The protective role of immunoglobulins in fungal infections and inflammation

Mycobiota and Antifungal Antibodies as Emerging Targets for the Diagnosis and Prognosis of Human Diseases

The human body is colonized by diverse microorganisms, with bacteria being the most extensively studied. However, fungi, collectively known as "the mycobiota," are increasingly recognized as integral components of the microbiota, inhabiting nearly all mucosal surfaces. Commensal fungi influence host immunity similarly to bacteria and contribute to other essential functions, including metabolism. This emerging understanding positions fungi as potential biomarkers for the diagnosis and prognosis of various diseases. In this review, we explore the dual roles of fungi as both commensals and pathogens, and the potential of antifungal antibodies to serve as diagnostic and prognostic tools, especially in chronic immune-inflammatory non-communicable diseases, including inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis, and neurodegenerative disorders. Finally, we address current challenges and outline future perspectives for leveraging fungal biomarkers in clinical practice.

Perioperative Use of IgM-Enriched Immunoglobulins in Liver Transplantation Recipients at High Risk for Infections: A Preliminary Study

Background: Infections frequently occur after orthotopic liver transplantation (OLT) and are associated with increased mortality. In 2018, we introduced perioperative administration of intravenous immunoglobulin enriched in IgM as an optional therapy in recipients at a high risk of infection. This preliminary study evaluated whether this preparation reduced infections in the early post-transplantation period. Methods: Adult patients with a high risk of postoperative infections who underwent OLT between January 2014 and December 2021 in our center were included in the study. The primary outcome was the occurrence of new postoperative bacterial and fungal infections within the first 30 days after OLT. Results: Ninety recipients at a high risk of postoperative infections who underwent OLT were included, of whom 51 (57%) received IgM preparation. Patients treated and not treated with IgM were similar in terms of demographics, model of end-stage liver disease score, and risk factors for postoperative infections. The occurrence of new infections was lower (absolute risk reduction (ARR) 21.2%; p = 0.038) in patients who received IgM than in those who did not. Multivariate analysis adjusted for confounders (OR 0.348; p = 0.033) and propensity score-based matching analysis (ARR 21.2%, p = 0.067) confirmed an association between IgM preparation and lower occurrence of postoperative infections. The 90-day mortality rate was lower (ARR 13.4%, p = 0.018) in patients who received IgM preparation. Conclusions: In OLT recipients at high risk for infections, perioperative administration of an IgM-enriched preparation seems to reduce the development of new infections within the first 30 days after OLT.

Anti-Candida Antibodies of Patients with Invasive Candidiasis Inhibit Growth, Alter Cell Wall Structure, and Kill Candida albicans In Vitro

Invasive candidiasis (IC), caused by Candida yeasts, particularly Candida albicans, poses a significant threat with high mortality rates. Diagnosis is challenging due to Candida's common presence in human microbiota. To address this, our research group developed an immunofluorescence assay detecting Candida albicans Germ Tube Antibodies (CAGTA) in IC patients. CAGTA, indicative of invasive processes, is associated with a lower mortality rate in ICU patients. Based on this premise, this study aims to provide results regarding the lack of knowledge about the potential activity of CAGTA against invasive infections in humans caused by the fungus Candida albicans. Therefore, in order to characterize the activity of CAGTA produced by patients with IC, we used sera from 29 patients with IC caused by either C. albicans or non-albicans Candida species. Whole serum IgG antibodies were fractionated into anti-blastospores, CAGTA-enriched, and purified CAGTA and the assessments included XTT colorimetric assays for metabolic activity, CFU counts for viability, and microscopy for growth, viability, and morphological analysis. The CAGTA-enriched IgG fraction significantly reduced the metabolic activity and viability of C. albicans compared to anti-blastospores. Purified CAGTA altered germ tube cell wall surfaces, as revealed by electron microscopy, and exhibited fungicidal properties by DiBAC fluorescent staining. In conclusion, antibodies in response to invasive candidiasis have antifungal activity against Candida albicans, influencing metabolic activity, viability, and cell wall structure, leading to cell death. These findings suggest the potential utility of CAGTA as diagnostic markers and support the possibility of developing immunization protocols against Candida infections.

The Structure Characteristics and Function of Non B Cell-Derived Immunoglobulin

According to classical immunology theory, immunoglobulin (Ig) is exclusively produced by differentiated B lymphocytes, which exhibit a typical tetrapeptide chain structure and are predominantly present on the surface of B cells and in bodily fluids. B-Ig is one of the critical effector molecules for humoral immune responses specifically recognising antigens and eliminating them. However, mounting evidence has demonstrated that Ig is widely expressed in non B lineage cells, especially malignant ones (referred to as non B-Ig). Interestingly, non B-Ig mainly resides in the cytoplasm and secretion, but to some extent on the cell surface. Furthermore non B-Ig not only displays a tetrapeptide chain structure but also shows free heavy chains and free light chains (FLCs). Additionally, Ig derived from non B cancer cell typically displays unique glycosylation modifications. Functionally, non B-Ig demonstrated diversity and versatility, showing antibody activity and cellular biological activity, such as promoting cell proliferation and survival, and it is implicated in cancer progression and some immune-related diseases, such as renal diseases.

Effects of Enterotoxigenic Escherichia coli Challenge on Jejunal Morphology and Microbial Community Profiles in Weaned Crossbred Piglets

Pathogenic enterotoxigenic Escherichia coli (ETEC) is a major cause of bacterial diarrhea in weaning piglets, which are vulnerable to changes in environment and feed. This study aimed to determine the effects of the ETEC challenge on piglet growth performance, diarrhea rate, jejunal microbial profile, jejunal morphology and goblet cell distribution. A total of 13 piglets from one litter were selected on postnatal day 21 and assigned to treatments with or without ETEC challenge at 1 × 108 CFUs, as ETEC group or control group, respectively. On postnatal day 28, samples were collected, followed by the detection of serum biochemical indexes and inflammatory indicators, HE staining, PAS staining and 16S rDNA gene amplicon sequencing. Results showed that the growth performance decreased, while the diarrhea rate increased for the ETEC group. The jejunum is the main segment of the injured intestine during the ETEC challenge. Compared with the control, the ETEC group displayed fewer goblet cells in the jejunum, where goblet cells are more distributed at the crypt and less distributed at the villus. In addition, ETEC piglets possessed higher abundances of the genus Desulfovibrio, genus Oxalobacter and genus Peptococus and lower abundances of the genus Prevotella 2, genus Flavonifractor and genus Blautra. In terms of alpha diversity, Chao 1 and observed features indexes were both increased for the ETEC group. Our study provides insights into jejunal histopathological impairment and microbial variation in response to ETEC infection for weaned piglets and is a valuable reference for researchers engaged in animal health research to select stress models.

Immunomodulatory Effects of Microcin C7 in Cyclophosphamide-Induced Immunosuppressed Mice

Microcin C7 (McC) as a viable immunomodulator peptide can be a potential solution for pathogenic microbial infection in the post-antibiotic era and has gained substantial attention. This study was designed to evaluate the immunomodulatory activity of Microcin C7 in a cyclophosphamide (CTX)-induced immunodeficient mouse model. We show that Microcin C7 treatment significantly alleviated the CTX-caused body weight loss, improved the feed and water consumption to improve the state of the mice, and elevated the absolute number and proportion of peripheral blood lymphocytes as well as the level of hemoglobulin. We further aim to characterize the phenotypes of the immune function and intestinal health profiles. The results demonstrate that Microcin C7 treatment increased serum levels of immunoglobulin A (IgA), IgG, interleukin 6, and hemolysin, promoted splenic lymphocyte proliferation induced by concanavalin A and LPS, and enhanced the phagocytosis of peritoneal macrophages immunized by sheep red blood cells. Additionally, Microcin C7 treatment decreased levels of diamine oxidase and d-lactate, ameliorated CTX-induced intestinal morphological damage, and increased the levels of zonula occluden 1, occludin, claudin-1, mucin 2, and secretary IgA in the jejunum and colon. Moreover, Microcin C7 administration is sufficient to reverse CTX-induced intestinal microbiota dysbiosis by increasing the number of Lactobacillus and Bifidobacterium, decreasing the number of Escherichia coli in colonic contents. Collectively, our results demonstrate that Microcin C7 may have protective and immunomodulatory functions and could be a potential candidate used in animal feed, functional foods, and immunological regimens..

Antifungal antibodies present in intravenous immunoglobulin derived from China

Fungal infections usually occur in immunocompromised patients. Intravenous immunoglobulin (IVIG) has been used as therapeutic interventions for many infectious diseases, but seldom applied in mycosis due to unknown antifungal specificity. This study aims to determine the presence of antifungal antibodies in IVIG. Binding reactivity of IVIG with crude and recombinant antigens of Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans and Talaromyces marneffei were observed in a dose-dependent manner, similar with mixed normal human sera. The antifungal specificity was further confirmed by competitive enzyme-linked immunosorbent assays (ELISA) inhibited by rabbit specific antifungal polyclonal antibodies (PAbs) and homogenous crude antigens with inhibitions of 65.5-87.2% and 73.1-94.2%, respectively. Moreover, IVIG also reacted with fungal glycoproteins (Csa2, Cpl1 and Mp1p) in a dose-dependent way, which was inhibited by specific rabbit PAbs and homogenous antigens with different inhibitions and pulled down 72.8-83.8% of specific antibodies if preabsorption IVIG with Dynabeads® coupled with homogenous glycoproteins. These results furthermore verified the antifungal specificity of IVIG. Among four brands of IVIG, there was different antifungal IgG against C. albicans (P < 0.05) and C. neoformans (P < 0.05), while no difference for A. fumigatus (P = 0.086) and T. marneffei (P = 0.057). IVIG contained a significantly higher level of specific IgG for C. albicans than other three fungi (P <0.001). In conclusion, we proved antifungal IgG against C. albicans, A. fumigatus, C. neoformans and T. marneffei present in IVIG, which might be expected to provide a possible immunoregulation choice for mycosis and an evaluation to humoral immunity against fungi.

Novel Intravenous Immunoglobulin Therapy for the Prevention and Treatment of Candida auris and Candida albicans Disseminated Candidiasis

Disseminated candidiasis is a life-threatening disease and remains the most common bloodstream infection in hospitalized patients in the United States. Despite the availability of modern antifungal therapy, the crude mortality rate in the last decade has remained unacceptably high. Novel approaches are urgently needed to supplement or replace current antifungal therapies. In our study, we show that human intravenous immunoglobulin (IVIG) can provide protection against Candida auris and Candida albicans disseminated infections in A/J and C57BL/6 mouse models. The protective efficacy of IVIG is evidenced by the prolonged survival of mice with invasive candidiasis that were treated with human IVIG alone or in combination with amphotericin B. Our previous studies have led to the identification of a panel of Candida cell surface peptide and glycan epitopes, which are targeted by protective mouse monoclonal antibodies (mAbs) against invasive candidiasis. Of interest, the peptide- and glycan-specific IgGs could be detected in all 18 human IVIG samples. In particular, the specific IVIG lots with the highest protective peptide- and glycan-related IgGs provided the best protection. The combination of IVIG and amphotericin B had enhanced efficacy in protection compared to monotherapy against both multidrug-resistant (MDR) C. auris and C. albicans, with evidence of significantly prolonged survival and lower fungal burdens in targeted organs. This study provides evidence that the protective effects of IVIG were associated with the protective antibodies found in normal human donor sera against pathogenic Candida, and IVIG can be a novel therapy or adjunctive therapy with modern antifungal drugs against disseminated candidiasis. IMPORTANCE Since current antifungal treatments are ineffective in the immunocompromised population and no vaccine is available for humans, hope remains that antibody preparations selected for specific fungal antigens may make it possible to reduce the incidence and mortality of invasive candidiasis. Intravenous immunoglobulin (IVIG) has long been approved as a standard treatment for patients with immunodeficiency disorders who are also susceptible to fungal infection. IVIG has been widely used as prophylaxis or supplemental treatment for sepsis and septic shock; however, this form of adjunctive therapy lacks convincing data to establish its efficacy. In this study, 18 samples from commercial IVIG preparations were screened and evaluated by enzyme-linked immunosorbent assays (ELISAs); Candida peptide- and glycan-specific IgGs were detected with various titers among all IVIG lots. Importantly, significantly reduced organ fungal burdens and mortality were demonstrated in IVIG-treated mouse models of invasive candidiasis. IVIG lots with higher titers of Candida-specific IgGs provided better protection. These findings are important in (i) selecting Candida-specific IVIG therapy that may overcome several shortcomings of conventional IVIG therapy by targeting specific antigens responsible for disease pathogenesis, (ii) enhancing protective efficacy, and (iii) validating data from our previous studies and those of others showing that antibodies combined with conventional antifungal drugs provided enhanced resistance to disease. To our knowledge, this study is the first to demonstrate that human IVIG samples contain protective IgGs targeting Candida cell surface antigens and can be a novel therapy or adjunctive therapy with modern antifungal drugs against disseminated candidiasis.

Invasive aspergillosis in the patient with focal segmental glomerulosclerosis initiating hemodialysis: a case report and mini-review

Background

Invasive aspergillosis (IA) is a severe form of fungal infection caused by the genus Aspergillus in immunocompromised hosts and has a high mortality rate. End-stage kidney disease (ESKD) is one of the risk factors for developing fungal infection; however, the detailed clinical and treatment course of ESKD patients with IA has been scarcely reported, especially for the patient initiating hemodialysis (HD). Here, we experienced a patient under immunosuppressive therapy for focal segmental glomerulosclerosis (FSGS) who suffered from IA involving lung and brain and resulted in initiating HD.

Case presentation

A 66-year-old male patient with a history of suspected non-tuberculosis mycobacterial lung disease was initially admitted to the hospital with minimal change disease and subsequently diagnosed as FSGS with worsening urinary protein levels. The combined treatment including immunosuppressive treatments of cyclosporin and glucocorticoids and low-density lipoprotein apheresis was initiated, and then, he experienced the symptoms of dry cough, somnolence, and disorientation, which were subsequently diagnosed as IA involving lung and brain. The patient required renal replacement therapy, and maintenance HD was continued. Despite the intensive treatment with multiple antifungals of liposomal amphotericin B, voriconazole, micafungin, and amphotericin B, the pneumonia of the patient did not improve, and he subsequently passed away.

Conclusions

We report the case of the IA under immunosuppressive treatment, who was subsequently initiated maintenance HD. The detailed clinical course of medications used to treat the patient is presented with the literature review of IA in ESKD and HD patients and those with past acid-fast bacterial infections. The careful determination of the intensity of immunosuppression and monitoring of the patient’s symptoms and early definitive diagnosis is crucial in treating IA in immunocompromised hosts with ESKD or in HD under immunosuppressive treatment, as the mortality for these patients is suspected to be high despite the intensive treatment.

Role of HLA-I Structural Variants and the Polyreactive Antibodies They Generate in Immune Homeostasis

Cell-surface HLA-I molecules consisting of β2-microglobulin (β2m) associated heavy chains (HCs), referred to as Face-1, primarily present peptides to CD8+ T-cells. HCs consist of three α-domains, with selected amino acid sequences shared by all alleles of all six isoforms. The cell-surface HLA undergoes changes upon activation by pathological conditions with the expression of β2m-free HCs (Face-2) resulting in exposure of β2m-masked sequences shared by almost all alleles and the generation of HLA-polyreactive antibodies (Abs) against them. Face-2 may homodimerize or heterodimerize with the same (Face-3) or different alleles (Face-4) preventing exposure of shared epitopes. Non-allo immunized males naturally carry HLA-polyreactive Abs. The therapeutic intravenous immunoglobulin (IVIg) purified from plasma of thousands of donors contains HLA-polyreactive Abs, admixed with non-HLA Abs. Purified HLA-polyreactive monoclonal Abs (TFL-006/007) generated in mice after immunizing with Face-2 are documented to be immunoregulatory by suppressing or activating different human lymphocytes, much better than IVIg. Our objectives are (a) to elucidate the complexity of the HLA-I structural variants, and their Abs that bind to both shared and uncommon epitopes on different variants, and (b) to examine the roles of those Abs against HLA-variants in maintaining immune homeostasis. These may enable the development of personalized therapeutic strategies for various pathological conditions.

Relationship Between Invasive Fungal Infection and Hypostatic Pneumonia: A Prospective Cohort Study

Background

The short-term mortality of hypostatic pneumonia (HP) is very high, and the treatment outcome is poor. The clinical diagnosis and treatment are primarily focused on bacterial and viral infection, ignoring the role of fungal infection at present. This study aims to validate the relationship between Invasive Fungal Infections (IFI) and HP.

Methods

In the cross-sectional study, a total of 11,371 participants have been enrolled. In the prospective cohort study, 4,441 individuals have been included at baseline and followed up from 2015 to 2019 with a total person years of 8,484.65. The standard procedures were used to assess questionnaire investigations, laboratory testing, and anthropometric indicators. For data analysis, logistic regression, restricted cubic spline, log-rank regression, Cox regression, and linear mixed effects model were applied to assess the relationship between IFI and HP risk longitudinally.

Results

In the cross-sectional study, elevated β-D-Glucan (BDG) concentrations are associated with a higher risk of HP prevalence in the total population, men, and women (OR_{T3 vs}._T1 [95% CIs]: 2.12 [1.55, 2.91]; 2.01 [1.35, 2.99]; 2.34 [1.39, 3.94]), which were verified by a dose–effect relationship in the restricted cubic spline model. In the cohort study, Cox and Log-rank regression showed that the elevated BDG concentrations are associated with a significantly higher risk of HP incidence than participants with lower BDG concentrations (HR_{T3 vs}._T1 [95% CIs]: 2.72 [1.36, 5.43], p_Log–rank = 0.0086). During 5 years, the globulin (GLB) and C-reactive protein (CRP) were always on the top in the highest category of BDG concentrations. Between low and high BDG concentration, the total trend of GLB concentration was falling and the total trend of CRP concentration was rising with the increase of years (all the p-values < 0.0001).

Conclusion

In this study, IFI is associated with a higher risk of HP, with time sequence and related mechanisms requiring further investigation in the future.

Divergent selection for natural antibodies in poultry in the presence of a major gene

Background

Natural antibodies (NAb) are antibodies that are present in a healthy individual without requiring previous exposure to an exogenous antigen. Selection for high NAb levels might contribute to improved general disease resistance. Our aim was to analyse the genetic background of NAb based on a divergent selection experiment in poultry, and in particular the effect of a polymorphism in the TLR1A gene.

Methods

The study population consisted of a base population from a commercial pure-bred elite white leghorn layer line and seven generations of birds from a High and Low selection line. Birds were selected for total KLH-binding NAb titer (IgTotal). An enzyme-linked immunosorbent assay was performed to determine NAb titers in blood plasma for IgTotal and the antibody isotypes IgM and IgG. NAb titers were available for 10,878 birds. Genotypes for a polymorphism in TLR1A were determined for chickens in generations 5, 6 and 7. The data were analysed using mixed linear animal models.

Results

The heritability estimate for IgM was 0.30 and higher than that for IgG and IgTotal (0.12). Maternal environmental effects explained 2 to 3% of the phenotypic variation in NAb. Selection for IgTotal resulted in a genetic difference between the High and Low line of 2.4 titer points (5.1 genetic standard deviation) in generation 7. For IgM, the selection response was asymmetrical and higher in the Low than the High line. The frequency of the TLR1A C allele was 0.45 in the base population and 0.66 and 0.04 in generation 7 of the High and Low line, respectively. The TLR1A polymorphism had large and significant effects on IgTotal and IgM. Estimated genotypic effects suggest full dominance of the TLR1A C allele. Significant TLR1A by generation interactions were detected for IgM and IgTotal.

Conclusions

The effect of a polymorphism in the TLR1A gene on IgTotal and IgM NAb was confirmed. Furthermore, we provide experimental verification of changes in allele frequencies at a major gene with dominant gene action on a quantitative trait that is subjected to mass selection. TLR1A by generation interactions indicate sensitivity to environmental factors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12711-022-00715-9.

Effects of Antimicrobial Peptide Microcin C7 on Growth Performance, Immune and Intestinal Barrier Functions, and Cecal Microbiota of Broilers

Microcin C7 is an antimicrobial peptide produced by Escherichia coli, composed of a heptapeptide with a modified adenosine monophosphate. This study was performed to evaluate the effects of Microcin C7 as a potential substrate to traditional antibiotics on growth performance, immune functions, intestinal barrier, and cecal microbiota of broilers. In the current study, 300 healthy Arbor Acres broiler chicks were randomly assigned to one of five treatments including a corn-soybean basal diet and basal diet supplemented with antibiotic or 2, 4, and 6 mg/kg Microcin C7. Results showed that Microcin C7 significantly decreased the F/G ratio of broilers; significantly increased the levels of serum cytokine IL-10, immunoglobulins IgG and IgM, and ileal sIgA secretion; significantly decreased the level of serum cytokine TNF-α. Microcin C7 significantly increased villus height and V/C ratio and significantly decreased crypt depth in small intestine of broilers. Microcin C7 significantly increased gene expression of tight junction protein Occludin and ZO-1 and significantly decreased gene expression of pro-inflammatory and chemokine TNF-α, IL-8, IFN-γ, Toll-like receptors TLR2 and TLR4, and downstream molecular MyD88 in the jejunum of broilers. Microcin C7 significantly increased the number of Lactobacillus and decreased the number of total bacteria and Escherichia coli in the cecum of broilers. Microcin C7 also significantly increased short-chain fatty acid (SCFA) and lactic acid levels in the ileum and cecum of broilers. In conclusion, diet supplemented with Microcin C7 significantly improved growth performance, strengthened immune functions, enhanced intestinal barrier, and regulated cecal microbiota of broilers. Therefore, the antimicrobial peptide Microcin C7 may have the potential to be an ideal alternative to antibiotic.

Humoral immune responses against facultative pathogen Candida utilis in atopic patients with vulvovaginal candidiasis. Candida utilis glucomannan - New serologic biomarker

Vulvovaginal candidiasis is one of the most commonly reported female genital tract infections, affecting approximately 70-75% of childbearing age women at least once during their lifetime. Approximately 50% of patients have refractory episodes and in 5-10% of cases the disease has a chronic course. The fungal cell wall represents the important host-invader interface. Cell-wall polysaccharides represent biological response modifiers and the pathogen-associated molecular patterns and virulence factors. Glycans are sensed by germ-line encoded pattern recognition receptors and reactively participate in immune system cell signaling. The most dominant cell-wall antigenic structures of Candida species as ß-glucan, α- and ß-mannans, glucomannan and other immunogenic polysaccharides are of particular relevancy for specific in vitro diagnosis and long-term follow-up of the Candida infection. In this study we assessed the immunobiological activity of facultative pathogen Candida utilis cell glucomannan and its effectivity as in vitro serological marker for antibody testing. The novel serologic assay has been developed and optimized for C. utilis serodiagnosis. The comparison assays were performed to establish relationship between antibodies against C. utilis, C. albicans and S. cerevisiae main cell-wall antigens in patient sera. The study evaluates applicability of glucomannan as serodiagnostic antigen and as a trigger of antigenspecific IgG, IgM and IgA antibody isotypes in the cohort of 35 atopic female subjects with recurrent vulvovaginal candidiasis. Statistically significant sera values of specific anti-glycan IgM and IgA class antibodies were revealed. The results are suggestive for efficient serological application of C.utilis glucomannan as in vitro disease marker and prospectively for follow-up of the specific long-term antimycotic therapy.

Evaluation of Reproductive Tract Cytokines in Post-partum Beef Cows Relating to Reproductive Microbiota and Fertility Outcomes

The activity of the immune system in the reproductive tract has been proven to be crucial in the response to uterine diseases, normal reproductive functions, and tolerance to the allogeneic fetus during pregnancy. The objectives of the current study were to (1) evaluate uterine and vaginal cytokine concentrations in postpartum cows undergoing estrus synchronization followed by timed artificial insemination (TAI) and (2) correlate bacterial communities with cytokine concentrations. Postpartum Angus cows (n = 20) were subjected to a 7-Day Co-Synch protocol with pre-synchronization beginning 21 days prior (d −21) to TAI (d 0). Uterine and vaginal flushes were collected on d −21 and −2. Pregnancy was determined by transrectal ultrasound on d 30. Cytokines include interleukin (IL)-1b, IL-6, IL-10, transforming growth factor beta (TGF-β), and immunoglobin A (IgA) and concentrations were determined by commercial ELISA kits. No differences by day or pregnancy status in cytokine concentrations were detected in vaginal samples. No differences by day or pregnancy status in IgA, IL-10, or IL-1b concentrations were detected in uterine samples. Overall TGF-β concentrations in the uterus were greater in resulting pregnant than non-pregnant cows (44.0 ± 13.4 pg/mL vs. 14.7 ± 4.9 pg/mL; P = 0.047). Uterine TGF-β was correlated with the relative abundance of genera Treponema (r = −0.668; P = 0.049) in resulting non-pregnant cows on d −21 and with the relative abundance of genera Ureaplasma (r = 0.901; P = 0.0004) in resulting pregnant cows on d −2. In resulting pregnant animals, a tendency for a strong correlation was detected between d −2 progesterone concentrations and uterine TGF-β concentrations (r = 0.591, P = 0.07). Overall IL-6 concentrations in the uterus were greater in resulting non-pregnant than pregnant cows (198.7 ± 21.8 pg/mL vs. 144.3 ± 16.1 pg/mL; P = 0.045). A correlation was also detected between uterine IL-6 concentrations and the relative abundance of genera Butyrivibrio (r = 0.742; P = 0.022) in resulting non-pregnant cows on d −21. These results suggest possible relationships between different bacterial communities and cytokine concentrations within the uterus of beef cattle prior to TAI that may ultimately affect fertility outcomes.

Candida Cell-Surface-Specific Monoclonal Antibodies Protect Mice against Candida auris Invasive Infection

Candida auris is a multidrug-resistant fungal pathogen that can cause disseminated bloodstream infections with up to 60% mortality in susceptible populations. Of the three major classes of antifungal drugs, most C. auris isolates show high resistance to azoles and polyenes, with some clinical isolates showing resistance to all three drug classes. We reported in this study a novel approach to treating C. auris disseminated infections through passive transfer of monoclonal antibodies (mAbs) targeting cell surface antigens with high homology in medically important Candida species. Using an established A/J mouse model of disseminated infection that mimics human candidiasis, we showed that C3.1, a mAb that targets β-1,2-mannotriose (β-Man₃), significantly extended survival and reduced fungal burdens in target organs, compared to control mice. We also demonstrated that two peptide-specific mAbs, 6H1 and 9F2, which target hyphal wall protein 1 (Hwp1) and phosphoglycerate kinase 1 (Pgk1), respectively, also provided significantly enhanced survival and reduction of fungal burdens. Finally, we showed that passive transfer of a 6H1+9F2 cocktail induced significantly enhanced protection, compared to treatment with either mAb individually. Our data demonstrate the utility of β-Man₃- and peptide-specific mAbs as an effective alternative to antifungals against medically important Candida species including multidrug-resistant C. auris.

[Genetic predisposition to mucocutaneous fungal infections]

Mucocutaneous fungal infections are common and usually occur in the presence of certain risk factors. However, these infections can occur in patients with no known risk factors. This indicates the presence of an underlying genetic susceptibility to fungi reflecting an innate or adaptive immune deficiency. In this review, we highlight genetic factors that predispose to mucocutaneous fungal infections specially candidiasis and dermatophytosis.

Clinical, Immunologic and Molecular Spectrum of Patients with Immunodeficiency, Centromeric Instability, and Facial Anomalies (ICF) Syndrome: A Systematic Review

BACKGROUND

Immunodeficiency, centromeric instability and facial dysmorphism (ICF) syndrome is a rare autosomal recessive immune disorder presenting with hypogammaglobulinemia, developmental delay, and facial anomalies. The ICF type 1, type 2, type 3 and type 4 are characterized by mutations in DNMT3B, ZBTB24, CDCA7 or HELLS gene, respectively. This study aimed to present a comprehensive description of the clinical, immunologic and genetic features of patients with ICF syndrome.

METHODS

PubMed, Web of Science, and Scopus were searched systemically to find eligible studies.

RESULTS

Forty-eight studies with 118 ICF patients who met the inclusion criteria were included in our study. Among these patients, 60% reported with ICF-1, 30% with ICF-2, 4% with ICF-3, and 6% with ICF-4. The four most common symptoms reported in patients with ICF syndrome were: delay in motor development, low birth weight, chronic infections, and diarrhea. Intellectual disability and preterm birth among patients with ICF-2 and failure to thrive, sepsis and fungal infections among patients with ICF-1 were also more frequent. Moreover, the median levels of all three immunoglobulins (IgA, IgG, IgM) were markedly reduced within four types of ICF syndrome.

CONCLUSION

The frequency of diagnosed patients with ICF syndrome has increased. Early diagnosis of ICF is important since immunoglobulin supplementation or allogeneic stem cell transplantation can improve the disease-free survival rate.

Single-cell approaches to investigate B cells and antibodies in autoimmune neurological disorders

Autoimmune neurological disorders, including neuromyelitis optica spectrum disorder, anti-N-methyl-D-aspartate receptor encephalitis, anti-MOG antibody-associated disorders, and myasthenia gravis, are clearly defined by the presence of autoantibodies against neurological antigens. Although these autoantibodies have been heavily studied for their biological activities, given the heterogeneity of polyclonal patient samples, the characteristics of a single antibody cannot be definitively assigned. This review details the findings of polyclonal serum and CSF studies and then explores the advances made by single-cell technologies to the field of antibody-mediated neurological disorders. High-resolution single-cell methods have revealed abnormalities in the tolerance mechanisms of several disorders and provided further insight into the B cells responsible for autoantibody production. Ultimately, several factors, including epitope specificity and binding affinity, finely regulate the pathogenic potential of an autoantibody, and a deeper appreciation of these factors may progress the development of targeted immunotherapies for patients.

Systemic anti-commensal response to fungi analyzed by flow cytometry is related to gut mycobiome ecology

BACKGROUND

Interest for the study of gut mycobiota in relation with human health and immune homeostasis has increased in the last years. From this perspective, new tools to study the immune/fungal interface are warranted. Systemic humoral immune responses could reflect the dynamic relationships between gut mycobiota and immunity. Using a novel flow cytometry technology (Fungi-Flow) to determine immunoglobulin (Ig) responses to fungi, we studied the relationships between gut mycobiota and systemic humoral anti-commensal immunity.

RESULTS

The Fungi-Flow method allows a sensitive and specific measurement of systemic IgG responses against 17 commensal and environmental fungi from the two main divisions; Ascomycota and Basidiomycota. IgG responses exhibited a high inter-individual variability. Anti-commensal IgG responses were contrasted with the relative abundance, alpha-diversity, and intra-genus richness of fungal species in gut mycobiota of twenty healthy donors. Categorization of gut mycobiota composition revealed two differentiated fungal ecosystems. Significant difference of anti-Saccharomyces systemic IgG responses were observed in healthy donors stratified according to the fungal ecosystem colonizing their gut. A positive and significant correlation was observed between the variety of IgG responses against fungal commensals and intestinal alpha-diversity. At the level of intra-genus species richness, intense IgG responses were associated with a low intra-genus richness for known pathobionts, but not commensals.

CONCLUSIONS

Fungi-Flow allows an easy and reliable measure of personalized humoral responses against commensal fungi. Combining sequencing technology with our novel Fungi-Flow immunological method, we propose that there are at least two defined ecosystems in the human gut mycobiome associated with systemic humoral responses. Fungi-Flow opens new opportunities to improve our knowledge about the impact of mycobiota in humoral anti-commensal immunity and homeostasis. Video Abstract.

The role of B7 family members in the generation of Immunoglobulin

Ig is a Y-shaped protein produced by plasma cells and exerts multiple functions in humoral immunity. There are five groups of Igs including IgA, IgD, IgE, IgG, and IgM, which differ in their heavy chain class. The primary function of Igs includes the neutralization of extrinsic pathogens, agglutination of foreign cells for phagocytosis, precipitation of soluble antigens in serum, and complement fixation. The B cells activated by antigen(s) can differentiate into antibody-producing cells that are called plasma cells and usually matured in the germinal center (GC). Follicular T helper (Tfh) cells crosstalk with antigen-presenting cells and play a crucial role in the development of the GC. Moreover, Tfh cells regulate trafficking through the GC to allow formative interaction with GC B cells that ultimately results in affinity maturation, B-cell memory, and Ig class switching. The B7 family is a series of number of structurally related membrane proteins that bind with a specific receptor to deliver costimulatory or co-inhibitory signals that regulate the activation of T cells in GC. Here, we review and summarize the recent advance of the effects of B7 family members on Ig production and relative diseases.

Multidimensional Analysis of Risk Factors for the Severity and Mortality of Patients with COVID-19 and Diabetes

Introduction

Diabetes is one of the most common comorbidities of COVID-19. We aimed to conduct a multidimensional analysis of risk factors associated with the severity and mortality of patients with COVID-19 and diabetes.

Methods

In this retrospective study involving 1443 patients with COVID-19, we analyzed the clinical and laboratory characteristics and risk factors associated with disease severity in patients with COVID-19 with and without diabetes. Binary logistic regression analyses were performed to identify the risk factors associated with mortality in patients with COVID-19 and diabetes. The 84-day survival duration for critical patients with COVID-19 and diabetes who had different levels of leukocytes and neutrophils, or treated with immunoglobulin or not, was conducted using Kaplan–Meier survival curves.

Results

Of the 1443 patients with COVID-19, 256 (17.7%) had diabetes, had a median age of 66.0 [IQR 58.0–73.8] years, and were more likely to develop severe (41.8% vs. 35.6%) and critical disease (34.0% vs. 14.9%), followed by higher mortality (21.1% vs. 7.0%), than those without diabetes. Higher levels of leukocytes (> 5.37 × 10⁹/L), older age, and comorbid cerebrovascular disease and chronic renal disease independently contributed to in-hospital death of patients with COVID-19 and diabetes. Leukocytes > 5.37 × 10⁹/L and the application of immunoglobulin were associated with shorter survival duration and lower mortality, respectively, in critical patients with COVID-19 and diabetes.

Conclusions

More attention should be paid to patients with COVID-19 and diabetes, especially when they have high leukocyte counts (> 5.37 × 10⁹/L). Timely and adequate intravenous immunoglobulin (IVIG) use may reduce the mortality of critical patients with COVID-19 and diabetes.

Electronic supplementary material

The online version of this article (10.1007/s40121-020-00359-6) contains supplementary material, which is available to authorized users.

Recent trends in molecular diagnostics of yeast infections: from PCR to NGS

The incidence of opportunistic yeast infections in humans has been increasing over recent years. These infections are difficult to treat and diagnose, in part due to the large number and broad diversity of species that can underlie the infection. In addition, resistance to one or several antifungal drugs in infecting strains is increasingly being reported, severely limiting therapeutic options and showcasing the need for rapid detection of the infecting agent and its drug susceptibility profile. Current methods for species and resistance identification lack satisfactory sensitivity and specificity, and often require prior culturing of the infecting agent, which delays diagnosis. Recently developed high-throughput technologies such as next generation sequencing or proteomics are opening completely new avenues for more sensitive, accurate and fast diagnosis of yeast pathogens. These approaches are the focus of intensive research, but translation into the clinics requires overcoming important challenges. In this review, we provide an overview of existing and recently emerged approaches that can be used in the identification of yeast pathogens and their drug resistance profiles. Throughout the text we highlight the advantages and disadvantages of each methodology and discuss the most promising developments in their path from bench to bedside.

Effects of Candida albicans infection on defense effector secretion by human oral mucosal epithelial cells

OBJECTIVE

The aim of this study was to investigate the effects of Candida albicans on the production of defense effector molecules by human oral mucosal epithelial cells in vitro.

DESIGN

Immortalized human oral mucosal epithelial (Leuk-1) cells and C. albicans strain 5314 were cocultured at different cell-to-C. albicans ratios. The viability of Leuk-1 cells was determined by MTT and RTCA measurements. The secretory levels of multiple defense effector molecules were determined by Enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our results indicated that C. albicans significantly decreased the secretion of IgG, cystatin C, lactoferrin, and TGF-β1 in a dose-dependent manner and remarkably reduced the production of IgA independent of the cell-to-C. albicans ratio. However, C. albicans clearly enhanced the secretion of IgM, galectin-3, P-selectin, granzyme B and perforin.

CONCLUSION

These results suggest that C. albicans may exert a regulatory role in the defense response of oral mucosal epithelial cells by altering secretory levels of defense effector molecules.

Intravenous Immunoglobulin Therapy Eliminates Candida albicans and Maintains Intestinal Homeostasis in a Murine Model of Dextran Sulfate Sodium-Induced Colitis

Intravenous immunoglobulin (IVIg) therapy has diverse anti-inflammatory and immunomodulatory effects and has been employed successfully in autoimmune and inflammatory diseases. The role of IVIg therapy in the modulation of intestinal inflammation and fungal elimination has not been yet investigated. We studied IVIg therapy in a murine model of dextran sulfate sodium (DSS)-induced colitis. Mice received a single oral inoculum of Candidaalbicans and were exposed to DSS treatment for 2 weeks to induce colitis. All mice received daily IVIg therapy starting on day 1 for 7 days. IVIg therapy not only prevented a loss of body weight caused by the development of colitis but also reduced the severity of intestinal inflammation, as determined by clinical and histological scores. IVIg treatment significantly reduced the Escherichiacoli,Enterococcusfaecalis, and C.albicans populations in mice. The beneficial effects of IVIg were associated with the suppression of inflammatory cytokine interleukin (IL)-6 and enhancement of IL-10 in the gut. IVIg therapy also led to an increased expression of peroxisome proliferator-activated receptor gamma (PPARγ), while toll-like receptor 4 (TLR-4) expression was reduced. IVIg treatment reduces intestinal inflammation in mice and eliminates C.albicans overgrowth from the gut in association with down-regulation of pro-inflammatory mediators combined with up-regulation of anti-inflammatory cytokines.

Matrine Mediates Inflammatory Response via Gut Microbiota in TNBS-Induced Murine Colitis

This study mainly investigated the effect of matrine on TNBS-induced intestinal inflammation in mice. TNBS treatment caused colonic injury and gut inflammation. Matrine (1, 5, and 10 mg/kg) treatment alleviated colonic injury and gut inflammation via reducing bleeding and diarrhea and downregulating cytokines expression (IL-1β and TNF-α). Meanwhile, serum immunoglobulin G (IgG) was markedly reduced in TNBS treated mice, while 5 and 10 mg/kg matrine alleviated IgG reduction. Fecal microbiota was tested using 16S sequencing and the results showed that TNBS caused gut microbiota dysbiosis, while matrine treatment markedly improved gut microbiota communities (i.e., Bacilli and Mollicutes). Functional analysis showed that cell motility, nucleotide metabolism, and replication and repair were markedly altered in the TNBS group, while matrine treatment significantly affected cell growth and death, membrane transport, nucleotide metabolism, and replication and repair. In conclusion, matrine may serve as a protective mechanism in TNBS-induced colonic inflammation and the beneficial effect may be associated with gut microbiota.

Heat-Killed Saccharomyces cerevisiae, A Dectin-1 Agonist, Selectively Induces IgG4 Production by Human B Cells

Dectin-1 is a major receptor that recognizes fungal cell wall β-glucan. We previously reported that heat-killed Saccharomyces cerevisiae (HKSC), a Dectin-1 agonist, selectively induces IgG1 class switching in mouse B cells. Dectin-1 is also expressed on human B cells; however, Dectin-1 function in human B cells remains unknown. This study aimed to investigate the direct effect of in vitro stimulation using HKSC on Ig class switching in human B cells. HKSC selectively induced the expression of germline γ4 transcripts (GLTγ4) by human B cell line 2E2, and HKSC significantly augmented GLTγ4 promoter activity. Moreover, HKSC selectively enhanced GLTγ4 expression and IgG4 production by anti-CD40-activated human tonsillar resting B cells. Thus, these results suggest that Dectin-1 maybe involved in selective IgG4 class switching by human B cells.

Role of TLR1, TLR2 and TLR6 in the modulation of intestinal inflammation and Candida albicans elimination

Background

Toll-like receptors (TLRs) are the major pattern recognition receptors that mediate sensing of a wide range of microorganisms. TLR2 forms heterodimers with either TLR1 or TLR6, broadening its ligand diversity against pathogens. TLR1, TLR2 and TLR6 have been implicated in the recognition of Candida albicans, an opportunistic fungal pathogen that colonizes the gastrointestinal tract. In this study, we explored whether the deficiency in TLR1, TLR2 or TLR6 impacts C. albicans colonization and inflammation-associated colonic injury in the dextran sulfate sodium (DSS)-induced colitis in mice.

Results

DSS treatment and C. albicans challenge induced greater weight loss, worse clinical signs of inflammation, higher histopathologic scores, and increased mortality rates in TLR1^−/− and TLR2^−/− mice when compared to TLR6^−/− and wild-type mice. The number of C. albicans colonies in the stomach, colon and feces was decreased in TLR6^−/− mice as compared to TLR2^−/−, TLR1^−/− and wild-type mice. Interestingly, the population of E. coli in colonic luminal contents, intestinal permeability to FITC-dextran and cytokine expression were significantly increased in TLR1^−/− and TLR2^−/− mice, while they were decreased in TLR6^−/− mice.

Conclusion

In contrast to TLR6, both TLR1 and TLR2 deficiencies increased intestinal inflammation, and the overgrowth of C. albicans and E. coli populations in the colitis model, suggesting the involvement of TLR1 and TLR2 in epithelial homeostasis, and a role of TLR6 in increasing intestinal inflammation in response to pathogen-sensing.

Electronic supplementary material

The online version of this article (doi:10.1186/s13099-017-0158-0) contains supplementary material, which is available to authorized users.

Prophylactic immunoglobulin therapy in secondary immune deficiency - an expert opinion

INTRODUCTION

In primary immunodeficiency (PID), immunoglobulin replacement therapy (IgRT) for infection prevention is well-established and supported by a wealth of clinical data. On the contrary, very little evidence-based data is available on the challenges surrounding the use of IgRT in secondary immune deficiencies (SID), and most published guidelines are mere extrapolations from the experience in PID.

AREAS COVERED

In this article, four European experts provide their consolidated opinion on open questions surrounding the prophylactic use of IgRT in SID, based on their clinical experience. The main topics are IgRT initiation, route of administration, dose optimization, and therapy discontinuation. The authors hope this discussion will be of assistance to practicing physicians in their daily decision-making. Expert commentary: Although growing experience indicates that IgRT could play an important role in the management of SID, very little robust evidence is available to guide clinical practice. The authors stress the urgent need for new studies in the field and discuss points they find of importance to design them adequately.

The Homophilic Domain - An Immunological Archetype

The homophilic potential emerges as an important biological principle to boost the potency of immunoglobulins. Since homophilic antibodies in human and mouse sera exist prior environmental exposure, they are part of the natural antibody repertoire. Nevertheless, hemophilic properties are also identified in induced antibody repertoire. The use of homophilicity of antibodies in the adaptive immunity signifies an archetypic antibody structure. The unique feature of homophilicity in the antibody repertoire also highlights an important mechanism to boost the antibody potency to protect against infection and atherosclerosis as well to treat cancer patients.

Immunoproteomics-Based Analysis of the Immunocompetent Serological Response to Lomentospora prolificans

The filamentous fungus Lomentospora prolificans is an emerging pathogen causing severe infections mainly among the immunocompromised population. These diseases course with high mortality rates due to great virulence of the fungus, its inherent resistance to available antifungals, and absence of specific diagnostic tools. Despite being widespread in humanized environments, L. prolificans rarely causes infections in immunocompetent individuals likely due to their developed protective immune response. In this study, conidial and hyphal immunomes against healthy human serum IgG were analyzed, identifying immunodominant antigens and establishing their prevalence among the immunocompetent population. Thirteen protein spots from each morph were detected as reactive against at least 70% of serum samples, and identified by liquid chromatography tandem mass spectrometry (LC-MS/MS). Hence, the most seroprevalent antigens were WD40 repeat 2 protein, malate dehydrogenase, and DHN1, in conidia, and heat shock protein (Hsp) 70, Hsp90, ATP synthase β subunit, and glyceraldehyde-3-phosphate dehydrogenase, in hyphae. More interestingly, the presence of some of these seroprevalent antigens was determined on the cell surface, as Hsp70, enolase, or Hsp90. Thus, we have identified a diverse set of antigenic proteins, both in the entire proteome and cell surface subproteome, which may be used as targets to develop innovative therapeutic or diagnostic tools.

B cells drive Th2 responses by instructing human dendritic cell maturation

Dendritic cells (DCs) are known to regulate the functions of various immune cells. Reciprocal signaling by these immune cells also "educate" the DCs and determine the quality of the ensuing immune responses. Recently, we demonstrated that human DCs undergo maturation upon interaction with activated B cells to acquire unique abilities to promote polarization of Th2 cells.