induced OX40L on DCs, which was supported by their altered expression of co-inhibitory receptor, PD-L1. CD8⁺ T cells, on the other hand, also enhanced their cytotoxicity towards target cells in response to OX40L expression on the DCs transferred in vivo. Finally, in a DC-mediated tumor immunity model, the strong immunogenic roles of OX40L on DCs led to better metastasis inhibition in vivo. Collectively, our results demonstrate that OX40L could serve as a potential target in the DC-based vaccine for enhanced anti-tumor efficacy in vivo.

Tetrahydroxy Stilbene Glucoside Alleviates Ischemic Stroke by Regulating Conformation-Dependent Intracellular Distribution of PKM2 for M2 Macrophage Polarization

Tetrahydroxy stilbene glucoside (TSG) is a bioactive ingredient with powerful anti-inflammatory and neuroprotective properties. However, the detailed mechanisms concerning the neuroprotective effect of TSG are not fully understood. This study aims to address the molecular mechanism involved in the protective effects of TSG on murine ischemic stroke. We found that TSG meliorated the phenotypes of ischemic stroke in vivo, which was correlated with the increased percentage of infiltrated M2 macrophages in brain after stroke. Mechanistically, TSG regulated macrophage polarization by significantly downregulating the transcriptional levels of M1 marker genes (iNOS and IL-1β) but upregulating that of the M2 marker genes (arg-1 and IL-4) following lipopolysaccharide/interferon-γ stimulation. Consistently, TSG reversed the metabolic profiling of M1 macrophage toward the M2 status at intracellular energy levels. Surprisingly, the knockdown of an established metabolic enzyme pyruvate kinase M2 (PKM2) that is important for M1 switch in macrophages abolished the promotive effect of TSG on the M2 polarization. Further investigation revealed that TSG markedly downregulated the intracellular ratio of dimer/monomer to the tetramer of PKM2 without affecting its total protein expression, leading to a suppressed nuclear translocation of functioning PKM2 in macrophages for M1 differentiation. Taken together, we identified a novel mechanism for macrophage M2 polarization regulation by a small-molecule chemical that controls the quality (conformation) rather than the quantity (expression) of an intracellular M1-promoting metabolic enzyme, which offers a better understanding of the mechanisms of macrophage plasticity and has serious implication in translational strategies for the treatment of macrophage-mediated neurological diseases with natural bioactive products.

In vivo hitchhiking of immune cells by intracellular self-assembly of bacteria-mimetic nanomedicine for targeted therapy of melanoma

Cell-based drug carriers are mostly prepared in vitro, which may negatively affect the physiological functions of cells, and induce possible immune rejections when applied to different individuals. In addition, the immunosuppressive tumor microenvironment limits immune cell-mediated delivery. Here, we report an in vivo strategy to construct cell-based nanomedicine carriers, where bacteria-mimetic gold nanoparticles (GNPs) are intravenously injected, selectively phagocytosed by phagocytic immune cells, and subsequently self-assemble into sizable intracellular aggregates via host-guest interactions. The intracellular aggregates minimize exocytosis of GNPs from immune cells and activate the photothermal property via plasmonic coupling effects. Phagocytic immune cells carry the intracellular GNP aggregates to melanoma tissue via inflammatory tropism. Moreover, an initial photothermal treatment (PTT) of the tumor induces tumor damage that subsequently provides positive feedback to recruit more immune cell-based carriers for enhanced targeting efficiency. The optimized secondary PTT notably improves antitumor immunotherapy, further strengthened by immune checkpoint blockade.

Self-Tolerance of Vascular Tissues Is Broken Down by Vascular Dendritic Cells in Response to Systemic Inflammation to Initiate Regional Autoinflammation

The correlation of infections with vascular autoinflammatory diseases such as vasculitis and atherosclerosis has been long recognized, and progressive inflammation with the formation of tertiary lymphoid organs in arterial adventitia intensively studied, the immunological basis of the nondiseased vasculatures that predispose to subsequent vascular autoimmunity during inflammation, however, is not well characterized. Here, we investigated the vascular immunity in situ of steady-state C57BL/6 mice and found that healthy vascular tissues contained a comprehensive set of immune cells with relatively higher proportion of innate components than lymphoid organs. Notably, a complete set of dendritic cell (DC) subsets was observed with monocyte-derived DCs (moDCs) constituting a major proportion; this is in contrast to moDCs being considered rare in the steady state. Interestingly, these vascular DCs constitutively expressed more suppressive factors with cDC1 for PD-L1 and moDCs for IL-10; this is concordant with the inhibitive phenotype of T cells in normal vascular tissues. The immunotolerant state of the vascular tissues, however, was readily eroded by systemic inflammation, demonstrated by the upregulation of proinflammatory cytokines and enhanced antigen presentation by vascular DCs to activate both cellular and humoral immunity in situ, which ultimately led to vascular destruction. Different vascular DC subsets elicited selective effects: moDCs were potent cytokine producers and B-cell activators, whereas cDCs, particularly, cDC1, were efficient at presenting antigens to stimulate T cells. Together, we unveil regional immunological features of vascular tissues to explain their dual facets under physiological versus pathological conditions for the better understanding and treatment of cardiovascular autoinflammation.

Mendelian randomization study supports the causal association between serum cystatin C and risk of diabetic nephropathy

AIMS

Cystatin C, an inhibitor of cysteine protease, has been used as a biomarker for estimating glomerular filtration rate. However, the causal relation between cystatin C and diabetic nephropathy remains uncertain.

METHODS

We assessed the causal effect of cystatin C together with other five serum biomarkers including KIM-1, GDF-15, TBIL, uric acid, and Scr on diabetic nephropathy by Mendelian randomization (MR) analysis. 234 genetic variants were selected as instrumental variables to evaluate the causal effect of cystatin C (N_GWAS=361194) on diabetic nephropathy (Ncase/Ncontrol up to 3283/210463). Multivariable MR (MVMR) was performed to assess the stability of cystatin C's causal relationship. Two-step MR was used to assess the mediation effect of BMI and SBP.

RESULTS

Among the six serum biomarkers, only cystatin C causally associated with diabetic nephropathy (IVW OR: 1.36, 95%CI [1.15, 1.61]). After adjusting for the potential confounders BMI and SBP, cystatin C maintained its causal effect on the DN (OR: 1.17, 95%CI [1.02, 1.33]), which means that the risk of DN increased by 17% with an approximate 1 standard deviation (SD) increment of serum cystatin C level. Two-step MR results indicated that BMI might mediate the causal effect of cystatin C on diabetic nephropathy.

INTERPRETATION

Our findings discovered that cystatin C was a risk factor for diabetic nephropathy independent of BMI and SBP in diabetes mellitus patients. Future research is required to illustrate the underlying mechanism and prove targeting circulating cystatin C could be a potential therapy method.

Modulation of Cystatin C in Human Macrophages Improves Anti-Mycobacterial Immune Responses to Mycobacterium tuberculosis Infection and Coinfection With HIV

Tuberculosis owes its resurgence as a major global health threat mostly to the emergence of drug resistance and coinfection with HIV. The synergy between HIV and Mycobacterium tuberculosis (Mtb) modifies the host immune environment to enhance both viral and bacterial replication and spread. In the lung immune context, both pathogens infect macrophages, establishing favorable intracellular niches. Both manipulate the endocytic pathway in order to avoid destruction. Relevant players of the endocytic pathway to control pathogens include endolysosomal proteases, cathepsins, and their natural inhibitors, cystatins. Here, a mapping of the human macrophage transcriptome for type I and II cystatins during Mtb, HIV, or Mtb-HIV infection displayed different profiles of gene expression, revealing cystatin C as a potential target to control mycobacterial infection as well as HIV coinfection. We found that cystatin C silencing in macrophages significantly improves the intracellular killing of Mtb, which was concomitant with an increased general proteolytic activity of cathepsins. In addition, downmodulation of cystatin C led to an improved expression of the human leukocyte antigen (HLA) class II in macrophages and an increased CD4⁺ T-lymphocyte proliferation along with enhanced IFN-γ secretion. Overall, our results suggest that the targeting of cystatin C in human macrophages represents a promising approach to improve the control of mycobacterial infections including multidrug-resistant (MDR) TB.

Assessment of seminal cystatin C levels in infertile men with varicocele: A preliminary study

Varicocele has been raised as a contributor to male infertility supported by the improvement of sperm parameters after varicocelectomy. Cystatin C (Cys C) has been linked to several cellular changes that are common in male infertility cases associated with varicocele such as apoptosis and autophagy. This preliminary study aimed to assess the seminal levels of Cys C in infertile oligoasthenoteratozoospermic (OAT) men associated with varicocele that have been shown to have spermatic vein vasodilation and active death pathway. Overall, 60 men were investigated being divided into two equivalent groups-infertile OAT men with varicocele who underwent varicocelectomy and healthy fertile men as a control group. These men were subjected to history taking, clinical examination, semen analysis and assessment of seminal Cys C pre and 6 months post-varicocelectomy. The results showed a significant increase of seminal Cys C in infertile OAT men with varicocele than the fertile control (55.57 ± 25.6 ng/ml versus 10.78 ± 1.88 ng/ml, p = .001). Seminal Cys C was a significantly decreased post-operative than its pre-operative level (34.69 ± 14.02 versus 55.57 ± 25.6 ng/ml, p = .01). These results show a potential role of Cys C in varicocele-induced infertility.

The Role of Cysteine Peptidases in Hematopoietic Stem Cell Differentiation and Modulation of Immune System Function

Cysteine cathepsins are primarily involved in the degradation and recycling of proteins in endo-lysosomal compartments but are also gaining recognition as pivotal proteolytic contributors to various immune functions. Through their extracellular proteolytic activities within the hematopoietic stem cell niche, they are involved in progenitor cell mobilization and differentiation. Cysteine cathepsins, such as cathepsins L and S contribute to antigen-induced adaptive immunity through major histocompatibility complex class II antigen presentation whereas cathepsin X regulates T-cell migration. By regulating toll-like receptor signaling and cytokine secretion cysteine cathepsins activate innate immune cells and affect their functional differentiation. Cathepsins C and H are expressed in cytotoxic T lymphocytes and natural killer cells and are involved in processing of pro-granzymes into proteolytically active forms. Cytoplasmic activities of cathepsins B and L contribute to the maintenance of homeostasis of the adaptive immune response by regulating cell death of T and B lymphocytes. The expression pattern, localization, and activity of cysteine cathepsins is tightly connected to their function in immune cells. Furthermore, cysteine cathepsins together with their endogenous inhibitors, serve as mediators in the interplay between cancer and immune cells that results in immune cell anergy. The aim of the present article is to review the mechanisms of dysregulation of cysteine cathepsins and their inhibitors in relation to immune dysfunction to address new possibilities for regulation of their function.

Secreted cystatins decrease proliferation and enhance apoptosis of human leukemic cells

Cysteine proteases are implicated in proteolysis events favoring cancer cell growth, spread, and death by apoptosis. Herein, we have studied whether the net growth and survival of the leukemic cell lines Jurkat, U937, and HL‐60 are affected by external addition of five proteins acting as natural cysteine protease inhibitors. None of the cystatins examined (A, C, D, and E/M) or chagasin showed consistent effects on Fas‐induced apoptosis when evaluated at 1 µm. In contrast, when the intrinsic apoptosis pathway was activated by hydrogen peroxide, addition of cystatin D augmented caspase‐3‐like activity within all three cell lines. Flow cytometric analysis of U937 cells also showed increased numbers of annexin V‐positive cells when hydrogen peroxide was used to initiate apoptosis and cells were cultured in the presence of cystatin D or C. Moreover, stimulation of hydrogen peroxide‐induced apoptotic U937 cells with either cystatin C or D resulted in a dose‐dependent decrease in the number of cells. Cell viability was also decreased when U937 cells were cultured in the presence of cystatin C or D (1–9 µm) only, demonstrating that these cystatins can reduce cell proliferation by themselves in addition to enhancing apoptosis induced by oxidative stress. These effects on U937 cells were paralleled by internalization of cystatins C and D, indicating these effects are caused by downregulation of intracellular proteolysis. External addition of cystatins C and D to HL‐60 and Jurkat cells demonstrated similar degrees of cystatin D uptake and decreased viability as for U937 cells, indicating that these effects are general for leukemic cells.

Suppressed dendritic cell functions by cystatin C lead to compromised immunity in vivo

Pathogenic microorganisms utilize multiple approaches to break down host immunity in favor of their invasion, of which, cystatin C is one of the soluble factors secreted by parasites reported to affect host immunity in vivo. The cellular targets and mechanisms of action in vivo of cystatin C, however, are far from clear. As professional antigen-presenting cells, dendritic cells (DCs) are first immune cells that contact foreign pathogenic agents or their products to initiate immune responses. We previously reported that cystatin C can regulate the functions of DCs in terms of suppressed CD4⁺ T cell activation but enhanced Th1/Th17 differentiation via different mechanisms. Here, we further verified these regulatory effects of cystatin C on DCs in vivo. We found that the suppressive role of DC-mediated CD4⁺ T cell proliferation by cystatin C was partly cell-contact independent and extended to CD8⁺ T cells in vivo. Although cystatin C-overexpressing DCs trafficked equally as their mock-transduced counterparts, their adoptive transfer suppressed CD8⁺ T cell immunity and resulted in compromised tumor rejection in both vaccination and treatment regimes. Compared with their role in promoting Th17 differentiation in vivo, cystatin C-transduced DCs had far greater ability to induce T regulatory cells (Tregs), leading to collectively a higher Treg/Th17 ratio in an adoptively transferred disease model, and thus relieved Th17-dependent autoimmunity. Collectively, these data demonstrated strong in vivo evidences for immune regulatory roles of cystatin C in DCs and provided theoretical basis for the application of cystatin C-transduced cell therapy in the treatment or remission of certain autoimmune diseases. (246).