Whole blood profiling of leprosy type 1(reversal) reactions highlights prominence of innate immune response genes.

BACKGROUND: The major factors contributing for nerve damage and permanent disabilities in leprosy are type 1 or reversal reactions (RR) and type 2 or erythema nodosum leprosum (ENL). Gene profiling of leprosy reactions have shown that different pathways are activated during the course of reactions, which is consistent with the exacerbated immune response exhibited by these patients. METHODS: We used qPCR to screen a panel of 90 genes related to the immune response in leprosy in RNA-derived peripheral leukocytes of patients with (N = 94) and without leprosy reactions (N = 57) in order to define expression signatures correlated to RR or ENL. RESULTS: Our results show that there is a marked signature for RR in the blood, comprising genes mostly related to the innate immune responses, including type I IFN components, autophagy, parkins and Toll like receptors. On the other hand, only Parkin was differentially expressed in the ENL group. CONCLUSIONS: The data put together corroborates previous work that brings evidence that an acute uncontrolled exacerbated immune response designed to contain the spread of M. leprae antigens might be cause of RR pathogenesis. Identifying a blood profile useful to predict leprosy reactions prior to its development might help to reduce the morbidity associated to this disabling disease.

Association of rs1285933 single nucleotide polymorphism in CLEC5A gene with dengue severity and its functional effects.

Outbreaks of the Zika, dengue, and chikungunya viruses, especially in the Americas, pose a global threat due to their rapid spread and difficulty controlling the vector. Extreme phenotypes are often observed, from asymptomatic to severe clinical manifestations, which are well-studied in dengue. Host variations are also important contributors to disease outcomes, and many case-control studies have associated single nucleotide polymorphisms (SNPs) with severe dengue. Here, we found that the TC genotype and T-carriers for SNP rs1285933 in the C-type lectin superfamily member 5 (CLEC5A) gene was associated with severe dengue in a Northern Brazilian population (OR=2.75 and p-value=0.01, OR=2.11 and p-value=0.04, respectively). We also tested the functional effect of the CLEC5A protein and found that it is upregulated on the surface of human monocytes after in vitro dengue infection. CLEC5A was correlated with viral load inside the monocytes (Spearman r=0.55, p=0.008) and TNF production in culture supernatants (Spearman r=0.72, p=0.03). Analysis of mRNA in blood samples from DENV4-infected patients exhibiting mild symptoms showed that CLEC5A mRNA expression is correlated with TNF (r=0.67, p=0.0001) and other immune mediators. Monocytes from rs1285933 TT/TC individuals showed lower CLEC5A expression compared to CC genotypes. However, in these cells, CLEC5A was not correlated with TNF production. In summary, we confirmed that CLEC5A is genetically associated with dengue severity outcome, playing a central role during the immune response triggered by a dengue viral infection, and rs1285933 is a relevant SNP that is able to regulate signaling pathways after interactions between the dengue virus and CLEC5A receptors.

Indoleamine 2,3-dioxygenase and iron are required for Mycobacterium leprae survival.

Our previous study has demonstrated that IL-10 may modulate both indoleamine 2,3-dioxygenase (IDO) and CD163 expression in lepromatous leprosy (LL) cells, favoring Mycobacterium leprae persistence through induction of regulatory pathways and iron storage. Here, we observed that in LL lesion cells there is an increase in the expression of proteins involved in iron metabolism such as hemoglobin (Hb), haptoglobin, heme oxygenase 1 and transferrin receptor 1 (TfR1) when compared to tuberculoid leprosy (BT) cells. We also found increased iron deposits and diminished expression of the iron exporter ferroportin 1 in LL lesion cells. Hemin, but not FeSO4 stimulation, was able to enhance M. leprae viability by a mechanism that involves IDO. Analysis of cell phenotype in lesions demonstrated a predominance of M2 markers in LL when compared with BT lesion cells. A positive correlation between CD163 and PPARG with the bacillary index (BI) was observed. In contrast, TNF, STAT1 and CSF2 presented a negative correlation with the BI. In summary, this study demonstrates that iron may regulate IDO expression by a mechanism that involves IL-10, which may contribute for the predominance of M2-like phenotype in LL lesions that favors the phagocytosis and maintenance of M. leprae in host cells.

STING-Dependent 2'-5' Oligoadenylate Synthetase-Like Production Is Required for Intracellular Mycobacterium leprae Survival.

Cytosolic detection of nucleic acids elicits a type I interferon (IFN) response and plays a critical role in host defense against intracellular pathogens. Herein, a global gene expression profile of Mycobacterium leprae-infected primary human Schwann cells identified the genes differentially expressed in the type I IFN pathway. Among them, the gene encoding 2'-5' oligoadenylate synthetase-like (OASL) underwent the greatest upregulation and was also shown to be upregulated in M. leprae-infected human macrophage cell lineages, primary monocytes, and skin lesion specimens from patients with a disseminated form of leprosy. OASL knock down was associated with decreased viability of M. leprae that was concomitant with upregulation of either antimicrobial peptide expression or autophagy levels. Downregulation of MCP-1/CCL2 release was also observed during OASL knock down. M. leprae-mediated OASL expression was dependent on cytosolic DNA sensing mediated by stimulator of IFN genes signaling. The addition of M. leprae DNA enhanced nonpathogenic Mycobacterium bovis bacillus Calmette-Guerin intracellular survival, downregulated antimicrobial peptide expression, and increased MCP-1/CCL2 secretion. Thus, our data uncover a promycobacterial role for OASL during M. leprae infection that directs the host immune response toward a niche that permits survival of the pathogen.