Impact of Strongyloides stercoralis infection on complement activation in Type 2 diabetes mellitus: Insights from a clinical and anthelmintic intervention study

BACKGROUND

Numerous studies indicate a potential protective role of helminths in diabetes mellitus (DM) progression. The complement system, vital for host defense, plays a crucial role in tissue homeostasis and immune surveillance. Dysregulated complement activation is implicated in diabetic complications. We aimed to investigate the influence of the helminth, Strongyloides stercoralis (Ss) on complement activation in individuals with type 2 DM (T2D).

METHODOLOGY

We assessed circulating levels of complement proteins (C1q, C2, C3, C4, C4b, C5, C5a, and MBL (Lectin)) and their regulatory components (Factor B, Factor D, Factor H, and Factor I) in individuals with T2D with (n = 60) or without concomitant Ss infection (n = 58). Additionally, we evaluated the impact of anthelmintic therapy on these parameters after 6 months in Ss-infected individuals (n = 60).

RESULTS

Ss+DM+ individuals demonstrated reduced levels of complement proteins (C1q, C4b, MBL (Lectin), C3, C5a, and C3b/iC3b) and complement regulatory proteins (Factor B and Factor D) compared to Ss-DM+ individuals. Following anthelmintic therapy, there was a partial reversal of these levels in Ss+DM+ individuals.

CONCLUSION

Our findings indicate that Ss infection reduces complement activation, potentially mitigating inflammatory processes in individuals with T2D. The study underscores the complex interplay between helminth infections, complement regulation, and diabetes mellitus, offering insights into potential therapeutic avenues.

Hookworm infection induces glycometabolic modulation in South Indian individuals with type 2 diabetes

Objectives

A number of epidemiological studies have demonstrated that there is an inverse relationship between helminth infections and diabetes mellitus, suggesting that helminth infection may have a positive effect on type 2 diabetes mellitus (T2DM). However, the association between hookworm infection and T2DM has barely been studied. Hence, we aimed to investigate and analyze the interaction and association between hookworm infection and T2DM.

Methods

We examined the effect of hookworm infection on biochemical parameters, including plasma random blood glucose, glycated hemoglobin, and the plasma levels of pancreatic hormones, incretins, and adipokines in individuals with T2DM with (INF, n = 35) or without (UN, n = 35) hookworm infection. Moreover, we re-evaluated these analyte concentrations in a subset of INF individuals 6 months following anthelmintic therapy.

Results

Compared to UN individuals, INF individuals had significantly lowered levels of random blood glucose and glycated hemoglobin. INF individuals also exhibited significantly diminished levels of adiponectin, adipsin, C-peptide, insulin, and glucagon compared to UN individuals. In contrast, INF individuals displayed substantially elevated levels of visfatin and incretins compared to UN individuals. Interestingly, this effect was not seen following anthelmintic treatment.

Conclusion

Our study findings indicate that concomitant hookworm infection exerts a beneficial effect on glycometabolic parameters in T2DM.

Restoration of dendritic cell homeostasis and Type I/Type III interferon levels in convalescent COVID-19 individuals

Background

Plasmacytoid and myeloid dendritic cells play a vital role in the protection against viral infections. In COVID-19, there is an impairment of dendritic cell (DC) function and interferon secretion which has been correlated with disease severity.

Results

In this study, we described the frequency of DC subsets and the plasma levels of Type I (IFNα, IFNβ) and Type III Interferons (IFNλ1), IFNλ2) and IFNλ3) in seven groups of COVID-19 individuals, classified based on days since RT-PCR confirmation of SARS-CoV2 infection. Our data shows that the frequencies of pDC and mDC increase from Days 15–30 to Days 61–90 and plateau thereafter. Similarly, the levels of IFNα, IFNβ, IFNλ1, IFNλ2 and IFNλ3 increase from Days 15–30 to Days 61–90 and plateau thereafter. COVID-19 patients with severe disease exhibit diminished frequencies of pDC and mDC and decreased levels of IFNα, IFNβ, IFNλ1, IFNλ2 and IFNλ3. Finally, the percentages of DC subsets positively correlated with the levels of Type I and Type III IFNs.

Conclusion

Thus, our study provides evidence of restoration of homeostatic levels in DC subset frequencies and circulating levels of Type I and Type III IFNs in convalescent COVID-19 individuals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00526-z.

Prevalence of proximate risk factors of active tuberculosis in latent tuberculosis infection: A cross-sectional study from South India

The prevalence of proximate risk factors for active tuberculosis (TB) in areas of high prevalence of latent tuberculosis infection (LTBI) is not clearly understood. We aimed at assessing the prevalence of non-communicable multi-morbidity focusing on diabetes mellitus (DM), malnutrition, and hypertension (HTN) as common risk factors of LTBI progressing to active TB. In a cross-sectional study, 2,351 adults (45% male and 55% female) from villages in the Kancheepuram district of South India were enrolled between 2013 and 2020. DM was defined as HbA1c >6.4%, undernutrition was defined as low body mass index (LBMI) <18.5 kg/m², obesity was classified as BMI ≥25 kg/m², HTN was reported as systolic pressure >130 mmHg, and LTBI was defined as positive (≥ 0.35 international units/ml) by QuantiFERON Gold In-Tube assay. A total of 1,226 individuals (52%) were positive for LTBI out of 2351 tested individuals. The prevalence of DM and pre-diabetes mellitus (PDM) was 21 and 35%, respectively, HTN was 15% in latent tuberculosis (LTB)-infected individuals. The association of DM [odds ratio (OR)]; adjusted odds ratio (aOR) (OR = 1.26, 95% CI: 1.13-1.65; aOR = 1.19, 95% CI: 1.10-1.58), PDM (OR = 1.11, 95% CI: 1.0-1.35), and HTN (OR = 1.28, 95% CI: 1.11-1.62; aOR = 1.18, 95% CI: 1.0-1.56) poses as risk factors of LTBI progression to active TB. The prevalence of LBMI 9% (OR = 1.07, 95% CI: 0.78-1.48) and obesity 42% (OR = 0.85, 95% CI: 0.70-1.03) did not show any statistically significant association with LTB-infected individuals. The present evidence of a high burden of multi-morbidity suggests that proximate risk factors of active TB in LTBI can be managed by nutrition and lifestyle modification.

Seroprevalence of Strongyloides stercoralis infection in a South Indian adult population

Background

The prevalence of Strongyloides stercoralis infection is estimated to be 30–100 million worldwide, although this an underestimate. Most cases remain undiagnosed due to the asymptomatic nature of the infection. We wanted to estimate the seroprevalence of S. stercoralis infection in a South Indian adult population.

Methods

To this end, we performed community-based screening of 2351 individuals (aged 18–65) in Kanchipuram District of Tamil Nadu between 2013 and 2020. Serological testing for S. stercoralis was performed using the NIE ELISA.

Results

Our data shows a seroprevalence of 33% (768/2351) for S. stercoralis infection which had a higher prevalence among males 36% (386/1069) than among females 29.8% (382/1282). Adults aged ≥55 (aOR = 1.65, 95% CI: 1.25–2.18) showed higher adjusted odds of association compared with other age groups. Eosinophil levels (39%) (aOR = 1.43, 95% CI: 1.19–1.74) and hemoglobin levels (24%) (aOR = 1.25, 95% CI: 1.11–1.53) were significantly associated with S. stercoralis infection. In contrast, low BMI (aOR = 1.15, 95% CI: 0.82–1.61) or the presence of diabetes mellitus (OR = 1.18, 95% CI: 0.83–1.69) was not associated with S. stercoralis seropositivity.

Conclusions

Our study provides evidence for a very high baseline prevalence of S. stercoralis infection in South Indian communities and this information could provide realistic and concrete planning of control measures.

Characterization of memory T cell subsets and common γ-chain cytokines in convalescent COVID-19 individuals

T cells are thought to be an important correlates of protection against SARS‐CoV2 infection. However, the composition of T cell subsets in convalescent individuals of SARS‐CoV2 infection has not been well studied. The authors determined the lymphocyte absolute counts, the frequency of memory T cell subsets, and the plasma levels of common γ−chain in 7 groups of COVID‐19 individuals, based on days since RT‐PCR confirmation of SARS‐CoV‐2 infection. The data show that both absolute counts and frequencies of lymphocytes as well as, the frequencies of CD4⁺ central and effector memory cells increased, and the frequencies of CD4⁺ naïve T cells, transitional memory, stem cell memory T cells, and regulatory cells decreased from Days 15–30 to Days 61–90 and plateaued thereafter. In addition, the frequencies of CD8⁺ central memory, effector, and terminal effector memory T cells increased, and the frequencies of CD8⁺ naïve cells, transitional memory, and stem cell memory T cells decreased from Days 15–30 to Days 61–90 and plateaued thereafter. The plasma levels of IL‐2, IL‐7, IL‐15, and IL‐21—common γc cytokines started decreasing from Days 15–30 till Days 151–180. Severe COVID‐19 patients exhibit decreased levels of lymphocyte counts and frequencies, higher frequencies of naïve cells, regulatory T cells, lower frequencies of central memory, effector memory, and stem cell memory, and elevated plasma levels of IL‐2, IL‐7, IL‐15, and IL‐21. Finally, there was a significant correlation between memory T cell subsets and common γc cytokines. Thus, the study provides evidence of alterations in lymphocyte counts, memory T cell subset frequencies, and common γ−chain cytokines in convalescent COVID‐19 individuals.

Dynamic alterations in monocyte numbers, subset frequencies and activation markers in acute and convalescent COVID-19 individuals

Monocytes are thought to play an important role in host defence and pathogenesis of COVID-19. However, a comprehensive examination of monocyte numbers and function has not been performed longitudinally in acute and convalescent COVID-19. We examined the absolute counts of monocytes, the frequency of monocyte subsets, the plasma levels of monocyte activation markers using flowcytometry and ELISA in seven groups of COVID-19 individuals, classified based on days since RT-PCR confirmation of SARS-CoV2 infection. Our data shows that the absolute counts of total monocytes and the frequencies of intermediate and non-classical monocytes increases from Days 15-30 to Days 61-90 and plateau thereafter. In contrast, the frequency of classical monocytes decreases from Days 15-30 till Days 121-150. The plasma levels of sCD14, CRP, sCD163 and sTissue Factor (sTF)-all decrease from Days 15-30 till Days 151-180. COVID-19 patients with severe disease exhibit higher levels of monocyte counts and higher frequencies of classical monocytes and lower frequencies of intermediate and non-classical monocytes and elevated plasma levels of sCD14, CRP, sCD163 and sTF in comparison with mild disease. Thus, our study provides evidence of dynamic alterations in monocyte counts, subset frequencies and activation status in acute and convalescent COVID-19 individuals.

Augmented Innate and Adaptive Immune Responses Under Conditions of Diabetes-Filariasis Comorbidity

Metainflammation, as seen in chronic diabetes subjects, impairs immunity and increases the susceptibility to infections. In the present study, the effect of diabetes on immune response against filariasis was studied. Both toll-like receptor (TLR)-mediated and crude antigen-induced immune responses were quantified, in whole blood cultures from filariasis-infected subjects (LF+), with and without diabetes. Blood cultures were stimulated with TLR ligands (TLR2 and TLR4) or filarial antigen or were left unstimulated (control) for 18 h. Cytokine, chemokine, and defensin secretion was quantified by ELISA. Expression of HLA-DR, B7-1, B7-2, activation marker (CD69), and Th (Th1, Th2, Th17, and Th9) phenotypes was quantified by flow cytometry. Expression of immunomodulatory effectors (Cox-2, HO-1, IDO-1, and p47Phox) and Th-polarizing transcription factors (T-bet, GATA3, and ROR-γt) was quantified by quantitative PCR. Secretion of IL-27, IL-1Ra, IL-12, IL-33, IL-9, and SDF-1 was increased under diabetes conditions with increased Th9 polarization and increased expression of Cox-2 and IDO. Overall, diabetes was found to augment both TLR-mediated and antigen-induced inflammation, which can promote chronic pathology in LF+ subjects.

Recovery of Memory B-cell Subsets and Persistence of Antibodies in Convalescent COVID-19 Patients

It is essential to examine the longevity of the defensive immune response engendered by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. We examined the SARS-CoV-2-specific antibody responses and ex vivo memory B-cell subsets in seven groups of individuals with COVID-19 classified based on days since reverse-transcription polymerase chain reaction confirmation of SARS-CoV-2 infection. Our data showed that the levels of IgG and neutralizing antibodies started increasing from days 15 to 30 to days 61 to 90, and plateaued thereafter. The frequencies of naive B cells and atypical memory B cells decreased from days 15 to 30 to days 61 to 90, and plateaued thereafter. In contrast, the frequencies of immature B cells, classical memory B cells, activated memory B cells, and plasma cells increased from days 15 to 30 to days 61 to 90, and plateaued thereafter. Patients with severe COVID-19 exhibited increased frequencies of naive cells, atypical memory B cells, and activated memory B cells, and lower frequencies of immature B cells, central memory B cells, and plasma cells when compared with patients with mild COVID-19. Therefore, our data suggest modifications in memory B-cell subset frequencies and persistence of humoral immunity in convalescent individuals with COVID-19.

Diminished circulating levels of angiogenic factors and RAGE ligands in helminth-diabetes comorbidity and reversal following anthelmintic treatment

BACKGROUND

Various epidemiological and experimental studies propose that helminths could play a preventive role against the progression of Type 2 diabetes mellitus (T2DM). T2DM induces microvascular and large vessel complications mediated by elevated levels of angiogenic factors and soluble RAGE ligands. However, the interactions between helminths and host angiogenic factors and RAGE ligands are unexplored.

METHODS

To assess the relationship between a soil-transmitted helminth, Strongyloides stercoralis (Ss) and T2DM, we measured plasma levels of VEGF-A, C, D, Angio-1 and Angio-2 and their receptors VEGF-R1, R2 and R3 as well as sRAGE and their ligands AGE, S100A12 and HMBG-1 in individuals with T2DM with Ss+ or without Ss infection (Ss-). In Ss+ individuals, we also measured the levels of aforementioned factors 6 months following anthelmintic therapy.

RESULTS

Ss+ individuals exhibited significantly decreased levels of VEGF-A, C, D, Angio-1 and Angio-2 and their soluble receptors VEGF-R1, R2 and R3, that increased following anthelmintic therapy. Likewise, Ss+ individuals exhibited significantly decreased levels of AGE and their ligands sRAGE, S100A12 and HMBG-1 which reversed following anthelmintic therapy.

CONCLUSION

Our data suggest that Ss infection could play a beneficial role by limiting or delaying the T2DM related vascular complications.

Impact of malnutrition on systemic immune and metabolic profiles in type 2 diabetes

BACKGROUND

While obesity and overweight status are firmly established risk factors for Type 2 diabetes mellitus (T2DM), a substantial proportion of diabetic individuals, especially in Africa and Asia, are often underweight or normal weight. However, very little is known about the immunological and metabolic profiles of these individuals.

METHODS

This study aimed to assess the relationship between malnutrition and Type 2 diabetes mellitus (T2DM). We examined a variety of analytes associated with the immunological and metabolic profiles of T2DM individuals with low (< 18.5 kg/m2) or normal (18.5-24.9 kg/m2) body mass index (BMI). To this end, we measured plasma levels of HbA1c, glucose, insulin, glucagon, adipocytokines and Type 1, Type 2, Type 17, pro-inflammatory and regulatory cytokines in T2DM individuals with low BMI (LBMI) or normal BMI (NBMI) with small sample size n = 44 in each group.

RESULTS

LBMI individuals exhibited significantly higher levels of HbA1c, random blood glucose, insulin and glucagon compared to NBMI individuals. Similarly, LBMI individuals exhibited significantly higher levels of adiponectin and adipsin and significantly lower levels of leptin in comparison to NBMI individuals. LBMI individuals also exhibited significantly lower levels of the Type 1, Type 2, Type 17, pro-inflammatory and regulatory cytokines in comparison to NBMI individuals. Finally, while the metabolic parameters exhibited a significant negative correlation with BMI, the immunological parameters exhibited a significant positive correlation with BMI.

CONCLUSIONS

Malnutrition is associated with a significant modulation of glycemic, hormonal and cytokine parameters in T2DM. Hence, the biochemical and immunological profiles of T2DM is significantly influenced by BMI.

Impact of Helminth Infection on Metabolic and Immune Homeostasis in Non-diabetic Obesity

Several epidemiological and immunological studies indicate a reciprocal association between obesity/metabolic syndrome and helminth infections. Numerous studies demonstrated that obesity is concomitant with chronic low-grade inflammation, which is marked by vital changes in cellular composition and function of adipose tissue. However, the effect of helminth infection on the homeostatic milieu in obesity is not well-understood. To determine the relationship between Strongyloides stercoralis (Ss) infection and obesity, we examined an array of parameters linked with obesity both before and at 6 months following anthelmintic treatment. To this end, we measured serum levels of pancreatic hormones, incretins, adipokines and Type-1, Type-2, Type-17, and other proinflammatory cytokines in those with non-diabetic obesity with (INF) or without Ss infection (UN). In INF individuals, we evaluated the levels of these parameters at 6 months following anthelmintic treatment. INF individuals revealed significantly lower levels of insulin, glucagon, C-peptide, and GLP-1 and significantly elevated levels of GIP compared to UN individuals. INF individuals also showed significantly lower levels of Type-1, Type-17 and other pro-inflammatory cytokines and significantly increased levels of Type-2 and regulatory cytokines in comparison to UN individuals. Most of these changes were significantly reversed following anthelmintic treatment. Ss infection is associated with a significant alteration of pancreatic hormones, incretins, adipokines, and cytokines in obese individuals and its partial reversal following anthelmintic treatment. Our data offer a possible biological mechanism for the protective effect of Ss infection on obesity.

Helminth Mediated Attenuation of Systemic Inflammation and Microbial Translocation in Helminth-Diabetes Comorbidity

Type 2 diabetes mellitus (T2DM) is characterized by heightened systemic inflammation and microbial translocation. Whether concomitant helminth infections can modulate this systemic response is unclear. We examined the presence of markers of systemic inflammation (levels of acute phase proteins) and of microbial translocation [levels of lipopolysaccharide (LPS) and its associated products] in T2DM individuals with (Ss ⁺) or without (Ss ^-) Strongyloides stercoralis (Ss) infection. We also analyzed these parameters at 6 months following anthelmintic treatment in Ss ⁺ individuals. Ss ⁺ individuals exhibited significantly diminished levels of alpha-2 macroglobulin, C-reactive protein, haptoglobin and serum amyloid protein A1 compared to Ss ^- individuals and these levels increased significantly following therapy. Similarly, Ss ⁺ individuals exhibited significantly diminished levels of LPS, sCD14, intestinal fatty acid binding protein, LPS binding protein and endotoxin IgG antibody and most of these levels increased significantly following therapy. Thus, helminth infection is associated with attenuation of systemic inflammation and microbial translocation in T2DM and its reversal following anthelmintic therapy.

Metabolic Consequences of Concomitant Strongyloides stercoralis Infection in Patients With Type 2 Diabetes Mellitus

BACKGROUND

Human and animal studies have demonstrated that helminth infections are associated with a decreased prevalence of type 2 diabetes mellitus (T2DM). However, very little is known about their biochemical and immunological interactions.

METHODS

To assess the relationship between a soil-transmitted helminth, Strongyloides stercoralis (Ss), and T2DM, we examined analytes associated with glycemic control, metabolic processes, and T-cell-driven inflammation at the time of Ss diagnosis and 6 months after definitive anthelmintic treatment. We measured plasma levels of hemoglobin A1c, glucose, insulin, glucagon, adipocytokines, and T-helper (TH) 1-, 2-, and 17- associated cytokines in patients with T2DM with (INF group) or without (UN group) Ss infection. In INF individuals, we again assessed the levels of these analytes 6 months following anthelmintic treatment.

RESULTS

Compared to UN individuals, INF individuals exhibited significantly diminished levels of insulin and glucagon that increased significantly following therapy. Similarly, INF individuals exhibited significantly diminished levels of adiponectin and adipsin that reversed following therapy. INF individuals also exhibited significantly decreased levels of the TH1- and TH17- associated cytokines in comparison to UN individuals; again, anthelmintic therapy augmented these levels. As expected, INF individuals had elevated levels of TH2-associated and regulatory cytokines that normalized following definitive therapy. Multivariate analysis revealed that these changes were independent of age, sex, body mass index, and liver and renal function.

CONCLUSIONS

Strongyloides stercoralis infection is associated with a significant modulation of glycemic, hormonal, and cytokine parameters in T2DM and its reversal following anthelmintic therapy. Hence, Ss infection has a protective effect on diabetes-related parameters.

Diminished Systemic and Mycobacterial Antigen Specific Anti-microbial Peptide Responses in Low Body Mass Index-Latent Tuberculosis Co-morbidity

Low body mass index (BMI) is a risk factor for progression from latent Mycobacterium tuberculosis infection to active tuberculosis (TB) disease. Anti-microbial peptides (AMPs) are multifunctional molecules that play a crucial role in the mammalian host innate defense mechanism. AMPs have been shown to have an important role in host immunity to TB infection. The association of antimicrobial peptides with low BMI–latent tuberculosis (LTBI) co-morbidity has not been explored. To study the association of AMPs with LTBI-BMI, we examined the systemic, baseline, and mycobacterial antigen stimulated levels of human neutrophil peptides 1–3, (HNP1-3), granulysin, human beta defensin–2 (HBD-2), and cathelicidin (LL-37) in individuals with LTBI and low BMI (LBMI) and compared them with individuals with LTBI and normal BMI (NBMI). LBMI was characterized by diminished systemic levels of HNP1-3, granulysin, HBD-2 and cathelicidin in comparison with NBMI. Similarly, LBMI was also characterized by diminished unstimulated levels of HNP1-3 and granulysin and diminished mycobacterial antigen stimulated levels of HNP1-3, granulysin, and HBD-2. In addition, certain AMPs exhibited a positive correlation with BMI. Our data, therefore, demonstrates that coexistent LBMI in LTBI is characterized by the diminished levels of HNP1-3, granulysin, HBD-2, and cathelicidin, thereby potentially increasing the risk of progression to active TB.

Filarial Coinfection Is Associated With Higher Bacterial Burdens and Altered Plasma Cytokine and Chemokine Responses in Tuberculous Lymphadenitis

Filarial infections are known to modulate cytokine responses in pulmonary tuberculosis by their propensity to induce Type 2 and regulatory cytokines. However, very little is known about the effect of filarial infections on extra-pulmonary forms of tuberculosis. Thus, we have examined the effect of filarial infections on the plasma levels of various families of (IL-1, IL-12, γC, and regulatory) cytokines and (CC and CXC) chemokines in tuberculous lymphadenitis coinfection. We also measured lymph node culture grades in order to assess the burden of Mycobacterium tuberculosis in the two study groups [Fil+ (n = 67) and Fil– (n = 109)]. Our data reveal that bacterial burden was significantly higher in Fil+ compared to Fil– individuals. Plasma levels of IL-1 family (IL-1α, IL-β, IL-18) cytokines were significantly lower with the exception of IL-33 in Fil+ compared to Fil– individuals. Similarly, plasma levels of IL-12 family cytokines -IL-12 and IL-23 were significantly reduced, while IL-35 was significantly elevated in Fil+ compared to Fil– individuals. Filarial infection was also associated with diminished levels of IL-2, IL-9 and enhanced levels of IL-4, IL-10, and IL-1Ra. Similarly, the Fil+ individuals were linked to elevated levels of different CC (CCL-1, CCL-2, CCL-3, CCL-11) and CXC (CXCL-2, CXCL-8, CXCL-9, CXCL-11) chemokines. Therefore, we conclude that filarial infections exert powerful bystander effects on tuberculous lymphadenitis, effects including modulation of protective cytokines and chemokines with a direct impact on bacterial burdens.

Helminth infection modulates systemic pro-inflammatory cytokines and chemokines implicated in type 2 diabetes mellitus pathogenesis

BACKGROUND

The prevalence of helminth infections exhibits an inverse association with the prevalence of Type 2 diabetes mellitus (T2DM), and helminths are postulated to mediate a protective effect against T2DM. However, the biological mechanism behind this effect is not known.

AIMS/METHODS

We postulated that helminth infections act by modulating the pro-inflammatory cytokine and chemokine milieu that is characteristic of T2DM. To examine the association of cytokines and chemokines in helminth-diabetes co-morbidity, we measured the plasma levels of a panel of pro-inflammatory cytokines and chemokines in individuals with Strongyloides stercoralis infection (Ss+) and T2DM at the time of Ss diagnosis and then 6 months after definitive anthelmintic treatment along with uninfected control individuals with T2DM alone (Ss-).

PRINCIPAL FINDINGS

Ss+ individuals exhibited significantly diminished levels of the pro-inflammatory cytokines-IL-1α, IL-1β, IL-6, IL-12, IL-18, IL-23, IL-27, G-CSF and GM-CSF and chemokines-CCL1, CCL2, CCL3, CCL11, CXCL1, CXCL2, CXCL8, CXCL9, CXCL10 and CXCL11. In contrast, Ss+ individuals exhibited significantly elevated levels of IL-1Ra. Anthelmintic treatment resulted in increased levels of all of the cytokines and chemokines.

CONCLUSIONS

Thus, helminth infections alleviate and anthelmintic therapy partially restores the plasma cytokine and chemokine levels in helminth-diabetes co-morbidity. Our data therefore offer a plausible biological mechanism for the protective effect of helminth infections against T2DM.

Helminth Coinfection Alters Monocyte Activation, Polarization, and Function in Latent Mycobacterium tuberculosis Infection

Helminth infections are known to influence T and B cell responses in latent tuberculosis infection (LTBI). Whether helminth infections also modulate monocyte responses in helminth-LTBI coinfection has not been fully explored. To this end, we examined the activation, polarization, and function of human monocytes isolated from individuals with LTBI with (n = 25) or without (n = 25) coincident Strongyloides stercoralis infection (S. stercoralis-positive and S. stercoralis-negative respectively). Our data reveal that the presence of S. stercoralis infection is associated with lower frequencies of monocytes expressing CD54, CD80, CD86 at baseline (absence of stimulation) and in response to mycobacterial-Ag stimulation than monocytes from S. stercoralis-negative individuals. In contrast, S. stercoralis infection was associated with higher frequencies of M2-like monocytes, as determined by expression of CD206 and CD163. Monocytes from S. stercoralis-positive individuals had a reduced capacity to phagocytose or exhibit respiratory burst activity following mycobacterial-Ag or LPS stimulation and were less capable of expression of IL-1β, TNF-α, IL-6, and IL-12 at baseline and/or following Ag stimulation compared with those without S. stercoralis infection. In addition, definitive treatment of S. stercoralis infection resulted in a significant reversal of the altered monocyte function 6 mo after anthelmintic therapy. Finally, T cells from S. stercoralis-positive individuals exhibited significantly lower activation at baseline or following mycobacterial-Ag stimulation. Therefore, our data highlight the induction of dampened monocyte activation, enhanced M2 polarization, and impaired monocyte function in helminth-LTBI coinfection. Our data also reveal a different mechanism by which helminth infection modulates immune function in LTBI.

Undernutrition is associated with perturbations in T cell-, B cell-, monocyte- and dendritic cell- subsets in latent Mycobacterium tuberculosis infection

Undernutrition, as described by low body mass index (BMI), is a foremost risk factor for the progression of active Tuberculosis (TB). Undernutrition is also known to impact the baseline frequencies of innate and adaptive immune cells in animal models. To verify whether undernutrition has any influence on the baseline frequencies of immune cells in latent Mycobacterium tuberculosis infection (LTBI), we examined the frequencies of T cell-, B cell, monocyte- and dendritic cell (DC)- subsets in individuals with LTBI and low BMI (LBMI) and contrasted them with LTBI and normal BMI (NBMI) groups. LBMI was characterized by decreased frequencies and absolute cell counts of T cells, B cells and NK cells in comparison with NBMI. LBMI individuals demonstrated significantly enhanced frequencies of naïve and effector CD4⁺ and CD8⁺ T cells and significantly decreased frequencies of central memory, effector memory CD4⁺ and CD8⁺ T cells and regulatory T cells. Among B cell subsets, LBMI individuals demonstrated significantly diminished frequencies of naïve, immature, classical memory, activated memory, atypical memory and plasma cells. In addition, LBMI individuals showed significantly decreased frequencies of classical monocytes, myeloid DCs and plasmacytoid DCs and significantly increased frequencies of intermediate and non-classical monocytes and myeloid derived suppressor cells. BMI exhibited a positive correlation with B cell and NK cell counts. Our data, therefore, demonstrates that coexistent undernutrition in LTBI is characterized by the occurrence of a significant modulation in the frequency of innate and adaptive immune cell subsets.

Helminth mediated modulation of the systemic and mycobacterial antigen - stimulated cytokine profiles in extra-pulmonary tuberculosis

Background

Helminth infections are known to regulate cytokine responses in both pulmonary and latent tuberculosis infection. Whether helminth infections also modulate cytokine responses in extra-pulmonary tuberculosis, specifically tuberculous lymphadenitis (TBL), has not been examined thus far.

Methodology

Hence, to determine the cytokine profile in helminth-TBL coinfection, we measured the systemic and mycobacterial (TB)–antigen stimulated levels of Type 1, Type 2, Type 17, regulatory and pro-inflammatory cytokines in TBL individuals coinfected with or without Strongyloides stercoralis (Ss) infection.

Significant findings

TBL-Ss+ individuals have significantly higher bacterial burdens in the affected lymph nodes in comparison to TBL-Ss- individuals. TBL-Ss+ individuals exhibit significantly enhanced plasma levels of Type 2 (IL-5 and IL-13), Type 17 (IL-17 and IL-22) and regulatory (IL-10) cytokines in comparison to TBL-Ss- individuals. In contrast, TBL-Ss+ individuals exhibit significantly diminished plasma levels of pro-inflammatory cytokines (IL-1α and GM-CSF) in comparison to TBL-Ss- individuals. TBL-Ss+ individuals also exhibit significantly diminished unstimulated or mycobacterial—antigen stimulated levels of Type 1, Type 17 or IL-1 family cytokines in comparison to TBL-Ss- individuals but no differences in mitogen stimulated cytokine levels.

Conclusion

Therefore, our data reveal a profound influence of Ss infection on the bacteriological profile of TBL and suggesting that the underlying modulation of cytokine responses might be a mechanism by which this helminth infection could impart a detrimental effect on the pathogenesis of TBL disease.

Strongyloides stercoralis (Ss) infects about 30–100 million people worldwide and it is the main causative agent of strongyloidiasis, a chronic parasitic infection. Similarly, tuberculosis (TB) affects nearly 2 billion people and both Ss and TB are co-endemic as well as share a major global disease burden. Earlier studies have revealed that helminth co-infection can modify the effect produced by the host immunity against Mycobacterium tuberculosis. However, no studies have examined the association of helminth co-infection with extra-pulmonary TB, especially in tuberculous lymphadenitis (TBL). In the present study, we have addressed this gap by measuring the cytokine profile in co-infected helminth-TBL individuals. Our study first shows that TBL-Ss+ co-infection is associated with “higher bacterial burden” in the affected lymph nodes. Our study also shows that co-infection is associated with alterations in plasma cytokines, specifically Type 2, regulatory and Type 17 cytokines were elevated and pro-inflammatory cytokines were reduced. Our study demonstrates significantly diminished unstimulated or TB—antigen stimulated levels of Type 1, Type 17 or IL-1 family of cytokines in TBL-Ss+ coinfected individuals. Hence, we conclude that helminth coinfection can possibly skew the protective immunity in TBL disease or infection.

Coexistent Helminth Infection-Mediated Modulation of Chemokine Responses in Latent Tuberculosis

Coexistent helminth infections are known to modulate T cell and cytokine responses in latent infection with Mycobacterium tuberculosis However, their role in modulating chemokine responses in latent tuberculosis (LTB) has not been explored. Because chemokines play a vital role in the protective immune responses in LTB, we postulated that coexistent helminth infection could modulate chemokine production in helminth-LTB coinfection. To test this, we measured the levels of a panel of CC and CXC chemokines at baseline and following mycobacterial Ag or mitogen stimulation in individuals with LTB with (Strongyloides stercoralis ⁺LTB⁺) or without S. stercoralis (S. stercoralis ^-LTB⁺) infection and in individuals without both infections, healthy controls (HC). At baseline (in the absence of a stimulus), S. stercoralis ⁺LTB⁺ individuals exhibited significantly diminished production of CCL1, CCL2, CCL4, CCL11, CXCL9, CXCL10, and CXCL11 in comparison with S. stercoralis ^-LTB⁺ and/or HC individuals. Upon mycobacterial Ag stimulation, S. stercoralis ⁺LTB⁺ individuals exhibited significantly diminished production of CCL1, CCL2, CCL4, CCL11, CXCL2, CXCL9, and CXCL10 in comparison with S. stercoralis ^-LTB⁺ and/or HC individuals. No differences were observed upon mitogen stimulation. Finally, after anthelmintic treatment, the baseline levels of CCL1, CCL2, CCL4, CCL11, and CXCL11 and mycobacterial Ag-stimulated levels of CCL1, CCL2, CCL11, CXCL2, and CXCL10 were significantly increased in S. stercoralis ⁺LTB⁺ individuals. Thus, our data demonstrate that S. stercoralis ⁺LTB⁺ individuals are associated with a compromised ability to express both CC and CXC chemokines and that this defect is at least partially reversible upon treatment. Hence, coexistent helminth infection induces downmodulation of chemokine responses in LTB individuals with likely potential effects on tuberculosis pathogenesis.

Elevated Systemic and Parasite-Antigen Stimulated Levels of Type III IFNs in a Chronic Helminth Infection and Reversal Following Anthelmintic Treatment

Type III IFNs are important players in immunity to viral and bacterial infections. However, their association with helminth infections has not been examined. To explore the association of Type III IFNs with Strongyloides stercoralis (Ss) infection, we examined the systemic levels of IFN lambda-1, IFN lambda-2 and IFN lambda-3, IL-10, and CXCL10/IP-10 in Ss infected (INF, n = 44), helminth—uninfected (UN, n = 44) and in post-treatment INF individuals. We also examined the levels of IFN lambda-1, IFN lambda-2 and IFN lambda-3, IL-10, and CXCL10/IP-10 in whole blood culture supernatants stimulated with Ss somatic antigens, or PPD or LPS. Finally, we performed correlations of systemic Type III IFN levels with absolute numbers of dendritic cell subsets. Ss infection is characterized by elevated systemic levels of IFN lambda-1, IFN lambda-2 and IFN lambda-3, IL-10, and CXCL10/IP-10 in comparison to UN individuals and a significant reduction following anthelmintic treatment. Ss infection is also characterized by elevated levels of unstimulated or Ss antigen stimulated levels of IFN lambda-1, IFN lambda-2 and IFN lambda-3, CXCL10/IP-10 and a significant reduction following treatment. In addition, Ss infection is characterized by increased numbers of plasmacytoid and myeloid dendritic cells in comparison to UN individuals, with a significant reduction following anthelmintic treatment of INF individuals. Finally, Ss infection exhibits a significant positive correlation between the systemic levels of IFN lambda-2 and IFN lambda-3 and the numbers of plasmacytoid dendritic cells. Thus, Ss infection is characterized by elevations in systemic and antigen—induced levels of Type III IFNs, which is positively associated with the numbers of plasmacytoid dendritic cells and reversed upon anthelmintic treatment.

Malnutrition is associated with diminished baseline and mycobacterial antigen - stimulated chemokine responses in latent tuberculosis infection

OBJECTIVES

Previous studies have demonstrated a diminution in the baseline and mycobacterial antigen - specific cytokines in low body mass index (LBMI) individuals with latent tuberculosis infection (LTBI). We hypothesized that LBMI might be also associated with alteration in the baseline and antigen - stimulated levels of chemokines in LTBI.

METHODS

To test this hypothesis, we examined baseline, TB-antigen and mitogen stimulated levels of chemokines in these individuals and compared them with those with LTBI and normal BMI (NBMI).

RESULTS

LBMI with LTBI is characterized by diminished baseline levels of CCL1, CCL4, CCL11, CXCL1, CXCL9, CXCL10 and CXCL11 in comparison to NBMI with LTBI. Similarly, LTBI with LBMI is also characterized by diminished TB-antigen stimulated levels of CCL1, CCL2, CCL3, CCL4, CCL11, CXCL1, CXCL2, CXCL9, CXCL10 and CXCL11. In contrast, there were no significant differences in the mitogen stimulated chemokine levels between the groups. Finally, there was a significant positive correlation between BMI and CCL1, CCL4, CCL11, CXCL11, CXCL2, CXCL9 and CXCL11 levels in LTBI individuals.

CONCLUSIONS

Therefore, our data reveal that LTBI subjects with low BMI are characterized by diminished levels of a variety of important chemokines, providing a novel biological mechanism for the increased risk of developing active TB.

Elevated Systemic Levels of Eosinophil, Neutrophil, and Mast Cell Granular Proteins in Strongyloides Stercoralis Infection that Diminish following Treatment

Infection with the helminth parasite Strongyloides stercoralis (Ss) is commonly clinically asymptomatic that is often accompanied by peripheral eosinophilia. Granulocytes are activated during helminth infection and can act as immune effector cells. Plasma levels of eosinophil and neutrophil granular proteins convey an indirect measure of granulocyte degranulation and are prominently augmented in numerous helminth-infected patients. In this study, we sought to examine the levels of eosinophil, neutrophil, and mast cell activation-associated granule proteins in asymptomatic Ss infection and to understand their kinetics following anthelmintic therapy. To this end, we measured the plasma levels of eosinophil cationic protein, eosinophil-derived neurotoxin, eosinophil peroxidase, eosinophil major basic protein, neutrophil elastase, myeloperoxidase, neutrophil proteinase-3, mast cell tryptase, leukotriene C4, and mast cell carboxypeptidase-A3 in individuals with asymptomatic Ss infection or without Ss infection [uninfected (UN)]. We also estimated the levels of all of these analytes in infected individuals following definitive treatment of Ss infection. We demonstrated that those infected individuals have significantly enhanced plasma levels of eosinophil cationic protein, eosinophil-derived neurotoxin, eosinophil peroxidase, eosinophil major basic protein, elastase, myeloperoxidase, mast cell tryptase, leukotriene C4, and carboxypeptidase-A3 compared to UN individuals. Following the treatment of Ss infection, each of these granulocyte-associated proteins drops significantly. Our data suggest that eosinophil, neutrophil, and mast cell activation may play a role in the response to Ss infection.

Modulation of CD4+ and CD8+ T Cell Function and Cytokine Responses in Strongyloides stercoralis Infection by Interleukin-27 (IL-27) and IL-37

Strongyloides stercoralis infection is associated with diminished antigen-specific Th1- and Th17-associated responses and enhanced Th2-associated responses. Interleukin-27 (IL-27) and IL-37 are two known anti-inflammatory cytokines that are highly expressed in S. stercoralis infection. We therefore wanted to examine the role of IL-27 and IL-37 in regulating CD4+ and CD8+ T cell responses in S. stercoralis infection. To this end, we examined the frequency of Th1/Tc1, Th2/Tc2, Th9/Tc9, Th17/Tc17, and Th22/Tc22 cells in 15 S. stercoralis-infected individuals and 10 uninfected individuals stimulated with parasite antigen following IL-27 or IL-37 neutralization. We also examined the production of prototypical type 1, type 2, type 9, type 17, and type 22 cytokines in the whole-blood supernatants. Our data reveal that IL-27 or IL-37 neutralization resulted in significantly enhanced frequencies of Th1/Tc1, Th2/Tc2, Th17/Tc17, Th9, and Th22 cells with parasite antigen stimulation. There was no induction of any T cell response in uninfected individuals following parasite antigen stimulation and IL-27 or IL-37 neutralization. Moreover, we also observed increased production of gamma interferon (IFN-γ), IL-5, IL-9, IL-17, and IL-22 and decreased production of IL-10 following IL-27 and IL-37 neutralization and parasite antigen stimulation in whole-blood cultures. Thus, we demonstrate that IL-27 and IL-37 limit the induction of particular T cell subsets along with cytokine responses in S. stercoralis infections, which suggest the importance of IL-27 and IL-37 in immune modulation in a chronic helminth infection.

Modulation of Mycobacterium tuberculosis-specific humoral immune responses is associated with Strongyloides stercoralis co-infection

Background / Objectives

Helminth infections are known to influence T cell responses in latent tuberculosis (LTBI). Whether helminth infections also modulate B cell responses in helminth-tuberculosis co-infection is not known.

Methods

We assessed Mycobacterium tuberculosis (Mtb)–antigen specific IgM and IgG levels, circulating levels of the B cell growth factors, BAFF and APRIL and the absolute numbers of the various B cell subsets in individuals with LTBI, LTBI with coincident Strongyloides stercoralis (Ss) infection (LTBI/Ss) and in those with Ss infection alone (Ss). We also measured the above-mentioned parameters in the LTBI-Ss group after anthelmintic therapy.

Results

Our data reveal that LTBI-Ss exhibit significantly diminished levels of Mtb-specific IgM and IgG, BAFF and APRIL levels in comparison to those with LTBI. Similarly, those with LTBI-Ss had significantly diminished numbers of all B cell subsets (naïve, immature, classical memory, activated memory, atypical memory and plasma cells) compared to those with LTBI. There was a positive correlation between Mtb—antigen specific IgM and IgG levels and BAFF and APRIL levels that were in turn related to the numbers of activated memory B cells, atypical memory B cells and plasma cells. Finally, anthelmintic treatment resulted in significantly increased levels of Mtb—antigen specific IgM and IgG levels and the numbers of each of the B cell subsets.

Conclusions

Our data, therefore, reveal that Ss infection is associated with significant modulation of Mtb-specific antibody responses, the levels of B cell growth factors and the numbers of B cells (and their component subsets).

Helminth infections and tuberculosis are two of the major health care problems worldwide and share a great deal of geographical overlap. Moreover, helminth infections are known to induce immune responses that are antagonistic to the protective immune responses elicited by Mycobacterium tuberculosis. Having previously demonstrated that helminth infections can profoundly alter protective T cell responses needed to control tuberculosis infection, we examined how Strongyloides stercoralis (Ss) infection influences B cell responses in latent tuberculosis infection (LTBI) in the context of co-infection and showed the Ss infection is associated with dramatic alterations in mycobacterial-specific IgG and IgM responses and levels of B cells and their growth factors BAFF and APRIL. These alterations in B cell responses could have implications for vaccine-induced immune responses to tuberculosis in helminth—endemic countries.

High body mass index is associated with heightened systemic and mycobacterial antigen - Specific pro-inflammatory cytokines in latent tuberculosis

High body mass index (HBMI) has been shown to be protective against active tuberculosis (TB), although the biological mechanism underlying this protection is poorly understood. The immunological association between HBMI and latent TB has never been examined. In order to study the association of HBMI with latent TB, we examined the circulating and TB- antigen or mitogen stimulated levels of a large panel of cytokines in individuals with latent TB (LTB) and high or normal body mass index (HBMI or NBMI). HBMI is characterized by heightened circulating levels of pro-inflammatory (IFNγ, TNFα, IL-22, IL-1α, IL-12 and GM-CSF) cytokines but decreased circulating levels of anti-inflammatory cytokines (IL-4, IL-5 and TGFβ). This systemic cytokine profile is associated with elevated TB-antigen and mitogen stimulated levels of IFNγ, TNFα, IL-2 and IL-1α and diminished levels of IL-10 and TGFβ. In addition, we also observed a positive correlation between the circulating levels of IFNγ, TNFα, IL-22, IL-1α with BMI and a negative correlation between the circulating levels of IL-10, TGFβ and BMI. Our data, therefore, suggest the modulation of protective and regulatory cytokines might underlie the protective effect of HBMI against the development of active TB.

IL-10- and TGFβ-mediated Th9 Responses in a Human Helminth Infection

Background

Th9 cells are a subset of CD4⁺ T cells that express the protoypical cytokine, IL-9. Th9 cells are known to effect protective immunity in animal models of intestinal helminth infections. However, the role of Th9 cells in human intestinal helminth infections has never been examined.

Methodology

To examine the role of Th9 cells in Strongyloidis stercoralis (Ss), a common intestinal helminth infection, we compared the frequency of Th9 expressing IL-9 either singly (mono-functional) or co-expressing IL-4 or IL-10 (dual-functional) in Ss-infected individuals (INF) to frequencies in uninfected (UN) individuals.

Principal Findings

INF individuals exhibited a significant increase in the spontaneously expressed and/or antigen specific frequencies of both mono- and dual-functional Th9 cells as well as Th2 cells expressing IL-9 compared to UN. The differences in Th9 induction between INF and UN individuals was predominantly antigen-specific as the differences were no longer seen following control antigen or mitogen stimulation. In addition, the increased frequency of Th9 cells in response to parasite antigens was dependent on IL-10 and TGFx since neutralization of either of these cytokines resulted in diminished Th9 frequencies. Finally, following successful treatment of Ss infection, the frequencies of antigen-specific Th9 cells diminished in INF individuals, suggesting a role for the Th9 response in active Ss infection. Moreover, IL-9 levels in whole blood culture supernatants following Ss antigen stimulation were higher in INF compared to UN individuals.

Conclusion

Thus, Ss infection is characterized by an IL-10- and TGFβ dependent expansion of Th9 cells, an expansion found to reversible by anti-helmintic treatment.

Strongyloides stercoralis is a common intestinal parasite affecting about 50–100 million people worldwide. It is characterized by a complex lifecycle involving both free- living and parasitic stages and the clinical manifestations range from asymptomatic infection to multi-organ failure. It has the propensity to cause disseminated disease and death in immunocompromised individuals. Therefore, an in depth understanding of the immune responses to this helminth parasite is warranted. However, what we know about the immunity to this infection is mostly derived from animal studies. Th9 cells are a subset of CD4+ T cells producing the cytokine—IL-9. Since Th9 cells are increasingly recognized as being important in immunity to intestinal infection with helminths, we examined the induction and regulation Th9 cell responses to Ss infection utilizing infected and uninfected individuals from an endemic area in India. We show that Ss infection is characterized by profound alterations in the Th9 compartment and that this response is mainly regulated by the cytokines—IL-10 and TGFβ. In addition, we also demonstrate that active infection is a pre-requisite for this regulation and anti-Ss treatment can dampen enhanced Th9 responses.

Modulation of CD4+ and CD8+ T-Cell Function by Interleukin 19 and Interleukin 24 During Filarial Infections

Interleukin 19 (IL-19) and interleukin 24 (IL-24) are cytokines that are highly expressed in filarial infections. To study the role of IL-19 and IL-24 in regulating T-cell responses, we examined the frequency of T-helper type 1 (Th1)/Tc1, Th2/Tc2, Th9/Tc9, Th17/Tc17, Th22/Tc22, and Tr1 cells in 26 filariae-infected individuals stimulated with filarial antigen following IL-19 or IL-24 neutralization. IL-19 or IL-24 neutralization resulted in significantly enhanced frequencies of Th1/Tc1 and/or Th17/Tc17 cells and significantly reduced frequencies of Th2/Tc2, Tr1, and/or Th9/Tc9 cells. Thus, we demonstrate that IL-19 and IL-24 are associated with the modulation of T-cell responses in filarial infections.

Parasite Antigen-Specific Regulation of Th1, Th2, and Th17 Responses in Strongyloides stercoralis Infection

Chronic helminth infections are known to be associated with modulation of Ag-specific CD4(+) T responses. However, the role of CD4(+) T cell responses in human infection with Strongyloides stercoralis is not well defined. To examine the role of CD4(+) T cells expressing Th1, Th2, and Th17 cytokines in strongyloidiasis, we compared the frequency (Fo) of these subsets in infected (INF) individuals with Fo in S. stercoralis-uninfected (UN) individuals. INF individuals exhibited a significant decrease in the spontaneous and Ag-specific Fo of both monofunctional and dual-functional Th1 cells compared with UN. Similarly, INF individuals also exhibited significantly decreased Fo of monofunctional and dual-functional Th17 cells upon Ag stimulation compared with UN. In contrast, both the spontaneous and the Ag-induced Fo of monofunctional and dual-functional Th2 cells was significantly increased in INF compared with UN individuals. This differential T cell response was predominantly Ag specific because it was abrogated upon control Ag or mitogen stimulation. The regulation of Th1, Th2, and Th17 cells was predominantly dependent on IL-10, whereas the regulation of Th2, but not Th1 or Th17, cells was also dependent on TGF-β. In addition, treatment of S. stercoralis infection significantly increased the Ag-specific Fo of Th1 and Th17 cells and decreased the Fo of Th2 cells in INF individuals. Thus, S. stercoralis infection is characterized by a parasite Ag-dependent regulation of monofunctional and dual-functional Th1, Th2, and Th17 cells, a regulation also reversible by antihelminthic treatment.