Leishmania amazonensis induces modulation of costimulatory and surface marker molecules in human macrophages

Manipulation of costimulatory and surface molecules that shape the extent of immune responses by Leishmania is suggested as one of the mechanisms of evading the host's defences. The experiments reported here were designed to evaluate the expressions of CD11b, CD11c, CD14, CD18, CD54, CD80, CD86, CD206, MHC class II and TLR‐2 (Toll‐like receptor 2) in human macrophages infected with L. amazonensis. Phenotypic evaluation revealed a negative modulation in CD11b, CD11c, CD14, CD18, CD54 and MHC class II molecules, depending on the level of infection. The results showed that as early as 1 hour after infection no reduction in marker expression occurs, whereas after 24 hours, downregulation of these molecules was observed in macrophages. No significant changes were observed in the expressions of CD80, CD86, CD206 and TLR2. Evidence of the differential modulation of markers expression and that after parasite uptake no reduction in surface marker expression occurs indicates that parasite internalization is not involved in the phenomena of down‐modulation.     

Prostaglandin E2 receptors have differential effects on Leishmania major infection

Through their receptors, prostaglandins play crucial roles in various infections. Although prostaglandin E₂ (PGE₂) is implicated as a susceptibility factor in Leishmania infection, the relative contributions of its four receptors – EP1, EP2, EP3 and EP4 – to this infection remain unknown. We report that Leishmania major infection of BALB/c‐derived peritoneal macrophages up‐regulated EP1 and EP3 expressions but down‐regulated EP2 and EP4 expressions. EP2 and EP4 agonists reduced parasite load, but EP1 and EP3 agonists increased parasite load in macrophages in vitro. Agonists of EP2 and EP4, antagonists of EP1 and EP3, or lentivirally expressed EP1‐shRNA and EP3‐shRNA significantly reduced parasite burden in susceptible BALB/c mice. These novel data suggest differential regulation and counteractive functions of EP receptor subsets.     

Mannose receptor (MR) and Toll‐like receptor 2 (TLR2) influence phagosome maturation during Leishmania infection

Leishmania enter macrophages through receptor‐mediated phagocytosis and survive the harsh environment of a phagolysosome. Here, we investigated the interaction between mannose receptor (MR), Toll‐like receptor 2 (TLR2), and Leishmania, and the subsequent impact on phagosome maturation. Leishmania parasites are able to delay phagosome maturation, not reaching full maturation until 5 hours post‐engulfment. Here, maturation of Leishmania major‐ and Leishmania donovani‐containing phagosomes proceeded as expected in the WT macrophages becoming LAMP1 positive by 6 hours. Interestingly, MR?/? macrophages become LAMP1 positive by ~2 hours and ~4 hours post‐infection Leishmania‐containing phagosomes lost LAMP1 expression and gained the early marker EEA1. LAMP1 expression was again observed by 6 hours. Leishmania LPG was essential for the delay in both WT and MR?/? macrophages but was not essential for the early maturation (2 hours) observed in MR?/? macrophages. Serum opsonization of Leishmania prior to infection induced identical phagosome maturation patterns in WT and MR?/? macrophages. In the absence of MyD88 or TLR2 on macrophages, Leishmania phagosomes matured significantly faster, becoming LAMP1 positive by ~1‐2 hours. These studies add to the knowledge that phagosome maturation is influenced by multiple receptor‐ligand interactions and signalling pathways     

CCR7 facilitates the pro‐inflammatory function of dendritic cells in experimental leishmaniasis

Cutaneous leishmaniasis, caused by the parasite Leishmania major, results in lesions at the site of infection, which are self‐healing in resistant hosts. However, in the absence of the chemokine receptor CCR7, mice are unable to heal the lesion and develop chronic disease. These B6.CCR7^?/? mice display an increased number of Th2 cells and immunosuppressive cytokine levels, as well as more regulatory T cells. As CCR7 is expressed on activated dendritic cells (DCs), and these cells require CCR7 to migrate to the draining lymph node, we expected decreased migration of DCs into the lymph node in the absence of CCR7 during cutaneous leishmaniasis. Consequently, in an attempt to initiate a self‐healing response, we adoptively transferred CCR7⁺ (B6.WT) DCs into the site of infection of B6.CCR7^?/? mice. Surprisingly, instead of healing the lesion, B6.CCR7^?/? mice inoculated with B6.WT DCs developed augmented lesions and showed increased immunosuppression compared to control B6.CCR7^?/? mice transferred with B6.CCR7^?/? DCs or B6.WT mice with B6.WT DCs. Finally, B6.WT mice injected with B6.CCR7^?/? DCs also presented delayed healing of the lesion. These results indicate that CCR7 must be expressed on DCs, as well as peripheral cells, to allow an efficient immune response to L. major.     

Vaccine potential of HLA‐A2 epitopes from Leishmania Cysteine Protease Type III (CPC)

Although the precise host‐defence mechanisms are not completely understood, T‐cell‐mediated immune responses are believed to play a pivotal role in controlling parasite infection. In this study, the potential HLA*A2 restricted peptides were predicted and the ability of peptides to bind HLA‐A*02 was confirmed by a MHC stabilization assay. Two of the peptides tested stabilized HLA‐A*02: (a) LLATTVSGL (P1) and (b) LMTNGPLEV (P3). The potential of the peptides to generate protective immune response was evaluated in patients with treated visceral leishmaniasis as well as in healthy control subjects. Our data suggest that CD8⁺ T‐cell proliferation against the selected peptide was significantly higher compared to unstimulated culture conditions. The stimulation of peripheral blood mononuclear cells with epitopes individually or as a cocktail upregulated IFN‐γ production, which indicates its pivotal role in protective immune response. The IFN‐γ production was mainly in a CD8⁺ T‐cells‐dependent manner, which suggested that these epitopes had an immunoprophylactic potential in a MHC class I‐dependent manner. Moreover, no role of the CD3⁺ T cell was observed in the IL‐10 production against the selected peptides, and no role was found in disease pathogenesis. Further studies on the role of these synthetic peptides may contribute significantly to developing a polytope vaccine idea towards leishmaniasis.     

Leishmania donovani infection drives the priming of human monocyte‐derived dendritic cells during Plasmodium falciparum co‐infections

Functional impairment of dendritic cells (DCs) is part of a survival strategy evolved by Leishmania and Plasmodium parasites to evade host immune responses. Here, the effects of co‐exposing human monocyte‐derived DCs to Leishmania donovani promastigotes and Plasmodium falciparum‐infected erythrocytes were investigated. Co‐stimulation resulted in a dual, dose‐dependent effect on DC differentiation which ranged from semi‐mature cells, secreting low interleukin(‐12p70 levels to a complete lack of phenotypic maturation in the presence of high parasite amounts. The effect was mainly triggered by the Leishmania parasites, as illustrated by their ability to induce semi‐mature, interleukin‐10‐producing DCs, that poorly responded to lipopolysaccharide stimulation. Conversely, P. falciparum blood‐stage forms failed to activate DCs and only slightly interfered with lipopolysaccharide effects. Stimulation with high L. donovani concentrations triggered phosphatidylserine translocation, whose onset presented after initiating the maturation impairment process. When added in combination, the two parasites could co‐localize in the same DCs, confirming that the leading effects of Leishmania over Plasmodium may not be due to mutual exclusion. Altogether, these results suggest that in the presence of visceral leishmaniasis–malaria co‐infections, Leishmania‐driven effects may overrule the more silent response elicited by P. falciparum, shaping host immunity towards a regulatory pattern and possibly delaying disease resolution.     

Role of Functional IFNL4, IFNLR1, IFNA,IFNAR2 Polymorphisms in Hepatitis B virus‐related liver disease in Han Chinese population

Recent studies show that variants in some interferon genes together with interferon receptor genes are associated with the outcome of infectious diseases. We examined the association between the risk of hepatitis B virus (HBV)‐related liver disease and the functional polymorphisms within IFNL4, IFNLR1, IFNA1, IFNA2, IFNA5 and IFNAR2 genes (14 loci in all) in a Han Chinese population. A total of 3128 people participated and were divided into 5 groups: healthy controls, natural clearance, chronic hepatitis B(CHB), liver cirrhosis and hepatocellular carcinoma (HCC). Significant associations were observed for 4 variants in IFNAR2, IFNLR1 with HBV infection, and IFNLR1‐rs4649203 was associated with HBV recovery. Moreover, we demonstrated the clear relevance of 5 polymorphisms in IFNA1, IFNA2, IFNL4 with HCC. Three SNPs in IFNL4 gene may be important susceptible factors for the progression of HBV‐related liver disease by trend chi‐square test. The IFNL4 haplotype conformed by rs12971396_G, rs8113007_T and rs7248668A was more frequent in HCC than CHB and LC group. Three polymorphisms in the 5′ region of the IFNL4 gene are associated with the progression of HBV‐related liver disease. IFNA1‐ rs1831583 and IFNA2‐ rs649053 are associated with the development of HCC. IFNLR1‐ rs4649203, rs7525481 are predictors for HBV infection, and rs4649203 is a predictor of spontaneous clearance. IFNAR2 ‐rs1051393, rs12233338 may be predictive markers of HBV infection in the Chinese population.     

Type 2 diabetes in young adults in Central Auckland: demography and complications

Background

Type 2 diabetes (T2D) in young adults is associated with a high risk of diabetes complications.

Aims

To investigated the demography and the emergence of complications of young adults with T2D in the central Auckland region where there has been substantial immigration.

Methods

In total, 310 young adults with T2D (<40 years) were registered with the Auckland Diabetes Centre in 2015. We documented demographic, anthropometric and metabolic variables and prevalence and the emergence of complications.

Results

Three demographic groups accounted for 243 participants (78%): 135 (44%) were migrants of Asian or Pacific Island origin, diagnosed a median 9 years after migration at a mean age of 28 ± 6 years; 88 (29%) were New Zealand‐born Pāsifika descent, with a high prevalence of morbid obesity and 37 (12%) had major mental illness or intellectual disability. At diagnosis, the median HbA1c was 80 mmol/mol, and in 28%, it was ≥100 mmol/mol. A median 6 years after diagnosis, 56% had some degree of retinopathy, with the prevalence related both to the duration of diabetes and glycaemic control (P = 0.001). Forty‐four percent of subjects had abnormal albuminuria at diagnosis (12% with macroalbuminuria). Increased albuminuria was strongly associated with obesity (P = 0.002). The development of CKD stages 4–5 was related both to the severity of retinopathy and degree of albuminuria at diagnosis (P = 0.0001). Major cardiovascular events were related to the severity of retinopathy at diagnosis (P = 0.0001).

Conclusions

New migrants, New Zealand‐born Pāsifika and patients with mental illness or an intellectual disability comprise the bulk of young onset T2D. The disease is aggressive, and by the age of 40, patients are already developing advanced complications.     

Dihydrotestosterone enhances growth and infectivity of Leishmania Mexicana

A strong sex‐associated susceptibility towards Leishmania has been reported in males, yet little is known on the effect of hormones in Leishmania physiopathogenicity. Due to the enhanced susceptibility of males to Leishmania mexicana infections, we were interested in analysing the effect exerted by the main androgen produced in males (DHT) on L. mexicana promastigotes. Thus, the aim of this study was to assess the regulation exerted by dihydrotestosterone (DHT) on L. mexicana replication, infectivity, survival and development of tissue lesions. Experiments included growth curves of L. mexicana promastigotes incubated with different doses of DHT, their infection rate, intracellular survival and lesion development in BALB/c mice. Our data show that DHT significantly enhances parasite replication, infection rate and survival in bone marrow‐derived macrophages (BMMФ). Promastigotes in the presence of DHT produced significantly larger lesions in BALB/c earlobes. These results suggest that DHT probably plays a critical role during L. mexicana infections, and the higher susceptibility of males possibly relates to benefits gained by the parasite from host‐derived hormones. Our data shed new light on the physiopathology of Leishmania infections and are the first attempt to understand the direct interaction between Leishmania and androgens, particularly DHT. Understanding this trans‐regulation process employed by parasites to exploit host molecules sheds new light on L. mexicana physiopathogenesis and opens a possible field for studies on drug development.     

Role of IFN‐λs,IFN‐λs related genes and the DEPDC5 gene in Hepatitis B virus‐related liver disease

Recent studies have associated genetic variation near the interleukin 28B (IL28B/IFN‐λ3) gene with natural clearance of the hepatitis C virus (HCV) infection, and a common variant in the DEP domain containing 5 (DEPDC5) locus on chromosome 22 has been shown to affect susceptibility to hepatocellular carcinoma (HCC) in Japanese individuals with chronic HCV infection. This study was conducted to determine whether polymorphisms near or in interferon‐lambda (IFN‐λs) genes and their receptor genes such as interleukin 28 receptor, alpha (IL28RA) and interleukin 10 receptor, beta (IL10RB) as well as p21_activated kinases 4 (PAK4) and iron/zinc purple acid phosphatase‐like protein (PAPL), which are locate upstream of IFN‐λs, and lastly the DEPDC5 gene are associated with hepatitis B virus‐related liver disease in Han Chinese. The study subjects included 507 normal healthy controls, 350 individuals with natural clearance of HBV and 792 HBV‐infected patients. The patients were categorized into 157 inactive carriers (Case I), 216 active carriers (Case II), 111 cirrhotics (Case III) and 308 HCC patients (Case IV) subgroups. Seven single nucleotide polymorphisms (SNPs) were genotyped using the Matrix‐assisted Laser Desorption/Ionisation mass spectrometric (MALDI‐TOF MS) SNP genotyping assay. Rs423058 upstream of PAPL, rs2834167 in IL10RB and rs1012068 in DEPDC5 were associated with chronic HBV status, HBV natural clearance and the presence of HCC (P = 0.0004–0.024), respectively. PAPL, IL10RB and DEPDC5 polymorphisms have an impact on progression of HBV‐related liver disease. However, IFN‐λs genes as a tool to differentiate between different clinical courses of HBV infection were not useful in the Han Chinese population.