Early reduction in PD-L1 expression predicts faster treatment response in human cutaneous leishmaniasis

Intralesional gene expression profile of JAK-STAT signaling pathway and associated cytokines in Leishmania tropica-infected patients

Background

The JAK-STAT signaling pathway is a central cascade of signal transduction for the myriad of cytokines in which dysregulation has been implicated in progression of inflammatory and infectious diseases. However, the involvement of this pathway in human cutaneous leishmaniasis (CL) due to Leishmania (L.) tropica warrants further investigation.

Methods

This study sought to investigate differential gene expression of several cytokines and their associated jak-stat genes in the lesions of L. tropica-infected patients byquantitative Real-Time PCR. Further, the expression of five inhibitory immune checkpoint genes was evaluated.

Results

Results showed that the gene expression levelsof both Th1 (ifng, il12, il23) and Th2 (il4, il10) types cytokines were increased in the lesion of studied patients. Further, elevated expression levels of il35, il21, il27 and il24 genes were detected in the lesions of CL patients. Notably, the expression of the majority of genes involved in JAK/STAT signaling pathway as well as checkpoint genes including pdl1, ctla4 and their corresponding receptors was increased.

Conclusion

Our finding revealed dysregulation of cytokines and related jak-stat genes in the lesion of CL patients. These results highlight the need for further exploration of the functional importance of these genes in the pathogenesis of, and immunity to, CL.

A randomized, double-blind phase 2b trial to evaluate efficacy of ChAd63-KH for treatment of post kala-azar dermal leishmaniasis

In a recent phase 2a clinical trial, the candidate leishmaniasis vaccine ChAd63-KH was shown to be safe and immunogenic in Sudanese patients with post kala-azar dermal leishmaniasis (PKDL). However, its value as a stand-alone therapeutic was unknown. To assess the therapeutic efficacy of ChAd63-KH, we conducted a randomized, double-blind, placebo-controlled phase 2b trial (ClinicalTrials.gov: NCT03969134). Primary outcomes were safety and efficacy (≥90% improvement in clinical disease). Secondary outcomes were change in severity grade and vaccine-induced immune response. 86 participants with uncomplicated PKDL of ≥6 month duration were randomized to receive ChAd63-KH (7.5 × 1010 viral particles, once by the intramuscular route) or placebo. 75 participants (87%) completed the trial as per protocol. No severe or serious adverse events were observed. At day 90 post-vaccination, 6/40 (15%) and 4/35 (11%) participants in the vaccine and placebo groups, respectively, showed ≥90% clinical improvement (risk ratio [RR] 1.31 [95% confidence interval (CI), 0.40-4.28], p = 0.742). There were also no significant differences in PKDL severity grade between study arms. Whole-blood transcriptomic analysis identified transcriptional modules associated with interferon responses and monocyte and dendritic cell activation. Thus, a single vaccination with ChAd63-KH showed no therapeutic efficacy in this subset of Sudanese patients with PKDL.

Evaluation of Less Invasive Sampling Tools for the Diagnosis of Cutaneous Leishmaniasis

Background

Diagnosis of cutaneous leishmaniasis (CL) usually relies on invasive samples, but it is unclear whether more patient-friendly tools are good alternatives for diverse lesions when used with polymerase chain reaction (PCR).

Methods

Patients with suspected CL were enrolled consecutively in a prospective diagnostic accuracy study. We compared dental broach, tape disc, and microbiopsy samples with PCR as index tests, using PCR with skin slit samples as reference test. Subsequently, we constructed a composite reference test including microscopy, the 3 index tests and skin slit PCR, and we compared these same tests with the composite reference test. We assessed diagnostic accuracy parameters with 95% confidence intervals for all comparisons.

Results

Among 344 included patients, 282 (82.0%) had CL diagnosed, and 62 (18.0%) CL absence, by skin slit PCR. The sensitivity and specificity by PCR were 89.0% (95% confidence interval, 84.8%-92.1%) and 58.1% (45.7%-69.5%), respectively, for dental broach, 96.1% (93.2%-97.8%) and 27.4% (17.9%-39.6%) for tape disc, and 74.8% (66.3%-81.7%) and 72.7% (51.8%-86.8%) for microbiopsy. Several reference test-negative patients were consistently positive with the index tests. Using the composite reference test, dental broach, and skin slit had similar diagnostic performance.

Discussion

Dental broach seems a less invasive but similarly accurate alternative to skin slit for diagnosing CL when using PCR. Tape discs lack specificity and seem unsuitable for CL diagnosis without cutoff. Reference tests for CL are problematic, since using a single reference test is likely to miss true cases, while composite reference tests are often biased and impractical as they require multiple tests.

Characterisation of tumor microenvironment and prevalence of CD274/PD-L1 genetic alterations difference in colorectal Cancer

BACKGROUND

Large-scale genomic alterations, especially CD274/PD-L1 gene amplification, have great impact on anti-PD-1 efficacy on cancers such as Hodgkin's lymphoma. However, the prevalence of PD-L1 genetic alterations in colorectal cancer (CRC) and its correlation with the tumor immune microenvironment and clinical implications remain unknown.

MATERIALS AND METHODS

PD-L1 genetic alterations were evaluated in 324 patients with newly diagnosed CRC including 160 mismatch repair-deficient (dMMR) patients and 164 mismatch repair-proficient (pMMR) patients using fluorescence in situ hybridization (FISH) method. The correlation between PD-L1 and the expression of the common immune markers was analyzed.

RESULTS

Totally 33 (10.2%) patients were identified with aberrant PD-L1 genetic alternations including deletion (2.2%), polysomy (4.9%), and amplification (3.1%); They had more aggressive features such as advanced stage (P = 0.02), shorter overall survival (OS) (P < 0.001) than patients with disomy. The aberrations correlated with positive lymph node (PLN) (p = 0.001), PD-L1 expression by immunohistochemistry (IHC) in tumor cells (TCs) or tumor-infiltrated immunocytes (ICs) (both p < 0.001), and pMMR (p = 0.029). When dMMR and pMMR were analyzed independently, the correlations of aberrant PD-L1 genetic alterations with PD-1 expression (p = 0.016), CD4 + T cells (p = 0.032), CD8 T + cells (p = 0.032) and CD68 + cells (p = 0.04) were only found in dMMR cohort.

CONCLUSIONS

The prevalence of PD-L1 genetic alterations was relatively low in CRC, but the aberrations usually correlate with aggressive nature. The correlation between PD-L1 genetic alterations and tumor immune features was only observed in dMMR CRC.

Excretory/secretory proteins inhibit host immune responses by downregulating the TLR4/NF-κB/MAPKs signaling pathway: A possible mechanism of immune evasion in parasitic nematode Haemonchus contortus

Haemonchus contortus is an important parasitic nematode of ruminants. Previous studies showed that H. contortus escape the immunity through complex mechanisms, including releasing excretory/secretory proteins (ESPs) to modulate the host immune response. However, the detailed mechanism through which H. contortus excretory/secretory proteins (HcESPs) promote immune evasion remains unknown. In the present study, we demonstrated that HcESPs inhibit the adaptive immune response of goats including downregulation of immune cell antigen presentation, upregulation of immune checkpoint molecules, activation of the STAT3/PD-L1 pathway, and activation of immunosuppressive regulatory T (Treg) cells. Furthermore, HcESPs reversed the LPS-induced upregulation of pro-inflammatory mediators in PBMCs by inhibiting the TLR4/NF-κB/MAPKs/NLRP3 signaling pathway. Our study provides a better understanding of the evasion mechanisms for H. contortus, which could be helpful in providing an alternative way to prevent the infection of this parasite.

Visceral Leishmaniasis and the Skin: Dermal Parasite Transmission to Sand Flies

Visceral leishmaniasis is a parasitic disease with significant dermal tropism. The skin is an important site of infection contributing to parasite transmission to naïve sand flies, but understanding how parasitism of host skin and the related immune microenvironment supports or prevents skin parasite replication is now the focus of major investigation in the field of leishmaniasis research. Here, we review dermatoimmunology during visceral leishmaniasis (VL), dermal Leishmania parasite burden, and the role of skin parasitism in transmissibility to sand fly vectors. First, we discuss the epidemiology of VL amongst dogs, the primary zoonotic reservoir for human infection. We explore the association between spatial distribution and the burden of parasites in the skin in driving outward transmission. Factors associated with parasite persistence in the skin are examined. We discuss systemic immunity during VL and what is known about immunological correlates in the skin microenvironment. Finally, we touch on factors egested into the skin during Leishmania inoculation by sand flies. Throughout, we discuss factors associated with the early and chronic establishment of Leishmania parasites in the skin and the role of the dermal immune response.