Expansion of epidemic dengue viral infections to Pakistan

OBJECTIVES

Antibodies to dengue viruses have occasionally been reported in individuals in Pakistan, but the frequency of occurrence of dengue infection in Pakistan is unclear. The first confirmed dengue hemorrhagic fever outbreak in Pakistan occurred in 1994. In October 1995, the authors investigated an outbreak of a febrile illness among employees of a construction contractor at a power generation plant in Baluchistan, Pakistan, to determine the cause of illness and recommend appropriate preventive measures.

METHODS

The work site and living arrangements were inspected, a questionnaire was administered, and serum samples were collected from all consenting contractor employees and their families if they lived at the camp. Sera were analyzed for IgM against dengue virus, using an enzyme-linked immunosorbent assay.

RESULTS

Interviews were conducted with 76 persons (mean age, 42y); 95% were men. Forty-two persons (55%) reported having experienced fever, headache, or myalgia in the preceding 6 weeks. Fifty-seven subjects (75%) had IgM antibodies against at least one dengue serotype; 45 subjects (59%) had IgM antibodies against dengue serotype 2.

CONCLUSION

This was an outbreak of dengue fever due to multiple serotypes of dengue virus. This confirms that epidemic dengue infection was present in southern Pakistan for 2 consecutive years.

Differential regulation of somatostatin receptor types 1-5 in rat aorta after angioplasty

Treatment of restenosis after angioplasty with octapeptide somatostatin (SST) analogs has met with variable success. These analogs bind with high affinity to only two SST receptor (SSTR) subtypes (2 and 5), display moderate affinity for SSTR3, and low affinity for SSTR1 and 4. To optimize the vasculoprotective effect of SST, we have investigated the pattern of expression of all five SSTRs in rat thoracic aorta in the resting state and at 15 min, 3, 7, and 14 days after balloon endothelial denudation. SSTR1-5 were analyzed as mRNA by semiquantitative reverse transcriptase-polymerase chain reaction and as protein by immunocytochemistry. All five SSTRs were expressed in rat aorta both as mRNA and protein and displayed a time-dependent, subtype-selective response to endothelial denudation. mRNA for SSTR1 and 2 increased acutely (SSTR1 > SSTR2) on days 3 and 7, coincident with smooth muscle cell (SMC) proliferation, and declined to basal levels by day 14. SSTR3 and 4 displayed a different pattern with a delayed, more gradual increase in mRNA beginning at days 3-7 and continued to increase thereafter. SSTR5 mRNA was constitutively expressed at a low level and showed no change during the 2 wk postinjury period. By immunohistochemistry, SSTR1-5 antigens were localized predominantly in SMC that were present in the media or had migrated into the intima; antigen expression correlated with receptor mRNA expression. Notably, only SSTR1,3,4 were expressed in the intima: SSTR1 and 4 during the proliferative burst and SSTR3 and 4 after proliferation, when SMC migration into the intima continues. These results demonstrate dynamic changes in SSTR1-5 expression after vascular trauma localized to areas of vascular SMC migration and replication. In view of their early and prominent induction, SSTR1 may be the optimal subtype to target for inhibition of myointimal proliferation, and SSTR3 and 4 for migration and remodeling.

Clonally expanded, thyrotoxic effector CD8+ T cells driven by IL-21 contribute to checkpoint inhibitor thyroiditis

Autoimmune toxicity occurs in up to 60% of patients treated with immune checkpoint inhibitor (ICI) therapy for cancer and represents an increasing clinical challenge for expanding the use of these treatments. To date, human immunopathogenic studies of immune-related adverse events (IRAEs) have relied on sampling of circulating peripheral blood cells rather than affected tissues. Here, we directly obtained thyroid specimens from individuals with ICI-thyroiditis, one of the most common IRAEs, and compared immune infiltrates with those from individuals with spontaneous autoimmune Hashimoto's thyroiditis (HT) or no thyroid disease. Single-cell RNA sequencing revealed a dominant, clonally expanded population of thyroid-infiltrating cytotoxic CXCR6+ CD8+ T cells (effector CD8+ T cells) present in ICI-thyroiditis but not HT or healthy controls. Furthermore, we identified a crucial role for interleukin-21 (IL-21), a cytokine secreted by intrathyroidal T follicular (TFH) and T peripheral helper (TPH) cells, as a driver of these thyrotoxic effector CD8+ T cells. In the presence of IL-21, human CD8+ T cells acquired the activated effector phenotype with up-regulation of the cytotoxic molecules interferon-γ (IFN-γ) and granzyme B, increased expression of the chemokine receptor CXCR6, and thyrotoxic capacity. We validated these findings in vivo using a mouse model of IRAEs and further demonstrated that genetic deletion of IL-21 signaling protected ICI-treated mice from thyroid immune infiltration. Together, these studies reveal mechanisms and candidate therapeutic targets for individuals who develop IRAEs.

Inhibition of IL-17A Protects against Thyroid Immune-Related Adverse Events while Preserving Checkpoint Inhibitor Antitumor Efficacy

Immune checkpoint inhibitor (ICI) immunotherapy leverages the body's own immune system to attack cancer cells but leads to unwanted autoimmune side effects in up to 60% of patients. Such immune-related adverse events (IrAEs) may lead to treatment interruption, permanent organ dysfunction, hospitalization, and premature death. Thyroiditis is one of the most common IrAEs, but the cause of thyroid IrAEs remains unknown. In this study, we use a new, physiologically relevant mouse model of ICI-associated autoimmunity to identify a key role for type 3 immune cells in the development of thyroid IrAEs. Multiple lineages of IL-17A-producing T cells expand in thyroid tissue with ICI treatment. Intrathyroidal IL-17A-producing innate-like γδT17 cells were increased in tumor-free mice, whereas adaptive Th17 cells were also prominent in tumor-bearing mice, following ICI treatment. Furthermore, Ab-based inhibition of IL-17A, a clinically available therapy, significantly reduced thyroid IrAE development in ICI-treated mice with and without tumor challenge. Finally, combination of IL-17A neutralization with ICI treatment in multiple tumor models did not reduce ICI antitumor efficacy. These studies suggest that targeting Th17 and γδT17 cell function via the IL-17A axis may reduce IrAEs without impairing ICI antitumor efficacy and may be a generalizable strategy to address type 3 immune-mediated IrAEs.

Role of ataxia telangiectasia mutated in insulin signalling of muscle-derived cell lines and mouse soleus

AIM

Ataxia telangiectasia mutated (ATM) reportedly plays a role in insulin-stimulated activation of Akt in some cell types but not in others. The role of ATM in insulin signalling has not been firmly resolved for skeletal muscle cells, for which Akt phosphorylation is a pivotal step in stimulation of glucose transport. Accordingly, our aim was to determine the role of ATM in insulin effects for cell lines derived from skeletal muscle and for skeletal muscle.

METHODS

We examined insulin effects in L6 myotubes, mouse soleus, C2C12 myotubes and differentiated rhabdomyosarcoma (RD) cells in the presence and absence of a low concentration (1 microm) of the ATM inhibitor KU55933. We also compared insulin signalling in C2C12 cells expressing shRNA against ATM and control cell lines (empty vector; cells expressing non-targeting shRNA).

RESULTS

In L6 myotubes and mouse soleus muscle, KU55933 inhibited insulin-stimulated phosphorylation of the 160 kDa substrate of Akt (AS160) despite no effect on Akt. In contrast, KU55933 prevented insulin-stimulated Akt phosphorylation in C2C12 myotubes. Furthermore, C2C12 myotubes expressing shRNA against ATM displayed reduced insulin-stimulated Akt phosphorylation compared to controls. KU55933 also decreased insulin-stimulated Akt phosphorylation in differentiated RD cells.

CONCLUSION

These model-dependent differences in the role of ATM in insulin action demonstrate a role of ATM in insulin-stimulated phosphorylation of Akt (in C2C12 and RD cells) but also allow the elucidation of a novel, Akt-independent role of ATM (in L6 myotubes and mouse soleus, at the level of AS160) in insulin signalling.