Antiretroviral drug exposure in lymph nodes is heterogeneous and drug dependent

Introduction

HIV reservoirs and infected cells may persist in tissues with low concentrations of antiretrovirals (ARVs). Traditional pharmacology methods cannot assess variability in ARV concentrations within morphologically complex tissues, such as lymph nodes (LNs). We evaluated the distribution of six ARVs into LNs and the proximity of these ARVs to CD4⁺ T cells and cell‐associated RT‐SHIV viral RNA.

Methods

Between December 2014 and April 2017, RT‐SHIV infected (SHIV+; N = 6) and healthy (SHIV–; N = 6) male rhesus macaques received two selected four‐drug combinations of six ARVs over 10 days to attain steady‐state conditions. Serial cryosections of axillary LN were analysed by a multimodal imaging approach that combined mass spectrometry imaging (MSI) for ARV disposition, RNAscope in situ hybridization for viral RNA (vRNA) and immunohistochemistry for CD4⁺ T cell and collagen expression. Spatial relationships across these four imaging domains were investigated by nearest neighbour search on co‐registered images using MATLAB.

Results

Through MSI, ARV‐dependent, heterogeneous concentrations were observed in different morphological LN regions, such as the follicles and medullary sinuses. After 5–6 weeks of infection, more limited ARV penetration into LN tissue relative to the blood marker heme was found in SHIV+ animals (SHIV+: 0.7 [0.2–1.4] mm; SHIV–: 1.3 [0.5–1.7] mm), suggesting alterations in the microcirculation. However, we found no detectable increase in collagen deposition. Regimen‐wide maps of composite ARV distribution indicated that up to 27% of SHIV+ LN tissue area was not exposed to detectable ARVs. Regions associated with B cell follicles had median 1.15 [0.94–2.69] ‐fold reduction in areas with measurable drug, though differences were only statistically significant for tenofovir (p = 0.03). Median co‐localization of drug with CD4⁺ target cells and vRNA varied widely by ARV (5.1–100%), but nearest neighbour analysis indicated that up to 10% of target cells and cell‐associated vRNA were not directly contiguous to at least one drug at concentrations greater than the IC50 value.

Conclusions

Our investigation of the spatial distributions of drug, virus and target cells underscores the influence of location and microenvironment within LN, where a small population of T cells may remain vulnerable to infection and low‐level viral replication during suppressive ART.

Next-generation Viral RNA/DNA in situ Hybridization Applications in Human Immunodeficiency Virus/Simian Immunodeficiency Virus Research

In situ hybridization is a powerful technique to identify specific RNA or DNA sequences within individual cells in tissue sections, providing important insights into physiological processes and disease pathogenesis. In situ hybridization (ISH) has been used for many years to assess the location of cells infected by viruses, but recently a next-generation ISH approach was developed with a unique probe design strategy that allows simultaneous signal amplification and background suppression to achieve single-molecule visualization while preserving tissue morphology. This next-generation ISH is based on an approach like branched PCR, but performed in situ and is more facile, sensitive, and reproducible than classical ISH methods or in situ PCR approaches in routinely detecting RNA or DNA in formalin-fixed paraffin embedded (FFPE) tissues. For the last several years our laboratory has been applying this ISH platform for the detection of human immunodeficiency (HIV) and simian immunodeficiency (SIV) viral RNA (vRNA) and/or viral DNA (vDNA) positive cells within a multitude of FFPE tissues. With this detailed technical manuscript, we would like to share our knowledge and advice with all individuals interested in using next-generation ISH in their research.

Gammaherpesvirus infection and malignant disease in rhesus macaques experimentally infected with SIV or SHIV

Human gammaherpesviruses are associated with malignancies in HIV infected individuals; in macaques used in non-human primate models of HIV infection, gammaherpesvirus infections also occur. Limited data on prevalence and tumorigenicity of macaque gammaherpesviruses, mostly cross-sectional analyses of small series, are available. We comprehensively examine all three-rhesus macaque gammaherpesviruses -Rhesus rhadinovirus (RRV), Rhesus Lymphocryptovirus (RLCV) and Retroperitoneal Fibromatosis Herpesvirus (RFHV) in macaques experimentally infected with Simian Immunodeficiency Virus or Simian Human Immunodeficiency Virus (SIV/SHIV) in studies spanning 15 years at the AIDS and Cancer Virus Program of the Frederick National Laboratory for Cancer Research. We evaluated 18 animals with malignancies (16 lymphomas, one fibrosarcoma and one carcinoma) and 32 controls. We developed real time quantitative PCR assays for each gammaherpesvirus DNA viral load (VL) in malignant and non-tumor tissues; we also characterized the tumors using immunohistochemistry and in situ hybridization. Furthermore, we retrospectively quantified gammaherpesvirus DNA VL and SIV/SHIV RNA VL in longitudinally-collected PBMCs and plasma, respectively. One or more gammaherpesviruses were detected in 17 tumors; generally, one was predominant, and the relevant DNA VL in the tumor was very high compared to surrounding tissues. RLCV was predominant in tumors resembling diffuse large B cell lymphomas; in a Burkitt-like lymphoma, RRV was predominant; and in the fibrosarcoma, RFHV was predominant. Median RRV and RLCV PBMC DNA VL were significantly higher in cases than controls; SIV/SHIV VL and RLCV VL were independently associated with cancer. Local regressions showed that longitudinal VL patterns in cases and controls, from SIV infection to necropsy, differed for each gammaherpesvirus: while RFHV VL increased only slightly in all animals, RLCV and RRV VL increased significantly and continued to increase steeply in cases; in controls, VL flattened. In conclusion, the data suggest that gammaherpesviruses may play a significant role in tumorogenesis in macaques infected with immunodeficiency viruses.

Splenic abscess complicating infective endocarditis: three case reports

We present three case-reports of splenic abscess in patients who were initially diagnosed with bacterial endocarditis. In all cases the diagnosis of splenic abscess was based on the findings of abdominal CT scan or MRI. All patients were treated by laparotomy and splenectomy. Two patients fully recovered and one patient, who suffered from splenic rupture and massive blood loss before surgery, died. Splenic abscess is a well-described but rare complication of infective endocarditis. Rapid diagnosis and treatment are essential as its course can prove fatal. Abdominal CT scan or MRI should be performed if there is clinical suspicion of splenic abscedation. Immediate splenectomy combined with appropriate antibiotics and valve replacement surgery is the treatment of choice. Splenic tissue is very fragile--especially if the abscess is located subcapsular--and a splenic rupture can result from minimal trauma. If the patient's general state allows it, it is best to perform splenectomy prior to valve replacement surgery to prevent re-infection of the valve prosthesis. A combined one-stage procedure is also an option.

[Fixation of nasogastric tubes in agitated and uncooperative patients]

To prevent extubation, nasogastric tubes (NGT) were attached to a fine bore polyurethane tube, which loops loosely around the nasal septum. In a prospective study 180 cases were evaluated concerning the efficacy and possible complications related to this techniques. On average, a nasal septal loop (NSL) remained 20.1 +/- 1.3 days and a NGT 14 +/- 0.9 days. Complications were rare. In 45 of the cases NGT had to be replaced after self extubation and in 2.2% extubation presented more than twice. We think NSL is an easy and useful technique to secure NGT in non-cooperative and/or agitated patients for a relatively short term enteral nutrition or gastric decompression.

Diagnosis of amoebic infection of the liver: report of 36 cases

The classical clinical picture of amoebic infection of the liver consists of fever, right upper quadrant pain and hepatomegaly. In recent years, the widespread availability of ultrasound and serology made an early diagnosis possible, which could result in less prominent clinical pictures. Thirty six cases of liver amoebiasis diagnosed in Antwerp between 1985 and 1992, were reviewed. Three patients acquired their infection in Belgium. For the other patients, the average delay between arrival in Belgium and the first symptoms was 5.64 months. The classical triad of clinical signs (fever, right upper quadrant pain and hepatomegaly), was observed in only 13.9% of the patients, whereas it was much more frequent in earlier studies (68-75%). The right lobe was the most frequently affected (94%). The colour of the liquid, obtained by puncture, was brown in 61% of patients in whom it was reported. Amoebic cysts were found in the stools of only one patient. Amoebic serology was initially negative in only one patient, but became positive on second testing. Chest X-rays were abnormal in 34% of the patients. All patients who develop unexplained fever during the year after a stay in tropical countries should undergo an abdominal ultrasound examination and serological testing for Entamoeba histolytica.

Multiple cerebral infarctions in a young patient with secondary thrombocythemia due to iron deficiency anemia

A 30-year-old woman developed multiple cerebral infarctions. In the absence of other risk factors, thrombocythemia secondary to iron deficiency anemia due to polymenorrhoea was considered to underlie the cerebral infarctions. Platelet count was normalized after iron therapy. The importance of vigorous treatment of iron deficiency anemia in preventing complications of secondary thrombocythemia is emphasized.

[Anaphylaxis induced by exertion]

A 44-year-old man with a two-year history of episodes of exercise-related urticaria and facial angioedema was admitted to our department because of vascular collapse during an athletic activity. The diagnosis of exercise-induced anaphylaxis was established after excluding other causes of shock. This clinical syndrome was described recently; it consists of urticaria, local angioedema and/or cardiorespiratory failure following exercise. Factors possibly associated with or predisposing to attacks include personal and family histories of atopy, food ingestion and weather conditions. Not every effort evokes these reactions, indicating the presence of other, still unknown variables and therefore complicating the diagnosis because provocation tests often have false-negative results. With reference to this case, the clinical syndrome, its pathophysiology and its treatment are discussed.